Store the uuid argument in "struct dm_snapshot" structure.

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

---
 drivers/md/dm-snap.c |   35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

Index: linux-2.6.31-fast/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.31-fast.orig/drivers/md/dm-snap.c	2009-10-19 12:07:40.000000000 +0200
+++ linux-2.6.31-fast/drivers/md/dm-snap.c	2009-10-19 12:50:23.000000000 +0200
@@ -19,6 +19,7 @@
 #include <linux/vmalloc.h>
 #include <linux/log2.h>
 #include <linux/dm-kcopyd.h>
+#include <linux/dm-ioctl.h>
 #include <linux/workqueue.h>
 
 #include "dm-exception-store.h"
@@ -150,6 +151,8 @@ struct dm_snapshot {
 	 * of racing with merge
 	 */
 	struct bio_list merge_write_list;
+
+	char lockid[DM_UUID_LEN];
 };
 
 struct dm_dev *dm_snap_cow(struct dm_snapshot *s)
@@ -180,6 +183,8 @@ static int snapshot_merge_map(struct dm_
 
 #define is_merge(ti)	((ti)->type->map == snapshot_merge_map)
 
+#define is_clustered(s)	((s)->lockid[0])
+
 struct dm_snap_pending_exception {
 	struct dm_exception e;
 
@@ -894,8 +899,8 @@ static int snapshot_ctr(struct dm_target
 	char *origin_path, *cow_path;
 	unsigned args_used;
 
-	if (argc != 4) {
-		ti->error = "requires exactly 4 arguments";
+	if (argc < 4) {
+		ti->error = "requires at least 4 arguments";
 		r = -EINVAL;
 		goto bad;
 	}
@@ -923,6 +928,28 @@ static int snapshot_ctr(struct dm_target
 		goto bad_cow;
 	}
 
+	s->lockid[0] = 0;
+	if (argc >= 2 && !strcmp(argv[0], "cluster-lock")) {
+
+		/* prevent concurrent creation of lockspace handle */
+		down_write(&_origins_lock);
+		if (!lockspace_handle) {
+			lockspace_handle = dm_cluster_lock_init("dm-snap");
+			if (IS_ERR(lockspace_handle))
+				lockspace_handle = NULL;
+		}
+		up_write(&_origins_lock);
+
+		if (!lockspace_handle || is_merge(ti)) {
+			ti->error = "Clustering not supported";
+			r = -EINVAL;
+			goto bad_clustering;
+		}
+		strlcpy(s->lockid, argv[1], sizeof s->lockid);
+		argv += 2;
+		argc -= 2;
+	}
+
 	r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store);
 	if (r) {
 		ti->error = "Couldn't create exception store";
@@ -1069,6 +1096,7 @@ bad_hash_tables:
 bad_origin:
 	dm_exception_store_destroy(s->store);
 
+bad_clustering:
 bad_store:
 	dm_put_device(ti, s->cow);
 
@@ -1675,6 +1703,9 @@ static int snapshot_status(struct dm_tar
 		DMEMIT("%s %s", snap->origin->name, snap->cow->name);
 		snap->store->type->status(snap->store, type, result + sz,
 					  maxlen - sz);
+		sz = strlen(result);
+		if (is_clustered(snap))
+			snprintf(result + sz, maxlen - sz, " %s", snap->lockid);
 		break;
 	}