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authorTejun Heo <htejun@gmail.com>2010-08-04 17:59:39 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-10 11:09:14 -0700
commitacdc70839d626fa98417b8905bfa1e88087f3097 (patch)
treec726e8db60168cb8ddfee44a4eab918413518541
parent2812c8f70ec3a6c5abd0305a42366c880a18a85a (diff)
downloadlinux-2.6.34-ux500-acdc70839d626fa98417b8905bfa1e88087f3097.tar.gz
block_dev: always serialize exclusive open attempts
commit e75aa85892b2ee78c79edac720868cbef16e62eb upstream. 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. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-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);