dm io: fix duplicate bio completion due to missing ref count
authorMike Snitzer <snitzer@redhat.com>
Tue, 20 Jun 2017 23:14:30 +0000 (19:14 -0400)
committerMike Snitzer <snitzer@redhat.com>
Wed, 21 Jun 2017 16:04:50 +0000 (12:04 -0400)
commitfeb7695fe9fb83084aa29de0094774f4c9d4c9fc
treedbdc175a3abd214ec6cef8531d07944407610421
parent7def52b78a5fda14864aab9b6fd14f09a4d4ff72
dm io: fix duplicate bio completion due to missing ref count

If only a subset of the devices associated with multiple regions support
a given special operation (eg. DISCARD) then the dec_count() that is
used to set error for the region must increment the io->count.

Otherwise, when the dec_count() is called it can cause the dm-io
caller's bio to be completed multiple times.  As was reported against
the dm-mirror target that had mirror legs with a mix of discard
capabilities.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=196077
Reported-by: Zhang Yi <yizhan@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
drivers/md/dm-io.c