Add a new target snapshot-merge.
For now, the target is identical to snapshot.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 drivers/md/dm-snap.c |   43 ++++++++++++++++++++++++++++++++++---------
 1 file changed, 34 insertions(+), 9 deletions(-)

Index: linux-2.6.26-rc8/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.26-rc8.orig/drivers/md/dm-snap.c	2008-07-01 18:52:52.000000000 +0200
+++ linux-2.6.26-rc8/drivers/md/dm-snap.c	2008-07-01 18:52:59.000000000 +0200
@@ -1370,14 +1370,26 @@ static struct target_type snapshot_targe
 	.status  = snapshot_status,
 };
 
+static struct target_type snapshot_merge_target = {
+	.name    = "snapshot-merge",
+	.version = {1, 6, 0},
+	.module  = THIS_MODULE,
+	.ctr     = snapshot_ctr,
+	.dtr     = snapshot_dtr,
+	.map     = snapshot_map,
+	.end_io  = snapshot_end_io,
+	.resume  = snapshot_resume,
+	.status  = snapshot_status,
+};
+
 static int __init dm_snapshot_init(void)
 {
 	int r;
 
 	r = dm_register_target(&snapshot_target);
-	if (r) {
+	if (r < 0) {
 		DMERR("snapshot target register failed %d", r);
-		return r;
+		goto bad0;
 	}
 
 	r = dm_register_target(&origin_target);
@@ -1386,45 +1398,54 @@ static int __init dm_snapshot_init(void)
 		goto bad1;
 	}
 
+	r = dm_register_target(&snapshot_merge_target);
+	if (r < 0) {
+		DMERR("snapshot_merge target register failed %d", r);
+		goto bad2;
+	}
+
 	r = init_origin_hash();
 	if (r) {
 		DMERR("init_origin_hash failed.");
-		goto bad2;
+		goto bad3;
 	}
 
 	exception_cache = KMEM_CACHE(dm_snap_exception, 0);
 	if (!exception_cache) {
 		DMERR("Couldn't create exception cache.");
 		r = -ENOMEM;
-		goto bad3;
+		goto bad4;
 	}
 
 	pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0);
 	if (!pending_cache) {
 		DMERR("Couldn't create pending cache.");
 		r = -ENOMEM;
-		goto bad4;
+		goto bad5;
 	}
 
 	tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0);
 	if (!tracked_chunk_cache) {
 		DMERR("Couldn't create chunk in use cache.");
 		r = -ENOMEM;
-		goto bad5;
+		goto bad6;
 	}
 
 	return 0;
 
-      bad5:
+      bad6:
 	kmem_cache_destroy(pending_cache);
-      bad4:
+      bad5:
 	kmem_cache_destroy(exception_cache);
-      bad3:
+      bad4:
 	exit_origin_hash();
+      bad3:
+	dm_unregister_target(&snapshot_merge_target);
       bad2:
 	dm_unregister_target(&origin_target);
       bad1:
 	dm_unregister_target(&snapshot_target);
+      bad0:
 	return r;
 }
 
@@ -1440,6 +1461,10 @@ static void __exit dm_snapshot_exit(void
 	if (r)
 		DMERR("origin unregister failed %d", r);
 
+	r = dm_unregister_target(&snapshot_merge_target);
+	if (r)
+		DMERR("snapshot_merge unregister failed %d", r);
+
 	exit_origin_hash();
 	kmem_cache_destroy(pending_cache);
 	kmem_cache_destroy(exception_cache);