dm snapshot: fix oversights in optional discard support
authorMike Snitzer <snitzer@redhat.com>
Wed, 17 Jul 2019 15:12:30 +0000 (11:12 -0400)
committerMike Snitzer <snitzer@redhat.com>
Wed, 17 Jul 2019 15:12:30 +0000 (11:12 -0400)
commit3ee25485ba8e8271fe9401eef5003c20ab648ddf
treeba1c9bde48555434b3343143d2f84fcf8770c037
parent3b8cafdd5436f9298b3bf6eb831df5eef5ee82b6
dm snapshot: fix oversights in optional discard support

__find_snapshots_sharing_cow() should always be used with _origins_lock
held so fix snapshot_io_hints() accordingly.  Also, once a snapshot is
being merged discards must not be allowed -- otherwise incorrect or
duplicate work will be performed.

Fixes: 2e6023850e177d ("dm snapshot: add optional discard support features")
Reported-by: Nikos Tsironis <ntsironis@arrikto.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
drivers/md/dm-snap.c