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@xxxxxxxxxx> Reported-by: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx> Cc: stable@xxxxxxxxxx --- Oops, had the wrong reported-by credit. Updated. Thanks. fs/block_dev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 99d6af8..b3171fb 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); -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
