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author | Miao Xie <miaox@cn.fujitsu.com> | 2012-02-16 07:01:24 (GMT) |
---|---|---|
committer | David Sterba <dsterba@suse.cz> | 2012-02-16 16:23:16 (GMT) |
commit | 600a45e1d5e376f679ff9ecc4ce9452710a6d27c (patch) | |
tree | c4bf84eee1db132b5ff18700b95da8426a909f2f /fs/cachefiles | |
parent | 013bd4c336ad0d30e9e41f9cff0dbc1858934e75 (diff) | |
download | linux-fsl-qoriq-600a45e1d5e376f679ff9ecc4ce9452710a6d27c.tar.xz |
Btrfs: fix deadlock on page lock when doing auto-defragment
When I ran xfstests circularly on a auto-defragment btrfs, the deadlock
happened.
Steps to reproduce:
[tty0]
# export MOUNT_OPTIONS="-o autodefrag"
# export TEST_DEV=<partition1>
# export TEST_DIR=<mountpoint1>
# export SCRATCH_DEV=<partition2>
# export SCRATCH_MNT=<mountpoint2>
# while [ 1 ]
> do
> ./check 091 127 263
> sleep 1
> done
[tty1]
# while [ 1 ]
> do
> echo 3 > /proc/sys/vm/drop_caches
> done
Several hours later, the test processes will hang on, and the deadlock will
happen on page lock.
The reason is that:
Auto defrag task Flush thread Test task
btrfs_writepages()
add ordered extent
(including page 1, 2)
set page 1 writeback
set page 2 writeback
endio_fn()
end page 2 writeback
release page 2
lock page 1
alloc and lock page 2
page 2 is not uptodate
btrfs_readpage()
start ordered extent()
btrfs_writepages()
try to lock page 1
so deadlock happens.
Fix this bug by unlocking the page which is in writeback, and re-locking it
after the writeback end.
Signed-off-by: Miao Xie <miax@cn.fujitsu.com>
Diffstat (limited to 'fs/cachefiles')
0 files changed, 0 insertions, 0 deletions