dm: zero silently drop discards

Have the zero target silently drop a discard rather than fail the
request with -EOPNOTSUPP.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/md/dm-zero.c b/drivers/md/dm-zero.c
index bbc97030c0c2..cc2b3cb81946 100644
--- a/drivers/md/dm-zero.c
+++ b/drivers/md/dm-zero.c
@@ -22,6 +22,11 @@ static int zero_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                 return -EINVAL;
         }
 
+        /*
+         * Silently drop discards, avoiding -EOPNOTSUPP.
+         */
+        ti->num_discard_requests = 1;
+
         return 0;
 }