dm: disable barriers

This patch causes device-mapper to reject any barrier requests.  This is done
since most of the targets won't handle this correctly anyway.  So until the
situation improves it is better to reject these requests at the first place.
Since barrier requests won't get to the targets, the checks there can be
removed.

Cc: stable@kernel.org
Signed-off-by: Stefan Bader <shbader@de.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 3 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index fc6c1021178d..d6ca9d0a6fd1 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -798,9 +798,6 @@ static int multipath_map(struct dm_target *ti, struct bio *bio,
         struct dm_mpath_io *mpio;
         struct multipath *m = (struct multipath *) ti->private;
 
-        if (bio_barrier(bio))
-                return -EOPNOTSUPP;
-
         mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
         dm_bio_record(&mpio->details, bio);