dm io: retry after barrier error

If -EOPNOTSUPP was returned and the request was a barrier request, retry it
without barrier.

Retry all regions for now. Barriers are submitted only for one-region requests,
so it doesn't matter.  (In the future, retries can be limited to the actual
regions that failed.)

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index a89f41f00757..3a2e6a2f8bdd 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -364,6 +364,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
                 return -EIO;
         }
 
+retry:
         io.error_bits = 0;
         io.eopnotsupp_bits = 0;
         atomic_set(&io.count, 1); /* see dispatch_io() */
@@ -382,6 +383,11 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
         }
         set_current_state(TASK_RUNNING);
 
+        if (io.eopnotsupp_bits && (rw & (1 << BIO_RW_BARRIER))) {
+                rw &= ~(1 << BIO_RW_BARRIER);
+                goto retry;
+        }
+
         if (error_bits)
                 *error_bits = io.error_bits;