Stefan Behrens
2012-Nov-27 16:10 UTC
[PATCH] 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>
---
fs/btrfs/check-integrity.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index 5a3e45d..a6baa8e 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -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 */
--
1.8.0.1
--
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