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fa5566e xfs: remove log force from xfs_buf_trylock()
5337fe9 xfs: recheck buffer pinned status after push trylock failure
a1e16c2 xfs: limit speculative prealloc size on sparse files
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commit fa5566e4ffb918131a054413eb42075a77a41413
Author: Brian Foster <bfoster@xxxxxxxxxx>
Date: Mon Feb 11 10:08:22 2013 -0500
xfs: remove log force from xfs_buf_trylock()
The trylock log force invoked via xfs_buf_item_push() can attempt
to acquire xa_lock, thus leading to a recursion bug when called
with xa_lock held.
This log force was originally added to xfs_buf_trylock() to address
xfsaild stalls due to pinned and stale buffers. Since the addition
of this behavior, the log item pushing code had been reworked to
detect and track pinned items to inform xfsaild to issue a log
force itself when necessary. As such, the log force on trylock
failure is redundant and safe to remove.
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Signed-off-by: Ben Myers <bpm@xxxxxxx>
commit 5337fe9b108d602c483fe9d62ffef9227acf3a74
Author: Brian Foster <bfoster@xxxxxxxxxx>
Date: Mon Feb 11 10:08:21 2013 -0500
xfs: recheck buffer pinned status after push trylock failure
The buffer pinned check and trylock sequence in xfs_buf_item_push()
can race with an active transaction on marking the buffer pinned.
This can result in the buffer becoming pinned and stale after the
initial check and the trylock failure, but before the check in
xfs_buf_trylock() that issues a log force. If the log force is
issued from this context, a spinlock recursion occurs on xa_lock.
Prepare xfs_buf_item_push() to handle the race by detecting a
pinned buffer after the trylock failure so xfsaild issues a log
force from a safe context. This, along with various previous fixes,
renders the log force in xfs_buf_trylock() redundant.
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Signed-off-by: Ben Myers <bpm@xxxxxxx>
commit a1e16c26660b301cc8423185924cf1b0b16ea92b
Author: Dave Chinner <dchinner@xxxxxxxxxx>
Date: Mon Feb 11 16:05:01 2013 +1100
xfs: limit speculative prealloc size on sparse files
Speculative preallocation based on the current file size works well
for contiguous files, but is sub-optimal for sparse files where the
EOF preallocation can fill holes and result in large amounts of
zeros being written when it is not necessary.
The algorithm is modified to prevent EOF speculative preallocation
from triggering larger allocations on IO patterns of
truncate--to-zero-seek-write-seek-write-.... which results in
non-sparse files for large files. This, unfortunately, is the way cp
now behaves when copying sparse files and so needs to be fixed.
What this code does is that it looks at the existing extent adjacent
to the current EOF and if it determines that it is a hole we disable
speculative preallocation altogether. To avoid the next write from
doing a large prealloc, it takes the size of subsequent
preallocations from the current size of the existing EOF extent.
IOWs, if you leave a hole in the file, it resets preallocation
behaviour to the same as if it was a zero size file.
Example new behaviour:
$ xfs_io -f -c "pwrite 0 31m" \
-c "pwrite 33m 1m" \
-c "pwrite 128m 1m" \
-c "fiemap -v" /mnt/scratch/blah
wrote 32505856/32505856 bytes at offset 0
31 MiB, 7936 ops; 0.0000 sec (1.608 GiB/sec and 421432.7439 ops/sec)
wrote 1048576/1048576 bytes at offset 34603008
1 MiB, 256 ops; 0.0000 sec (1.462 GiB/sec and 383233.5329 ops/sec)
wrote 1048576/1048576 bytes at offset 134217728
1 MiB, 256 ops; 0.0000 sec (1.719 GiB/sec and 450704.2254 ops/sec)
/mnt/scratch/blah:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..65535]: 96..65631 65536 0x0
1: [65536..67583]: hole 2048
2: [67584..69631]: 67680..69727 2048 0x0
3: [69632..262143]: hole 192512
4: [262144..264191]: 262240..264287 2048 0x1
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Mark Tinguely <tinguely@xxxxxxx>
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
Signed-off-by: Ben Myers <bpm@xxxxxxx>
-----------------------------------------------------------------------
Summary of changes:
fs/xfs/xfs_buf.c | 2 --
fs/xfs/xfs_buf_item.c | 12 +++++++-
fs/xfs/xfs_iomap.c | 77 ++++++++++++++++++++++++++++++++++++++++++++-------
3 files changed, 78 insertions(+), 13 deletions(-)
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