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authorMikulas Patocka <mpatocka@redhat.com>2009-04-02 22:55:26 +0400
committerAlasdair G Kergon <agk@redhat.com>2009-04-02 22:55:26 +0400
commit35bf659b008e83e725dcd30f542e38461dbb867c (patch)
tree40be2f357f0905573bd4d21ff59e0db3cda26442 /drivers/md/dm-target.c
parentc66213921c816f6b1b16a84911618ba9a363b134 (diff)
downloadlinux-35bf659b008e83e725dcd30f542e38461dbb867c.tar.xz
dm snapshot: avoid having two exceptions for the same chunk
We need to check if the exception was completed after dropping the lock. After regaining the lock, __find_pending_exception checks if the exception was already placed into &s->pending hash. But we don't check if the exception was already completed and placed into &s->complete hash. If the process waiting in alloc_pending_exception was delayed at this point because of a scheduling latency and the exception was meanwhile completed, we'd miss that and allocate another pending exception for already completed chunk. It would lead to a situation where two records for the same chunk exist and potential data corruption because multiple snapshot I/Os to the affected chunk could be redirected to different locations in the snapshot. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-target.c')
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