linux/fs/fscache/page.c

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FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/* Cache page management and data I/O routines
*
* Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL PAGE
#include <linux/module.h>
#include <linux/fscache-cache.h>
#include <linux/buffer_head.h>
#include <linux/pagevec.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 09:04:11 +01:00
#include <linux/slab.h>
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
#include "internal.h"
/*
* check to see if a page is being written to the cache
*/
bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page)
{
void *val;
rcu_read_lock();
val = radix_tree_lookup(&cookie->stores, page->index);
rcu_read_unlock();
return val != NULL;
}
EXPORT_SYMBOL(__fscache_check_page_write);
/*
* wait for a page to finish being written to the cache
*/
void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page)
{
wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
wait_event(*wq, !__fscache_check_page_write(cookie, page));
}
EXPORT_SYMBOL(__fscache_wait_on_page_write);
FS-Cache: Handle pages pending storage that get evicted under OOM conditions Handle netfs pages that the vmscan algorithm wants to evict from the pagecache under OOM conditions, but that are waiting for write to the cache. Under these conditions, vmscan calls the releasepage() function of the netfs, asking if a page can be discarded. The problem is typified by the following trace of a stuck process: kslowd005 D 0000000000000000 0 4253 2 0x00000080 ffff88001b14f370 0000000000000046 ffff880020d0d000 0000000000000007 0000000000000006 0000000000000001 ffff88001b14ffd8 ffff880020d0d2a8 000000000000ddf0 00000000000118c0 00000000000118c0 ffff880020d0d2a8 Call Trace: [<ffffffffa00782d8>] __fscache_wait_on_page_write+0x8b/0xa7 [fscache] [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffffa0078240>] ? __fscache_check_page_write+0x63/0x70 [fscache] [<ffffffffa00b671d>] nfs_fscache_release_page+0x4e/0xc4 [nfs] [<ffffffffa00927f0>] nfs_release_page+0x3c/0x41 [nfs] [<ffffffff810885d3>] try_to_release_page+0x32/0x3b [<ffffffff81093203>] shrink_page_list+0x316/0x4ac [<ffffffff8109372b>] shrink_inactive_list+0x392/0x67c [<ffffffff813532fa>] ? __mutex_unlock_slowpath+0x100/0x10b [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130 [<ffffffff8135330e>] ? mutex_unlock+0x9/0xb [<ffffffff81093aa2>] shrink_list+0x8d/0x8f [<ffffffff81093d1c>] shrink_zone+0x278/0x33c [<ffffffff81052d6c>] ? ktime_get_ts+0xad/0xba [<ffffffff81094b13>] try_to_free_pages+0x22e/0x392 [<ffffffff81091e24>] ? isolate_pages_global+0x0/0x212 [<ffffffff8108e743>] __alloc_pages_nodemask+0x3dc/0x5cf [<ffffffff81089529>] grab_cache_page_write_begin+0x65/0xaa [<ffffffff8110f8c0>] ext3_write_begin+0x78/0x1eb [<ffffffff81089ec5>] generic_file_buffered_write+0x109/0x28c [<ffffffff8103cb69>] ? current_fs_time+0x22/0x29 [<ffffffff8108a509>] __generic_file_aio_write+0x350/0x385 [<ffffffff8108a588>] ? generic_file_aio_write+0x4a/0xae [<ffffffff8108a59e>] generic_file_aio_write+0x60/0xae [<ffffffff810b2e82>] do_sync_write+0xe3/0x120 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810b18e1>] ? __dentry_open+0x1a5/0x2b8 [<ffffffff810b1a76>] ? dentry_open+0x82/0x89 [<ffffffffa00e693c>] cachefiles_write_page+0x298/0x335 [cachefiles] [<ffffffffa0077147>] fscache_write_op+0x178/0x2c2 [fscache] [<ffffffffa0075656>] fscache_op_execute+0x7a/0xd1 [fscache] [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308 [<ffffffff8104be91>] kthread+0x7a/0x82 [<ffffffff8100beda>] child_rip+0xa/0x20 [<ffffffff8100b87c>] ? restore_args+0x0/0x30 [<ffffffff8102ef83>] ? tg_shares_up+0x171/0x227 [<ffffffff8104be17>] ? kthread+0x0/0x82 [<ffffffff8100bed0>] ? child_rip+0x0/0x20 In the above backtrace, the following is happening: (1) A page storage operation is being executed by a slow-work thread (fscache_write_op()). (2) FS-Cache farms the operation out to the cache to perform (cachefiles_write_page()). (3) CacheFiles is then calling Ext3 to perform the actual write, using Ext3's standard write (do_sync_write()) under KERNEL_DS directly from the netfs page. (4) However, for Ext3 to perform the write, it must allocate some memory, in particular, it must allocate at least one page cache page into which it can copy the data from the netfs page. (5) Under OOM conditions, the memory allocator can't immediately come up with a page, so it uses vmscan to find something to discard (try_to_free_pages()). (6) vmscan finds a clean netfs page it might be able to discard (possibly the one it's trying to write out). (7) The netfs is called to throw the page away (nfs_release_page()) - but it's called with __GFP_WAIT, so the netfs decides to wait for the store to complete (__fscache_wait_on_page_write()). (8) This blocks a slow-work processing thread - possibly against itself. The system ends up stuck because it can't write out any netfs pages to the cache without allocating more memory. To avoid this, we make FS-Cache cancel some writes that aren't in the middle of actually being performed. This means that some data won't make it into the cache this time. To support this, a new FS-Cache function is added fscache_maybe_release_page() that replaces what the netfs releasepage() functions used to do with respect to the cache. The decisions fscache_maybe_release_page() makes are counted and displayed through /proc/fs/fscache/stats on a line labelled "VmScan". There are four counters provided: "nos=N" - pages that weren't pending storage; "gon=N" - pages that were pending storage when we first looked, but weren't by the time we got the object lock; "bsy=N" - pages that we ignored as they were actively being written when we looked; and "can=N" - pages that we cancelled the storage of. What I'd really like to do is alter the behaviour of the cancellation heuristics, depending on how necessary it is to expel pages. If there are plenty of other pages that aren't waiting to be written to the cache that could be ejected first, then it would be nice to hold up on immediate cancellation of cache writes - but I don't see a way of doing that. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:35 +01:00
/*
* decide whether a page can be released, possibly by cancelling a store to it
* - we're allowed to sleep if __GFP_WAIT is flagged
*/
bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
struct page *xpage;
void *val;
_enter("%p,%p,%x", cookie, page, gfp);
NFS: nfs_migrate_page() does not wait for FS-Cache to finish with a page nfs_migrate_page() does not wait for FS-Cache to finish with a page, probably leading to the following bad-page-state: BUG: Bad page state in process python-bin pfn:17d39b page:ffffea00053649e8 flags:004000000000100c count:0 mapcount:0 mapping:(null) index:38686 (Tainted: G B ---------------- ) Pid: 31053, comm: python-bin Tainted: G B ---------------- 2.6.32-71.24.1.el6.x86_64 #1 Call Trace: [<ffffffff8111bfe7>] bad_page+0x107/0x160 [<ffffffff8111ee69>] free_hot_cold_page+0x1c9/0x220 [<ffffffff8111ef19>] __pagevec_free+0x59/0xb0 [<ffffffff8104b988>] ? flush_tlb_others_ipi+0x128/0x130 [<ffffffff8112230c>] release_pages+0x21c/0x250 [<ffffffff8115b92a>] ? remove_migration_pte+0x28a/0x2b0 [<ffffffff8115f3f8>] ? mem_cgroup_get_reclaim_stat_from_page+0x18/0x70 [<ffffffff81122687>] ____pagevec_lru_add+0x167/0x180 [<ffffffff811226f8>] __lru_cache_add+0x58/0x70 [<ffffffff81122731>] lru_cache_add_lru+0x21/0x40 [<ffffffff81123f49>] putback_lru_page+0x69/0x100 [<ffffffff8115c0bd>] migrate_pages+0x13d/0x5d0 [<ffffffff81122687>] ? ____pagevec_lru_add+0x167/0x180 [<ffffffff81152ab0>] ? compaction_alloc+0x0/0x370 [<ffffffff8115255c>] compact_zone+0x4cc/0x600 [<ffffffff8111cfac>] ? get_page_from_freelist+0x15c/0x820 [<ffffffff810672f4>] ? check_preempt_wakeup+0x1c4/0x3c0 [<ffffffff8115290e>] compact_zone_order+0x7e/0xb0 [<ffffffff81152a49>] try_to_compact_pages+0x109/0x170 [<ffffffff8111e94d>] __alloc_pages_nodemask+0x5ed/0x850 [<ffffffff814c9136>] ? thread_return+0x4e/0x778 [<ffffffff81150d43>] alloc_pages_vma+0x93/0x150 [<ffffffff81167ea5>] do_huge_pmd_anonymous_page+0x135/0x340 [<ffffffff814cb6f6>] ? rwsem_down_read_failed+0x26/0x30 [<ffffffff81136755>] handle_mm_fault+0x245/0x2b0 [<ffffffff814ce383>] do_page_fault+0x123/0x3a0 [<ffffffff814cbdf5>] page_fault+0x25/0x30 nfs_migrate_page() calls nfs_fscache_release_page() which doesn't actually wait - even if __GFP_WAIT is set. The reason that doesn't wait is that fscache_maybe_release_page() might deadlock the allocator as the work threads writing to the cache may all end up sleeping on memory allocation. However, I wonder if that is actually a problem. There are a number of things I can do to deal with this: (1) Make nfs_migrate_page() wait. (2) Make fscache_maybe_release_page() honour the __GFP_WAIT flag. (3) Set a timeout around the wait. (4) Make nfs_migrate_page() return an error if the page is still busy. For the moment, I'll select (2) and (4). Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2012-12-05 14:34:49 +01:00
try_again:
FS-Cache: Handle pages pending storage that get evicted under OOM conditions Handle netfs pages that the vmscan algorithm wants to evict from the pagecache under OOM conditions, but that are waiting for write to the cache. Under these conditions, vmscan calls the releasepage() function of the netfs, asking if a page can be discarded. The problem is typified by the following trace of a stuck process: kslowd005 D 0000000000000000 0 4253 2 0x00000080 ffff88001b14f370 0000000000000046 ffff880020d0d000 0000000000000007 0000000000000006 0000000000000001 ffff88001b14ffd8 ffff880020d0d2a8 000000000000ddf0 00000000000118c0 00000000000118c0 ffff880020d0d2a8 Call Trace: [<ffffffffa00782d8>] __fscache_wait_on_page_write+0x8b/0xa7 [fscache] [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffffa0078240>] ? __fscache_check_page_write+0x63/0x70 [fscache] [<ffffffffa00b671d>] nfs_fscache_release_page+0x4e/0xc4 [nfs] [<ffffffffa00927f0>] nfs_release_page+0x3c/0x41 [nfs] [<ffffffff810885d3>] try_to_release_page+0x32/0x3b [<ffffffff81093203>] shrink_page_list+0x316/0x4ac [<ffffffff8109372b>] shrink_inactive_list+0x392/0x67c [<ffffffff813532fa>] ? __mutex_unlock_slowpath+0x100/0x10b [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130 [<ffffffff8135330e>] ? mutex_unlock+0x9/0xb [<ffffffff81093aa2>] shrink_list+0x8d/0x8f [<ffffffff81093d1c>] shrink_zone+0x278/0x33c [<ffffffff81052d6c>] ? ktime_get_ts+0xad/0xba [<ffffffff81094b13>] try_to_free_pages+0x22e/0x392 [<ffffffff81091e24>] ? isolate_pages_global+0x0/0x212 [<ffffffff8108e743>] __alloc_pages_nodemask+0x3dc/0x5cf [<ffffffff81089529>] grab_cache_page_write_begin+0x65/0xaa [<ffffffff8110f8c0>] ext3_write_begin+0x78/0x1eb [<ffffffff81089ec5>] generic_file_buffered_write+0x109/0x28c [<ffffffff8103cb69>] ? current_fs_time+0x22/0x29 [<ffffffff8108a509>] __generic_file_aio_write+0x350/0x385 [<ffffffff8108a588>] ? generic_file_aio_write+0x4a/0xae [<ffffffff8108a59e>] generic_file_aio_write+0x60/0xae [<ffffffff810b2e82>] do_sync_write+0xe3/0x120 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810b18e1>] ? __dentry_open+0x1a5/0x2b8 [<ffffffff810b1a76>] ? dentry_open+0x82/0x89 [<ffffffffa00e693c>] cachefiles_write_page+0x298/0x335 [cachefiles] [<ffffffffa0077147>] fscache_write_op+0x178/0x2c2 [fscache] [<ffffffffa0075656>] fscache_op_execute+0x7a/0xd1 [fscache] [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308 [<ffffffff8104be91>] kthread+0x7a/0x82 [<ffffffff8100beda>] child_rip+0xa/0x20 [<ffffffff8100b87c>] ? restore_args+0x0/0x30 [<ffffffff8102ef83>] ? tg_shares_up+0x171/0x227 [<ffffffff8104be17>] ? kthread+0x0/0x82 [<ffffffff8100bed0>] ? child_rip+0x0/0x20 In the above backtrace, the following is happening: (1) A page storage operation is being executed by a slow-work thread (fscache_write_op()). (2) FS-Cache farms the operation out to the cache to perform (cachefiles_write_page()). (3) CacheFiles is then calling Ext3 to perform the actual write, using Ext3's standard write (do_sync_write()) under KERNEL_DS directly from the netfs page. (4) However, for Ext3 to perform the write, it must allocate some memory, in particular, it must allocate at least one page cache page into which it can copy the data from the netfs page. (5) Under OOM conditions, the memory allocator can't immediately come up with a page, so it uses vmscan to find something to discard (try_to_free_pages()). (6) vmscan finds a clean netfs page it might be able to discard (possibly the one it's trying to write out). (7) The netfs is called to throw the page away (nfs_release_page()) - but it's called with __GFP_WAIT, so the netfs decides to wait for the store to complete (__fscache_wait_on_page_write()). (8) This blocks a slow-work processing thread - possibly against itself. The system ends up stuck because it can't write out any netfs pages to the cache without allocating more memory. To avoid this, we make FS-Cache cancel some writes that aren't in the middle of actually being performed. This means that some data won't make it into the cache this time. To support this, a new FS-Cache function is added fscache_maybe_release_page() that replaces what the netfs releasepage() functions used to do with respect to the cache. The decisions fscache_maybe_release_page() makes are counted and displayed through /proc/fs/fscache/stats on a line labelled "VmScan". There are four counters provided: "nos=N" - pages that weren't pending storage; "gon=N" - pages that were pending storage when we first looked, but weren't by the time we got the object lock; "bsy=N" - pages that we ignored as they were actively being written when we looked; and "can=N" - pages that we cancelled the storage of. What I'd really like to do is alter the behaviour of the cancellation heuristics, depending on how necessary it is to expel pages. If there are plenty of other pages that aren't waiting to be written to the cache that could be ejected first, then it would be nice to hold up on immediate cancellation of cache writes - but I don't see a way of doing that. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:35 +01:00
rcu_read_lock();
val = radix_tree_lookup(&cookie->stores, page->index);
if (!val) {
rcu_read_unlock();
fscache_stat(&fscache_n_store_vmscan_not_storing);
__fscache_uncache_page(cookie, page);
return true;
}
/* see if the page is actually undergoing storage - if so we can't get
* rid of it till the cache has finished with it */
if (radix_tree_tag_get(&cookie->stores, page->index,
FSCACHE_COOKIE_STORING_TAG)) {
rcu_read_unlock();
goto page_busy;
}
/* the page is pending storage, so we attempt to cancel the store and
* discard the store request so that the page can be reclaimed */
spin_lock(&cookie->stores_lock);
rcu_read_unlock();
if (radix_tree_tag_get(&cookie->stores, page->index,
FSCACHE_COOKIE_STORING_TAG)) {
/* the page started to undergo storage whilst we were looking,
* so now we can only wait or return */
spin_unlock(&cookie->stores_lock);
goto page_busy;
}
xpage = radix_tree_delete(&cookie->stores, page->index);
spin_unlock(&cookie->stores_lock);
if (xpage) {
fscache_stat(&fscache_n_store_vmscan_cancelled);
fscache_stat(&fscache_n_store_radix_deletes);
ASSERTCMP(xpage, ==, page);
} else {
fscache_stat(&fscache_n_store_vmscan_gone);
}
wake_up_bit(&cookie->flags, 0);
if (xpage)
page_cache_release(xpage);
__fscache_uncache_page(cookie, page);
return true;
page_busy:
NFS: nfs_migrate_page() does not wait for FS-Cache to finish with a page nfs_migrate_page() does not wait for FS-Cache to finish with a page, probably leading to the following bad-page-state: BUG: Bad page state in process python-bin pfn:17d39b page:ffffea00053649e8 flags:004000000000100c count:0 mapcount:0 mapping:(null) index:38686 (Tainted: G B ---------------- ) Pid: 31053, comm: python-bin Tainted: G B ---------------- 2.6.32-71.24.1.el6.x86_64 #1 Call Trace: [<ffffffff8111bfe7>] bad_page+0x107/0x160 [<ffffffff8111ee69>] free_hot_cold_page+0x1c9/0x220 [<ffffffff8111ef19>] __pagevec_free+0x59/0xb0 [<ffffffff8104b988>] ? flush_tlb_others_ipi+0x128/0x130 [<ffffffff8112230c>] release_pages+0x21c/0x250 [<ffffffff8115b92a>] ? remove_migration_pte+0x28a/0x2b0 [<ffffffff8115f3f8>] ? mem_cgroup_get_reclaim_stat_from_page+0x18/0x70 [<ffffffff81122687>] ____pagevec_lru_add+0x167/0x180 [<ffffffff811226f8>] __lru_cache_add+0x58/0x70 [<ffffffff81122731>] lru_cache_add_lru+0x21/0x40 [<ffffffff81123f49>] putback_lru_page+0x69/0x100 [<ffffffff8115c0bd>] migrate_pages+0x13d/0x5d0 [<ffffffff81122687>] ? ____pagevec_lru_add+0x167/0x180 [<ffffffff81152ab0>] ? compaction_alloc+0x0/0x370 [<ffffffff8115255c>] compact_zone+0x4cc/0x600 [<ffffffff8111cfac>] ? get_page_from_freelist+0x15c/0x820 [<ffffffff810672f4>] ? check_preempt_wakeup+0x1c4/0x3c0 [<ffffffff8115290e>] compact_zone_order+0x7e/0xb0 [<ffffffff81152a49>] try_to_compact_pages+0x109/0x170 [<ffffffff8111e94d>] __alloc_pages_nodemask+0x5ed/0x850 [<ffffffff814c9136>] ? thread_return+0x4e/0x778 [<ffffffff81150d43>] alloc_pages_vma+0x93/0x150 [<ffffffff81167ea5>] do_huge_pmd_anonymous_page+0x135/0x340 [<ffffffff814cb6f6>] ? rwsem_down_read_failed+0x26/0x30 [<ffffffff81136755>] handle_mm_fault+0x245/0x2b0 [<ffffffff814ce383>] do_page_fault+0x123/0x3a0 [<ffffffff814cbdf5>] page_fault+0x25/0x30 nfs_migrate_page() calls nfs_fscache_release_page() which doesn't actually wait - even if __GFP_WAIT is set. The reason that doesn't wait is that fscache_maybe_release_page() might deadlock the allocator as the work threads writing to the cache may all end up sleeping on memory allocation. However, I wonder if that is actually a problem. There are a number of things I can do to deal with this: (1) Make nfs_migrate_page() wait. (2) Make fscache_maybe_release_page() honour the __GFP_WAIT flag. (3) Set a timeout around the wait. (4) Make nfs_migrate_page() return an error if the page is still busy. For the moment, I'll select (2) and (4). Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2012-12-05 14:34:49 +01:00
/* We will wait here if we're allowed to, but that could deadlock the
* allocator as the work threads writing to the cache may all end up
* sleeping on memory allocation, so we may need to impose a timeout
* too. */
FS-Cache: Don't sleep in page release if __GFP_FS is not set Don't sleep in __fscache_maybe_release_page() if __GFP_FS is not set. This goes some way towards mitigating fscache deadlocking against ext4 by way of the allocator, eg: INFO: task flush-8:0:24427 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. flush-8:0 D ffff88003e2b9fd8 0 24427 2 0x00000000 ffff88003e2b9138 0000000000000046 ffff880012e3a040 ffff88003e2b9fd8 0000000000011c80 ffff88003e2b9fd8 ffffffff81a10400 ffff880012e3a040 0000000000000002 ffff880012e3a040 ffff88003e2b9098 ffffffff8106dcf5 Call Trace: [<ffffffff8106dcf5>] ? __lock_is_held+0x31/0x53 [<ffffffff81219b61>] ? radix_tree_lookup_element+0xf4/0x12a [<ffffffff81454bed>] schedule+0x60/0x62 [<ffffffffa01d349c>] __fscache_wait_on_page_write+0x8b/0xa5 [fscache] [<ffffffff810498a8>] ? __init_waitqueue_head+0x4d/0x4d [<ffffffffa01d393a>] __fscache_maybe_release_page+0x30c/0x324 [fscache] [<ffffffffa01d369a>] ? __fscache_maybe_release_page+0x6c/0x324 [fscache] [<ffffffff81071b53>] ? trace_hardirqs_on_caller+0x114/0x170 [<ffffffffa01fd7b2>] nfs_fscache_release_page+0x68/0x94 [nfs] [<ffffffffa01ef73e>] nfs_release_page+0x7e/0x86 [nfs] [<ffffffff810aa553>] try_to_release_page+0x32/0x3b [<ffffffff810b6c70>] shrink_page_list+0x535/0x71a [<ffffffff81071b53>] ? trace_hardirqs_on_caller+0x114/0x170 [<ffffffff810b7352>] shrink_inactive_list+0x20a/0x2dd [<ffffffff81071a13>] ? mark_held_locks+0xbe/0xea [<ffffffff810b7a65>] shrink_lruvec+0x34c/0x3eb [<ffffffff810b7bd3>] do_try_to_free_pages+0xcf/0x355 [<ffffffff810b7fc8>] try_to_free_pages+0x9a/0xa1 [<ffffffff810b08d2>] __alloc_pages_nodemask+0x494/0x6f7 [<ffffffff810d9a07>] kmem_getpages+0x58/0x155 [<ffffffff810dc002>] fallback_alloc+0x120/0x1f3 [<ffffffff8106db23>] ? trace_hardirqs_off+0xd/0xf [<ffffffff810dbed3>] ____cache_alloc_node+0x177/0x186 [<ffffffff81162a6c>] ? ext4_init_io_end+0x1c/0x37 [<ffffffff810dc403>] kmem_cache_alloc+0xf1/0x176 [<ffffffff810b17ac>] ? test_set_page_writeback+0x101/0x113 [<ffffffff81162a6c>] ext4_init_io_end+0x1c/0x37 [<ffffffff81162ce4>] ext4_bio_write_page+0x20f/0x3af [<ffffffff8115cc02>] mpage_da_submit_io+0x26e/0x2f6 [<ffffffff811088e5>] ? __find_get_block_slow+0x38/0x133 [<ffffffff81161348>] mpage_da_map_and_submit+0x3a7/0x3bd [<ffffffff81161a60>] ext4_da_writepages+0x30d/0x426 [<ffffffff810b3359>] do_writepages+0x1c/0x2a [<ffffffff81102f4d>] __writeback_single_inode+0x3e/0xe5 [<ffffffff81103995>] writeback_sb_inodes+0x1bd/0x2f4 [<ffffffff81103b3b>] __writeback_inodes_wb+0x6f/0xb4 [<ffffffff81103c81>] wb_writeback+0x101/0x195 [<ffffffff81071b53>] ? trace_hardirqs_on_caller+0x114/0x170 [<ffffffff811043aa>] ? wb_do_writeback+0xaa/0x173 [<ffffffff8110434a>] wb_do_writeback+0x4a/0x173 [<ffffffff81071bbc>] ? trace_hardirqs_on+0xd/0xf [<ffffffff81038554>] ? del_timer+0x4b/0x5b [<ffffffff811044e0>] bdi_writeback_thread+0x6d/0x147 [<ffffffff81104473>] ? wb_do_writeback+0x173/0x173 [<ffffffff81048fbc>] kthread+0xd0/0xd8 [<ffffffff81455eb2>] ? _raw_spin_unlock_irq+0x29/0x3e [<ffffffff81048eec>] ? __init_kthread_worker+0x55/0x55 [<ffffffff81456aac>] ret_from_fork+0x7c/0xb0 [<ffffffff81048eec>] ? __init_kthread_worker+0x55/0x55 2 locks held by flush-8:0/24427: #0: (&type->s_umount_key#41){.+.+..}, at: [<ffffffff810e3b73>] grab_super_passive+0x4c/0x76 #1: (jbd2_handle){+.+...}, at: [<ffffffff81190d81>] start_this_handle+0x475/0x4ea The problem here is that another thread, which is attempting to write the to-be-stored NFS page to the on-ext4 cache file is waiting for the journal lock, eg: INFO: task kworker/u:2:24437 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u:2 D ffff880039589768 0 24437 2 0x00000000 ffff8800395896d8 0000000000000046 ffff8800283bf040 ffff880039589fd8 0000000000011c80 ffff880039589fd8 ffff880039f0b040 ffff8800283bf040 0000000000000006 ffff8800283bf6b8 ffff880039589658 ffffffff81071a13 Call Trace: [<ffffffff81071a13>] ? mark_held_locks+0xbe/0xea [<ffffffff81455e73>] ? _raw_spin_unlock_irqrestore+0x3a/0x50 [<ffffffff81071b53>] ? trace_hardirqs_on_caller+0x114/0x170 [<ffffffff81071bbc>] ? trace_hardirqs_on+0xd/0xf [<ffffffff81454bed>] schedule+0x60/0x62 [<ffffffff81190c23>] start_this_handle+0x317/0x4ea [<ffffffff810498a8>] ? __init_waitqueue_head+0x4d/0x4d [<ffffffff81190fcc>] jbd2__journal_start+0xb3/0x12e [<ffffffff81176606>] __ext4_journal_start_sb+0xb2/0xc6 [<ffffffff8115f137>] ext4_da_write_begin+0x109/0x233 [<ffffffff810a964d>] generic_file_buffered_write+0x11a/0x264 [<ffffffff811032cf>] ? __mark_inode_dirty+0x2d/0x1ee [<ffffffff810ab1ab>] __generic_file_aio_write+0x2a5/0x2d5 [<ffffffff810ab24a>] generic_file_aio_write+0x6f/0xd0 [<ffffffff81159a2c>] ext4_file_write+0x38c/0x3c4 [<ffffffff810e0915>] do_sync_write+0x91/0xd1 [<ffffffffa00a17f0>] cachefiles_write_page+0x26f/0x310 [cachefiles] [<ffffffffa01d470b>] fscache_write_op+0x21e/0x37a [fscache] [<ffffffff81455eb2>] ? _raw_spin_unlock_irq+0x29/0x3e [<ffffffffa01d2479>] fscache_op_work_func+0x78/0xd7 [fscache] [<ffffffff8104455a>] process_one_work+0x232/0x3a8 [<ffffffff810444ff>] ? process_one_work+0x1d7/0x3a8 [<ffffffff81044ee0>] worker_thread+0x214/0x303 [<ffffffff81044ccc>] ? manage_workers+0x245/0x245 [<ffffffff81048fbc>] kthread+0xd0/0xd8 [<ffffffff81455eb2>] ? _raw_spin_unlock_irq+0x29/0x3e [<ffffffff81048eec>] ? __init_kthread_worker+0x55/0x55 [<ffffffff81456aac>] ret_from_fork+0x7c/0xb0 [<ffffffff81048eec>] ? __init_kthread_worker+0x55/0x55 4 locks held by kworker/u:2/24437: #0: (fscache_operation){.+.+.+}, at: [<ffffffff810444ff>] process_one_work+0x1d7/0x3a8 #1: ((&op->work)){+.+.+.}, at: [<ffffffff810444ff>] process_one_work+0x1d7/0x3a8 #2: (sb_writers#14){.+.+.+}, at: [<ffffffff810ab22c>] generic_file_aio_write+0x51/0xd0 #3: (&sb->s_type->i_mutex_key#19){+.+.+.}, at: [<ffffffff810ab236>] generic_file_aio_write+0x5b/0x fscache already tries to cancel pending stores, but it can't cancel a write for which I/O is already in progress. An alternative would be to accept writing garbage to the cache under extreme circumstances and to kill the afflicted cache object if we have to do this. However, we really need to know how strapped the allocator is before deciding to do that. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:25 +02:00
if (!(gfp & __GFP_WAIT) || !(gfp & __GFP_FS)) {
NFS: nfs_migrate_page() does not wait for FS-Cache to finish with a page nfs_migrate_page() does not wait for FS-Cache to finish with a page, probably leading to the following bad-page-state: BUG: Bad page state in process python-bin pfn:17d39b page:ffffea00053649e8 flags:004000000000100c count:0 mapcount:0 mapping:(null) index:38686 (Tainted: G B ---------------- ) Pid: 31053, comm: python-bin Tainted: G B ---------------- 2.6.32-71.24.1.el6.x86_64 #1 Call Trace: [<ffffffff8111bfe7>] bad_page+0x107/0x160 [<ffffffff8111ee69>] free_hot_cold_page+0x1c9/0x220 [<ffffffff8111ef19>] __pagevec_free+0x59/0xb0 [<ffffffff8104b988>] ? flush_tlb_others_ipi+0x128/0x130 [<ffffffff8112230c>] release_pages+0x21c/0x250 [<ffffffff8115b92a>] ? remove_migration_pte+0x28a/0x2b0 [<ffffffff8115f3f8>] ? mem_cgroup_get_reclaim_stat_from_page+0x18/0x70 [<ffffffff81122687>] ____pagevec_lru_add+0x167/0x180 [<ffffffff811226f8>] __lru_cache_add+0x58/0x70 [<ffffffff81122731>] lru_cache_add_lru+0x21/0x40 [<ffffffff81123f49>] putback_lru_page+0x69/0x100 [<ffffffff8115c0bd>] migrate_pages+0x13d/0x5d0 [<ffffffff81122687>] ? ____pagevec_lru_add+0x167/0x180 [<ffffffff81152ab0>] ? compaction_alloc+0x0/0x370 [<ffffffff8115255c>] compact_zone+0x4cc/0x600 [<ffffffff8111cfac>] ? get_page_from_freelist+0x15c/0x820 [<ffffffff810672f4>] ? check_preempt_wakeup+0x1c4/0x3c0 [<ffffffff8115290e>] compact_zone_order+0x7e/0xb0 [<ffffffff81152a49>] try_to_compact_pages+0x109/0x170 [<ffffffff8111e94d>] __alloc_pages_nodemask+0x5ed/0x850 [<ffffffff814c9136>] ? thread_return+0x4e/0x778 [<ffffffff81150d43>] alloc_pages_vma+0x93/0x150 [<ffffffff81167ea5>] do_huge_pmd_anonymous_page+0x135/0x340 [<ffffffff814cb6f6>] ? rwsem_down_read_failed+0x26/0x30 [<ffffffff81136755>] handle_mm_fault+0x245/0x2b0 [<ffffffff814ce383>] do_page_fault+0x123/0x3a0 [<ffffffff814cbdf5>] page_fault+0x25/0x30 nfs_migrate_page() calls nfs_fscache_release_page() which doesn't actually wait - even if __GFP_WAIT is set. The reason that doesn't wait is that fscache_maybe_release_page() might deadlock the allocator as the work threads writing to the cache may all end up sleeping on memory allocation. However, I wonder if that is actually a problem. There are a number of things I can do to deal with this: (1) Make nfs_migrate_page() wait. (2) Make fscache_maybe_release_page() honour the __GFP_WAIT flag. (3) Set a timeout around the wait. (4) Make nfs_migrate_page() return an error if the page is still busy. For the moment, I'll select (2) and (4). Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2012-12-05 14:34:49 +01:00
fscache_stat(&fscache_n_store_vmscan_busy);
return false;
}
fscache_stat(&fscache_n_store_vmscan_wait);
__fscache_wait_on_page_write(cookie, page);
gfp &= ~__GFP_WAIT;
goto try_again;
FS-Cache: Handle pages pending storage that get evicted under OOM conditions Handle netfs pages that the vmscan algorithm wants to evict from the pagecache under OOM conditions, but that are waiting for write to the cache. Under these conditions, vmscan calls the releasepage() function of the netfs, asking if a page can be discarded. The problem is typified by the following trace of a stuck process: kslowd005 D 0000000000000000 0 4253 2 0x00000080 ffff88001b14f370 0000000000000046 ffff880020d0d000 0000000000000007 0000000000000006 0000000000000001 ffff88001b14ffd8 ffff880020d0d2a8 000000000000ddf0 00000000000118c0 00000000000118c0 ffff880020d0d2a8 Call Trace: [<ffffffffa00782d8>] __fscache_wait_on_page_write+0x8b/0xa7 [fscache] [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffffa0078240>] ? __fscache_check_page_write+0x63/0x70 [fscache] [<ffffffffa00b671d>] nfs_fscache_release_page+0x4e/0xc4 [nfs] [<ffffffffa00927f0>] nfs_release_page+0x3c/0x41 [nfs] [<ffffffff810885d3>] try_to_release_page+0x32/0x3b [<ffffffff81093203>] shrink_page_list+0x316/0x4ac [<ffffffff8109372b>] shrink_inactive_list+0x392/0x67c [<ffffffff813532fa>] ? __mutex_unlock_slowpath+0x100/0x10b [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130 [<ffffffff8135330e>] ? mutex_unlock+0x9/0xb [<ffffffff81093aa2>] shrink_list+0x8d/0x8f [<ffffffff81093d1c>] shrink_zone+0x278/0x33c [<ffffffff81052d6c>] ? ktime_get_ts+0xad/0xba [<ffffffff81094b13>] try_to_free_pages+0x22e/0x392 [<ffffffff81091e24>] ? isolate_pages_global+0x0/0x212 [<ffffffff8108e743>] __alloc_pages_nodemask+0x3dc/0x5cf [<ffffffff81089529>] grab_cache_page_write_begin+0x65/0xaa [<ffffffff8110f8c0>] ext3_write_begin+0x78/0x1eb [<ffffffff81089ec5>] generic_file_buffered_write+0x109/0x28c [<ffffffff8103cb69>] ? current_fs_time+0x22/0x29 [<ffffffff8108a509>] __generic_file_aio_write+0x350/0x385 [<ffffffff8108a588>] ? generic_file_aio_write+0x4a/0xae [<ffffffff8108a59e>] generic_file_aio_write+0x60/0xae [<ffffffff810b2e82>] do_sync_write+0xe3/0x120 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810b18e1>] ? __dentry_open+0x1a5/0x2b8 [<ffffffff810b1a76>] ? dentry_open+0x82/0x89 [<ffffffffa00e693c>] cachefiles_write_page+0x298/0x335 [cachefiles] [<ffffffffa0077147>] fscache_write_op+0x178/0x2c2 [fscache] [<ffffffffa0075656>] fscache_op_execute+0x7a/0xd1 [fscache] [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308 [<ffffffff8104be91>] kthread+0x7a/0x82 [<ffffffff8100beda>] child_rip+0xa/0x20 [<ffffffff8100b87c>] ? restore_args+0x0/0x30 [<ffffffff8102ef83>] ? tg_shares_up+0x171/0x227 [<ffffffff8104be17>] ? kthread+0x0/0x82 [<ffffffff8100bed0>] ? child_rip+0x0/0x20 In the above backtrace, the following is happening: (1) A page storage operation is being executed by a slow-work thread (fscache_write_op()). (2) FS-Cache farms the operation out to the cache to perform (cachefiles_write_page()). (3) CacheFiles is then calling Ext3 to perform the actual write, using Ext3's standard write (do_sync_write()) under KERNEL_DS directly from the netfs page. (4) However, for Ext3 to perform the write, it must allocate some memory, in particular, it must allocate at least one page cache page into which it can copy the data from the netfs page. (5) Under OOM conditions, the memory allocator can't immediately come up with a page, so it uses vmscan to find something to discard (try_to_free_pages()). (6) vmscan finds a clean netfs page it might be able to discard (possibly the one it's trying to write out). (7) The netfs is called to throw the page away (nfs_release_page()) - but it's called with __GFP_WAIT, so the netfs decides to wait for the store to complete (__fscache_wait_on_page_write()). (8) This blocks a slow-work processing thread - possibly against itself. The system ends up stuck because it can't write out any netfs pages to the cache without allocating more memory. To avoid this, we make FS-Cache cancel some writes that aren't in the middle of actually being performed. This means that some data won't make it into the cache this time. To support this, a new FS-Cache function is added fscache_maybe_release_page() that replaces what the netfs releasepage() functions used to do with respect to the cache. The decisions fscache_maybe_release_page() makes are counted and displayed through /proc/fs/fscache/stats on a line labelled "VmScan". There are four counters provided: "nos=N" - pages that weren't pending storage; "gon=N" - pages that were pending storage when we first looked, but weren't by the time we got the object lock; "bsy=N" - pages that we ignored as they were actively being written when we looked; and "can=N" - pages that we cancelled the storage of. What I'd really like to do is alter the behaviour of the cancellation heuristics, depending on how necessary it is to expel pages. If there are plenty of other pages that aren't waiting to be written to the cache that could be ejected first, then it would be nice to hold up on immediate cancellation of cache writes - but I don't see a way of doing that. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:35 +01:00
}
EXPORT_SYMBOL(__fscache_maybe_release_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/*
* note that a page has finished being written to the cache
*/
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
static void fscache_end_page_write(struct fscache_object *object,
struct page *page)
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
{
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
struct fscache_cookie *cookie;
struct page *xpage = NULL;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_lock(&object->lock);
cookie = object->cookie;
if (cookie) {
/* delete the page from the tree if it is now no longer
* pending */
spin_lock(&cookie->stores_lock);
FS-Cache: Handle pages pending storage that get evicted under OOM conditions Handle netfs pages that the vmscan algorithm wants to evict from the pagecache under OOM conditions, but that are waiting for write to the cache. Under these conditions, vmscan calls the releasepage() function of the netfs, asking if a page can be discarded. The problem is typified by the following trace of a stuck process: kslowd005 D 0000000000000000 0 4253 2 0x00000080 ffff88001b14f370 0000000000000046 ffff880020d0d000 0000000000000007 0000000000000006 0000000000000001 ffff88001b14ffd8 ffff880020d0d2a8 000000000000ddf0 00000000000118c0 00000000000118c0 ffff880020d0d2a8 Call Trace: [<ffffffffa00782d8>] __fscache_wait_on_page_write+0x8b/0xa7 [fscache] [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffffa0078240>] ? __fscache_check_page_write+0x63/0x70 [fscache] [<ffffffffa00b671d>] nfs_fscache_release_page+0x4e/0xc4 [nfs] [<ffffffffa00927f0>] nfs_release_page+0x3c/0x41 [nfs] [<ffffffff810885d3>] try_to_release_page+0x32/0x3b [<ffffffff81093203>] shrink_page_list+0x316/0x4ac [<ffffffff8109372b>] shrink_inactive_list+0x392/0x67c [<ffffffff813532fa>] ? __mutex_unlock_slowpath+0x100/0x10b [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130 [<ffffffff8135330e>] ? mutex_unlock+0x9/0xb [<ffffffff81093aa2>] shrink_list+0x8d/0x8f [<ffffffff81093d1c>] shrink_zone+0x278/0x33c [<ffffffff81052d6c>] ? ktime_get_ts+0xad/0xba [<ffffffff81094b13>] try_to_free_pages+0x22e/0x392 [<ffffffff81091e24>] ? isolate_pages_global+0x0/0x212 [<ffffffff8108e743>] __alloc_pages_nodemask+0x3dc/0x5cf [<ffffffff81089529>] grab_cache_page_write_begin+0x65/0xaa [<ffffffff8110f8c0>] ext3_write_begin+0x78/0x1eb [<ffffffff81089ec5>] generic_file_buffered_write+0x109/0x28c [<ffffffff8103cb69>] ? current_fs_time+0x22/0x29 [<ffffffff8108a509>] __generic_file_aio_write+0x350/0x385 [<ffffffff8108a588>] ? generic_file_aio_write+0x4a/0xae [<ffffffff8108a59e>] generic_file_aio_write+0x60/0xae [<ffffffff810b2e82>] do_sync_write+0xe3/0x120 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810b18e1>] ? __dentry_open+0x1a5/0x2b8 [<ffffffff810b1a76>] ? dentry_open+0x82/0x89 [<ffffffffa00e693c>] cachefiles_write_page+0x298/0x335 [cachefiles] [<ffffffffa0077147>] fscache_write_op+0x178/0x2c2 [fscache] [<ffffffffa0075656>] fscache_op_execute+0x7a/0xd1 [fscache] [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308 [<ffffffff8104be91>] kthread+0x7a/0x82 [<ffffffff8100beda>] child_rip+0xa/0x20 [<ffffffff8100b87c>] ? restore_args+0x0/0x30 [<ffffffff8102ef83>] ? tg_shares_up+0x171/0x227 [<ffffffff8104be17>] ? kthread+0x0/0x82 [<ffffffff8100bed0>] ? child_rip+0x0/0x20 In the above backtrace, the following is happening: (1) A page storage operation is being executed by a slow-work thread (fscache_write_op()). (2) FS-Cache farms the operation out to the cache to perform (cachefiles_write_page()). (3) CacheFiles is then calling Ext3 to perform the actual write, using Ext3's standard write (do_sync_write()) under KERNEL_DS directly from the netfs page. (4) However, for Ext3 to perform the write, it must allocate some memory, in particular, it must allocate at least one page cache page into which it can copy the data from the netfs page. (5) Under OOM conditions, the memory allocator can't immediately come up with a page, so it uses vmscan to find something to discard (try_to_free_pages()). (6) vmscan finds a clean netfs page it might be able to discard (possibly the one it's trying to write out). (7) The netfs is called to throw the page away (nfs_release_page()) - but it's called with __GFP_WAIT, so the netfs decides to wait for the store to complete (__fscache_wait_on_page_write()). (8) This blocks a slow-work processing thread - possibly against itself. The system ends up stuck because it can't write out any netfs pages to the cache without allocating more memory. To avoid this, we make FS-Cache cancel some writes that aren't in the middle of actually being performed. This means that some data won't make it into the cache this time. To support this, a new FS-Cache function is added fscache_maybe_release_page() that replaces what the netfs releasepage() functions used to do with respect to the cache. The decisions fscache_maybe_release_page() makes are counted and displayed through /proc/fs/fscache/stats on a line labelled "VmScan". There are four counters provided: "nos=N" - pages that weren't pending storage; "gon=N" - pages that were pending storage when we first looked, but weren't by the time we got the object lock; "bsy=N" - pages that we ignored as they were actively being written when we looked; and "can=N" - pages that we cancelled the storage of. What I'd really like to do is alter the behaviour of the cancellation heuristics, depending on how necessary it is to expel pages. If there are plenty of other pages that aren't waiting to be written to the cache that could be ejected first, then it would be nice to hold up on immediate cancellation of cache writes - but I don't see a way of doing that. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:35 +01:00
radix_tree_tag_clear(&cookie->stores, page->index,
FSCACHE_COOKIE_STORING_TAG);
if (!radix_tree_tag_get(&cookie->stores, page->index,
FSCACHE_COOKIE_PENDING_TAG)) {
fscache_stat(&fscache_n_store_radix_deletes);
xpage = radix_tree_delete(&cookie->stores, page->index);
}
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_unlock(&cookie->stores_lock);
wake_up_bit(&cookie->flags, 0);
}
spin_unlock(&object->lock);
if (xpage)
page_cache_release(xpage);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
}
/*
* actually apply the changed attributes to a cache object
*/
static void fscache_attr_changed_op(struct fscache_operation *op)
{
struct fscache_object *object = op->object;
int ret;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
_enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
fscache_stat(&fscache_n_attr_changed_calls);
if (fscache_object_is_active(object)) {
fscache_stat(&fscache_n_cop_attr_changed);
ret = object->cache->ops->attr_changed(object);
fscache_stat_d(&fscache_n_cop_attr_changed);
if (ret < 0)
fscache_abort_object(object);
}
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
fscache_op_complete(op, true);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
_leave("");
}
/*
* notification that the attributes on an object have changed
*/
int __fscache_attr_changed(struct fscache_cookie *cookie)
{
struct fscache_operation *op;
struct fscache_object *object;
bool wake_cookie;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
_enter("%p", cookie);
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
fscache_stat(&fscache_n_attr_changed);
op = kzalloc(sizeof(*op), GFP_KERNEL);
if (!op) {
fscache_stat(&fscache_n_attr_changed_nomem);
_leave(" = -ENOMEM");
return -ENOMEM;
}
fscache_operation_init(op, fscache_attr_changed_op, NULL);
op->flags = FSCACHE_OP_ASYNC |
(1 << FSCACHE_OP_EXCLUSIVE) |
(1 << FSCACHE_OP_UNUSE_COOKIE);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_lock(&cookie->lock);
FS-Cache: Provide the ability to enable/disable cookies Provide the ability to enable and disable fscache cookies. A disabled cookie will reject or ignore further requests to: Acquire a child cookie Invalidate and update backing objects Check the consistency of a backing object Allocate storage for backing page Read backing pages Write to backing pages but still allows: Checks/waits on the completion of already in-progress objects Uncaching of pages Relinquishment of cookies Two new operations are provided: (1) Disable a cookie: void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate); If the cookie is not already disabled, this locks the cookie against other dis/enablement ops, marks the cookie as being disabled, discards or invalidates any backing objects and waits for cessation of activity on any associated object. This is a wrapper around a chunk split out of fscache_relinquish_cookie(), but it reinitialises the cookie such that it can be reenabled. All possible failures are handled internally. The caller should consider calling fscache_uncache_all_inode_pages() afterwards to make sure all page markings are cleared up. (2) Enable a cookie: void fscache_enable_cookie(struct fscache_cookie *cookie, bool (*can_enable)(void *data), void *data) If the cookie is not already enabled, this locks the cookie against other dis/enablement ops, invokes can_enable() and, if the cookie is not an index cookie, will begin the procedure of acquiring backing objects. The optional can_enable() function is passed the data argument and returns a ruling as to whether or not enablement should actually be permitted to begin. All possible failures are handled internally. The cookie will only be marked as enabled if provisional backing objects are allocated. A later patch will introduce these to NFS. Cookie enablement during nfs_open() is then contingent on i_writecount <= 0. can_enable() checks for a race between open(O_RDONLY) and open(O_WRONLY/O_RDWR). This simplifies NFS's cookie handling and allows us to get rid of open(O_RDONLY) accidentally introducing caching to an inode that's open for writing already. One operation has its API modified: (3) Acquire a cookie. struct fscache_cookie *fscache_acquire_cookie( struct fscache_cookie *parent, const struct fscache_cookie_def *def, void *netfs_data, bool enable); This now has an additional argument that indicates whether the requested cookie should be enabled by default. It doesn't need the can_enable() function because the caller must prevent multiple calls for the same netfs object and it doesn't need to take the enablement lock because no one else can get at the cookie before this returns. Signed-off-by: David Howells <dhowells@redhat.com
2013-09-21 01:09:31 +02:00
if (!fscache_cookie_enabled(cookie) ||
hlist_empty(&cookie->backing_objects))
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
goto nobufs;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
__fscache_use_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (fscache_submit_exclusive_op(object, op) < 0)
goto nobufs;
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_attr_changed_ok);
fscache_put_operation(op);
_leave(" = 0");
return 0;
nobufs:
wake_cookie = __fscache_unuse_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&cookie->lock);
kfree(op);
if (wake_cookie)
__fscache_wake_unused_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
fscache_stat(&fscache_n_attr_changed_nobufs);
_leave(" = %d", -ENOBUFS);
return -ENOBUFS;
}
EXPORT_SYMBOL(__fscache_attr_changed);
/*
* release a retrieval op reference
*/
static void fscache_release_retrieval_op(struct fscache_operation *_op)
{
struct fscache_retrieval *op =
container_of(_op, struct fscache_retrieval, op);
_enter("{OP%x}", op->op.debug_id);
FS-Cache: The retrieval remaining-pages counter needs to be atomic_t struct fscache_retrieval contains a count of the number of pages that still need some processing (n_pages). This is decremented as the pages are processed. However, this needs to be atomic as fscache_retrieval_complete() (I think) just occasionally may be called from cachefiles_read_backing_file() and cachefiles_read_copier() simultaneously. This happens when an fscache_read_or_alloc_pages() request containing a lot of pages (say a couple of hundred) is being processed. The read on each backing page is dispatched individually because we need to insert a monitor into the waitqueue to catch when the read completes. However, under low-memory conditions, we might be forced to wait in the allocator - and this gives the I/O on the backing page a chance to complete first. When the I/O completes, fscache_enqueue_retrieval() chucks the retrieval onto the workqueue without waiting for the operation to finish the initial I/O dispatch (we want to release any pages we can as soon as we can), thus both can end up running simultaneously and potentially attempting to partially complete the retrieval simultaneously (ENOMEM may occur, backing pages may already be in the page cache). This was demonstrated by parallelling the non-atomic counter with an atomic counter and printing both of them when the assertion fails. At this point, the atomic counter has reached zero, but the non-atomic counter has not. To fix this, make the counter an atomic_t. This results in the following bug appearing FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:421! or FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:414! With a backtrace like the following: RIP: 0010:[<ffffffffa0211b1d>] fscache_put_operation+0x1ad/0x240 [fscache] Call Trace: [<ffffffffa0213185>] fscache_retrieval_work+0x55/0x270 [fscache] [<ffffffffa0213130>] ? fscache_retrieval_work+0x0/0x270 [fscache] [<ffffffff81090b10>] worker_thread+0x170/0x2a0 [<ffffffff81096d10>] ? autoremove_wake_function+0x0/0x40 [<ffffffff810909a0>] ? worker_thread+0x0/0x2a0 [<ffffffff81096966>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968d0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-21 14:44:15 +02:00
ASSERTCMP(atomic_read(&op->n_pages), ==, 0);
FS-Cache: Fix operation state management and accounting Fix the state management of internal fscache operations and the accounting of what operations are in what states. This is done by: (1) Give struct fscache_operation a enum variable that directly represents the state it's currently in, rather than spreading this knowledge over a bunch of flags, who's processing the operation at the moment and whether it is queued or not. This makes it easier to write assertions to check the state at various points and to prevent invalid state transitions. (2) Add an 'operation complete' state and supply a function to indicate the completion of an operation (fscache_op_complete()) and make things call it. The final call to fscache_put_operation() can then check that an op in the appropriate state (complete or cancelled). (3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better govern the state of an object: (a) The ->n_ops is now the number of extant operations on the object and is now decremented by fscache_put_operation() only. (b) The ->n_in_progress is simply the number of objects that have been taken off of the object's pending queue for the purposes of being run. This is decremented by fscache_op_complete() only. (c) The ->n_exclusive is the number of exclusive ops that have been submitted and queued or are in progress. It is decremented by fscache_op_complete() and by fscache_cancel_op(). fscache_put_operation() and fscache_operation_gc() now no longer try to clean up ->n_exclusive and ->n_in_progress. That was leading to double decrements against fscache_cancel_op(). fscache_cancel_op() now no longer decrements ->n_ops. That was leading to double decrements against fscache_put_operation(). fscache_submit_exclusive_op() now decides whether it has to queue an op based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter will persist in being true even after all preceding operations have been cancelled or completed. Furthermore, if an object is active and there are runnable ops against it, there must be at least one op running. (4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and provide a function to record completion of the pages as they complete. When n_pages reaches 0, the operation is deemed to be complete and fscache_op_complete() is called. Add calls to fscache_retrieval_complete() anywhere we've finished with a page we've been given to read or allocate for. This includes places where we just return pages to the netfs for reading from the server and where accessing the cache fails and we discard the proposed netfs page. The bugs in the unfixed state management manifest themselves as oopses like the following where the operation completion gets out of sync with return of the cookie by the netfs. This is possible because the cache unlocks and returns all the netfs pages before recording its completion - which means that there's nothing to stop the netfs discarding them and returning the cookie. FS-Cache: Cookie 'NFS.fh' still has outstanding reads ------------[ cut here ]------------ kernel BUG at fs/fscache/cookie.c:519! invalid opcode: 0000 [#1] SMP CPU 1 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache] RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282 RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000 RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000 R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98 R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370 FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040) Stack: ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0 ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0 ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91 Call Trace: [<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs] [<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs] [<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs] [<ffffffff810d8d47>] evict+0xa1/0x15c [<ffffffff810d8e2e>] dispose_list+0x2c/0x38 [<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b [<ffffffff810c56b7>] prune_super+0xd5/0x140 [<ffffffff8109b615>] shrink_slab+0x102/0x1ab [<ffffffff8109d690>] balance_pgdat+0x2f2/0x595 [<ffffffff8103e009>] ? process_timeout+0xb/0xb [<ffffffff8109dba3>] kswapd+0x270/0x289 [<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46 [<ffffffff8109d933>] ? balance_pgdat+0x595/0x595 [<ffffffff8104bf7a>] kthread+0x7f/0x87 [<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0 [<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe [<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53 [<ffffffff813ad6b0>] ? gs_change+0xb/0xb Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-20 22:52:35 +01:00
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
fscache_hist(fscache_retrieval_histogram, op->start_time);
if (op->context)
fscache_put_context(op->op.object->cookie, op->context);
_leave("");
}
/*
* allocate a retrieval op
*/
static struct fscache_retrieval *fscache_alloc_retrieval(
FS-Cache: Simplify cookie retention for fscache_objects, fixing oops Simplify the way fscache cache objects retain their cookie. The way I implemented the cookie storage handling made synchronisation a pain (ie. the object state machine can't rely on the cookie actually still being there). Instead of the the object being detached from the cookie and the cookie being freed in __fscache_relinquish_cookie(), we defer both operations: (*) The detachment of the object from the list in the cookie now takes place in fscache_drop_object() and is thus governed by the object state machine (fscache_detach_from_cookie() has been removed). (*) The release of the cookie is now in fscache_object_destroy() - which is called by the cache backend just before it frees the object. This means that the fscache_cookie struct is now available to the cache all the way through from ->alloc_object() to ->drop_object() and ->put_object() - meaning that it's no longer necessary to take object->lock to guarantee access. However, __fscache_relinquish_cookie() doesn't wait for the object to go all the way through to destruction before letting the netfs proceed. That would massively slow down the netfs. Since __fscache_relinquish_cookie() leaves the cookie around, in must therefore break all attachments to the netfs - which includes ->def, ->netfs_data and any outstanding page read/writes. To handle this, struct fscache_cookie now has an n_active counter: (1) This starts off initialised to 1. (2) Any time the cache needs to get at the netfs data, it calls fscache_use_cookie() to increment it - if it is not zero. If it was zero, then access is not permitted. (3) When the cache has finished with the data, it calls fscache_unuse_cookie() to decrement it. This does a wake-up on it if it reaches 0. (4) __fscache_relinquish_cookie() decrements n_active and then waits for it to reach 0. The initialisation to 1 in step (1) ensures that we only get wake ups when we're trying to get rid of the cookie. This leaves __fscache_relinquish_cookie() a lot simpler. *** This fixes a problem in the current code whereby if fscache_invalidate() is followed sufficiently quickly by fscache_relinquish_cookie() then it is possible for __fscache_relinquish_cookie() to have detached the cookie from the object and cleared the pointer before a thread is dispatched to process the invalidation state in the object state machine. Since the pending write clearance was deferred to the invalidation state to make it asynchronous, we need to either wait in relinquishment for the stores tree to be cleared in the invalidation state or we need to handle the clearance in relinquishment. Further, if the relinquishment code does clear the tree, then the invalidation state need to make the clearance contingent on still having the cookie to hand (since that's where the tree is rooted) and we have to prevent the cookie from disappearing for the duration. This can lead to an oops like the following: BUG: unable to handle kernel NULL pointer dereference at 000000000000000c ... RIP: 0010:[<ffffffff8151023e>] _spin_lock+0xe/0x30 ... CR2: 000000000000000c ... ... Process kslowd002 (...) .... Call Trace: [<ffffffffa01c3278>] fscache_invalidate_writes+0x38/0xd0 [fscache] [<ffffffff810096f0>] ? __switch_to+0xd0/0x320 [<ffffffff8105e759>] ? find_busiest_queue+0x69/0x150 [<ffffffff8110ddd4>] ? slow_work_enqueue+0x104/0x180 [<ffffffffa01c1303>] fscache_object_slow_work_execute+0x5e3/0x9d0 [fscache] [<ffffffff81096b67>] ? bit_waitqueue+0x17/0xd0 [<ffffffff8110e233>] slow_work_execute+0x233/0x310 [<ffffffff8110e515>] slow_work_thread+0x205/0x360 [<ffffffff81096ca0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff8110e310>] ? slow_work_thread+0x0/0x360 [<ffffffff81096936>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968a0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 The parameter to fscache_invalidate_writes() was object->cookie which is NULL. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
struct fscache_cookie *cookie,
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
struct address_space *mapping,
fscache_rw_complete_t end_io_func,
void *context)
{
struct fscache_retrieval *op;
/* allocate a retrieval operation and attempt to submit it */
op = kzalloc(sizeof(*op), GFP_NOIO);
if (!op) {
fscache_stat(&fscache_n_retrievals_nomem);
return NULL;
}
fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op);
FS-Cache: Simplify cookie retention for fscache_objects, fixing oops Simplify the way fscache cache objects retain their cookie. The way I implemented the cookie storage handling made synchronisation a pain (ie. the object state machine can't rely on the cookie actually still being there). Instead of the the object being detached from the cookie and the cookie being freed in __fscache_relinquish_cookie(), we defer both operations: (*) The detachment of the object from the list in the cookie now takes place in fscache_drop_object() and is thus governed by the object state machine (fscache_detach_from_cookie() has been removed). (*) The release of the cookie is now in fscache_object_destroy() - which is called by the cache backend just before it frees the object. This means that the fscache_cookie struct is now available to the cache all the way through from ->alloc_object() to ->drop_object() and ->put_object() - meaning that it's no longer necessary to take object->lock to guarantee access. However, __fscache_relinquish_cookie() doesn't wait for the object to go all the way through to destruction before letting the netfs proceed. That would massively slow down the netfs. Since __fscache_relinquish_cookie() leaves the cookie around, in must therefore break all attachments to the netfs - which includes ->def, ->netfs_data and any outstanding page read/writes. To handle this, struct fscache_cookie now has an n_active counter: (1) This starts off initialised to 1. (2) Any time the cache needs to get at the netfs data, it calls fscache_use_cookie() to increment it - if it is not zero. If it was zero, then access is not permitted. (3) When the cache has finished with the data, it calls fscache_unuse_cookie() to decrement it. This does a wake-up on it if it reaches 0. (4) __fscache_relinquish_cookie() decrements n_active and then waits for it to reach 0. The initialisation to 1 in step (1) ensures that we only get wake ups when we're trying to get rid of the cookie. This leaves __fscache_relinquish_cookie() a lot simpler. *** This fixes a problem in the current code whereby if fscache_invalidate() is followed sufficiently quickly by fscache_relinquish_cookie() then it is possible for __fscache_relinquish_cookie() to have detached the cookie from the object and cleared the pointer before a thread is dispatched to process the invalidation state in the object state machine. Since the pending write clearance was deferred to the invalidation state to make it asynchronous, we need to either wait in relinquishment for the stores tree to be cleared in the invalidation state or we need to handle the clearance in relinquishment. Further, if the relinquishment code does clear the tree, then the invalidation state need to make the clearance contingent on still having the cookie to hand (since that's where the tree is rooted) and we have to prevent the cookie from disappearing for the duration. This can lead to an oops like the following: BUG: unable to handle kernel NULL pointer dereference at 000000000000000c ... RIP: 0010:[<ffffffff8151023e>] _spin_lock+0xe/0x30 ... CR2: 000000000000000c ... ... Process kslowd002 (...) .... Call Trace: [<ffffffffa01c3278>] fscache_invalidate_writes+0x38/0xd0 [fscache] [<ffffffff810096f0>] ? __switch_to+0xd0/0x320 [<ffffffff8105e759>] ? find_busiest_queue+0x69/0x150 [<ffffffff8110ddd4>] ? slow_work_enqueue+0x104/0x180 [<ffffffffa01c1303>] fscache_object_slow_work_execute+0x5e3/0x9d0 [fscache] [<ffffffff81096b67>] ? bit_waitqueue+0x17/0xd0 [<ffffffff8110e233>] slow_work_execute+0x233/0x310 [<ffffffff8110e515>] slow_work_thread+0x205/0x360 [<ffffffff81096ca0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff8110e310>] ? slow_work_thread+0x0/0x360 [<ffffffff81096936>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968a0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 The parameter to fscache_invalidate_writes() was object->cookie which is NULL. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
op->op.flags = FSCACHE_OP_MYTHREAD |
(1UL << FSCACHE_OP_WAITING) |
(1UL << FSCACHE_OP_UNUSE_COOKIE);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
op->mapping = mapping;
op->end_io_func = end_io_func;
op->context = context;
op->start_time = jiffies;
INIT_LIST_HEAD(&op->to_do);
return op;
}
/*
* wait for a deferred lookup to complete
*/
int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
{
unsigned long jif;
_enter("");
if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
_leave(" = 0 [imm]");
return 0;
}
fscache_stat(&fscache_n_retrievals_wait);
jif = jiffies;
if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
fscache_wait_bit_interruptible,
TASK_INTERRUPTIBLE) != 0) {
fscache_stat(&fscache_n_retrievals_intr);
_leave(" = -ERESTARTSYS");
return -ERESTARTSYS;
}
ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
smp_rmb();
fscache_hist(fscache_retrieval_delay_histogram, jif);
_leave(" = 0 [dly]");
return 0;
}
FS-Cache: Clear remaining page count on retrieval cancellation Provide fscache_cancel_op() with a pointer to a function it should invoke under lock if it cancels an operation. Use this to clear the remaining page count upon cancellation of a pending retrieval operation so that fscache_release_retrieval_op() doesn't get an assertion failure (see below). This can happen when a signal occurs, say from CTRL-C being pressed during data retrieval. FS-Cache: Assertion failed 3 == 0 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/page.c:237! invalid opcode: 0000 [#641] SMP Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F) CPU 0 Pid: 6075, comm: slurp-q Tainted: GF D 3.7.0-rc8-fsdevel+ #411 /DG965RY RIP: 0010:[<ffffffffa007f328>] [<ffffffffa007f328>] fscache_release_retrieval_op+0x75/0xff [fscache] RSP: 0000:ffff88001c6d7988 EFLAGS: 00010296 RAX: 000000000000000f RBX: ffff880014cdfe00 RCX: ffffffff6c102000 RDX: ffffffff8102d1ad RSI: ffffffff6c102000 RDI: ffffffff8102d1d6 RBP: ffff88001c6d7998 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffe00 R13: ffff88001c6d7ab4 R14: ffff88001a8638a0 R15: ffff88001552b190 FS: 00007f877aaf0700(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fff11378fd2 CR3: 000000001c6c6000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process slurp-q (pid: 6075, threadinfo ffff88001c6d6000, task ffff88001c6c4080) Stack: ffffffffa007ec07 ffff880014cdfe00 ffff88001c6d79c8 ffffffffa007db4d ffffffffa007ec07 ffff880014cdfe00 00000000fffffe00 ffff88001c6d7ab4 ffff88001c6d7a38 ffffffffa008116d 0000000000000000 ffff88001c6c4080 Call Trace: [<ffffffffa007ec07>] ? fscache_cancel_op+0x194/0x1cf [fscache] [<ffffffffa007db4d>] fscache_put_operation+0x135/0x2ed [fscache] [<ffffffffa007ec07>] ? fscache_cancel_op+0x194/0x1cf [fscache] [<ffffffffa008116d>] __fscache_read_or_alloc_pages+0x413/0x4bc [fscache] [<ffffffff810ac8ae>] ? __alloc_pages_nodemask+0x195/0x75c [<ffffffffa00aab0f>] __nfs_readpages_from_fscache+0x86/0x13d [nfs] [<ffffffffa00a5fe0>] nfs_readpages+0x186/0x1bd [nfs] [<ffffffff810d23c8>] ? alloc_pages_current+0xc7/0xe4 [<ffffffff810a68b5>] ? __page_cache_alloc+0x84/0x91 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0 [<ffffffff810afaa3>] __do_page_cache_readahead+0x237/0x2e0 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0 [<ffffffff810afe3e>] ra_submit+0x1c/0x20 [<ffffffff810b019b>] ondemand_readahead+0x359/0x382 [<ffffffff810b0279>] page_cache_sync_readahead+0x38/0x3a [<ffffffff810a77b5>] generic_file_aio_read+0x26b/0x637 [<ffffffffa00f1852>] ? nfs_mark_delegation_referenced+0xb/0xb [nfsv4] [<ffffffffa009cc85>] nfs_file_read+0xaa/0xcf [nfs] [<ffffffff810db5b3>] do_sync_read+0x91/0xd1 [<ffffffff810dbb8b>] vfs_read+0x9b/0x144 [<ffffffff810dbc78>] sys_read+0x44/0x75 [<ffffffff81422892>] system_call_fastpath+0x16/0x1b Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-14 12:02:22 +01:00
/*
* Handle cancellation of a pending retrieval op
*/
static void fscache_do_cancel_retrieval(struct fscache_operation *_op)
{
struct fscache_retrieval *op =
container_of(_op, struct fscache_retrieval, op);
FS-Cache: The retrieval remaining-pages counter needs to be atomic_t struct fscache_retrieval contains a count of the number of pages that still need some processing (n_pages). This is decremented as the pages are processed. However, this needs to be atomic as fscache_retrieval_complete() (I think) just occasionally may be called from cachefiles_read_backing_file() and cachefiles_read_copier() simultaneously. This happens when an fscache_read_or_alloc_pages() request containing a lot of pages (say a couple of hundred) is being processed. The read on each backing page is dispatched individually because we need to insert a monitor into the waitqueue to catch when the read completes. However, under low-memory conditions, we might be forced to wait in the allocator - and this gives the I/O on the backing page a chance to complete first. When the I/O completes, fscache_enqueue_retrieval() chucks the retrieval onto the workqueue without waiting for the operation to finish the initial I/O dispatch (we want to release any pages we can as soon as we can), thus both can end up running simultaneously and potentially attempting to partially complete the retrieval simultaneously (ENOMEM may occur, backing pages may already be in the page cache). This was demonstrated by parallelling the non-atomic counter with an atomic counter and printing both of them when the assertion fails. At this point, the atomic counter has reached zero, but the non-atomic counter has not. To fix this, make the counter an atomic_t. This results in the following bug appearing FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:421! or FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:414! With a backtrace like the following: RIP: 0010:[<ffffffffa0211b1d>] fscache_put_operation+0x1ad/0x240 [fscache] Call Trace: [<ffffffffa0213185>] fscache_retrieval_work+0x55/0x270 [fscache] [<ffffffffa0213130>] ? fscache_retrieval_work+0x0/0x270 [fscache] [<ffffffff81090b10>] worker_thread+0x170/0x2a0 [<ffffffff81096d10>] ? autoremove_wake_function+0x0/0x40 [<ffffffff810909a0>] ? worker_thread+0x0/0x2a0 [<ffffffff81096966>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968d0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-21 14:44:15 +02:00
atomic_set(&op->n_pages, 0);
FS-Cache: Clear remaining page count on retrieval cancellation Provide fscache_cancel_op() with a pointer to a function it should invoke under lock if it cancels an operation. Use this to clear the remaining page count upon cancellation of a pending retrieval operation so that fscache_release_retrieval_op() doesn't get an assertion failure (see below). This can happen when a signal occurs, say from CTRL-C being pressed during data retrieval. FS-Cache: Assertion failed 3 == 0 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/page.c:237! invalid opcode: 0000 [#641] SMP Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F) CPU 0 Pid: 6075, comm: slurp-q Tainted: GF D 3.7.0-rc8-fsdevel+ #411 /DG965RY RIP: 0010:[<ffffffffa007f328>] [<ffffffffa007f328>] fscache_release_retrieval_op+0x75/0xff [fscache] RSP: 0000:ffff88001c6d7988 EFLAGS: 00010296 RAX: 000000000000000f RBX: ffff880014cdfe00 RCX: ffffffff6c102000 RDX: ffffffff8102d1ad RSI: ffffffff6c102000 RDI: ffffffff8102d1d6 RBP: ffff88001c6d7998 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffe00 R13: ffff88001c6d7ab4 R14: ffff88001a8638a0 R15: ffff88001552b190 FS: 00007f877aaf0700(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fff11378fd2 CR3: 000000001c6c6000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process slurp-q (pid: 6075, threadinfo ffff88001c6d6000, task ffff88001c6c4080) Stack: ffffffffa007ec07 ffff880014cdfe00 ffff88001c6d79c8 ffffffffa007db4d ffffffffa007ec07 ffff880014cdfe00 00000000fffffe00 ffff88001c6d7ab4 ffff88001c6d7a38 ffffffffa008116d 0000000000000000 ffff88001c6c4080 Call Trace: [<ffffffffa007ec07>] ? fscache_cancel_op+0x194/0x1cf [fscache] [<ffffffffa007db4d>] fscache_put_operation+0x135/0x2ed [fscache] [<ffffffffa007ec07>] ? fscache_cancel_op+0x194/0x1cf [fscache] [<ffffffffa008116d>] __fscache_read_or_alloc_pages+0x413/0x4bc [fscache] [<ffffffff810ac8ae>] ? __alloc_pages_nodemask+0x195/0x75c [<ffffffffa00aab0f>] __nfs_readpages_from_fscache+0x86/0x13d [nfs] [<ffffffffa00a5fe0>] nfs_readpages+0x186/0x1bd [nfs] [<ffffffff810d23c8>] ? alloc_pages_current+0xc7/0xe4 [<ffffffff810a68b5>] ? __page_cache_alloc+0x84/0x91 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0 [<ffffffff810afaa3>] __do_page_cache_readahead+0x237/0x2e0 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0 [<ffffffff810afe3e>] ra_submit+0x1c/0x20 [<ffffffff810b019b>] ondemand_readahead+0x359/0x382 [<ffffffff810b0279>] page_cache_sync_readahead+0x38/0x3a [<ffffffff810a77b5>] generic_file_aio_read+0x26b/0x637 [<ffffffffa00f1852>] ? nfs_mark_delegation_referenced+0xb/0xb [nfsv4] [<ffffffffa009cc85>] nfs_file_read+0xaa/0xcf [nfs] [<ffffffff810db5b3>] do_sync_read+0x91/0xd1 [<ffffffff810dbb8b>] vfs_read+0x9b/0x144 [<ffffffff810dbc78>] sys_read+0x44/0x75 [<ffffffff81422892>] system_call_fastpath+0x16/0x1b Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-14 12:02:22 +01:00
}
/*
* wait for an object to become active (or dead)
*/
int fscache_wait_for_operation_activation(struct fscache_object *object,
struct fscache_operation *op,
atomic_t *stat_op_waits,
atomic_t *stat_object_dead,
void (*do_cancel)(struct fscache_operation *))
{
int ret;
if (!test_bit(FSCACHE_OP_WAITING, &op->flags))
goto check_if_dead;
_debug(">>> WT");
if (stat_op_waits)
fscache_stat(stat_op_waits);
if (wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
fscache_wait_bit_interruptible,
FS-Cache: Fix signal handling during waits wait_on_bit() with TASK_INTERRUPTIBLE returns 1 rather than a negative error code, so change what we check for. This means that the signal handling in fscache_wait_for_retrieval_activation() should now work properly. Without this, the following bug can be seen if CTRL-C is pressed during fscache read operation: FS-Cache: Assertion failed 2 == 3 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/page.c:347! invalid opcode: 0000 [#1] SMP Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F) CPU 1 Pid: 15006, comm: slurp-q Tainted: GF 3.7.0-rc8-fsdevel+ #411 /DG965RY RIP: 0010:[<ffffffffa007fcb4>] [<ffffffffa007fcb4>] fscache_wait_for_retrieval_activation+0x167/0x177 [fscache] RSP: 0018:ffff88002a4c39a8 EFLAGS: 00010292 RAX: 000000000000001a RBX: ffff88002d3dc158 RCX: 0000000000008685 RDX: ffffffff8102ccd6 RSI: 0000000000000001 RDI: ffffffff8102d1d6 RBP: ffff88002a4c39c8 R08: 0000000000000002 R09: 0000000000000000 R10: ffffffff8163afa0 R11: ffff88003bd11900 R12: ffffffffa00868c8 R13: ffff880028306458 R14: ffff88002d3dc1b0 R15: ffff88001372e538 FS: 00007f17426a0700(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007f1742494a44 CR3: 0000000031bd7000 CR4: 00000000000007e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process slurp-q (pid: 15006, threadinfo ffff88002a4c2000, task ffff880023de3040) Stack: ffff88002d3dc158 ffff88001372e538 ffff88002a4c3ab4 ffff8800283064e0 ffff88002a4c3a38 ffffffffa0080f6d 0000000000000000 ffff880023de3040 ffff88002a4c3ac8 ffffffff810ac8ae ffff880028306458 ffff88002a4c3bc8 Call Trace: [<ffffffffa0080f6d>] __fscache_read_or_alloc_pages+0x24f/0x4bc [fscache] [<ffffffff810ac8ae>] ? __alloc_pages_nodemask+0x195/0x75c [<ffffffffa00aab0f>] __nfs_readpages_from_fscache+0x86/0x13d [nfs] [<ffffffffa00a5fe0>] nfs_readpages+0x186/0x1bd [nfs] [<ffffffff810d23c8>] ? alloc_pages_current+0xc7/0xe4 [<ffffffff810a68b5>] ? __page_cache_alloc+0x84/0x91 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0 [<ffffffff810afaa3>] __do_page_cache_readahead+0x237/0x2e0 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0 [<ffffffff810afe3e>] ra_submit+0x1c/0x20 [<ffffffff810b019b>] ondemand_readahead+0x359/0x382 [<ffffffff810b0279>] page_cache_sync_readahead+0x38/0x3a [<ffffffff810a77b5>] generic_file_aio_read+0x26b/0x637 [<ffffffffa00f1852>] ? nfs_mark_delegation_referenced+0xb/0xb [nfsv4] [<ffffffffa009cc85>] nfs_file_read+0xaa/0xcf [nfs] [<ffffffff810db5b3>] do_sync_read+0x91/0xd1 [<ffffffff810dbb8b>] vfs_read+0x9b/0x144 [<ffffffff810dbc78>] sys_read+0x44/0x75 [<ffffffff81422892>] system_call_fastpath+0x16/0x1b Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-07 19:08:02 +01:00
TASK_INTERRUPTIBLE) != 0) {
ret = fscache_cancel_op(op, do_cancel);
if (ret == 0)
return -ERESTARTSYS;
/* it's been removed from the pending queue by another party,
* so we should get to run shortly */
wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
}
_debug("<<< GO");
check_if_dead:
if (op->state == FSCACHE_OP_ST_CANCELLED) {
if (stat_object_dead)
fscache_stat(stat_object_dead);
FS-Cache: Fix operation state management and accounting Fix the state management of internal fscache operations and the accounting of what operations are in what states. This is done by: (1) Give struct fscache_operation a enum variable that directly represents the state it's currently in, rather than spreading this knowledge over a bunch of flags, who's processing the operation at the moment and whether it is queued or not. This makes it easier to write assertions to check the state at various points and to prevent invalid state transitions. (2) Add an 'operation complete' state and supply a function to indicate the completion of an operation (fscache_op_complete()) and make things call it. The final call to fscache_put_operation() can then check that an op in the appropriate state (complete or cancelled). (3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better govern the state of an object: (a) The ->n_ops is now the number of extant operations on the object and is now decremented by fscache_put_operation() only. (b) The ->n_in_progress is simply the number of objects that have been taken off of the object's pending queue for the purposes of being run. This is decremented by fscache_op_complete() only. (c) The ->n_exclusive is the number of exclusive ops that have been submitted and queued or are in progress. It is decremented by fscache_op_complete() and by fscache_cancel_op(). fscache_put_operation() and fscache_operation_gc() now no longer try to clean up ->n_exclusive and ->n_in_progress. That was leading to double decrements against fscache_cancel_op(). fscache_cancel_op() now no longer decrements ->n_ops. That was leading to double decrements against fscache_put_operation(). fscache_submit_exclusive_op() now decides whether it has to queue an op based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter will persist in being true even after all preceding operations have been cancelled or completed. Furthermore, if an object is active and there are runnable ops against it, there must be at least one op running. (4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and provide a function to record completion of the pages as they complete. When n_pages reaches 0, the operation is deemed to be complete and fscache_op_complete() is called. Add calls to fscache_retrieval_complete() anywhere we've finished with a page we've been given to read or allocate for. This includes places where we just return pages to the netfs for reading from the server and where accessing the cache fails and we discard the proposed netfs page. The bugs in the unfixed state management manifest themselves as oopses like the following where the operation completion gets out of sync with return of the cookie by the netfs. This is possible because the cache unlocks and returns all the netfs pages before recording its completion - which means that there's nothing to stop the netfs discarding them and returning the cookie. FS-Cache: Cookie 'NFS.fh' still has outstanding reads ------------[ cut here ]------------ kernel BUG at fs/fscache/cookie.c:519! invalid opcode: 0000 [#1] SMP CPU 1 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache] RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282 RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000 RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000 R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98 R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370 FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040) Stack: ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0 ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0 ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91 Call Trace: [<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs] [<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs] [<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs] [<ffffffff810d8d47>] evict+0xa1/0x15c [<ffffffff810d8e2e>] dispose_list+0x2c/0x38 [<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b [<ffffffff810c56b7>] prune_super+0xd5/0x140 [<ffffffff8109b615>] shrink_slab+0x102/0x1ab [<ffffffff8109d690>] balance_pgdat+0x2f2/0x595 [<ffffffff8103e009>] ? process_timeout+0xb/0xb [<ffffffff8109dba3>] kswapd+0x270/0x289 [<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46 [<ffffffff8109d933>] ? balance_pgdat+0x595/0x595 [<ffffffff8104bf7a>] kthread+0x7f/0x87 [<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0 [<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe [<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53 [<ffffffff813ad6b0>] ? gs_change+0xb/0xb Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-20 22:52:35 +01:00
_leave(" = -ENOBUFS [cancelled]");
return -ENOBUFS;
}
if (unlikely(fscache_object_is_dead(object))) {
pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->state);
fscache_cancel_op(op, do_cancel);
if (stat_object_dead)
fscache_stat(stat_object_dead);
return -ENOBUFS;
}
return 0;
}
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/*
* read a page from the cache or allocate a block in which to store it
* - we return:
* -ENOMEM - out of memory, nothing done
* -ERESTARTSYS - interrupted
* -ENOBUFS - no backing object available in which to cache the block
* -ENODATA - no data available in the backing object for this block
* 0 - dispatched a read - it'll call end_io_func() when finished
*/
int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
struct page *page,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp)
{
struct fscache_retrieval *op;
struct fscache_object *object;
bool wake_cookie = false;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
int ret;
_enter("%p,%p,,,", cookie, page);
fscache_stat(&fscache_n_retrievals);
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
_leave(" = -ENOBUFS [invalidating]");
return -ENOBUFS;
}
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(page, !=, NULL);
if (fscache_wait_for_deferred_lookup(cookie) < 0)
return -ERESTARTSYS;
FS-Cache: Simplify cookie retention for fscache_objects, fixing oops Simplify the way fscache cache objects retain their cookie. The way I implemented the cookie storage handling made synchronisation a pain (ie. the object state machine can't rely on the cookie actually still being there). Instead of the the object being detached from the cookie and the cookie being freed in __fscache_relinquish_cookie(), we defer both operations: (*) The detachment of the object from the list in the cookie now takes place in fscache_drop_object() and is thus governed by the object state machine (fscache_detach_from_cookie() has been removed). (*) The release of the cookie is now in fscache_object_destroy() - which is called by the cache backend just before it frees the object. This means that the fscache_cookie struct is now available to the cache all the way through from ->alloc_object() to ->drop_object() and ->put_object() - meaning that it's no longer necessary to take object->lock to guarantee access. However, __fscache_relinquish_cookie() doesn't wait for the object to go all the way through to destruction before letting the netfs proceed. That would massively slow down the netfs. Since __fscache_relinquish_cookie() leaves the cookie around, in must therefore break all attachments to the netfs - which includes ->def, ->netfs_data and any outstanding page read/writes. To handle this, struct fscache_cookie now has an n_active counter: (1) This starts off initialised to 1. (2) Any time the cache needs to get at the netfs data, it calls fscache_use_cookie() to increment it - if it is not zero. If it was zero, then access is not permitted. (3) When the cache has finished with the data, it calls fscache_unuse_cookie() to decrement it. This does a wake-up on it if it reaches 0. (4) __fscache_relinquish_cookie() decrements n_active and then waits for it to reach 0. The initialisation to 1 in step (1) ensures that we only get wake ups when we're trying to get rid of the cookie. This leaves __fscache_relinquish_cookie() a lot simpler. *** This fixes a problem in the current code whereby if fscache_invalidate() is followed sufficiently quickly by fscache_relinquish_cookie() then it is possible for __fscache_relinquish_cookie() to have detached the cookie from the object and cleared the pointer before a thread is dispatched to process the invalidation state in the object state machine. Since the pending write clearance was deferred to the invalidation state to make it asynchronous, we need to either wait in relinquishment for the stores tree to be cleared in the invalidation state or we need to handle the clearance in relinquishment. Further, if the relinquishment code does clear the tree, then the invalidation state need to make the clearance contingent on still having the cookie to hand (since that's where the tree is rooted) and we have to prevent the cookie from disappearing for the duration. This can lead to an oops like the following: BUG: unable to handle kernel NULL pointer dereference at 000000000000000c ... RIP: 0010:[<ffffffff8151023e>] _spin_lock+0xe/0x30 ... CR2: 000000000000000c ... ... Process kslowd002 (...) .... Call Trace: [<ffffffffa01c3278>] fscache_invalidate_writes+0x38/0xd0 [fscache] [<ffffffff810096f0>] ? __switch_to+0xd0/0x320 [<ffffffff8105e759>] ? find_busiest_queue+0x69/0x150 [<ffffffff8110ddd4>] ? slow_work_enqueue+0x104/0x180 [<ffffffffa01c1303>] fscache_object_slow_work_execute+0x5e3/0x9d0 [fscache] [<ffffffff81096b67>] ? bit_waitqueue+0x17/0xd0 [<ffffffff8110e233>] slow_work_execute+0x233/0x310 [<ffffffff8110e515>] slow_work_thread+0x205/0x360 [<ffffffff81096ca0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff8110e310>] ? slow_work_thread+0x0/0x360 [<ffffffff81096936>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968a0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 The parameter to fscache_invalidate_writes() was object->cookie which is NULL. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
op = fscache_alloc_retrieval(cookie, page->mapping,
FS-Cache: Provide the ability to enable/disable cookies Provide the ability to enable and disable fscache cookies. A disabled cookie will reject or ignore further requests to: Acquire a child cookie Invalidate and update backing objects Check the consistency of a backing object Allocate storage for backing page Read backing pages Write to backing pages but still allows: Checks/waits on the completion of already in-progress objects Uncaching of pages Relinquishment of cookies Two new operations are provided: (1) Disable a cookie: void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate); If the cookie is not already disabled, this locks the cookie against other dis/enablement ops, marks the cookie as being disabled, discards or invalidates any backing objects and waits for cessation of activity on any associated object. This is a wrapper around a chunk split out of fscache_relinquish_cookie(), but it reinitialises the cookie such that it can be reenabled. All possible failures are handled internally. The caller should consider calling fscache_uncache_all_inode_pages() afterwards to make sure all page markings are cleared up. (2) Enable a cookie: void fscache_enable_cookie(struct fscache_cookie *cookie, bool (*can_enable)(void *data), void *data) If the cookie is not already enabled, this locks the cookie against other dis/enablement ops, invokes can_enable() and, if the cookie is not an index cookie, will begin the procedure of acquiring backing objects. The optional can_enable() function is passed the data argument and returns a ruling as to whether or not enablement should actually be permitted to begin. All possible failures are handled internally. The cookie will only be marked as enabled if provisional backing objects are allocated. A later patch will introduce these to NFS. Cookie enablement during nfs_open() is then contingent on i_writecount <= 0. can_enable() checks for a race between open(O_RDONLY) and open(O_WRONLY/O_RDWR). This simplifies NFS's cookie handling and allows us to get rid of open(O_RDONLY) accidentally introducing caching to an inode that's open for writing already. One operation has its API modified: (3) Acquire a cookie. struct fscache_cookie *fscache_acquire_cookie( struct fscache_cookie *parent, const struct fscache_cookie_def *def, void *netfs_data, bool enable); This now has an additional argument that indicates whether the requested cookie should be enabled by default. It doesn't need the can_enable() function because the caller must prevent multiple calls for the same netfs object and it doesn't need to take the enablement lock because no one else can get at the cookie before this returns. Signed-off-by: David Howells <dhowells@redhat.com
2013-09-21 01:09:31 +02:00
end_io_func, context);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (!op) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
FS-Cache: The retrieval remaining-pages counter needs to be atomic_t struct fscache_retrieval contains a count of the number of pages that still need some processing (n_pages). This is decremented as the pages are processed. However, this needs to be atomic as fscache_retrieval_complete() (I think) just occasionally may be called from cachefiles_read_backing_file() and cachefiles_read_copier() simultaneously. This happens when an fscache_read_or_alloc_pages() request containing a lot of pages (say a couple of hundred) is being processed. The read on each backing page is dispatched individually because we need to insert a monitor into the waitqueue to catch when the read completes. However, under low-memory conditions, we might be forced to wait in the allocator - and this gives the I/O on the backing page a chance to complete first. When the I/O completes, fscache_enqueue_retrieval() chucks the retrieval onto the workqueue without waiting for the operation to finish the initial I/O dispatch (we want to release any pages we can as soon as we can), thus both can end up running simultaneously and potentially attempting to partially complete the retrieval simultaneously (ENOMEM may occur, backing pages may already be in the page cache). This was demonstrated by parallelling the non-atomic counter with an atomic counter and printing both of them when the assertion fails. At this point, the atomic counter has reached zero, but the non-atomic counter has not. To fix this, make the counter an atomic_t. This results in the following bug appearing FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:421! or FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:414! With a backtrace like the following: RIP: 0010:[<ffffffffa0211b1d>] fscache_put_operation+0x1ad/0x240 [fscache] Call Trace: [<ffffffffa0213185>] fscache_retrieval_work+0x55/0x270 [fscache] [<ffffffffa0213130>] ? fscache_retrieval_work+0x0/0x270 [fscache] [<ffffffff81090b10>] worker_thread+0x170/0x2a0 [<ffffffff81096d10>] ? autoremove_wake_function+0x0/0x40 [<ffffffff810909a0>] ? worker_thread+0x0/0x2a0 [<ffffffff81096966>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968d0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-21 14:44:15 +02:00
atomic_set(&op->n_pages, 1);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_lock(&cookie->lock);
FS-Cache: Provide the ability to enable/disable cookies Provide the ability to enable and disable fscache cookies. A disabled cookie will reject or ignore further requests to: Acquire a child cookie Invalidate and update backing objects Check the consistency of a backing object Allocate storage for backing page Read backing pages Write to backing pages but still allows: Checks/waits on the completion of already in-progress objects Uncaching of pages Relinquishment of cookies Two new operations are provided: (1) Disable a cookie: void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate); If the cookie is not already disabled, this locks the cookie against other dis/enablement ops, marks the cookie as being disabled, discards or invalidates any backing objects and waits for cessation of activity on any associated object. This is a wrapper around a chunk split out of fscache_relinquish_cookie(), but it reinitialises the cookie such that it can be reenabled. All possible failures are handled internally. The caller should consider calling fscache_uncache_all_inode_pages() afterwards to make sure all page markings are cleared up. (2) Enable a cookie: void fscache_enable_cookie(struct fscache_cookie *cookie, bool (*can_enable)(void *data), void *data) If the cookie is not already enabled, this locks the cookie against other dis/enablement ops, invokes can_enable() and, if the cookie is not an index cookie, will begin the procedure of acquiring backing objects. The optional can_enable() function is passed the data argument and returns a ruling as to whether or not enablement should actually be permitted to begin. All possible failures are handled internally. The cookie will only be marked as enabled if provisional backing objects are allocated. A later patch will introduce these to NFS. Cookie enablement during nfs_open() is then contingent on i_writecount <= 0. can_enable() checks for a race between open(O_RDONLY) and open(O_WRONLY/O_RDWR). This simplifies NFS's cookie handling and allows us to get rid of open(O_RDONLY) accidentally introducing caching to an inode that's open for writing already. One operation has its API modified: (3) Acquire a cookie. struct fscache_cookie *fscache_acquire_cookie( struct fscache_cookie *parent, const struct fscache_cookie_def *def, void *netfs_data, bool enable); This now has an additional argument that indicates whether the requested cookie should be enabled by default. It doesn't need the can_enable() function because the caller must prevent multiple calls for the same netfs object and it doesn't need to take the enablement lock because no one else can get at the cookie before this returns. Signed-off-by: David Howells <dhowells@redhat.com
2013-09-21 01:09:31 +02:00
if (!fscache_cookie_enabled(cookie) ||
hlist_empty(&cookie->backing_objects))
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
FS-Cache: Fix object state machine to have separate work and wait states Fix object state machine to have separate work and wait states as that makes it easier to envision. There are now three kinds of state: (1) Work state. This is an execution state. No event processing is performed by a work state. The function attached to a work state returns a pointer indicating the next state to which the OSM should transition. Returning NO_TRANSIT repeats the current state, but goes back to the scheduler first. (2) Wait state. This is an event processing state. No execution is performed by a wait state. Wait states are just tables of "if event X occurs, clear it and transition to state Y". The dispatcher returns to the scheduler if none of the events in which the wait state has an interest are currently pending. (3) Out-of-band state. This is a special work state. Transitions to normal states can be overridden when an unexpected event occurs (eg. I/O error). Instead the dispatcher disables and clears the OOB event and transits to the specified work state. This then acts as an ordinary work state, though object->state points to the overridden destination. Returning NO_TRANSIT resumes the overridden transition. In addition, the states have names in their definitions, so there's no need for tables of state names. Further, the EV_REQUEUE event is no longer necessary as that is automatic for work states. Since the states are now separate structs rather than values in an enum, it's not possible to use comparisons other than (non-)equality between them, so use some object->flags to indicate what phase an object is in. The EV_RELEASE, EV_RETIRE and EV_WITHDRAW events have been squished into one (EV_KILL). An object flag now carries the information about retirement. Similarly, the RELEASING, RECYCLING and WITHDRAWING states have been merged into an KILL_OBJECT state and additional states have been added for handling waiting dependent objects (JUMPSTART_DEPS and KILL_DEPENDENTS). A state has also been added for synchronising with parent object initialisation (WAIT_FOR_PARENT) and another for initiating look up (PARENT_READY). Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
ASSERT(test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags));
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
__fscache_use_cookie(cookie);
atomic_inc(&object->n_reads);
FS-Cache: Fix operation state management and accounting Fix the state management of internal fscache operations and the accounting of what operations are in what states. This is done by: (1) Give struct fscache_operation a enum variable that directly represents the state it's currently in, rather than spreading this knowledge over a bunch of flags, who's processing the operation at the moment and whether it is queued or not. This makes it easier to write assertions to check the state at various points and to prevent invalid state transitions. (2) Add an 'operation complete' state and supply a function to indicate the completion of an operation (fscache_op_complete()) and make things call it. The final call to fscache_put_operation() can then check that an op in the appropriate state (complete or cancelled). (3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better govern the state of an object: (a) The ->n_ops is now the number of extant operations on the object and is now decremented by fscache_put_operation() only. (b) The ->n_in_progress is simply the number of objects that have been taken off of the object's pending queue for the purposes of being run. This is decremented by fscache_op_complete() only. (c) The ->n_exclusive is the number of exclusive ops that have been submitted and queued or are in progress. It is decremented by fscache_op_complete() and by fscache_cancel_op(). fscache_put_operation() and fscache_operation_gc() now no longer try to clean up ->n_exclusive and ->n_in_progress. That was leading to double decrements against fscache_cancel_op(). fscache_cancel_op() now no longer decrements ->n_ops. That was leading to double decrements against fscache_put_operation(). fscache_submit_exclusive_op() now decides whether it has to queue an op based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter will persist in being true even after all preceding operations have been cancelled or completed. Furthermore, if an object is active and there are runnable ops against it, there must be at least one op running. (4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and provide a function to record completion of the pages as they complete. When n_pages reaches 0, the operation is deemed to be complete and fscache_op_complete() is called. Add calls to fscache_retrieval_complete() anywhere we've finished with a page we've been given to read or allocate for. This includes places where we just return pages to the netfs for reading from the server and where accessing the cache fails and we discard the proposed netfs page. The bugs in the unfixed state management manifest themselves as oopses like the following where the operation completion gets out of sync with return of the cookie by the netfs. This is possible because the cache unlocks and returns all the netfs pages before recording its completion - which means that there's nothing to stop the netfs discarding them and returning the cookie. FS-Cache: Cookie 'NFS.fh' still has outstanding reads ------------[ cut here ]------------ kernel BUG at fs/fscache/cookie.c:519! invalid opcode: 0000 [#1] SMP CPU 1 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache] RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282 RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000 RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000 R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98 R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370 FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040) Stack: ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0 ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0 ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91 Call Trace: [<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs] [<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs] [<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs] [<ffffffff810d8d47>] evict+0xa1/0x15c [<ffffffff810d8e2e>] dispose_list+0x2c/0x38 [<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b [<ffffffff810c56b7>] prune_super+0xd5/0x140 [<ffffffff8109b615>] shrink_slab+0x102/0x1ab [<ffffffff8109d690>] balance_pgdat+0x2f2/0x595 [<ffffffff8103e009>] ? process_timeout+0xb/0xb [<ffffffff8109dba3>] kswapd+0x270/0x289 [<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46 [<ffffffff8109d933>] ? balance_pgdat+0x595/0x595 [<ffffffff8104bf7a>] kthread+0x7f/0x87 [<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0 [<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe [<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53 [<ffffffff813ad6b0>] ? gs_change+0xb/0xb Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-20 22:52:35 +01:00
__set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (fscache_submit_op(object, &op->op) < 0)
FS-Cache: Fix operation state management and accounting Fix the state management of internal fscache operations and the accounting of what operations are in what states. This is done by: (1) Give struct fscache_operation a enum variable that directly represents the state it's currently in, rather than spreading this knowledge over a bunch of flags, who's processing the operation at the moment and whether it is queued or not. This makes it easier to write assertions to check the state at various points and to prevent invalid state transitions. (2) Add an 'operation complete' state and supply a function to indicate the completion of an operation (fscache_op_complete()) and make things call it. The final call to fscache_put_operation() can then check that an op in the appropriate state (complete or cancelled). (3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better govern the state of an object: (a) The ->n_ops is now the number of extant operations on the object and is now decremented by fscache_put_operation() only. (b) The ->n_in_progress is simply the number of objects that have been taken off of the object's pending queue for the purposes of being run. This is decremented by fscache_op_complete() only. (c) The ->n_exclusive is the number of exclusive ops that have been submitted and queued or are in progress. It is decremented by fscache_op_complete() and by fscache_cancel_op(). fscache_put_operation() and fscache_operation_gc() now no longer try to clean up ->n_exclusive and ->n_in_progress. That was leading to double decrements against fscache_cancel_op(). fscache_cancel_op() now no longer decrements ->n_ops. That was leading to double decrements against fscache_put_operation(). fscache_submit_exclusive_op() now decides whether it has to queue an op based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter will persist in being true even after all preceding operations have been cancelled or completed. Furthermore, if an object is active and there are runnable ops against it, there must be at least one op running. (4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and provide a function to record completion of the pages as they complete. When n_pages reaches 0, the operation is deemed to be complete and fscache_op_complete() is called. Add calls to fscache_retrieval_complete() anywhere we've finished with a page we've been given to read or allocate for. This includes places where we just return pages to the netfs for reading from the server and where accessing the cache fails and we discard the proposed netfs page. The bugs in the unfixed state management manifest themselves as oopses like the following where the operation completion gets out of sync with return of the cookie by the netfs. This is possible because the cache unlocks and returns all the netfs pages before recording its completion - which means that there's nothing to stop the netfs discarding them and returning the cookie. FS-Cache: Cookie 'NFS.fh' still has outstanding reads ------------[ cut here ]------------ kernel BUG at fs/fscache/cookie.c:519! invalid opcode: 0000 [#1] SMP CPU 1 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache] RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282 RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000 RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000 R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98 R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370 FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040) Stack: ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0 ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0 ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91 Call Trace: [<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs] [<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs] [<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs] [<ffffffff810d8d47>] evict+0xa1/0x15c [<ffffffff810d8e2e>] dispose_list+0x2c/0x38 [<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b [<ffffffff810c56b7>] prune_super+0xd5/0x140 [<ffffffff8109b615>] shrink_slab+0x102/0x1ab [<ffffffff8109d690>] balance_pgdat+0x2f2/0x595 [<ffffffff8103e009>] ? process_timeout+0xb/0xb [<ffffffff8109dba3>] kswapd+0x270/0x289 [<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46 [<ffffffff8109d933>] ? balance_pgdat+0x595/0x595 [<ffffffff8104bf7a>] kthread+0x7f/0x87 [<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0 [<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe [<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53 [<ffffffff813ad6b0>] ? gs_change+0xb/0xb Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-20 22:52:35 +01:00
goto nobufs_unlock_dec;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_retrieval_ops);
/* pin the netfs read context in case we need to do the actual netfs
* read because we've encountered a cache read failure */
fscache_get_context(object->cookie, op->context);
/* we wait for the operation to become active, and then process it
* *here*, in this thread, and not in the thread pool */
ret = fscache_wait_for_operation_activation(
object, &op->op,
__fscache_stat(&fscache_n_retrieval_op_waits),
__fscache_stat(&fscache_n_retrievals_object_dead),
fscache_do_cancel_retrieval);
if (ret < 0)
goto error;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/* ask the cache to honour the operation */
if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
fscache_stat(&fscache_n_cop_allocate_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
ret = object->cache->ops->allocate_page(op, page, gfp);
fscache_stat_d(&fscache_n_cop_allocate_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (ret == 0)
ret = -ENODATA;
} else {
fscache_stat(&fscache_n_cop_read_or_alloc_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
fscache_stat_d(&fscache_n_cop_read_or_alloc_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
}
error:
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (ret == -ENOMEM)
fscache_stat(&fscache_n_retrievals_nomem);
else if (ret == -ERESTARTSYS)
fscache_stat(&fscache_n_retrievals_intr);
else if (ret == -ENODATA)
fscache_stat(&fscache_n_retrievals_nodata);
else if (ret < 0)
fscache_stat(&fscache_n_retrievals_nobufs);
else
fscache_stat(&fscache_n_retrievals_ok);
fscache_put_retrieval(op);
_leave(" = %d", ret);
return ret;
FS-Cache: Fix operation state management and accounting Fix the state management of internal fscache operations and the accounting of what operations are in what states. This is done by: (1) Give struct fscache_operation a enum variable that directly represents the state it's currently in, rather than spreading this knowledge over a bunch of flags, who's processing the operation at the moment and whether it is queued or not. This makes it easier to write assertions to check the state at various points and to prevent invalid state transitions. (2) Add an 'operation complete' state and supply a function to indicate the completion of an operation (fscache_op_complete()) and make things call it. The final call to fscache_put_operation() can then check that an op in the appropriate state (complete or cancelled). (3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better govern the state of an object: (a) The ->n_ops is now the number of extant operations on the object and is now decremented by fscache_put_operation() only. (b) The ->n_in_progress is simply the number of objects that have been taken off of the object's pending queue for the purposes of being run. This is decremented by fscache_op_complete() only. (c) The ->n_exclusive is the number of exclusive ops that have been submitted and queued or are in progress. It is decremented by fscache_op_complete() and by fscache_cancel_op(). fscache_put_operation() and fscache_operation_gc() now no longer try to clean up ->n_exclusive and ->n_in_progress. That was leading to double decrements against fscache_cancel_op(). fscache_cancel_op() now no longer decrements ->n_ops. That was leading to double decrements against fscache_put_operation(). fscache_submit_exclusive_op() now decides whether it has to queue an op based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter will persist in being true even after all preceding operations have been cancelled or completed. Furthermore, if an object is active and there are runnable ops against it, there must be at least one op running. (4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and provide a function to record completion of the pages as they complete. When n_pages reaches 0, the operation is deemed to be complete and fscache_op_complete() is called. Add calls to fscache_retrieval_complete() anywhere we've finished with a page we've been given to read or allocate for. This includes places where we just return pages to the netfs for reading from the server and where accessing the cache fails and we discard the proposed netfs page. The bugs in the unfixed state management manifest themselves as oopses like the following where the operation completion gets out of sync with return of the cookie by the netfs. This is possible because the cache unlocks and returns all the netfs pages before recording its completion - which means that there's nothing to stop the netfs discarding them and returning the cookie. FS-Cache: Cookie 'NFS.fh' still has outstanding reads ------------[ cut here ]------------ kernel BUG at fs/fscache/cookie.c:519! invalid opcode: 0000 [#1] SMP CPU 1 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache] RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282 RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000 RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000 R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98 R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370 FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040) Stack: ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0 ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0 ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91 Call Trace: [<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs] [<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs] [<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs] [<ffffffff810d8d47>] evict+0xa1/0x15c [<ffffffff810d8e2e>] dispose_list+0x2c/0x38 [<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b [<ffffffff810c56b7>] prune_super+0xd5/0x140 [<ffffffff8109b615>] shrink_slab+0x102/0x1ab [<ffffffff8109d690>] balance_pgdat+0x2f2/0x595 [<ffffffff8103e009>] ? process_timeout+0xb/0xb [<ffffffff8109dba3>] kswapd+0x270/0x289 [<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46 [<ffffffff8109d933>] ? balance_pgdat+0x595/0x595 [<ffffffff8104bf7a>] kthread+0x7f/0x87 [<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0 [<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe [<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53 [<ffffffff813ad6b0>] ? gs_change+0xb/0xb Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-20 22:52:35 +01:00
nobufs_unlock_dec:
atomic_dec(&object->n_reads);
wake_cookie = __fscache_unuse_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
nobufs_unlock:
spin_unlock(&cookie->lock);
if (wake_cookie)
__fscache_wake_unused_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
kfree(op);
nobufs:
fscache_stat(&fscache_n_retrievals_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
EXPORT_SYMBOL(__fscache_read_or_alloc_page);
/*
* read a list of page from the cache or allocate a block in which to store
* them
* - we return:
* -ENOMEM - out of memory, some pages may be being read
* -ERESTARTSYS - interrupted, some pages may be being read
* -ENOBUFS - no backing object or space available in which to cache any
* pages not being read
* -ENODATA - no data available in the backing object for some or all of
* the pages
* 0 - dispatched a read on all pages
*
* end_io_func() will be called for each page read from the cache as it is
* finishes being read
*
* any pages for which a read is dispatched will be removed from pages and
* nr_pages
*/
int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp)
{
struct fscache_retrieval *op;
struct fscache_object *object;
bool wake_cookie = false;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
int ret;
_enter("%p,,%d,,,", cookie, *nr_pages);
fscache_stat(&fscache_n_retrievals);
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
_leave(" = -ENOBUFS [invalidating]");
return -ENOBUFS;
}
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(*nr_pages, >, 0);
ASSERT(!list_empty(pages));
if (fscache_wait_for_deferred_lookup(cookie) < 0)
return -ERESTARTSYS;
FS-Cache: Simplify cookie retention for fscache_objects, fixing oops Simplify the way fscache cache objects retain their cookie. The way I implemented the cookie storage handling made synchronisation a pain (ie. the object state machine can't rely on the cookie actually still being there). Instead of the the object being detached from the cookie and the cookie being freed in __fscache_relinquish_cookie(), we defer both operations: (*) The detachment of the object from the list in the cookie now takes place in fscache_drop_object() and is thus governed by the object state machine (fscache_detach_from_cookie() has been removed). (*) The release of the cookie is now in fscache_object_destroy() - which is called by the cache backend just before it frees the object. This means that the fscache_cookie struct is now available to the cache all the way through from ->alloc_object() to ->drop_object() and ->put_object() - meaning that it's no longer necessary to take object->lock to guarantee access. However, __fscache_relinquish_cookie() doesn't wait for the object to go all the way through to destruction before letting the netfs proceed. That would massively slow down the netfs. Since __fscache_relinquish_cookie() leaves the cookie around, in must therefore break all attachments to the netfs - which includes ->def, ->netfs_data and any outstanding page read/writes. To handle this, struct fscache_cookie now has an n_active counter: (1) This starts off initialised to 1. (2) Any time the cache needs to get at the netfs data, it calls fscache_use_cookie() to increment it - if it is not zero. If it was zero, then access is not permitted. (3) When the cache has finished with the data, it calls fscache_unuse_cookie() to decrement it. This does a wake-up on it if it reaches 0. (4) __fscache_relinquish_cookie() decrements n_active and then waits for it to reach 0. The initialisation to 1 in step (1) ensures that we only get wake ups when we're trying to get rid of the cookie. This leaves __fscache_relinquish_cookie() a lot simpler. *** This fixes a problem in the current code whereby if fscache_invalidate() is followed sufficiently quickly by fscache_relinquish_cookie() then it is possible for __fscache_relinquish_cookie() to have detached the cookie from the object and cleared the pointer before a thread is dispatched to process the invalidation state in the object state machine. Since the pending write clearance was deferred to the invalidation state to make it asynchronous, we need to either wait in relinquishment for the stores tree to be cleared in the invalidation state or we need to handle the clearance in relinquishment. Further, if the relinquishment code does clear the tree, then the invalidation state need to make the clearance contingent on still having the cookie to hand (since that's where the tree is rooted) and we have to prevent the cookie from disappearing for the duration. This can lead to an oops like the following: BUG: unable to handle kernel NULL pointer dereference at 000000000000000c ... RIP: 0010:[<ffffffff8151023e>] _spin_lock+0xe/0x30 ... CR2: 000000000000000c ... ... Process kslowd002 (...) .... Call Trace: [<ffffffffa01c3278>] fscache_invalidate_writes+0x38/0xd0 [fscache] [<ffffffff810096f0>] ? __switch_to+0xd0/0x320 [<ffffffff8105e759>] ? find_busiest_queue+0x69/0x150 [<ffffffff8110ddd4>] ? slow_work_enqueue+0x104/0x180 [<ffffffffa01c1303>] fscache_object_slow_work_execute+0x5e3/0x9d0 [fscache] [<ffffffff81096b67>] ? bit_waitqueue+0x17/0xd0 [<ffffffff8110e233>] slow_work_execute+0x233/0x310 [<ffffffff8110e515>] slow_work_thread+0x205/0x360 [<ffffffff81096ca0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff8110e310>] ? slow_work_thread+0x0/0x360 [<ffffffff81096936>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968a0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 The parameter to fscache_invalidate_writes() was object->cookie which is NULL. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
op = fscache_alloc_retrieval(cookie, mapping, end_io_func, context);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (!op)
return -ENOMEM;
FS-Cache: The retrieval remaining-pages counter needs to be atomic_t struct fscache_retrieval contains a count of the number of pages that still need some processing (n_pages). This is decremented as the pages are processed. However, this needs to be atomic as fscache_retrieval_complete() (I think) just occasionally may be called from cachefiles_read_backing_file() and cachefiles_read_copier() simultaneously. This happens when an fscache_read_or_alloc_pages() request containing a lot of pages (say a couple of hundred) is being processed. The read on each backing page is dispatched individually because we need to insert a monitor into the waitqueue to catch when the read completes. However, under low-memory conditions, we might be forced to wait in the allocator - and this gives the I/O on the backing page a chance to complete first. When the I/O completes, fscache_enqueue_retrieval() chucks the retrieval onto the workqueue without waiting for the operation to finish the initial I/O dispatch (we want to release any pages we can as soon as we can), thus both can end up running simultaneously and potentially attempting to partially complete the retrieval simultaneously (ENOMEM may occur, backing pages may already be in the page cache). This was demonstrated by parallelling the non-atomic counter with an atomic counter and printing both of them when the assertion fails. At this point, the atomic counter has reached zero, but the non-atomic counter has not. To fix this, make the counter an atomic_t. This results in the following bug appearing FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:421! or FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:414! With a backtrace like the following: RIP: 0010:[<ffffffffa0211b1d>] fscache_put_operation+0x1ad/0x240 [fscache] Call Trace: [<ffffffffa0213185>] fscache_retrieval_work+0x55/0x270 [fscache] [<ffffffffa0213130>] ? fscache_retrieval_work+0x0/0x270 [fscache] [<ffffffff81090b10>] worker_thread+0x170/0x2a0 [<ffffffff81096d10>] ? autoremove_wake_function+0x0/0x40 [<ffffffff810909a0>] ? worker_thread+0x0/0x2a0 [<ffffffff81096966>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968d0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-21 14:44:15 +02:00
atomic_set(&op->n_pages, *nr_pages);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_lock(&cookie->lock);
FS-Cache: Provide the ability to enable/disable cookies Provide the ability to enable and disable fscache cookies. A disabled cookie will reject or ignore further requests to: Acquire a child cookie Invalidate and update backing objects Check the consistency of a backing object Allocate storage for backing page Read backing pages Write to backing pages but still allows: Checks/waits on the completion of already in-progress objects Uncaching of pages Relinquishment of cookies Two new operations are provided: (1) Disable a cookie: void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate); If the cookie is not already disabled, this locks the cookie against other dis/enablement ops, marks the cookie as being disabled, discards or invalidates any backing objects and waits for cessation of activity on any associated object. This is a wrapper around a chunk split out of fscache_relinquish_cookie(), but it reinitialises the cookie such that it can be reenabled. All possible failures are handled internally. The caller should consider calling fscache_uncache_all_inode_pages() afterwards to make sure all page markings are cleared up. (2) Enable a cookie: void fscache_enable_cookie(struct fscache_cookie *cookie, bool (*can_enable)(void *data), void *data) If the cookie is not already enabled, this locks the cookie against other dis/enablement ops, invokes can_enable() and, if the cookie is not an index cookie, will begin the procedure of acquiring backing objects. The optional can_enable() function is passed the data argument and returns a ruling as to whether or not enablement should actually be permitted to begin. All possible failures are handled internally. The cookie will only be marked as enabled if provisional backing objects are allocated. A later patch will introduce these to NFS. Cookie enablement during nfs_open() is then contingent on i_writecount <= 0. can_enable() checks for a race between open(O_RDONLY) and open(O_WRONLY/O_RDWR). This simplifies NFS's cookie handling and allows us to get rid of open(O_RDONLY) accidentally introducing caching to an inode that's open for writing already. One operation has its API modified: (3) Acquire a cookie. struct fscache_cookie *fscache_acquire_cookie( struct fscache_cookie *parent, const struct fscache_cookie_def *def, void *netfs_data, bool enable); This now has an additional argument that indicates whether the requested cookie should be enabled by default. It doesn't need the can_enable() function because the caller must prevent multiple calls for the same netfs object and it doesn't need to take the enablement lock because no one else can get at the cookie before this returns. Signed-off-by: David Howells <dhowells@redhat.com
2013-09-21 01:09:31 +02:00
if (!fscache_cookie_enabled(cookie) ||
hlist_empty(&cookie->backing_objects))
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
__fscache_use_cookie(cookie);
atomic_inc(&object->n_reads);
FS-Cache: Fix operation state management and accounting Fix the state management of internal fscache operations and the accounting of what operations are in what states. This is done by: (1) Give struct fscache_operation a enum variable that directly represents the state it's currently in, rather than spreading this knowledge over a bunch of flags, who's processing the operation at the moment and whether it is queued or not. This makes it easier to write assertions to check the state at various points and to prevent invalid state transitions. (2) Add an 'operation complete' state and supply a function to indicate the completion of an operation (fscache_op_complete()) and make things call it. The final call to fscache_put_operation() can then check that an op in the appropriate state (complete or cancelled). (3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better govern the state of an object: (a) The ->n_ops is now the number of extant operations on the object and is now decremented by fscache_put_operation() only. (b) The ->n_in_progress is simply the number of objects that have been taken off of the object's pending queue for the purposes of being run. This is decremented by fscache_op_complete() only. (c) The ->n_exclusive is the number of exclusive ops that have been submitted and queued or are in progress. It is decremented by fscache_op_complete() and by fscache_cancel_op(). fscache_put_operation() and fscache_operation_gc() now no longer try to clean up ->n_exclusive and ->n_in_progress. That was leading to double decrements against fscache_cancel_op(). fscache_cancel_op() now no longer decrements ->n_ops. That was leading to double decrements against fscache_put_operation(). fscache_submit_exclusive_op() now decides whether it has to queue an op based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter will persist in being true even after all preceding operations have been cancelled or completed. Furthermore, if an object is active and there are runnable ops against it, there must be at least one op running. (4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and provide a function to record completion of the pages as they complete. When n_pages reaches 0, the operation is deemed to be complete and fscache_op_complete() is called. Add calls to fscache_retrieval_complete() anywhere we've finished with a page we've been given to read or allocate for. This includes places where we just return pages to the netfs for reading from the server and where accessing the cache fails and we discard the proposed netfs page. The bugs in the unfixed state management manifest themselves as oopses like the following where the operation completion gets out of sync with return of the cookie by the netfs. This is possible because the cache unlocks and returns all the netfs pages before recording its completion - which means that there's nothing to stop the netfs discarding them and returning the cookie. FS-Cache: Cookie 'NFS.fh' still has outstanding reads ------------[ cut here ]------------ kernel BUG at fs/fscache/cookie.c:519! invalid opcode: 0000 [#1] SMP CPU 1 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache] RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282 RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000 RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000 R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98 R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370 FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040) Stack: ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0 ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0 ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91 Call Trace: [<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs] [<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs] [<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs] [<ffffffff810d8d47>] evict+0xa1/0x15c [<ffffffff810d8e2e>] dispose_list+0x2c/0x38 [<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b [<ffffffff810c56b7>] prune_super+0xd5/0x140 [<ffffffff8109b615>] shrink_slab+0x102/0x1ab [<ffffffff8109d690>] balance_pgdat+0x2f2/0x595 [<ffffffff8103e009>] ? process_timeout+0xb/0xb [<ffffffff8109dba3>] kswapd+0x270/0x289 [<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46 [<ffffffff8109d933>] ? balance_pgdat+0x595/0x595 [<ffffffff8104bf7a>] kthread+0x7f/0x87 [<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0 [<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe [<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53 [<ffffffff813ad6b0>] ? gs_change+0xb/0xb Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-20 22:52:35 +01:00
__set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (fscache_submit_op(object, &op->op) < 0)
FS-Cache: Fix operation state management and accounting Fix the state management of internal fscache operations and the accounting of what operations are in what states. This is done by: (1) Give struct fscache_operation a enum variable that directly represents the state it's currently in, rather than spreading this knowledge over a bunch of flags, who's processing the operation at the moment and whether it is queued or not. This makes it easier to write assertions to check the state at various points and to prevent invalid state transitions. (2) Add an 'operation complete' state and supply a function to indicate the completion of an operation (fscache_op_complete()) and make things call it. The final call to fscache_put_operation() can then check that an op in the appropriate state (complete or cancelled). (3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better govern the state of an object: (a) The ->n_ops is now the number of extant operations on the object and is now decremented by fscache_put_operation() only. (b) The ->n_in_progress is simply the number of objects that have been taken off of the object's pending queue for the purposes of being run. This is decremented by fscache_op_complete() only. (c) The ->n_exclusive is the number of exclusive ops that have been submitted and queued or are in progress. It is decremented by fscache_op_complete() and by fscache_cancel_op(). fscache_put_operation() and fscache_operation_gc() now no longer try to clean up ->n_exclusive and ->n_in_progress. That was leading to double decrements against fscache_cancel_op(). fscache_cancel_op() now no longer decrements ->n_ops. That was leading to double decrements against fscache_put_operation(). fscache_submit_exclusive_op() now decides whether it has to queue an op based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter will persist in being true even after all preceding operations have been cancelled or completed. Furthermore, if an object is active and there are runnable ops against it, there must be at least one op running. (4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and provide a function to record completion of the pages as they complete. When n_pages reaches 0, the operation is deemed to be complete and fscache_op_complete() is called. Add calls to fscache_retrieval_complete() anywhere we've finished with a page we've been given to read or allocate for. This includes places where we just return pages to the netfs for reading from the server and where accessing the cache fails and we discard the proposed netfs page. The bugs in the unfixed state management manifest themselves as oopses like the following where the operation completion gets out of sync with return of the cookie by the netfs. This is possible because the cache unlocks and returns all the netfs pages before recording its completion - which means that there's nothing to stop the netfs discarding them and returning the cookie. FS-Cache: Cookie 'NFS.fh' still has outstanding reads ------------[ cut here ]------------ kernel BUG at fs/fscache/cookie.c:519! invalid opcode: 0000 [#1] SMP CPU 1 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache] RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282 RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000 RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000 R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98 R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370 FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040) Stack: ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0 ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0 ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91 Call Trace: [<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs] [<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs] [<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs] [<ffffffff810d8d47>] evict+0xa1/0x15c [<ffffffff810d8e2e>] dispose_list+0x2c/0x38 [<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b [<ffffffff810c56b7>] prune_super+0xd5/0x140 [<ffffffff8109b615>] shrink_slab+0x102/0x1ab [<ffffffff8109d690>] balance_pgdat+0x2f2/0x595 [<ffffffff8103e009>] ? process_timeout+0xb/0xb [<ffffffff8109dba3>] kswapd+0x270/0x289 [<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46 [<ffffffff8109d933>] ? balance_pgdat+0x595/0x595 [<ffffffff8104bf7a>] kthread+0x7f/0x87 [<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0 [<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe [<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53 [<ffffffff813ad6b0>] ? gs_change+0xb/0xb Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-20 22:52:35 +01:00
goto nobufs_unlock_dec;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_retrieval_ops);
/* pin the netfs read context in case we need to do the actual netfs
* read because we've encountered a cache read failure */
fscache_get_context(object->cookie, op->context);
/* we wait for the operation to become active, and then process it
* *here*, in this thread, and not in the thread pool */
ret = fscache_wait_for_operation_activation(
object, &op->op,
__fscache_stat(&fscache_n_retrieval_op_waits),
__fscache_stat(&fscache_n_retrievals_object_dead),
fscache_do_cancel_retrieval);
if (ret < 0)
goto error;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/* ask the cache to honour the operation */
if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
fscache_stat(&fscache_n_cop_allocate_pages);
ret = object->cache->ops->allocate_pages(
op, pages, nr_pages, gfp);
fscache_stat_d(&fscache_n_cop_allocate_pages);
} else {
fscache_stat(&fscache_n_cop_read_or_alloc_pages);
ret = object->cache->ops->read_or_alloc_pages(
op, pages, nr_pages, gfp);
fscache_stat_d(&fscache_n_cop_read_or_alloc_pages);
}
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
error:
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (ret == -ENOMEM)
fscache_stat(&fscache_n_retrievals_nomem);
else if (ret == -ERESTARTSYS)
fscache_stat(&fscache_n_retrievals_intr);
else if (ret == -ENODATA)
fscache_stat(&fscache_n_retrievals_nodata);
else if (ret < 0)
fscache_stat(&fscache_n_retrievals_nobufs);
else
fscache_stat(&fscache_n_retrievals_ok);
fscache_put_retrieval(op);
_leave(" = %d", ret);
return ret;
FS-Cache: Fix operation state management and accounting Fix the state management of internal fscache operations and the accounting of what operations are in what states. This is done by: (1) Give struct fscache_operation a enum variable that directly represents the state it's currently in, rather than spreading this knowledge over a bunch of flags, who's processing the operation at the moment and whether it is queued or not. This makes it easier to write assertions to check the state at various points and to prevent invalid state transitions. (2) Add an 'operation complete' state and supply a function to indicate the completion of an operation (fscache_op_complete()) and make things call it. The final call to fscache_put_operation() can then check that an op in the appropriate state (complete or cancelled). (3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better govern the state of an object: (a) The ->n_ops is now the number of extant operations on the object and is now decremented by fscache_put_operation() only. (b) The ->n_in_progress is simply the number of objects that have been taken off of the object's pending queue for the purposes of being run. This is decremented by fscache_op_complete() only. (c) The ->n_exclusive is the number of exclusive ops that have been submitted and queued or are in progress. It is decremented by fscache_op_complete() and by fscache_cancel_op(). fscache_put_operation() and fscache_operation_gc() now no longer try to clean up ->n_exclusive and ->n_in_progress. That was leading to double decrements against fscache_cancel_op(). fscache_cancel_op() now no longer decrements ->n_ops. That was leading to double decrements against fscache_put_operation(). fscache_submit_exclusive_op() now decides whether it has to queue an op based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter will persist in being true even after all preceding operations have been cancelled or completed. Furthermore, if an object is active and there are runnable ops against it, there must be at least one op running. (4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and provide a function to record completion of the pages as they complete. When n_pages reaches 0, the operation is deemed to be complete and fscache_op_complete() is called. Add calls to fscache_retrieval_complete() anywhere we've finished with a page we've been given to read or allocate for. This includes places where we just return pages to the netfs for reading from the server and where accessing the cache fails and we discard the proposed netfs page. The bugs in the unfixed state management manifest themselves as oopses like the following where the operation completion gets out of sync with return of the cookie by the netfs. This is possible because the cache unlocks and returns all the netfs pages before recording its completion - which means that there's nothing to stop the netfs discarding them and returning the cookie. FS-Cache: Cookie 'NFS.fh' still has outstanding reads ------------[ cut here ]------------ kernel BUG at fs/fscache/cookie.c:519! invalid opcode: 0000 [#1] SMP CPU 1 Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache] RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282 RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000 RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000 R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98 R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370 FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040) Stack: ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0 ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0 ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91 Call Trace: [<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs] [<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs] [<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs] [<ffffffff810d8d47>] evict+0xa1/0x15c [<ffffffff810d8e2e>] dispose_list+0x2c/0x38 [<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b [<ffffffff810c56b7>] prune_super+0xd5/0x140 [<ffffffff8109b615>] shrink_slab+0x102/0x1ab [<ffffffff8109d690>] balance_pgdat+0x2f2/0x595 [<ffffffff8103e009>] ? process_timeout+0xb/0xb [<ffffffff8109dba3>] kswapd+0x270/0x289 [<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46 [<ffffffff8109d933>] ? balance_pgdat+0x595/0x595 [<ffffffff8104bf7a>] kthread+0x7f/0x87 [<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0 [<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe [<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53 [<ffffffff813ad6b0>] ? gs_change+0xb/0xb Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-20 22:52:35 +01:00
nobufs_unlock_dec:
atomic_dec(&object->n_reads);
wake_cookie = __fscache_unuse_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
nobufs_unlock:
spin_unlock(&cookie->lock);
kfree(op);
if (wake_cookie)
__fscache_wake_unused_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
nobufs:
fscache_stat(&fscache_n_retrievals_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
/*
* allocate a block in the cache on which to store a page
* - we return:
* -ENOMEM - out of memory, nothing done
* -ERESTARTSYS - interrupted
* -ENOBUFS - no backing object available in which to cache the block
* 0 - block allocated
*/
int __fscache_alloc_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
struct fscache_retrieval *op;
struct fscache_object *object;
bool wake_cookie = false;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
int ret;
_enter("%p,%p,,,", cookie, page);
fscache_stat(&fscache_n_allocs);
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(page, !=, NULL);
if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
_leave(" = -ENOBUFS [invalidating]");
return -ENOBUFS;
}
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (fscache_wait_for_deferred_lookup(cookie) < 0)
return -ERESTARTSYS;
FS-Cache: Simplify cookie retention for fscache_objects, fixing oops Simplify the way fscache cache objects retain their cookie. The way I implemented the cookie storage handling made synchronisation a pain (ie. the object state machine can't rely on the cookie actually still being there). Instead of the the object being detached from the cookie and the cookie being freed in __fscache_relinquish_cookie(), we defer both operations: (*) The detachment of the object from the list in the cookie now takes place in fscache_drop_object() and is thus governed by the object state machine (fscache_detach_from_cookie() has been removed). (*) The release of the cookie is now in fscache_object_destroy() - which is called by the cache backend just before it frees the object. This means that the fscache_cookie struct is now available to the cache all the way through from ->alloc_object() to ->drop_object() and ->put_object() - meaning that it's no longer necessary to take object->lock to guarantee access. However, __fscache_relinquish_cookie() doesn't wait for the object to go all the way through to destruction before letting the netfs proceed. That would massively slow down the netfs. Since __fscache_relinquish_cookie() leaves the cookie around, in must therefore break all attachments to the netfs - which includes ->def, ->netfs_data and any outstanding page read/writes. To handle this, struct fscache_cookie now has an n_active counter: (1) This starts off initialised to 1. (2) Any time the cache needs to get at the netfs data, it calls fscache_use_cookie() to increment it - if it is not zero. If it was zero, then access is not permitted. (3) When the cache has finished with the data, it calls fscache_unuse_cookie() to decrement it. This does a wake-up on it if it reaches 0. (4) __fscache_relinquish_cookie() decrements n_active and then waits for it to reach 0. The initialisation to 1 in step (1) ensures that we only get wake ups when we're trying to get rid of the cookie. This leaves __fscache_relinquish_cookie() a lot simpler. *** This fixes a problem in the current code whereby if fscache_invalidate() is followed sufficiently quickly by fscache_relinquish_cookie() then it is possible for __fscache_relinquish_cookie() to have detached the cookie from the object and cleared the pointer before a thread is dispatched to process the invalidation state in the object state machine. Since the pending write clearance was deferred to the invalidation state to make it asynchronous, we need to either wait in relinquishment for the stores tree to be cleared in the invalidation state or we need to handle the clearance in relinquishment. Further, if the relinquishment code does clear the tree, then the invalidation state need to make the clearance contingent on still having the cookie to hand (since that's where the tree is rooted) and we have to prevent the cookie from disappearing for the duration. This can lead to an oops like the following: BUG: unable to handle kernel NULL pointer dereference at 000000000000000c ... RIP: 0010:[<ffffffff8151023e>] _spin_lock+0xe/0x30 ... CR2: 000000000000000c ... ... Process kslowd002 (...) .... Call Trace: [<ffffffffa01c3278>] fscache_invalidate_writes+0x38/0xd0 [fscache] [<ffffffff810096f0>] ? __switch_to+0xd0/0x320 [<ffffffff8105e759>] ? find_busiest_queue+0x69/0x150 [<ffffffff8110ddd4>] ? slow_work_enqueue+0x104/0x180 [<ffffffffa01c1303>] fscache_object_slow_work_execute+0x5e3/0x9d0 [fscache] [<ffffffff81096b67>] ? bit_waitqueue+0x17/0xd0 [<ffffffff8110e233>] slow_work_execute+0x233/0x310 [<ffffffff8110e515>] slow_work_thread+0x205/0x360 [<ffffffff81096ca0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff8110e310>] ? slow_work_thread+0x0/0x360 [<ffffffff81096936>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968a0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 The parameter to fscache_invalidate_writes() was object->cookie which is NULL. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
op = fscache_alloc_retrieval(cookie, page->mapping, NULL, NULL);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (!op)
return -ENOMEM;
FS-Cache: The retrieval remaining-pages counter needs to be atomic_t struct fscache_retrieval contains a count of the number of pages that still need some processing (n_pages). This is decremented as the pages are processed. However, this needs to be atomic as fscache_retrieval_complete() (I think) just occasionally may be called from cachefiles_read_backing_file() and cachefiles_read_copier() simultaneously. This happens when an fscache_read_or_alloc_pages() request containing a lot of pages (say a couple of hundred) is being processed. The read on each backing page is dispatched individually because we need to insert a monitor into the waitqueue to catch when the read completes. However, under low-memory conditions, we might be forced to wait in the allocator - and this gives the I/O on the backing page a chance to complete first. When the I/O completes, fscache_enqueue_retrieval() chucks the retrieval onto the workqueue without waiting for the operation to finish the initial I/O dispatch (we want to release any pages we can as soon as we can), thus both can end up running simultaneously and potentially attempting to partially complete the retrieval simultaneously (ENOMEM may occur, backing pages may already be in the page cache). This was demonstrated by parallelling the non-atomic counter with an atomic counter and printing both of them when the assertion fails. At this point, the atomic counter has reached zero, but the non-atomic counter has not. To fix this, make the counter an atomic_t. This results in the following bug appearing FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:421! or FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:414! With a backtrace like the following: RIP: 0010:[<ffffffffa0211b1d>] fscache_put_operation+0x1ad/0x240 [fscache] Call Trace: [<ffffffffa0213185>] fscache_retrieval_work+0x55/0x270 [fscache] [<ffffffffa0213130>] ? fscache_retrieval_work+0x0/0x270 [fscache] [<ffffffff81090b10>] worker_thread+0x170/0x2a0 [<ffffffff81096d10>] ? autoremove_wake_function+0x0/0x40 [<ffffffff810909a0>] ? worker_thread+0x0/0x2a0 [<ffffffff81096966>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968d0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-21 14:44:15 +02:00
atomic_set(&op->n_pages, 1);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_lock(&cookie->lock);
FS-Cache: Provide the ability to enable/disable cookies Provide the ability to enable and disable fscache cookies. A disabled cookie will reject or ignore further requests to: Acquire a child cookie Invalidate and update backing objects Check the consistency of a backing object Allocate storage for backing page Read backing pages Write to backing pages but still allows: Checks/waits on the completion of already in-progress objects Uncaching of pages Relinquishment of cookies Two new operations are provided: (1) Disable a cookie: void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate); If the cookie is not already disabled, this locks the cookie against other dis/enablement ops, marks the cookie as being disabled, discards or invalidates any backing objects and waits for cessation of activity on any associated object. This is a wrapper around a chunk split out of fscache_relinquish_cookie(), but it reinitialises the cookie such that it can be reenabled. All possible failures are handled internally. The caller should consider calling fscache_uncache_all_inode_pages() afterwards to make sure all page markings are cleared up. (2) Enable a cookie: void fscache_enable_cookie(struct fscache_cookie *cookie, bool (*can_enable)(void *data), void *data) If the cookie is not already enabled, this locks the cookie against other dis/enablement ops, invokes can_enable() and, if the cookie is not an index cookie, will begin the procedure of acquiring backing objects. The optional can_enable() function is passed the data argument and returns a ruling as to whether or not enablement should actually be permitted to begin. All possible failures are handled internally. The cookie will only be marked as enabled if provisional backing objects are allocated. A later patch will introduce these to NFS. Cookie enablement during nfs_open() is then contingent on i_writecount <= 0. can_enable() checks for a race between open(O_RDONLY) and open(O_WRONLY/O_RDWR). This simplifies NFS's cookie handling and allows us to get rid of open(O_RDONLY) accidentally introducing caching to an inode that's open for writing already. One operation has its API modified: (3) Acquire a cookie. struct fscache_cookie *fscache_acquire_cookie( struct fscache_cookie *parent, const struct fscache_cookie_def *def, void *netfs_data, bool enable); This now has an additional argument that indicates whether the requested cookie should be enabled by default. It doesn't need the can_enable() function because the caller must prevent multiple calls for the same netfs object and it doesn't need to take the enablement lock because no one else can get at the cookie before this returns. Signed-off-by: David Howells <dhowells@redhat.com
2013-09-21 01:09:31 +02:00
if (!fscache_cookie_enabled(cookie) ||
hlist_empty(&cookie->backing_objects))
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
__fscache_use_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (fscache_submit_op(object, &op->op) < 0)
goto nobufs_unlock_dec;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_alloc_ops);
ret = fscache_wait_for_operation_activation(
object, &op->op,
__fscache_stat(&fscache_n_alloc_op_waits),
__fscache_stat(&fscache_n_allocs_object_dead),
fscache_do_cancel_retrieval);
if (ret < 0)
goto error;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/* ask the cache to honour the operation */
fscache_stat(&fscache_n_cop_allocate_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
ret = object->cache->ops->allocate_page(op, page, gfp);
fscache_stat_d(&fscache_n_cop_allocate_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
error:
if (ret == -ERESTARTSYS)
fscache_stat(&fscache_n_allocs_intr);
else if (ret < 0)
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
fscache_stat(&fscache_n_allocs_nobufs);
else
fscache_stat(&fscache_n_allocs_ok);
fscache_put_retrieval(op);
_leave(" = %d", ret);
return ret;
nobufs_unlock_dec:
wake_cookie = __fscache_unuse_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
nobufs_unlock:
spin_unlock(&cookie->lock);
kfree(op);
if (wake_cookie)
__fscache_wake_unused_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
nobufs:
fscache_stat(&fscache_n_allocs_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
EXPORT_SYMBOL(__fscache_alloc_page);
fscache: Netfs function for cleanup post readpages Currently the fscache code expect the netfs to call fscache_readpages_or_alloc inside the aops readpages callback. It marks all the pages in the list provided by readahead with PG_private_2. In the cases that the netfs fails to read all the pages (which is legal) it ends up returning to the readahead and triggering a BUG. This happens because the page list still contains marked pages. This patch implements a simple fscache_readpages_cancel function that the netfs should call before returning from readpages. It will revoke the pages from the underlying cache backend and unmark them. The problem was originally worked out in the Ceph devel tree, but it also occurs in CIFS. It appears that NFS, AFS and 9P are okay as read_cache_pages() will clean up the unprocessed pages in the case of an error. This can be used to address the following oops: [12410647.597278] BUG: Bad page state in process petabucket pfn:3d504e [12410647.597292] page:ffffea000f541380 count:0 mapcount:0 mapping: (null) index:0x0 [12410647.597298] page flags: 0x200000000001000(private_2) ... [12410647.597334] Call Trace: [12410647.597345] [<ffffffff815523f2>] dump_stack+0x19/0x1b [12410647.597356] [<ffffffff8111def7>] bad_page+0xc7/0x120 [12410647.597359] [<ffffffff8111e49e>] free_pages_prepare+0x10e/0x120 [12410647.597361] [<ffffffff8111fc80>] free_hot_cold_page+0x40/0x170 [12410647.597363] [<ffffffff81123507>] __put_single_page+0x27/0x30 [12410647.597365] [<ffffffff81123df5>] put_page+0x25/0x40 [12410647.597376] [<ffffffffa02bdcf9>] ceph_readpages+0x2e9/0x6e0 [ceph] [12410647.597379] [<ffffffff81122a8f>] __do_page_cache_readahead+0x1af/0x260 [12410647.597382] [<ffffffff81122ea1>] ra_submit+0x21/0x30 [12410647.597384] [<ffffffff81118f64>] filemap_fault+0x254/0x490 [12410647.597387] [<ffffffff8113a74f>] __do_fault+0x6f/0x4e0 [12410647.597391] [<ffffffff810125bd>] ? __switch_to+0x16d/0x4a0 [12410647.597395] [<ffffffff810865ba>] ? finish_task_switch+0x5a/0xc0 [12410647.597398] [<ffffffff8113d856>] handle_pte_fault+0xf6/0x930 [12410647.597401] [<ffffffff81008c33>] ? pte_mfn_to_pfn+0x93/0x110 [12410647.597403] [<ffffffff81008cce>] ? xen_pmd_val+0xe/0x10 [12410647.597405] [<ffffffff81005469>] ? __raw_callee_save_xen_pmd_val+0x11/0x1e [12410647.597407] [<ffffffff8113f361>] handle_mm_fault+0x251/0x370 [12410647.597411] [<ffffffff812b0ac4>] ? call_rwsem_down_read_failed+0x14/0x30 [12410647.597414] [<ffffffff8155bffa>] __do_page_fault+0x1aa/0x550 [12410647.597418] [<ffffffff8108011d>] ? up_write+0x1d/0x20 [12410647.597422] [<ffffffff8113141c>] ? vm_mmap_pgoff+0xbc/0xe0 [12410647.597425] [<ffffffff81143bb8>] ? SyS_mmap_pgoff+0xd8/0x240 [12410647.597427] [<ffffffff8155c3ae>] do_page_fault+0xe/0x10 [12410647.597431] [<ffffffff81558818>] page_fault+0x28/0x30 Signed-off-by: Milosz Tanski <milosz@adfin.com> Signed-off-by: David Howells <dhowells@redhat.com>
2013-08-21 23:30:11 +02:00
/*
* Unmark pages allocate in the readahead code path (via:
* fscache_readpages_or_alloc) after delegating to the base filesystem
*/
void __fscache_readpages_cancel(struct fscache_cookie *cookie,
struct list_head *pages)
{
struct page *page;
list_for_each_entry(page, pages, lru) {
if (PageFsCache(page))
__fscache_uncache_page(cookie, page);
}
}
EXPORT_SYMBOL(__fscache_readpages_cancel);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/*
* release a write op reference
*/
static void fscache_release_write_op(struct fscache_operation *_op)
{
_enter("{OP%x}", _op->debug_id);
}
/*
* perform the background storage of a page into the cache
*/
static void fscache_write_op(struct fscache_operation *_op)
{
struct fscache_storage *op =
container_of(_op, struct fscache_storage, op);
struct fscache_object *object = op->op.object;
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
struct fscache_cookie *cookie;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
struct page *page;
unsigned n;
void *results[1];
int ret;
_enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
spin_lock(&object->lock);
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
cookie = object->cookie;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
FS-Cache: One of the write operation paths doesn't set the object state In fscache_write_op(), if the object is determined to have become inactive or to have lost its cookie, we don't move the operation state from in-progress, and so an assertion in fscache_put_operation() fails with an assertion (see below). Instrumenting fscache_op_work_func() indicates that it called fscache_write_op() before calling fscache_put_operation() - where the assertion failed. The assertion at line 433 indicates that the operation state is IN_PROGRESS rather than being COMPLETE or CANCELLED. Instrumenting fscache_write_op() showed that it was being called on an object that had had its cookie removed and that this was due to relinquishment of the cookie by the netfs. At this point fscache no longer has access to the pages of netfs data that were requested to be written, and so simply cancelling the operation is the thing to do. FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:433! invalid opcode: 0000 [#1] SMP Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F) CPU 0 Pid: 1035, comm: kworker/u:3 Tainted: GF 3.7.0-rc8-fsdevel+ #411 /DG965RY RIP: 0010:[<ffffffffa007db22>] [<ffffffffa007db22>] fscache_put_operation+0x11a/0x2ed [fscache] RSP: 0018:ffff88003e32bcf8 EFLAGS: 00010296 RAX: 000000000000000f RBX: ffff88001818eb78 RCX: ffffffff6c102000 RDX: ffffffff8102d1ad RSI: ffffffff6c102000 RDI: ffffffff8102d1d6 RBP: ffff88003e32bd18 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa00811da R13: 0000000000000001 R14: 0000000100625d26 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fff7dd31c68 CR3: 000000003d730000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/u:3 (pid: 1035, threadinfo ffff88003e32a000, task ffff88003bb38080) Stack: ffffffff8102d1ad ffff88001818eb78 ffffffffa00811da 0000000000000001 ffff88003e32bd48 ffffffffa007f0ad ffff88001818eb78 ffffffff819583c0 ffff88003df24e00 ffff88003882c3e0 ffff88003e32bde8 ffffffff81042de0 Call Trace: [<ffffffff8102d1ad>] ? vprintk_emit+0x3c6/0x41a [<ffffffffa00811da>] ? __fscache_read_or_alloc_pages+0x4bc/0x4bc [fscache] [<ffffffffa007f0ad>] fscache_op_work_func+0xec/0x123 [fscache] [<ffffffff81042de0>] process_one_work+0x21c/0x3b0 [<ffffffff81042d82>] ? process_one_work+0x1be/0x3b0 [<ffffffffa007efc1>] ? fscache_operation_gc+0x23e/0x23e [fscache] [<ffffffff8104332e>] worker_thread+0x202/0x2df [<ffffffff8104312c>] ? rescuer_thread+0x18e/0x18e [<ffffffff81047c1c>] kthread+0xd0/0xd8 [<ffffffff81421bfa>] ? _raw_spin_unlock_irq+0x29/0x3e [<ffffffff81047b4c>] ? __init_kthread_worker+0x55/0x55 [<ffffffff814227ec>] ret_from_fork+0x7c/0xb0 [<ffffffff81047b4c>] ? __init_kthread_worker+0x55/0x55 Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-07 11:41:26 +01:00
if (!fscache_object_is_active(object)) {
/* If we get here, then the on-disk cache object likely longer
* exists, so we should just cancel this write operation.
*/
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&object->lock);
fscache_op_complete(&op->op, false);
FS-Cache: One of the write operation paths doesn't set the object state In fscache_write_op(), if the object is determined to have become inactive or to have lost its cookie, we don't move the operation state from in-progress, and so an assertion in fscache_put_operation() fails with an assertion (see below). Instrumenting fscache_op_work_func() indicates that it called fscache_write_op() before calling fscache_put_operation() - where the assertion failed. The assertion at line 433 indicates that the operation state is IN_PROGRESS rather than being COMPLETE or CANCELLED. Instrumenting fscache_write_op() showed that it was being called on an object that had had its cookie removed and that this was due to relinquishment of the cookie by the netfs. At this point fscache no longer has access to the pages of netfs data that were requested to be written, and so simply cancelling the operation is the thing to do. FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:433! invalid opcode: 0000 [#1] SMP Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F) CPU 0 Pid: 1035, comm: kworker/u:3 Tainted: GF 3.7.0-rc8-fsdevel+ #411 /DG965RY RIP: 0010:[<ffffffffa007db22>] [<ffffffffa007db22>] fscache_put_operation+0x11a/0x2ed [fscache] RSP: 0018:ffff88003e32bcf8 EFLAGS: 00010296 RAX: 000000000000000f RBX: ffff88001818eb78 RCX: ffffffff6c102000 RDX: ffffffff8102d1ad RSI: ffffffff6c102000 RDI: ffffffff8102d1d6 RBP: ffff88003e32bd18 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa00811da R13: 0000000000000001 R14: 0000000100625d26 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fff7dd31c68 CR3: 000000003d730000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/u:3 (pid: 1035, threadinfo ffff88003e32a000, task ffff88003bb38080) Stack: ffffffff8102d1ad ffff88001818eb78 ffffffffa00811da 0000000000000001 ffff88003e32bd48 ffffffffa007f0ad ffff88001818eb78 ffffffff819583c0 ffff88003df24e00 ffff88003882c3e0 ffff88003e32bde8 ffffffff81042de0 Call Trace: [<ffffffff8102d1ad>] ? vprintk_emit+0x3c6/0x41a [<ffffffffa00811da>] ? __fscache_read_or_alloc_pages+0x4bc/0x4bc [fscache] [<ffffffffa007f0ad>] fscache_op_work_func+0xec/0x123 [fscache] [<ffffffff81042de0>] process_one_work+0x21c/0x3b0 [<ffffffff81042d82>] ? process_one_work+0x1be/0x3b0 [<ffffffffa007efc1>] ? fscache_operation_gc+0x23e/0x23e [fscache] [<ffffffff8104332e>] worker_thread+0x202/0x2df [<ffffffff8104312c>] ? rescuer_thread+0x18e/0x18e [<ffffffff81047c1c>] kthread+0xd0/0xd8 [<ffffffff81421bfa>] ? _raw_spin_unlock_irq+0x29/0x3e [<ffffffff81047b4c>] ? __init_kthread_worker+0x55/0x55 [<ffffffff814227ec>] ret_from_fork+0x7c/0xb0 [<ffffffff81047b4c>] ? __init_kthread_worker+0x55/0x55 Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-07 11:41:26 +01:00
_leave(" [inactive]");
return;
}
if (!cookie) {
/* If we get here, then the cookie belonging to the object was
* detached, probably by the cookie being withdrawn due to
* memory pressure, which means that the pages we might write
* to the cache from no longer exist - therefore, we can just
* cancel this write operation.
*/
spin_unlock(&object->lock);
fscache_op_complete(&op->op, false);
FS-Cache: Fix object state machine to have separate work and wait states Fix object state machine to have separate work and wait states as that makes it easier to envision. There are now three kinds of state: (1) Work state. This is an execution state. No event processing is performed by a work state. The function attached to a work state returns a pointer indicating the next state to which the OSM should transition. Returning NO_TRANSIT repeats the current state, but goes back to the scheduler first. (2) Wait state. This is an event processing state. No execution is performed by a wait state. Wait states are just tables of "if event X occurs, clear it and transition to state Y". The dispatcher returns to the scheduler if none of the events in which the wait state has an interest are currently pending. (3) Out-of-band state. This is a special work state. Transitions to normal states can be overridden when an unexpected event occurs (eg. I/O error). Instead the dispatcher disables and clears the OOB event and transits to the specified work state. This then acts as an ordinary work state, though object->state points to the overridden destination. Returning NO_TRANSIT resumes the overridden transition. In addition, the states have names in their definitions, so there's no need for tables of state names. Further, the EV_REQUEUE event is no longer necessary as that is automatic for work states. Since the states are now separate structs rather than values in an enum, it's not possible to use comparisons other than (non-)equality between them, so use some object->flags to indicate what phase an object is in. The EV_RELEASE, EV_RETIRE and EV_WITHDRAW events have been squished into one (EV_KILL). An object flag now carries the information about retirement. Similarly, the RELEASING, RECYCLING and WITHDRAWING states have been merged into an KILL_OBJECT state and additional states have been added for handling waiting dependent objects (JUMPSTART_DEPS and KILL_DEPENDENTS). A state has also been added for synchronising with parent object initialisation (WAIT_FOR_PARENT) and another for initiating look up (PARENT_READY). Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
_leave(" [cancel] op{f=%lx s=%u} obj{s=%s f=%lx}",
_op->flags, _op->state, object->state->short_name,
object->flags);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
return;
}
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_lock(&cookie->stores_lock);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
fscache_stat(&fscache_n_store_calls);
/* find a page to store */
page = NULL;
n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
FSCACHE_COOKIE_PENDING_TAG);
if (n != 1)
goto superseded;
page = results[0];
_debug("gang %d [%lx]", n, page->index);
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
if (page->index > op->store_limit) {
fscache_stat(&fscache_n_store_pages_over_limit);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
goto superseded;
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
}
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
radix_tree_tag_set(&cookie->stores, page->index,
FSCACHE_COOKIE_STORING_TAG);
radix_tree_tag_clear(&cookie->stores, page->index,
FSCACHE_COOKIE_PENDING_TAG);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_unlock(&cookie->stores_lock);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&object->lock);
fscache_stat(&fscache_n_store_pages);
fscache_stat(&fscache_n_cop_write_page);
ret = object->cache->ops->write_page(op, page);
fscache_stat_d(&fscache_n_cop_write_page);
fscache_end_page_write(object, page);
if (ret < 0) {
fscache_abort_object(object);
fscache_op_complete(&op->op, true);
} else {
fscache_enqueue_operation(&op->op);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
}
_leave("");
return;
superseded:
/* this writer is going away and there aren't any more things to
* write */
_debug("cease");
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_unlock(&cookie->stores_lock);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
spin_unlock(&object->lock);
fscache_op_complete(&op->op, true);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
_leave("");
}
/*
* Clear the pages pending writing for invalidation
*/
void fscache_invalidate_writes(struct fscache_cookie *cookie)
{
struct page *page;
void *results[16];
int n, i;
_enter("");
for (;;) {
spin_lock(&cookie->stores_lock);
n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0,
ARRAY_SIZE(results),
FSCACHE_COOKIE_PENDING_TAG);
if (n == 0) {
spin_unlock(&cookie->stores_lock);
break;
}
for (i = n - 1; i >= 0; i--) {
page = results[i];
radix_tree_delete(&cookie->stores, page->index);
}
spin_unlock(&cookie->stores_lock);
for (i = n - 1; i >= 0; i--)
page_cache_release(results[i]);
}
_leave("");
}
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/*
* request a page be stored in the cache
* - returns:
* -ENOMEM - out of memory, nothing done
* -ENOBUFS - no backing object available in which to cache the page
* 0 - dispatched a write - it'll call end_io_func() when finished
*
* if the cookie still has a backing object at this point, that object can be
* in one of a few states with respect to storage processing:
*
* (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
* set)
*
FS-Cache: Fix object state machine to have separate work and wait states Fix object state machine to have separate work and wait states as that makes it easier to envision. There are now three kinds of state: (1) Work state. This is an execution state. No event processing is performed by a work state. The function attached to a work state returns a pointer indicating the next state to which the OSM should transition. Returning NO_TRANSIT repeats the current state, but goes back to the scheduler first. (2) Wait state. This is an event processing state. No execution is performed by a wait state. Wait states are just tables of "if event X occurs, clear it and transition to state Y". The dispatcher returns to the scheduler if none of the events in which the wait state has an interest are currently pending. (3) Out-of-band state. This is a special work state. Transitions to normal states can be overridden when an unexpected event occurs (eg. I/O error). Instead the dispatcher disables and clears the OOB event and transits to the specified work state. This then acts as an ordinary work state, though object->state points to the overridden destination. Returning NO_TRANSIT resumes the overridden transition. In addition, the states have names in their definitions, so there's no need for tables of state names. Further, the EV_REQUEUE event is no longer necessary as that is automatic for work states. Since the states are now separate structs rather than values in an enum, it's not possible to use comparisons other than (non-)equality between them, so use some object->flags to indicate what phase an object is in. The EV_RELEASE, EV_RETIRE and EV_WITHDRAW events have been squished into one (EV_KILL). An object flag now carries the information about retirement. Similarly, the RELEASING, RECYCLING and WITHDRAWING states have been merged into an KILL_OBJECT state and additional states have been added for handling waiting dependent objects (JUMPSTART_DEPS and KILL_DEPENDENTS). A state has also been added for synchronising with parent object initialisation (WAIT_FOR_PARENT) and another for initiating look up (PARENT_READY). Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
* (a) no writes yet
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
*
* (b) writes deferred till post-creation (mark page for writing and
* return immediately)
*
* (2) negative lookup, object created, initial fill being made from netfs
*
* (a) fill point not yet reached this page (mark page for writing and
* return)
*
* (b) fill point passed this page (queue op to store this page)
*
* (3) object extant (queue op to store this page)
*
* any other state is invalid
*/
int __fscache_write_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
struct fscache_storage *op;
struct fscache_object *object;
bool wake_cookie = false;
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
int ret;
_enter("%p,%x,", cookie, (u32) page->flags);
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERT(PageFsCache(page));
fscache_stat(&fscache_n_stores);
if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
_leave(" = -ENOBUFS [invalidating]");
return -ENOBUFS;
}
op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (!op)
goto nomem;
fscache_operation_init(&op->op, fscache_write_op,
fscache_release_write_op);
FS-Cache: Simplify cookie retention for fscache_objects, fixing oops Simplify the way fscache cache objects retain their cookie. The way I implemented the cookie storage handling made synchronisation a pain (ie. the object state machine can't rely on the cookie actually still being there). Instead of the the object being detached from the cookie and the cookie being freed in __fscache_relinquish_cookie(), we defer both operations: (*) The detachment of the object from the list in the cookie now takes place in fscache_drop_object() and is thus governed by the object state machine (fscache_detach_from_cookie() has been removed). (*) The release of the cookie is now in fscache_object_destroy() - which is called by the cache backend just before it frees the object. This means that the fscache_cookie struct is now available to the cache all the way through from ->alloc_object() to ->drop_object() and ->put_object() - meaning that it's no longer necessary to take object->lock to guarantee access. However, __fscache_relinquish_cookie() doesn't wait for the object to go all the way through to destruction before letting the netfs proceed. That would massively slow down the netfs. Since __fscache_relinquish_cookie() leaves the cookie around, in must therefore break all attachments to the netfs - which includes ->def, ->netfs_data and any outstanding page read/writes. To handle this, struct fscache_cookie now has an n_active counter: (1) This starts off initialised to 1. (2) Any time the cache needs to get at the netfs data, it calls fscache_use_cookie() to increment it - if it is not zero. If it was zero, then access is not permitted. (3) When the cache has finished with the data, it calls fscache_unuse_cookie() to decrement it. This does a wake-up on it if it reaches 0. (4) __fscache_relinquish_cookie() decrements n_active and then waits for it to reach 0. The initialisation to 1 in step (1) ensures that we only get wake ups when we're trying to get rid of the cookie. This leaves __fscache_relinquish_cookie() a lot simpler. *** This fixes a problem in the current code whereby if fscache_invalidate() is followed sufficiently quickly by fscache_relinquish_cookie() then it is possible for __fscache_relinquish_cookie() to have detached the cookie from the object and cleared the pointer before a thread is dispatched to process the invalidation state in the object state machine. Since the pending write clearance was deferred to the invalidation state to make it asynchronous, we need to either wait in relinquishment for the stores tree to be cleared in the invalidation state or we need to handle the clearance in relinquishment. Further, if the relinquishment code does clear the tree, then the invalidation state need to make the clearance contingent on still having the cookie to hand (since that's where the tree is rooted) and we have to prevent the cookie from disappearing for the duration. This can lead to an oops like the following: BUG: unable to handle kernel NULL pointer dereference at 000000000000000c ... RIP: 0010:[<ffffffff8151023e>] _spin_lock+0xe/0x30 ... CR2: 000000000000000c ... ... Process kslowd002 (...) .... Call Trace: [<ffffffffa01c3278>] fscache_invalidate_writes+0x38/0xd0 [fscache] [<ffffffff810096f0>] ? __switch_to+0xd0/0x320 [<ffffffff8105e759>] ? find_busiest_queue+0x69/0x150 [<ffffffff8110ddd4>] ? slow_work_enqueue+0x104/0x180 [<ffffffffa01c1303>] fscache_object_slow_work_execute+0x5e3/0x9d0 [fscache] [<ffffffff81096b67>] ? bit_waitqueue+0x17/0xd0 [<ffffffff8110e233>] slow_work_execute+0x233/0x310 [<ffffffff8110e515>] slow_work_thread+0x205/0x360 [<ffffffff81096ca0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff8110e310>] ? slow_work_thread+0x0/0x360 [<ffffffff81096936>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968a0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 The parameter to fscache_invalidate_writes() was object->cookie which is NULL. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-05-10 20:50:26 +02:00
op->op.flags = FSCACHE_OP_ASYNC |
(1 << FSCACHE_OP_WAITING) |
(1 << FSCACHE_OP_UNUSE_COOKIE);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
lib/radix-tree.c: make radix_tree_node_alloc() work correctly within interrupt With users of radix_tree_preload() run from interrupt (block/blk-ioc.c is one such possible user), the following race can happen: radix_tree_preload() ... radix_tree_insert() radix_tree_node_alloc() if (rtp->nr) { ret = rtp->nodes[rtp->nr - 1]; <interrupt> ... radix_tree_preload() ... radix_tree_insert() radix_tree_node_alloc() if (rtp->nr) { ret = rtp->nodes[rtp->nr - 1]; And we give out one radix tree node twice. That clearly results in radix tree corruption with different results (usually OOPS) depending on which two users of radix tree race. We fix the problem by making radix_tree_node_alloc() always allocate fresh radix tree nodes when in interrupt. Using preloading when in interrupt doesn't make sense since all the allocations have to be atomic anyway and we cannot steal nodes from process-context users because some users rely on radix_tree_insert() succeeding after radix_tree_preload(). in_interrupt() check is somewhat ugly but we cannot simply key off passed gfp_mask as that is acquired from root_gfp_mask() and thus the same for all preload users. Another part of the fix is to avoid node preallocation in radix_tree_preload() when passed gfp_mask doesn't allow waiting. Again, preallocation in such case doesn't make sense and when preallocation would happen in interrupt we could possibly leak some allocated nodes. However, some users of radix_tree_preload() require following radix_tree_insert() to succeed. To avoid unexpected effects for these users, radix_tree_preload() only warns if passed gfp mask doesn't allow waiting and we provide a new function radix_tree_maybe_preload() for those users which get different gfp mask from different call sites and which are prepared to handle radix_tree_insert() failure. Signed-off-by: Jan Kara <jack@suse.cz> Cc: Jens Axboe <jaxboe@fusionio.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11 23:26:05 +02:00
ret = radix_tree_maybe_preload(gfp & ~__GFP_HIGHMEM);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (ret < 0)
goto nomem_free;
ret = -ENOBUFS;
spin_lock(&cookie->lock);
FS-Cache: Provide the ability to enable/disable cookies Provide the ability to enable and disable fscache cookies. A disabled cookie will reject or ignore further requests to: Acquire a child cookie Invalidate and update backing objects Check the consistency of a backing object Allocate storage for backing page Read backing pages Write to backing pages but still allows: Checks/waits on the completion of already in-progress objects Uncaching of pages Relinquishment of cookies Two new operations are provided: (1) Disable a cookie: void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate); If the cookie is not already disabled, this locks the cookie against other dis/enablement ops, marks the cookie as being disabled, discards or invalidates any backing objects and waits for cessation of activity on any associated object. This is a wrapper around a chunk split out of fscache_relinquish_cookie(), but it reinitialises the cookie such that it can be reenabled. All possible failures are handled internally. The caller should consider calling fscache_uncache_all_inode_pages() afterwards to make sure all page markings are cleared up. (2) Enable a cookie: void fscache_enable_cookie(struct fscache_cookie *cookie, bool (*can_enable)(void *data), void *data) If the cookie is not already enabled, this locks the cookie against other dis/enablement ops, invokes can_enable() and, if the cookie is not an index cookie, will begin the procedure of acquiring backing objects. The optional can_enable() function is passed the data argument and returns a ruling as to whether or not enablement should actually be permitted to begin. All possible failures are handled internally. The cookie will only be marked as enabled if provisional backing objects are allocated. A later patch will introduce these to NFS. Cookie enablement during nfs_open() is then contingent on i_writecount <= 0. can_enable() checks for a race between open(O_RDONLY) and open(O_WRONLY/O_RDWR). This simplifies NFS's cookie handling and allows us to get rid of open(O_RDONLY) accidentally introducing caching to an inode that's open for writing already. One operation has its API modified: (3) Acquire a cookie. struct fscache_cookie *fscache_acquire_cookie( struct fscache_cookie *parent, const struct fscache_cookie_def *def, void *netfs_data, bool enable); This now has an additional argument that indicates whether the requested cookie should be enabled by default. It doesn't need the can_enable() function because the caller must prevent multiple calls for the same netfs object and it doesn't need to take the enablement lock because no one else can get at the cookie before this returns. Signed-off-by: David Howells <dhowells@redhat.com
2013-09-21 01:09:31 +02:00
if (!fscache_cookie_enabled(cookie) ||
hlist_empty(&cookie->backing_objects))
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
goto nobufs;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
goto nobufs;
/* add the page to the pending-storage radix tree on the backing
* object */
spin_lock(&object->lock);
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_lock(&cookie->stores_lock);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
_debug("store limit %llx", (unsigned long long) object->store_limit);
ret = radix_tree_insert(&cookie->stores, page->index, page);
if (ret < 0) {
if (ret == -EEXIST)
goto already_queued;
_debug("insert failed %d", ret);
goto nobufs_unlock_obj;
}
radix_tree_tag_set(&cookie->stores, page->index,
FSCACHE_COOKIE_PENDING_TAG);
page_cache_get(page);
/* we only want one writer at a time, but we do need to queue new
* writers after exclusive ops */
if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
goto already_pending;
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_unlock(&cookie->stores_lock);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&object->lock);
op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
op->store_limit = object->store_limit;
__fscache_use_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
if (fscache_submit_op(object, &op->op) < 0)
goto submit_failed;
spin_unlock(&cookie->lock);
radix_tree_preload_end();
fscache_stat(&fscache_n_store_ops);
fscache_stat(&fscache_n_stores_ok);
/* the work queue now carries its own ref on the object */
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
fscache_put_operation(&op->op);
_leave(" = 0");
return 0;
already_queued:
fscache_stat(&fscache_n_stores_again);
already_pending:
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_unlock(&cookie->stores_lock);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&object->lock);
spin_unlock(&cookie->lock);
radix_tree_preload_end();
kfree(op);
fscache_stat(&fscache_n_stores_ok);
_leave(" = 0");
return 0;
submit_failed:
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_lock(&cookie->stores_lock);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
radix_tree_delete(&cookie->stores, page->index);
FS-Cache: Fix lock misorder in fscache_write_op() FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 19:11:25 +01:00
spin_unlock(&cookie->stores_lock);
wake_cookie = __fscache_unuse_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
page_cache_release(page);
ret = -ENOBUFS;
goto nobufs;
nobufs_unlock_obj:
spin_unlock(&cookie->stores_lock);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
spin_unlock(&object->lock);
nobufs:
spin_unlock(&cookie->lock);
radix_tree_preload_end();
kfree(op);
if (wake_cookie)
__fscache_wake_unused_cookie(cookie);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
fscache_stat(&fscache_n_stores_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
nomem_free:
kfree(op);
nomem:
fscache_stat(&fscache_n_stores_oom);
_leave(" = -ENOMEM");
return -ENOMEM;
}
EXPORT_SYMBOL(__fscache_write_page);
/*
* remove a page from the cache
*/
void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
{
struct fscache_object *object;
_enter(",%p", page);
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(page, !=, NULL);
fscache_stat(&fscache_n_uncaches);
/* cache withdrawal may beat us to it */
if (!PageFsCache(page))
goto done;
/* get the object */
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects)) {
ClearPageFsCache(page);
goto done_unlock;
}
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
/* there might now be stuff on disk we could read */
clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
/* only invoke the cache backend if we managed to mark the page
* uncached here; this deals with synchronisation vs withdrawal */
if (TestClearPageFsCache(page) &&
object->cache->ops->uncache_page) {
/* the cache backend releases the cookie lock */
fscache_stat(&fscache_n_cop_uncache_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
object->cache->ops->uncache_page(object, page);
fscache_stat_d(&fscache_n_cop_uncache_page);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
goto done;
}
done_unlock:
spin_unlock(&cookie->lock);
done:
_leave("");
}
EXPORT_SYMBOL(__fscache_uncache_page);
CacheFiles: Fix the marking of cached pages Under some circumstances CacheFiles defers the marking of pages with PG_fscache so that it can take advantage of pagevecs to reduce the number of calls to fscache_mark_pages_cached() and the netfs's hook to keep track of this. There are, however, two problems with this: (1) It can lead to the PG_fscache mark being applied _after_ the page is set PG_uptodate and unlocked (by the call to fscache_end_io()). (2) CacheFiles's ref on the page is dropped immediately following fscache_end_io() - and so may not still be held when the mark is applied. This can lead to the page being passed back to the allocator before the mark is applied. Fix this by, where appropriate, marking the page before calling fscache_end_io() and releasing the page. This means that we can't take advantage of pagevecs and have to make a separate call for each page to the marking routines. The symptoms of this are Bad Page state errors cropping up under memory pressure, for example: BUG: Bad page state in process tar pfn:002da page:ffffea0000009fb0 count:0 mapcount:0 mapping: (null) index:0x1447 page flags: 0x1000(private_2) Pid: 4574, comm: tar Tainted: G W 3.1.0-rc4-fsdevel+ #1064 Call Trace: [<ffffffff8109583c>] ? dump_page+0xb9/0xbe [<ffffffff81095916>] bad_page+0xd5/0xea [<ffffffff81095d82>] get_page_from_freelist+0x35b/0x46a [<ffffffff810961f3>] __alloc_pages_nodemask+0x362/0x662 [<ffffffff810989da>] __do_page_cache_readahead+0x13a/0x267 [<ffffffff81098942>] ? __do_page_cache_readahead+0xa2/0x267 [<ffffffff81098d7b>] ra_submit+0x1c/0x20 [<ffffffff8109900a>] ondemand_readahead+0x28b/0x29a [<ffffffff81098ee2>] ? ondemand_readahead+0x163/0x29a [<ffffffff810990ce>] page_cache_sync_readahead+0x38/0x3a [<ffffffff81091d8a>] generic_file_aio_read+0x2ab/0x67e [<ffffffffa008cfbe>] nfs_file_read+0xa4/0xc9 [nfs] [<ffffffff810c22c4>] do_sync_read+0xba/0xfa [<ffffffff81177a47>] ? security_file_permission+0x7b/0x84 [<ffffffff810c25dd>] ? rw_verify_area+0xab/0xc8 [<ffffffff810c29a4>] vfs_read+0xaa/0x13a [<ffffffff810c2a79>] sys_read+0x45/0x6c [<ffffffff813ac37b>] system_call_fastpath+0x16/0x1b As can be seen, PG_private_2 (== PG_fscache) is set in the page flags. Instrumenting fscache_mark_pages_cached() to verify whether page->mapping was set appropriately showed that sometimes it wasn't. This led to the discovery that sometimes the page has apparently been reclaimed by the time the marker got to see it. Reported-by: M. Stevens <m@tippett.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com>
2012-12-20 22:52:32 +01:00
/**
* fscache_mark_page_cached - Mark a page as being cached
* @op: The retrieval op pages are being marked for
* @page: The page to be marked
*
* Mark a netfs page as being cached. After this is called, the netfs
* must call fscache_uncache_page() to remove the mark.
*/
void fscache_mark_page_cached(struct fscache_retrieval *op, struct page *page)
{
struct fscache_cookie *cookie = op->op.object->cookie;
#ifdef CONFIG_FSCACHE_STATS
atomic_inc(&fscache_n_marks);
#endif
_debug("- mark %p{%lx}", page, page->index);
if (TestSetPageFsCache(page)) {
static bool once_only;
if (!once_only) {
once_only = true;
printk(KERN_WARNING "FS-Cache:"
" Cookie type %s marked page %lx"
" multiple times\n",
cookie->def->name, page->index);
}
}
if (cookie->def->mark_page_cached)
cookie->def->mark_page_cached(cookie->netfs_data,
op->mapping, page);
}
EXPORT_SYMBOL(fscache_mark_page_cached);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
/**
* fscache_mark_pages_cached - Mark pages as being cached
* @op: The retrieval op pages are being marked for
* @pagevec: The pages to be marked
*
* Mark a bunch of netfs pages as being cached. After this is called,
* the netfs must call fscache_uncache_page() to remove the mark.
*/
void fscache_mark_pages_cached(struct fscache_retrieval *op,
struct pagevec *pagevec)
{
unsigned long loop;
CacheFiles: Fix the marking of cached pages Under some circumstances CacheFiles defers the marking of pages with PG_fscache so that it can take advantage of pagevecs to reduce the number of calls to fscache_mark_pages_cached() and the netfs's hook to keep track of this. There are, however, two problems with this: (1) It can lead to the PG_fscache mark being applied _after_ the page is set PG_uptodate and unlocked (by the call to fscache_end_io()). (2) CacheFiles's ref on the page is dropped immediately following fscache_end_io() - and so may not still be held when the mark is applied. This can lead to the page being passed back to the allocator before the mark is applied. Fix this by, where appropriate, marking the page before calling fscache_end_io() and releasing the page. This means that we can't take advantage of pagevecs and have to make a separate call for each page to the marking routines. The symptoms of this are Bad Page state errors cropping up under memory pressure, for example: BUG: Bad page state in process tar pfn:002da page:ffffea0000009fb0 count:0 mapcount:0 mapping: (null) index:0x1447 page flags: 0x1000(private_2) Pid: 4574, comm: tar Tainted: G W 3.1.0-rc4-fsdevel+ #1064 Call Trace: [<ffffffff8109583c>] ? dump_page+0xb9/0xbe [<ffffffff81095916>] bad_page+0xd5/0xea [<ffffffff81095d82>] get_page_from_freelist+0x35b/0x46a [<ffffffff810961f3>] __alloc_pages_nodemask+0x362/0x662 [<ffffffff810989da>] __do_page_cache_readahead+0x13a/0x267 [<ffffffff81098942>] ? __do_page_cache_readahead+0xa2/0x267 [<ffffffff81098d7b>] ra_submit+0x1c/0x20 [<ffffffff8109900a>] ondemand_readahead+0x28b/0x29a [<ffffffff81098ee2>] ? ondemand_readahead+0x163/0x29a [<ffffffff810990ce>] page_cache_sync_readahead+0x38/0x3a [<ffffffff81091d8a>] generic_file_aio_read+0x2ab/0x67e [<ffffffffa008cfbe>] nfs_file_read+0xa4/0xc9 [nfs] [<ffffffff810c22c4>] do_sync_read+0xba/0xfa [<ffffffff81177a47>] ? security_file_permission+0x7b/0x84 [<ffffffff810c25dd>] ? rw_verify_area+0xab/0xc8 [<ffffffff810c29a4>] vfs_read+0xaa/0x13a [<ffffffff810c2a79>] sys_read+0x45/0x6c [<ffffffff813ac37b>] system_call_fastpath+0x16/0x1b As can be seen, PG_private_2 (== PG_fscache) is set in the page flags. Instrumenting fscache_mark_pages_cached() to verify whether page->mapping was set appropriately showed that sometimes it wasn't. This led to the discovery that sometimes the page has apparently been reclaimed by the time the marker got to see it. Reported-by: M. Stevens <m@tippett.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com>
2012-12-20 22:52:32 +01:00
for (loop = 0; loop < pagevec->nr; loop++)
fscache_mark_page_cached(op, pagevec->pages[loop]);
FS-Cache: Implement data I/O part of netfs API Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 17:42:39 +02:00
pagevec_reinit(pagevec);
}
EXPORT_SYMBOL(fscache_mark_pages_cached);
FS-Cache: Add a helper to bulk uncache pages on an inode Add an FS-Cache helper to bulk uncache pages on an inode. This will only work for the circumstance where the pages in the cache correspond 1:1 with the pages attached to an inode's page cache. This is required for CIFS and NFS: When disabling inode cookie, we were returning the cookie and setting cifsi->fscache to NULL but failed to invalidate any previously mapped pages. This resulted in "Bad page state" errors and manifested in other kind of errors when running fsstress. Fix it by uncaching mapped pages when we disable the inode cookie. This patch should fix the following oops and "Bad page state" errors seen during fsstress testing. ------------[ cut here ]------------ kernel BUG at fs/cachefiles/namei.c:201! invalid opcode: 0000 [#1] SMP Pid: 5, comm: kworker/u:0 Not tainted 2.6.38.7-30.fc15.x86_64 #1 Bochs Bochs RIP: 0010: cachefiles_walk_to_object+0x436/0x745 [cachefiles] RSP: 0018:ffff88002ce6dd00 EFLAGS: 00010282 RAX: ffff88002ef165f0 RBX: ffff88001811f500 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000282 RBP: ffff88002ce6dda0 R08: 0000000000000100 R09: ffffffff81b3a300 R10: 0000ffff00066c0a R11: 0000000000000003 R12: ffff88002ae54840 R13: ffff88002ae54840 R14: ffff880029c29c00 R15: ffff88001811f4b0 FS: 00007f394dd32720(0000) GS:ffff88002ef00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fffcb62ddf8 CR3: 000000001825f000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/u:0 (pid: 5, threadinfo ffff88002ce6c000, task ffff88002ce55cc0) Stack: 0000000000000246 ffff88002ce55cc0 ffff88002ce6dd58 ffff88001815dc00 ffff8800185246c0 ffff88001811f618 ffff880029c29d18 ffff88001811f380 ffff88002ce6dd50 ffffffff814757e4 ffff88002ce6dda0 ffffffff8106ac56 Call Trace: cachefiles_lookup_object+0x78/0xd4 [cachefiles] fscache_lookup_object+0x131/0x16d [fscache] fscache_object_work_func+0x1bc/0x669 [fscache] process_one_work+0x186/0x298 worker_thread+0xda/0x15d kthread+0x84/0x8c kernel_thread_helper+0x4/0x10 RIP cachefiles_walk_to_object+0x436/0x745 [cachefiles] ---[ end trace 1d481c9af1804caa ]--- I tested the uncaching by the following means: (1) Create a big file on my NFS server (104857600 bytes). (2) Read the file into the cache with md5sum on the NFS client. Look in /proc/fs/fscache/stats: Pages : mrk=25601 unc=0 (3) Open the file for read/write ("bash 5<>/warthog/bigfile"). Look in proc again: Pages : mrk=25601 unc=25601 Reported-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-Tested-by: Suresh Jayaraman <sjayaraman@suse.de> cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-07 13:19:48 +02:00
/*
* Uncache all the pages in an inode that are marked PG_fscache, assuming them
* to be associated with the given cookie.
*/
void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
struct inode *inode)
{
struct address_space *mapping = inode->i_mapping;
struct pagevec pvec;
pgoff_t next;
int i;
_enter("%p,%p", cookie, inode);
if (!mapping || mapping->nrpages == 0) {
_leave(" [no pages]");
return;
}
pagevec_init(&pvec, 0);
next = 0;
do {
if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE))
break;
FS-Cache: Add a helper to bulk uncache pages on an inode Add an FS-Cache helper to bulk uncache pages on an inode. This will only work for the circumstance where the pages in the cache correspond 1:1 with the pages attached to an inode's page cache. This is required for CIFS and NFS: When disabling inode cookie, we were returning the cookie and setting cifsi->fscache to NULL but failed to invalidate any previously mapped pages. This resulted in "Bad page state" errors and manifested in other kind of errors when running fsstress. Fix it by uncaching mapped pages when we disable the inode cookie. This patch should fix the following oops and "Bad page state" errors seen during fsstress testing. ------------[ cut here ]------------ kernel BUG at fs/cachefiles/namei.c:201! invalid opcode: 0000 [#1] SMP Pid: 5, comm: kworker/u:0 Not tainted 2.6.38.7-30.fc15.x86_64 #1 Bochs Bochs RIP: 0010: cachefiles_walk_to_object+0x436/0x745 [cachefiles] RSP: 0018:ffff88002ce6dd00 EFLAGS: 00010282 RAX: ffff88002ef165f0 RBX: ffff88001811f500 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000282 RBP: ffff88002ce6dda0 R08: 0000000000000100 R09: ffffffff81b3a300 R10: 0000ffff00066c0a R11: 0000000000000003 R12: ffff88002ae54840 R13: ffff88002ae54840 R14: ffff880029c29c00 R15: ffff88001811f4b0 FS: 00007f394dd32720(0000) GS:ffff88002ef00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fffcb62ddf8 CR3: 000000001825f000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/u:0 (pid: 5, threadinfo ffff88002ce6c000, task ffff88002ce55cc0) Stack: 0000000000000246 ffff88002ce55cc0 ffff88002ce6dd58 ffff88001815dc00 ffff8800185246c0 ffff88001811f618 ffff880029c29d18 ffff88001811f380 ffff88002ce6dd50 ffffffff814757e4 ffff88002ce6dda0 ffffffff8106ac56 Call Trace: cachefiles_lookup_object+0x78/0xd4 [cachefiles] fscache_lookup_object+0x131/0x16d [fscache] fscache_object_work_func+0x1bc/0x669 [fscache] process_one_work+0x186/0x298 worker_thread+0xda/0x15d kthread+0x84/0x8c kernel_thread_helper+0x4/0x10 RIP cachefiles_walk_to_object+0x436/0x745 [cachefiles] ---[ end trace 1d481c9af1804caa ]--- I tested the uncaching by the following means: (1) Create a big file on my NFS server (104857600 bytes). (2) Read the file into the cache with md5sum on the NFS client. Look in /proc/fs/fscache/stats: Pages : mrk=25601 unc=0 (3) Open the file for read/write ("bash 5<>/warthog/bigfile"). Look in proc again: Pages : mrk=25601 unc=25601 Reported-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-Tested-by: Suresh Jayaraman <sjayaraman@suse.de> cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-07 13:19:48 +02:00
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
next = page->index;
FS-Cache: Add a helper to bulk uncache pages on an inode Add an FS-Cache helper to bulk uncache pages on an inode. This will only work for the circumstance where the pages in the cache correspond 1:1 with the pages attached to an inode's page cache. This is required for CIFS and NFS: When disabling inode cookie, we were returning the cookie and setting cifsi->fscache to NULL but failed to invalidate any previously mapped pages. This resulted in "Bad page state" errors and manifested in other kind of errors when running fsstress. Fix it by uncaching mapped pages when we disable the inode cookie. This patch should fix the following oops and "Bad page state" errors seen during fsstress testing. ------------[ cut here ]------------ kernel BUG at fs/cachefiles/namei.c:201! invalid opcode: 0000 [#1] SMP Pid: 5, comm: kworker/u:0 Not tainted 2.6.38.7-30.fc15.x86_64 #1 Bochs Bochs RIP: 0010: cachefiles_walk_to_object+0x436/0x745 [cachefiles] RSP: 0018:ffff88002ce6dd00 EFLAGS: 00010282 RAX: ffff88002ef165f0 RBX: ffff88001811f500 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000282 RBP: ffff88002ce6dda0 R08: 0000000000000100 R09: ffffffff81b3a300 R10: 0000ffff00066c0a R11: 0000000000000003 R12: ffff88002ae54840 R13: ffff88002ae54840 R14: ffff880029c29c00 R15: ffff88001811f4b0 FS: 00007f394dd32720(0000) GS:ffff88002ef00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fffcb62ddf8 CR3: 000000001825f000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/u:0 (pid: 5, threadinfo ffff88002ce6c000, task ffff88002ce55cc0) Stack: 0000000000000246 ffff88002ce55cc0 ffff88002ce6dd58 ffff88001815dc00 ffff8800185246c0 ffff88001811f618 ffff880029c29d18 ffff88001811f380 ffff88002ce6dd50 ffffffff814757e4 ffff88002ce6dda0 ffffffff8106ac56 Call Trace: cachefiles_lookup_object+0x78/0xd4 [cachefiles] fscache_lookup_object+0x131/0x16d [fscache] fscache_object_work_func+0x1bc/0x669 [fscache] process_one_work+0x186/0x298 worker_thread+0xda/0x15d kthread+0x84/0x8c kernel_thread_helper+0x4/0x10 RIP cachefiles_walk_to_object+0x436/0x745 [cachefiles] ---[ end trace 1d481c9af1804caa ]--- I tested the uncaching by the following means: (1) Create a big file on my NFS server (104857600 bytes). (2) Read the file into the cache with md5sum on the NFS client. Look in /proc/fs/fscache/stats: Pages : mrk=25601 unc=0 (3) Open the file for read/write ("bash 5<>/warthog/bigfile"). Look in proc again: Pages : mrk=25601 unc=25601 Reported-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-Tested-by: Suresh Jayaraman <sjayaraman@suse.de> cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-07 13:19:48 +02:00
if (PageFsCache(page)) {
__fscache_wait_on_page_write(cookie, page);
__fscache_uncache_page(cookie, page);
}
}
pagevec_release(&pvec);
cond_resched();
} while (++next);
FS-Cache: Add a helper to bulk uncache pages on an inode Add an FS-Cache helper to bulk uncache pages on an inode. This will only work for the circumstance where the pages in the cache correspond 1:1 with the pages attached to an inode's page cache. This is required for CIFS and NFS: When disabling inode cookie, we were returning the cookie and setting cifsi->fscache to NULL but failed to invalidate any previously mapped pages. This resulted in "Bad page state" errors and manifested in other kind of errors when running fsstress. Fix it by uncaching mapped pages when we disable the inode cookie. This patch should fix the following oops and "Bad page state" errors seen during fsstress testing. ------------[ cut here ]------------ kernel BUG at fs/cachefiles/namei.c:201! invalid opcode: 0000 [#1] SMP Pid: 5, comm: kworker/u:0 Not tainted 2.6.38.7-30.fc15.x86_64 #1 Bochs Bochs RIP: 0010: cachefiles_walk_to_object+0x436/0x745 [cachefiles] RSP: 0018:ffff88002ce6dd00 EFLAGS: 00010282 RAX: ffff88002ef165f0 RBX: ffff88001811f500 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000282 RBP: ffff88002ce6dda0 R08: 0000000000000100 R09: ffffffff81b3a300 R10: 0000ffff00066c0a R11: 0000000000000003 R12: ffff88002ae54840 R13: ffff88002ae54840 R14: ffff880029c29c00 R15: ffff88001811f4b0 FS: 00007f394dd32720(0000) GS:ffff88002ef00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fffcb62ddf8 CR3: 000000001825f000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/u:0 (pid: 5, threadinfo ffff88002ce6c000, task ffff88002ce55cc0) Stack: 0000000000000246 ffff88002ce55cc0 ffff88002ce6dd58 ffff88001815dc00 ffff8800185246c0 ffff88001811f618 ffff880029c29d18 ffff88001811f380 ffff88002ce6dd50 ffffffff814757e4 ffff88002ce6dda0 ffffffff8106ac56 Call Trace: cachefiles_lookup_object+0x78/0xd4 [cachefiles] fscache_lookup_object+0x131/0x16d [fscache] fscache_object_work_func+0x1bc/0x669 [fscache] process_one_work+0x186/0x298 worker_thread+0xda/0x15d kthread+0x84/0x8c kernel_thread_helper+0x4/0x10 RIP cachefiles_walk_to_object+0x436/0x745 [cachefiles] ---[ end trace 1d481c9af1804caa ]--- I tested the uncaching by the following means: (1) Create a big file on my NFS server (104857600 bytes). (2) Read the file into the cache with md5sum on the NFS client. Look in /proc/fs/fscache/stats: Pages : mrk=25601 unc=0 (3) Open the file for read/write ("bash 5<>/warthog/bigfile"). Look in proc again: Pages : mrk=25601 unc=25601 Reported-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-Tested-by: Suresh Jayaraman <sjayaraman@suse.de> cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-07 13:19:48 +02:00
_leave("");
}
EXPORT_SYMBOL(__fscache_uncache_all_inode_pages);