Lock bitmap while joining the cluster

index 43b3cda..4c3ad2c 100644
@@ -37,6 +37,7 @@ struct md_cluster_info {
 	struct completion completion;
 	struct dlm_lock_resource *sb_lock;
 	struct mutex sb_mutex;
+	struct dlm_lock_resource *bitmap_lockres;
 };
 
 static void sync_ast(void *arg)

@@ -212,6 +213,20 @@ static int join(struct mddev *mddev, int nodes)
 		ret = -ENOMEM;
 		goto err;
 	}
+
+	pr_info("Joined cluster %s slot %d\n", str, cinfo->slot_number);
+
+	memset(str, '\0', 64);
+	snprintf(str, 64, "bitmap%04d", cinfo->slot_number - 1);
+	cinfo->bitmap_lockres = lockres_init(mddev, str, NULL, 1);
+	if (!cinfo->bitmap_lockres)
+		goto err;
+	if (dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW)) {
+		pr_err("Failed to get bitmap lock\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
 	return 0;
 err:
 	if (cinfo->lockspace)

@@ -228,6 +243,7 @@ static int leave(struct mddev *mddev)
 	if (!cinfo)
 		return 0;
 	lockres_free(cinfo->sb_lock);
+	lockres_free(cinfo->bitmap_lockres);
 	dlm_release_lockspace(cinfo->lockspace, 2);
 	return 0;
 }