ceph-rbd: osdc support for osd call and rollback operations

This will be used for rbd snapshots administration.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
diff --git a/fs/ceph/decode.h b/fs/ceph/decode.h
index 3d25415..c5b6939 100644
--- a/fs/ceph/decode.h
+++ b/fs/ceph/decode.h
@@ -191,6 +191,11 @@
 		ceph_encode_need(p, end, n, bad);		\
 		ceph_encode_copy(p, pv, n);			\
 	} while (0)
+#define ceph_encode_string_safe(p, end, s, n, bad)		\
+	do {							\
+		ceph_encode_need(p, end, n, bad);		\
+		ceph_encode_string(p, end, s, n);		\
+	} while (0)
 
 
 #endif