Commit Graph

30 Commits

Author SHA1 Message Date
Carlos Maiolino 6fb8a90aa3 xfs: fix race while discarding buffers [V4]
While xfs_buftarg_shrink() is freeing buffers from the dispose list (filled with
buffers from lru list), there is a possibility to have xfs_buf_stale() racing
with it, and removing buffers from dispose list before xfs_buftarg_shrink() does
it.

This happens because xfs_buftarg_shrink() handle the dispose list without
locking and the test condition in xfs_buf_stale() checks for the buffer being in
*any* list:

if (!list_empty(&bp->b_lru))

If the buffer happens to be on dispose list, this causes the buffer counter of
lru list (btp->bt_lru_nr) to be decremented twice (once in xfs_buftarg_shrink()
and another in xfs_buf_stale()) causing a wrong account usage of the lru list.

This may cause xfs_buftarg_shrink() to return a wrong value to the memory
shrinker shrink_slab(), and such account error may also cause an underflowed
value to be returned; since the counter is lower than the current number of
items in the lru list, a decrement may happen when the counter is 0, causing
an underflow on the counter.

The fix uses a new flag field (and a new buffer flag) to serialize buffer
handling during the shrink process. The new flag field has been designed to use
btp->bt_lru_lock/unlock instead of xfs_buf_lock/unlock mechanism.

dchinner, sandeen, aquini and aris also deserve credits for this.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-08-29 15:01:11 -05:00
Christoph Hellwig a2dcf5df5f xfs: do not call xfs_bdstrat_cb in xfs_buf_iodone_callbacks
xfs_bdstrat_cb only adds a check for a shutdown filesystem over
xfs_buf_iorequest, but xfs_buf_iodone_callbacks just checked for a shut down
filesystem a little earlier.  In addition the shutdown handling in
xfs_bdstrat_cb is not very suitable for this caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-07-13 12:50:54 -05:00
Dave Chinner 6dde27077e xfs: add discontiguous buffer map interface
With the internal interfaces supporting discontiguous buffer maps,
add external lookup, read and get interfaces so they can start to be
used.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-07-01 14:50:05 -05:00
Dave Chinner 3e85c868a6 xfs: convert internal buffer functions to pass maps
While the external interface currently uses separate blockno/length
variables, we need to move internal interfaces to passing and
parsing vector maps. This will then allow us to add external
interfaces to support discontiguous buffer maps as the internal code
will already support them.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-07-01 14:50:05 -05:00
Dave Chinner cbb7baab28 xfs: separate buffer indexing from block map
To support discontiguous buffers in the buffer cache, we need to
separate the cache index variables from the I/O map. While this is
currently a 1:1 mapping, discontiguous buffer support will break
this relationship.

However, for caching purposes, we can still treat them the same as a
contiguous buffer - the block number of the first block and the
length of the buffer - as that is still a unique representation.
Also, the only way we will ever access the discontiguous regions of
buffers is via bulding the complete buffer in the first place, so
using the initial block number and entire buffer length is a sane
way to index the buffers.

Add a block mapping vector construct to the xfs_buf and use it in
the places where we are doing IO instead of the current
b_bn/b_length variables.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-07-01 14:50:04 -05:00
Dave Chinner 611c99468c xfs: make XBF_MAPPED the default behaviour
Rather than specifying XBF_MAPPED for almost all buffers, introduce
XBF_UNMAPPED for the couple of users that use unmapped buffers.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:21:03 -05:00
Dave Chinner aa5c158ec9 xfs: kill XBF_DONTBLOCK
Just about all callers of xfs_buf_read() and xfs_buf_get() use XBF_DONTBLOCK.
This is used to make memory allocation use GFP_NOFS rather than GFP_KERNEL to
avoid recursion through memory reclaim back into the filesystem.

All the blocking get calls in growfs occur inside a transaction, even though
they are no part of the transaction, so all allocation will be GFP_NOFS due to
the task flag PF_TRANS being set. The blocking read calls occur during log
recovery, so they will probably be unaffected by converting to GFP_NOFS
allocations.

Hence make XBF_DONTBLOCK behaviour always occur for buffers and kill the flag.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:52 -05:00
Dave Chinner a8acad7073 xfs: kill XBF_LOCK
Buffers are always returned locked from the lookup routines. Hence
we don't need to tell the lookup routines to return locked buffers,
on to try and lock them. Remove XBF_LOCK from all the callers and
from internal buffer cache usage.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:50 -05:00
Dave Chinner 795cac72e9 xfs: kill xfs_buf_btoc
xfs_buf_btoc and friends are simple macros that do basic block
to page index conversion and vice versa. These aren't widely used,
and we use open coded masking and shifting everywhere else. Hence
remove the macros and open code the work they do.

Also, use of PAGE_CACHE_{SIZE|SHIFT|MASK} for these macros is now
incorrect - we are using pages directly and not the page cache, so
use PAGE_{SIZE|MASK|SHIFT} instead.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:49 -05:00
Dave Chinner aa0e8833b0 xfs: use blocks for storing the desired IO size
Now that we pass block counts everywhere, and index buffers by block
number and length in units of blocks, convert the desired IO size
into block counts rather than bytes. Convert the code to use block
counts, and those that need byte counts get converted at the time of
use.

Rename the b_desired_count variable to something closer to it's
purpose - b_io_length - as it is only used to specify the length of
an IO for a subset of the buffer.  The only time this is used is for
log IO - both writing iclogs and during log recovery. In all other
cases, the b_io_length matches b_length, and hence a lot of code
confuses the two. e.g. the buf item code uses the io count
exclusively when it should be using the buffer length. Fix these
apprpriately as they are found.

Also, remove the XFS_BUF_{SET_}COUNT() macros that are just wrappers
around the desired IO length. They only serve to make the code
shouty loud, don't actually add any real value, and are often used
incorrectly.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:48 -05:00
Dave Chinner 4e94b71b70 xfs: use blocks for counting length of buffers
Now that we pass block counts everywhere, and index buffers by block
number, track the length of the buffer in units of blocks rather
than bytes. Convert the code to use block counts, and those that
need byte counts get converted at the time of use.

Also, remove the XFS_BUF_{SET_}SIZE() macros that are just wrappers
around the buffer length. They only serve to make the code shouty
loud and don't actually add any real value.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:47 -05:00
Dave Chinner de1cbee462 xfs: kill b_file_offset
Seeing as we pass block numbers around everywhere in the buffer
cache now, it makes no sense to index everything by byte offset.
Replace all the byte offset indexing with block number based
indexing, and replace all uses of the byte offset with direct
conversion from the block index.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:46 -05:00
Dave Chinner e70b73f84f xfs: clean up buffer get/read call API
The xfs_buf_get/read API is not consistent in the units it uses, and
does not use appropriate or consistent units/types for the
variables.

Convert the API to use disk addresses and block counts for all
buffer get and read calls. Use consistent naming for all the
functions and their declarations, and convert the internal functions
to use disk addresses and block counts to avoid need to convert them
from one type to another and back again.

Fix all the callers to use disk addresses and block counts. In many
cases, this removes an additional conversion from the function call
as the callers already have a block count.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:45 -05:00
Dave Chinner 0e95f19ad9 xfs: check for buffer errors before waiting
If we call xfs_buf_iowait() on a buffer that failed dispatch due to
an IO error, it will wait forever for an Io that does not exist.
This is hndled in xfs_buf_read, but there is other code that calls
xfs_buf_iowait directly that doesn't.

Rather than make the call sites have to handle checking for dispatch
errors and then checking for completion errors, make
xfs_buf_iowait() check for dispatch errors on the buffer before
waiting. This means we handle both dispatch and completion errors
with one set of error handling at the caller sites.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:42 -05:00
Christoph Hellwig 43ff2122e6 xfs: on-stack delayed write buffer lists
Queue delwri buffers on a local on-stack list instead of a per-buftarg one,
and write back the buffers per-process instead of by waking up xfsbufd.

This is now easily doable given that we have very few places left that write
delwri buffers:

 - log recovery:
	Only done at mount time, and already forcing out the buffers
	synchronously using xfs_flush_buftarg

 - quotacheck:
	Same story.

 - dquot reclaim:
	Writes out dirty dquots on the LRU under memory pressure.  We might
	want to look into doing more of this via xfsaild, but it's already
	more optimal than the synchronous inode reclaim that writes each
	buffer synchronously.

 - xfsaild:
	This is the main beneficiary of the change.  By keeping a local list
	of buffers to write we reduce latency of writing out buffers, and
	more importably we can remove all the delwri list promotions which
	were hitting the buffer cache hard under sustained metadata loads.

The implementation is very straight forward - xfs_buf_delwri_queue now gets
a new list_head pointer that it adds the delwri buffers to, and all callers
need to eventually submit the list using xfs_buf_delwi_submit or
xfs_buf_delwi_submit_nowait.  Buffers that already are on a delwri list are
skipped in xfs_buf_delwri_queue, assuming they already are on another delwri
list.  The biggest change to pass down the buffer list was done to the AIL
pushing. Now that we operate on buffers the trylock, push and pushbuf log
item methods are merged into a single push routine, which tries to lock the
item, and if possible add the buffer that needs writeback to the buffer list.
This leads to much simpler code than the previous split but requires the
individual IOP_PUSH instances to unlock and reacquire the AIL around calls
to blocking routines.

Given that xfsailds now also handle writing out buffers, the conditions for
log forcing and the sleep times needed some small changes.  The most
important one is that we consider an AIL busy as long we still have buffers
to push, and the other one is that we do increment the pushed LSN for
buffers that are under flushing at this moment, but still count them towards
the stuck items for restart purposes.  Without this we could hammer on stuck
items without ever forcing the log and not make progress under heavy random
delete workloads on fast flash storage devices.

[ Dave Chinner:
	- rebase on previous patches.
	- improved comments for XBF_DELWRI_Q handling
	- fix XBF_ASYNC handling in queue submission (test 106 failure)
	- rename delwri submit function buffer list parameters for clarity
	- xfs_efd_item_push() should return XFS_ITEM_PINNED ]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-05-14 16:20:31 -05:00
David Howells 9ffc93f203 Remove all #inclusions of asm/system.h
Remove all #inclusions of asm/system.h preparatory to splitting and killing
it.  Performed with the following command:

perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *`

Signed-off-by: David Howells <dhowells@redhat.com>
2012-03-28 18:30:03 +01:00
Eric Sandeen 687d1c5e8e xfs: remove unused XBT_FORCE_SLEEP bit
XBT_FORCE_SLEEP is no longer ever tested; it is only set
and cleared.  Remove it.

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2011-12-16 15:12:33 -06:00
Christoph Hellwig a9add83e5a xfs: remove XFS_bflush
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:11 -05:00
Christoph Hellwig 02b102df15 xfs: remove xfs_buf_target_name
The calling convention that returns a pointer to a static buffer is
fairly nasty, so just opencode it in the only caller that is left.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:11 -05:00
Christoph Hellwig 901796afca xfs: clean up xfs_ioerror_alert
Instead of passing the block number and mount structure explicitly
get them off the bp and fix make the argument order more natural.

Also move it to xfs_buf.c and stop printing the device name given
that we already get the fs name as part of xfs_alert, and we know
what device is operates on because of the caller that gets printed,
finally rename it to xfs_buf_ioerror_alert and pass __func__ as
argument where it makes sense.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:10 -05:00
Christoph Hellwig 4347b9d7ad xfs: clean up buffer allocation
Change _xfs_buf_initialize to allocate the buffer directly and rename it to
xfs_buf_alloc now that is the only buffer allocation routine.  Also remove
the xfs_buf_deallocate wrapper around the kmem_zone_free calls for buffers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:10 -05:00
Christoph Hellwig c867cb6164 xfs: remove XFS_BUF_STALE and XFS_BUF_SUPER_STALE
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:10 -05:00
Christoph Hellwig 38f2323244 xfs: remove XFS_BUF_SET_VTYPE and XFS_BUF_SET_VTYPE_REF
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:09 -05:00
Christoph Hellwig 5fde0326dd xfs: remove XFS_BUF_FINISH_IOWAIT
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:09 -05:00
Christoph Hellwig b17b833443 xfs: remove xfs_get_buftarg_list
The code is unused and under a config option that doesn't exist, remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:09 -05:00
Christoph Hellwig 87c7bec7fc xfs: fix buffer flushing during unmount
The code to flush buffers in the umount code is a bit iffy: we first
flush all delwri buffers out, but then might be able to queue up a
new one when logging the sb counts.  On a normal shutdown that one
would get flushed out when doing the synchronous superblock write in
xfs_unmountfs_writesb, but we skip that one if the filesystem has
been shut down.

Fix this by moving the delwri list flushing until just before unmounting
the log, and while we're at it also remove the superflous delwri list
and buffer lru flusing for the rt and log device that can never have
cached or delwri buffers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Amit Sahrawat <amit.sahrawat83@gmail.com>
Tested-by: Amit Sahrawat <amit.sahrawat83@gmail.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:09 -05:00
Christoph Hellwig c4e1c098ee xfs: use the "delwri" terminology consistently
And also remove the strange local lock and delwri list pointers in a few
functions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:00 -05:00
Christoph Hellwig c2b006c1da xfs: let xfs_bwrite callers handle the xfs_buf_relse
Remove the xfs_buf_relse from xfs_bwrite and let the caller handle it to
mirror the delwri and read paths.

Also remove the mount pointer passed to xfs_bwrite, which is superflous now
that we have a mount pointer in the buftarg.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:15:00 -05:00
Christoph Hellwig 61551f1ee5 xfs: call xfs_buf_delwri_queue directly
Unify the ways we add buffers to the delwri queue by always calling
xfs_buf_delwri_queue directly.  The xfs_bdwrite functions is removed and
opencoded in its callers, and the two places setting XBF_DELWRI while a
buffer is locked and expecting xfs_buf_unlock to pick it up are converted
to call xfs_buf_delwri_queue directly, too.  Also replace the
XFS_BUF_UNDELAYWRITE macro with direct calls to xfs_buf_delwri_dequeue
to make the explicit queuing/dequeuing more obvious.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 21:14:59 -05:00
Christoph Hellwig c59d87c460 xfs: remove subdirectories
Use the move from Linux 2.6 to Linux 3.x as an excuse to kill the
annoying subdirectories in the XFS source code.  Besides the large
amount of file rename the only changes are to the Makefile, a few
files including headers with the subdirectory prefix, and the binary
sysctl compat code that includes a header under fs/xfs/ from
kernel/.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-08-12 16:21:35 -05:00