[PATCH] device-mapper snapshot: barriers not supported

The snapshot and origin targets are incapable of handling barriers and need to
indicate this.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index ad9b61f16c5e2611ec459df55be929e656a3aad4..f3759dd7828e585ed81b0819e9908fbf546da543 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -792,6 +792,9 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
        if (!s->valid)
                return -EIO;
 
+       if (unlikely(bio_barrier(bio)))
+               return -EOPNOTSUPP;
+
        /*
         * Write to snapshot - higher level takes care of RW/RO
         * flags so we should only get this if we are
@@ -1058,6 +1061,9 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
        struct dm_dev *dev = (struct dm_dev *) ti->private;
        bio->bi_bdev = dev->bdev;
 
+       if (unlikely(bio_barrier(bio)))
+               return -EOPNOTSUPP;
+
        /* Only tell snapshots if this is a write */
        return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : 1;
 }