From patchwork Tue Nov 17 16:12:23 2009
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
X-Patchwork-Submitter: Mike Snitzer <snitzer@redhat.com>
X-Patchwork-Id: 60710
Received: from hormel.redhat.com (hormel1.redhat.com [209.132.177.33])
	by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id nAHGCmvI001764
	for <patchwork-dm-devel@patchwork.kernel.org>;
	Tue, 17 Nov 2009 16:12:50 GMT
Received: from listman.util.phx.redhat.com (listman.util.phx.redhat.com
	[10.8.4.110])
	by hormel.redhat.com (Postfix) with ESMTP id 6502761B36D;
	Tue, 17 Nov 2009 11:12:41 -0500 (EST)
Received: from int-mx04.intmail.prod.int.phx2.redhat.com
	(nat-pool.util.phx.redhat.com [10.8.5.200])
	by listman.util.phx.redhat.com (8.13.1/8.13.1) with ESMTP id
	nAHGCWrM030067 for <dm-devel@listman.util.phx.redhat.com>;
	Tue, 17 Nov 2009 11:12:32 -0500
Received: from localhost (dhcp-100-19-150.bos.redhat.com [10.16.19.150])
	by int-mx04.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with
	ESMTP id nAHGCVq4025553
	for <dm-devel@redhat.com>; Tue, 17 Nov 2009 11:12:32 -0500
From: Mike Snitzer <snitzer@redhat.com>
To: dm-devel@redhat.com
Date: Tue, 17 Nov 2009 11:12:23 -0500
Message-Id: <1258474344-10886-12-git-send-email-snitzer@redhat.com>
In-Reply-To: <1258474344-10886-1-git-send-email-snitzer@redhat.com>
References: <1258474344-10886-1-git-send-email-snitzer@redhat.com>
X-Scanned-By: MIMEDefang 2.67 on 10.5.11.17
X-loop: dm-devel@redhat.com
Subject: [dm-devel] [PATCH v3 11/12] dm snapshot: redirect accesses to
	origin if merging snap invalidated
X-BeenThere: dm-devel@redhat.com
X-Mailman-Version: 2.1.5
Precedence: junk
Reply-To: device-mapper development <dm-devel@redhat.com>
List-Id: device-mapper development <dm-devel.redhat.com>
List-Unsubscribe: <https://www.redhat.com/mailman/listinfo/dm-devel>,
	<mailto:dm-devel-request@redhat.com?subject=unsubscribe>
List-Archive: <https://www.redhat.com/archives/dm-devel>
List-Post: <mailto:dm-devel@redhat.com>
List-Help: <mailto:dm-devel-request@redhat.com?subject=help>
List-Subscribe: <https://www.redhat.com/mailman/listinfo/dm-devel>,
	<mailto:dm-devel-request@redhat.com?subject=subscribe>
Sender: dm-devel-bounces@redhat.com
Errors-To: dm-devel-bounces@redhat.com


diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 5b2d0f4..3d214f4 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1520,11 +1520,9 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
 
 	down_write(&s->lock);
 
-	/* Full snapshots are not usable */
-	if (!s->valid) {
-		r = -EIO;
-		goto out_unlock;
-	}
+	/* Full merging snapshots are redirected to the origin */
+	if (!s->valid)
+		goto redirect_to_origin;
 
 	/* If the block is already remapped - use that */
 	e = dm_lookup_exception(&s->complete, chunk);
@@ -1548,6 +1546,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
 		goto out_unlock;
 	}
 
+ redirect_to_origin:
 	bio->bi_bdev = s->origin->bdev;
 
 	if (bio_rw(bio) == WRITE) {