[PATCH] device-mapper multipath: Barriers not supported

dm multipath will report barriers as not supported with this patch.
Signed-off-by: Lars Marowsky-Bree <lmb@suse.de>
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>

drivers/md/dm-mpath.c

@@ -765,6 +765,9 @@ static int multipath_map(struct dm_target *ti, struct bio *bio,
 	struct 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);
 
@@ -988,6 +991,9 @@ static int do_end_io(struct multipath *m, struct bio *bio,
 	if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
 		return error;
 
+	if (error == -EOPNOTSUPP)
+		return error;
+
 	spin_lock(&m->lock);
 	if (!m->nr_valid_paths) {
 		if (!m->queue_if_no_path || m->suspended) {

drivers/md/dm-snap.c

@@ -777,7 +777,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
 
 	/* Full snapshots are not usable */
 	if (!s->valid)
-		return -1;
+		return -EIO;
 
 	/*
 	 * Write to snapshot - higher level takes care of RW/RO

drivers/md/dm.c

@@ -384,7 +384,7 @@ static void __map_bio(struct dm_target *ti, struct bio *clone,
 		/* error the io and bail out */
 		struct dm_io *io = tio->io;
 		free_tio(tio->io->md, tio);
-		dec_pending(io, -EIO);
+		dec_pending(io, r);
 		bio_put(clone);
 	}
 }