ceph: decode updated mdsmap format

The mds map now uses the global_id as the 'key' (instead of the addr,
which was a poor choice).

This is protocol change.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/ceph_fs.h b/fs/ceph/ceph_fs.h
index 1e96a9a..4e5f49c 100644
--- a/fs/ceph/ceph_fs.h
+++ b/fs/ceph/ceph_fs.h
@@ -39,7 +39,7 @@
 #define CEPH_MDS_PROTOCOL     9 /* cluster internal */
 #define CEPH_MON_PROTOCOL     5 /* cluster internal */
 #define CEPH_OSDC_PROTOCOL   22 /* server/client */
-#define CEPH_MDSC_PROTOCOL   29 /* server/client */
+#define CEPH_MDSC_PROTOCOL   30 /* server/client */
 #define CEPH_MONC_PROTOCOL   15 /* server/client */