dm: remove limited barrier support

Prepare for full barrier implementation: first remove the restricted support.

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

1 files changed, 10 insertions, 5 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 25d86e2c01f2..ab3b5d84df65 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -851,11 +851,7 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
                 bio_io_error(bio);
                 return;
         }
-        if (unlikely(bio_barrier(bio) && !dm_table_barrier_ok(ci.map))) {
-                dm_table_put(ci.map);
-                bio_endio(bio, -EOPNOTSUPP);
-                return;
-        }
+
         ci.md = md;
         ci.bio = bio;
         ci.io = alloc_io(md);
@@ -937,6 +933,15 @@ static int dm_request(struct request_queue *q, struct bio *bio)
         struct mapped_device *md = q->queuedata;
         int cpu;
 
+        /*
+         * There is no use in forwarding any barrier request since we can't
+         * guarantee it is (or can be) handled by the targets correctly.
+         */
+        if (unlikely(bio_barrier(bio))) {
+                bio_endio(bio, -EOPNOTSUPP);
+                return 0;
+        }
+
         down_read(&md->io_lock);
 
         cpu = part_stat_lock();