vfs_create() ignores everything outside of 16bit subset of its
mode argument; switching it to umode_t is obviously equivalent
and it's the only caller of the method
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
vfs_mkdir() gets int, but immediately drops everything that might not
fit into umode_t and that's the only caller of ->mkdir()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Seeing that just about every destructor got that INIT_LIST_HEAD() copied into
it, there is no point whatsoever keeping this INIT_LIST_HEAD in inode_init_once();
the cost of taking it into inode_init_always() will be negligible for pipes
and sockets and negative for everything else. Not to mention the removal of
boilerplate code from ->destroy_inode() instances...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We need to zero out part of a page which beyond EOF before setting uptodate,
otherwise, mapread or write will see non-zero data beyond EOF.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
If a file is fallocated on a hole, map->m_lblk + map->m_len may be greater
than ee_block + ee_len.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
If a page has been read into memory and never been written, it has no
buffers, but we should handle the page in truncate or punch hole.
VFS code of writing operations has handled holes correctly, so this
patch removes the code handling holes in writing operations.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
If there is an unwritten but clean buffer in a page and there is a
dirty buffer after the buffer, then mpage_submit_io does not write the
dirty buffer out. As a result, da_writepages loops forever.
This patch fixes the problem by checking dirty flag.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
If the pte mapping in generic_perform_write() is unmapped between
iov_iter_fault_in_readable() and iov_iter_copy_from_user_atomic(), the
"copied" parameter to ->end_write can be zero. ext4 couldn't cope with
it with delayed allocations enabled. This skips the i_disksize
enlargement logic if copied is zero and no new data was appeneded to
the inode.
gdb> bt
#0 0xffffffff811afe80 in ext4_da_should_update_i_disksize (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x1\
08000, len=0x1000, copied=0x0, page=0xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2467
#1 ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\
xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512
#2 0xffffffff810d97f1 in generic_perform_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value o\
ptimized out>, pos=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2440
#3 generic_file_buffered_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value optimized out>, p\
os=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2482
#4 0xffffffff810db5d1 in __generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, ppos=0\
xffff88001e26be40) at mm/filemap.c:2600
#5 0xffffffff810db853 in generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=<value optimi\
zed out>, pos=<value optimized out>) at mm/filemap.c:2632
#6 0xffffffff811a71aa in ext4_file_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, pos=0x108000) a\
t fs/ext4/file.c:136
#7 0xffffffff811375aa in do_sync_write (filp=0xffff88003f606a80, buf=<value optimized out>, len=<value optimized out>, \
ppos=0xffff88001e26bf48) at fs/read_write.c:406
#8 0xffffffff81137e56 in vfs_write (file=0xffff88003f606a80, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x4\
000, pos=0xffff88001e26bf48) at fs/read_write.c:435
#9 0xffffffff8113816c in sys_write (fd=<value optimized out>, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x\
4000) at fs/read_write.c:487
#10 <signal handler called>
#11 0x00007f120077a390 in __brk_reservation_fn_dmi_alloc__ ()
#12 0x0000000000000000 in ?? ()
gdb> print offset
$22 = 0xffffffffffffffff
gdb> print idx
$23 = 0xffffffff
gdb> print inode->i_blkbits
$24 = 0xc
gdb> up
#1 ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\
xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512
2512 if (ext4_da_should_update_i_disksize(page, end)) {
gdb> print start
$25 = 0x0
gdb> print end
$26 = 0xffffffffffffffff
gdb> print pos
$27 = 0x108000
gdb> print new_i_size
$28 = 0x108000
gdb> print ((struct ext4_inode_info *)((char *)inode-((int)(&((struct ext4_inode_info *)0)->vfs_inode))))->i_disksize
$29 = 0xd9000
gdb> down
2467 for (i = 0; i < idx; i++)
gdb> print i
$30 = 0xd44acbee
This is 100% reproducible with some autonuma development code tuned in
a very aggressive manner (not normal way even for knumad) which does
"exotic" changes to the ptes. It wouldn't normally trigger but I don't
see why it can't happen normally if the page is added to swap cache in
between the two faults leading to "copied" being zero (which then
hangs in ext4). So it should be fixed. Especially possible with lumpy
reclaim (albeit disabled if compaction is enabled) as that would
ignore the young bits in the ptes.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
/proc/mounts was showing the mount option [no]init_inode_table when
the correct mount option that will be accepted by parse_options() is
[no]init_itable.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Commit 1939dd84b3 ("ext4: cleanup ext4_ext_grow_indepth code") added a
reference to ext4_extent_header.eh_depth, but forget to pass the value
read through le16_to_cpu. The result is a crash on big-endian
machines, such as this crash on a POWER7 server:
attempt to access beyond end of device
sda8: rw=0, want=776392648163376, limit=168558560
Unable to handle kernel paging request for data at address 0x6b6b6b6b6b6b6bcb
Faulting instruction address: 0xc0000000001f5f38
cpu 0x14: Vector: 300 (Data Access) at [c000001bd1aaecf0]
pc: c0000000001f5f38: .__brelse+0x18/0x60
lr: c0000000002e07a4: .ext4_ext_drop_refs+0x44/0x80
sp: c000001bd1aaef70
msr: 9000000000009032
dar: 6b6b6b6b6b6b6bcb
dsisr: 40000000
current = 0xc000001bd15b8010
paca = 0xc00000000ffe4600
pid = 19911, comm = flush-8:0
enter ? for help
[c000001bd1aaeff0] c0000000002e07a4 .ext4_ext_drop_refs+0x44/0x80
[c000001bd1aaf090] c0000000002e0c58 .ext4_ext_find_extent+0x408/0x4c0
[c000001bd1aaf180] c0000000002e145c .ext4_ext_insert_extent+0x2bc/0x14c0
[c000001bd1aaf2c0] c0000000002e3fb8 .ext4_ext_map_blocks+0x628/0x1710
[c000001bd1aaf420] c0000000002b2974 .ext4_map_blocks+0x224/0x310
[c000001bd1aaf4d0] c0000000002b7f2c .mpage_da_map_and_submit+0xbc/0x490
[c000001bd1aaf5a0] c0000000002b8688 .write_cache_pages_da+0x2c8/0x430
[c000001bd1aaf720] c0000000002b8b28 .ext4_da_writepages+0x338/0x670
[c000001bd1aaf8d0] c000000000157280 .do_writepages+0x40/0x90
[c000001bd1aaf940] c0000000001ea830 .writeback_single_inode+0xe0/0x530
[c000001bd1aafa00] c0000000001eb680 .writeback_sb_inodes+0x210/0x300
[c000001bd1aafb20] c0000000001ebc84 .__writeback_inodes_wb+0xd4/0x140
[c000001bd1aafbe0] c0000000001ebfec .wb_writeback+0x2fc/0x3e0
[c000001bd1aafce0] c0000000001ed770 .wb_do_writeback+0x2f0/0x300
[c000001bd1aafdf0] c0000000001ed848 .bdi_writeback_thread+0xc8/0x340
[c000001bd1aafed0] c0000000000c5494 .kthread+0xb4/0xc0
[c000001bd1aaff90] c000000000021f48 .kernel_thread+0x54/0x70
This is due to getting ext_depth(inode) == 0x101 and therefore running
off the end of the path array in ext4_ext_drop_refs into following
unallocated structures.
This fixes it by adding the necessary le16_to_cpu.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
We need to make sure iocb->private is cleared *before* we put the
io_end structure on i_completed_io_list. Otherwise fsync() could
potentially run on another CPU and free the iocb structure out from
under us.
Reported-by: Kent Overstreet <koverstreet@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
ext4_end_io_dio() queues io_end->work and then clears iocb->private;
however, io_end->work calls aio_complete() which frees the iocb
object. If that slab object gets reallocated, then ext4_end_io_dio()
can end up clearing someone else's iocb->private, this use-after-free
can cause a leak of a struct ext4_io_end_t structure.
Detected and tested with slab poisoning.
[ Note: Can also reproduce using 12 fio's against 12 file systems with the
following configuration file:
[global]
direct=1
ioengine=libaio
iodepth=1
bs=4k
ba=4k
size=128m
[create]
filename=${TESTDIR}
rw=write
-- tytso ]
Google-Bug-Id: 5354697
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reported-by: Kent Overstreet <koverstreet@google.com>
Tested-by: Kent Overstreet <koverstreet@google.com>
Cc: stable@kernel.org
* 'dev' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: fix up a undefined error in ext4_free_blocks in debugging code
ext4: add blk_finish_plug in error case of writepages.
ext4: Remove kernel_lock annotations
ext4: ignore journalled data options on remount if fs has no journal
sbi is not defined, so let ext4_free_blocks use EXT4_SB(sb) instead
when EXT4FS_DEBUG is defined.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
blk_finish_plug is needed in error case of writepages.
Signed-off-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This avoids a confusing failure in the init scripts when the
/etc/fstab has data=writeback or data=journal but the file system does
not have a journal. So check for this case explicitly, and warn the
user that we are ignoring the (pointless, since they have no journal)
data=* mount option.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
writeback: Add a 'reason' to wb_writeback_work
writeback: send work item to queue_io, move_expired_inodes
writeback: trace event balance_dirty_pages
writeback: trace event bdi_dirty_ratelimit
writeback: fix ppc compile warnings on do_div(long long, unsigned long)
writeback: per-bdi background threshold
writeback: dirty position control - bdi reserve area
writeback: control dirty pause time
writeback: limit max dirty pause time
writeback: IO-less balance_dirty_pages()
writeback: per task dirty rate limit
writeback: stabilize bdi->dirty_ratelimit
writeback: dirty rate control
writeback: add bg_threshold parameter to __bdi_update_bandwidth()
writeback: dirty position control
writeback: account per-bdi accumulated dirtied pages
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (97 commits)
jbd2: Unify log messages in jbd2 code
jbd/jbd2: validate sb->s_first in journal_get_superblock()
ext4: let ext4_ext_rm_leaf work with EXT_DEBUG defined
ext4: fix a syntax error in ext4_ext_insert_extent when debugging enabled
ext4: fix a typo in struct ext4_allocation_context
ext4: Don't normalize an falloc request if it can fit in 1 extent.
ext4: remove comments about extent mount option in ext4_new_inode()
ext4: let ext4_discard_partial_buffers handle unaligned range correctly
ext4: return ENOMEM if find_or_create_pages fails
ext4: move vars to local scope in ext4_discard_partial_page_buffers_no_lock()
ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwritten
ext4: optimize locking for end_io extent conversion
ext4: remove unnecessary call to waitqueue_active()
ext4: Use correct locking for ext4_end_io_nolock()
ext4: fix race in xattr block allocation path
ext4: trace punch_hole correctly in ext4_ext_map_blocks
ext4: clean up AGGRESSIVE_TEST code
ext4: move variables to their scope
ext4: fix quota accounting during migration
ext4: migrate cleanup
...
Replace remaining direct i_nlink updates with a new set_nlink()
updater function.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Replace direct i_nlink updates with the respective updater function
(inc_nlink, drop_nlink, clear_nlink, inode_dec_link_count).
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
The variable 'block' is removed by commit 750c9c47, so use the
replacement ex_ee_block instead.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This patch fixes a syntax error which omits a comma. Besides this,
logical block number is unsigend 32 bits, so printk should use %u
instead %d.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Direct reclaim should never writeback pages. Warn if an attempt is made.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alex Elder <aelder@sgi.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If an fallocate request fits in EXT_UNINIT_MAX_LEN, then set the
EXT4_GET_BLOCKS_NO_NORMALIZE flag. For larger fallocate requests,
let mballoc.c normalize the request.
This fixes a problem where large requests were being split into
non-contiguous extents due to commit 556b27abf7: ext4: do not
normalize block requests from fallocate.
Testing:
*) Checked that 8.x MB falloc'ed files are still laid down next to
each other (contiguously).
*) Checked that the maximum size extent (127.9MB) is allocated as 1
extent.
*) Checked that a 1GB file is somewhat contiguous (often 5-6
non-contiguous extents now).
*) Checked that a 120MB file can still be falloc'ed even if there are
no single extents large enough to hold it.
Signed-off-by: Greg Harm <gharm@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Remove comments about 'extent' mount option in ext4_new_inode(), since
it's no longer exists.
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
As comment says, we should handle unaligned range rather than aligned
one. This fixes a bug found by running xfstests #91.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten
should be done simultaneously since ext4_end_io_nolock always clear
the flag and decrease the counter in the same time.
We have found some bugs that the flag is set while leaving
i_aiodio_unwritten unchanged(commit 32c80b32c0). So this patch just tries
to create a helper function to wrap them to avoid any future bug.
The idea is inspired by Eric.
Cc: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Now that we are doing the locking correctly, we need to grab the
i_completed_io_lock() twice per end_io. We can clean this up by
removing the structure from the i_complted_io_list, and use this as
the locking mechanism to prevent ext4_flush_completed_IO() racing
against ext4_end_io_work(), instead of clearing the
EXT4_IO_END_UNWRITTEN in io->flag.
In addition, if the ext4_convert_unwritten_extents() returns an error,
we no longer keep the end_io structure on the linked list. This
doesn't help, because it tends to lock up the file system and wedges
the system. That's one way to call attention to the problem, but it
doesn't help the overall robustness of the system.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
We must hold i_completed_io_lock when manipulating anything on the
i_completed_io_list linked list. This includes io->lock, which we
were checking in ext4_end_io_nolock().
So move this check to ext4_end_io_work(). This also has the bonus of
avoiding extra work if it is already done without needing to take the
mutex.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This creates a new 'reason' field in a wb_writeback_work
structure, which unambiguously identifies who initiates
writeback activity. A 'wb_reason' enumeration has been
added to writeback.h, to enumerate the possible reasons.
The 'writeback_work_class' and tracepoint event class and
'writeback_queue_io' tracepoints are updated to include the
symbolic 'reason' in all trace events.
And the 'writeback_inodes_sbXXX' family of routines has had
a wb_stats parameter added to them, so callers can specify
why writeback is being started.
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Ceph users reported that when using Ceph on ext4, the filesystem
would often become corrupted, containing inodes with incorrect
i_blocks counters.
I managed to reproduce this with a very hacked-up "streamtest"
binary from the Ceph tree.
Ceph is doing a lot of xattr writes, to out-of-inode blocks.
There is also another thread which does sync_file_range and close,
of the same files. The problem appears to happen due to this race:
sync/flush thread xattr-set thread
----------------- ----------------
do_writepages ext4_xattr_set
ext4_da_writepages ext4_xattr_set_handle
mpage_da_map_blocks ext4_xattr_block_set
set DELALLOC_RESERVE
ext4_new_meta_blocks
ext4_mb_new_blocks
if (!i_delalloc_reserved_flag)
vfs_dq_alloc_block
ext4_get_blocks
down_write(i_data_sem)
set i_delalloc_reserved_flag
...
up_write(i_data_sem)
if (i_delalloc_reserved_flag)
vfs_dq_alloc_block_nofail
In other words, the sync/flush thread pops in and sets
i_delalloc_reserved_flag on the inode, which makes the xattr thread
think that it's in a delalloc path in ext4_new_meta_blocks(),
and add the block for a second time, after already having added
it once in the !i_delalloc_reserved_flag case in ext4_mb_new_blocks
The real problem is that we shouldn't be using the DELALLOC_RESERVED
state flag, and instead we should be passing
EXT4_GET_BLOCKS_DELALLOC_RESERVE down to ext4_map_blocks() instead of
using an inode state flag. We'll fix this for now with using
i_data_sem to prevent this race, but this is really not the right way
to fix things.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
When ext4_ext_map_blocks() is called by punch_hole, trace should
trace blocks punched out.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The tmp_inode should have same uid/gid as the original inode.
Otherwise new metadata blocks will be accounted to wrong quota-id,
which will result in a quota leak after the inode migration is
completed.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This patch cleanup code a bit, actual logic not changed
- Move current block pointer to migrate_structure, let's all
walk info will be in one structure.
- Get rid of usless null ind-block ptr checks, caller already
does that check.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue: (21 commits)
leases: fix write-open/read-lease race
nfs: drop unnecessary locking in llseek
ext4: replace cut'n'pasted llseek code with generic_file_llseek_size
vfs: add generic_file_llseek_size
vfs: do (nearly) lockless generic_file_llseek
direct-io: merge direct_io_walker into __blockdev_direct_IO
direct-io: inline the complete submission path
direct-io: separate map_bh from dio
direct-io: use a slab cache for struct dio
direct-io: rearrange fields in dio/dio_submit to avoid holes
direct-io: fix a wrong comment
direct-io: separate fields only used in the submission path from struct dio
vfs: fix spinning prevention in prune_icache_sb
vfs: add a comment to inode_permission()
vfs: pass all mask flags check_acl and posix_acl_permission
vfs: add hex format for MAY_* flag values
vfs: indicate that the permission functions take all the MAY_* flags
compat: sync compat_stats with statfs.
vfs: add "device" tag to /proc/self/mountstats
cleanup: vfs: small comment fix for block_invalidatepage
...
Fix up trivial conflict in fs/gfs2/file.c (llseek changes)
This gives ext4 the benefits of unlocked llseek.
Cc: tytso@mit.edu
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
ext4_ext_insert_extent() (respectively ext4_ext_insert_index())
was using EXT_MAX_EXTENT() (resp. EXT_MAX_INDEX()) to determine
how many entries needed to be moved beyond the insertion point.
In practice this means that (320 - I) * 24 bytes were memmove()'d
when I is the insertion point, rather than (#entries - I) * 24 bytes.
This patch uses EXT_LAST_EXTENT() (resp. EXT_LAST_INDEX()) instead
to only move existing entries. The code flow is also simplified
slightly to highlight similarities and reduce code duplication in
the insertion logic.
This patch reduces system CPU consumption by over 25% on a 4kB
synchronous append DIO write workload when used with the
pre-2.6.39 x86_64 memmove() implementation. With the much faster
2.6.39 memmove() implementation we still see a decrease in
system CPU usage between 2% and 7%.
Note that the ext_debug() output changes with this patch, splitting
some log information between entries. Users of the ext_debug() output
should note that the "move %d" units changed from reporting the number
of bytes moved to reporting the number of entries moved.
Signed-off-by: Eric Gouriou <egouriou@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This patch introduces a fast path in ext4_ext_convert_to_initialized()
for the case when the conversion can be performed by transferring
the newly initialized blocks from the uninitialized extent into
an adjacent initialized extent. Doing so removes the expensive
invocations of memmove() which occur during extent insertion and
the subsequent merge.
In practice this should be the common case for clients performing
append writes into files pre-allocated via
fallocate(FALLOC_FL_KEEP_SIZE). In such a workload performed via
direct IO and when using a suboptimal implementation of memmove()
(x86_64 prior to the 2.6.39 rewrite), this patch reduces kernel CPU
consumption by 32%.
Two new trace points are added to ext4_ext_convert_to_initialized()
to offer visibility into its operations. No exit trace point has
been added due to the multiplicity of return points. This can be
revisited once the upstream cleanup is backported.
Signed-off-by: Eric Gouriou <egouriou@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
