dm: error return error for discards

Have the error target respond to a discard request with a hard -EIO
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-target.c b/drivers/md/dm-target.c
index 11dea11dc0b6..8da366cf381c 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -113,6 +113,11 @@ void dm_unregister_target(struct target_type *tt)
  */
 static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args)
 {
+        /*
+         * Return error for discards instead of -EOPNOTSUPP
+         */
+        tt->num_discard_requests = 1;
+
         return 0;
 }