From: Alasdair G Kergon <agk@redhat.com>
Date: Wed, 1 Feb 2006 11:04:55 +0000 (-0800)
Subject: [PATCH] device-mapper snapshot: barriers not supported
X-Git-Tag: accepted/tizen/common/20141203.182822~40350
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4aac0a63fe8d418a2b74e43708f59380ba379a3b;p=platform%2Fkernel%2Flinux-arm64.git

[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 ad9b61f..f3759dd 100644
--- 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;
 }