ocfs2_dlmfs: Enable the use of user cluster stacks.

Unlike ocfs2, dlmfs has no permanent storage.  It can't store off a
cluster stack it is supposed to be using.  So it can't specify the stack
name in ocfs2_cluster_connect().

Instead, we create ocfs2_cluster_connect_agnostic(), which simply uses
the stack that is currently enabled.  This is find for dlmfs, which will
rely on the stack initialization.

We add the "stackglue" capability to dlmfs's capability list.  This lets
userspace know dlmfs can be used with all cluster stacks.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
index 31db2e8..39abf89 100644
--- a/fs/ocfs2/stackglue.c
+++ b/fs/ocfs2/stackglue.c
@@ -373,6 +373,24 @@
 }
 EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
 
+/* The caller will ensure all nodes have the same cluster stack */
+int ocfs2_cluster_connect_agnostic(const char *group,
+				   int grouplen,
+				   struct ocfs2_locking_protocol *lproto,
+				   void (*recovery_handler)(int node_num,
+							    void *recovery_data),
+				   void *recovery_data,
+				   struct ocfs2_cluster_connection **conn)
+{
+	char *stack_name = NULL;
+
+	if (cluster_stack_name[0])
+		stack_name = cluster_stack_name;
+	return ocfs2_cluster_connect(stack_name, group, grouplen, lproto,
+				     recovery_handler, recovery_data, conn);
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_connect_agnostic);
+
 /* If hangup_pending is 0, the stack driver will be dropped */
 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 			     int hangup_pending)