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authorTejun Heo <htejun@gmail.com>2010-08-04 17:59:39 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-04 11:17:10 -0700
commite75aa85892b2ee78c79edac720868cbef16e62eb (patch)
tree80b9ce187b207a1a817b9b4b172f86fa71d75212 /fs
parentd9b68e5e88248bb24fd4e455588bea1d56108fd6 (diff)
downloadvexpress-lsk-e75aa85892b2ee78c79edac720868cbef16e62eb.tar.gz
block_dev: always serialize exclusive open attempts
bd_prepare_to_claim() incorrectly allowed multiple attempts for exclusive open to progress in parallel if the attempting holders are identical. This triggered BUG_ON() as reported in the following bug. https://bugzilla.kernel.org/show_bug.cgi?id=16393 __bd_abort_claiming() is used to finish claiming blocks and doesn't work if multiple openers are inside a claiming block. Allowing multiple parallel open attempts to continue doesn't gain anything as those are serialized down in the call chain anyway. Fix it by always allowing only single open attempt in a claiming block. This problem can easily be reproduced by adding a delay after bd_prepare_to_claim() and attempting to mount two partitions of a disk. stable: only applicable to v2.6.35 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/block_dev.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 99d6af81174..b3171fb0dc9 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -681,8 +681,8 @@ retry:
if (!bd_may_claim(bdev, whole, holder))
return -EBUSY;
- /* if someone else is claiming, wait for it to finish */
- if (whole->bd_claiming && whole->bd_claiming != holder) {
+ /* if claiming is already in progress, wait for it to finish */
+ if (whole->bd_claiming) {
wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
DEFINE_WAIT(wait);