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Btrfs: fix race in check-integrity caused by usage of bitfield 

The structure member mirror_num is modified concurrently to the
structure member is_iodone. This doesn't require any locking by
design, unless everything is stored in the same 32 bits of a
bit field. This was the case and xfstest 284 was able to
trigger false warnings from the checker code. This patch
seperates the bits and fixes the race.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
This commit is contained in:
Stefan Behrens 2012-11-27 16:10:21 +00:00 committed by Chris Mason
parent b66f00da0c
commit cb3806ec88
1 changed files with 1 additions and 1 deletions
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fs/btrfs/check-integrity.c
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@ -137,7 +137,7 @@ struct btrfsic_block {
unsigned int never_written:1; /* block was added because it was
* referenced, not because it was
* written */
unsigned int mirror_num:2; /* large enough to hold
unsigned int mirror_num; /* large enough to hold
* BTRFS_SUPER_MIRROR_MAX */
struct btrfsic_dev_state *dev_state;
u64 dev_bytenr; /* key, physical byte num on disk */