ceph: report mount root in session metadata

Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 5fef3a6..0ea8640 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -70,6 +70,7 @@
 	 */
 
 	char *snapdir_name;   /* default ".snap" */
+	char *server_path;    /* default  "/" */
 };
 
 struct ceph_fs_client {