ceph: Convert struct ceph_mds_request to use kuid_t and kgid_t

Hold the uid and gid for a pending ceph mds request using the types
kuid_t and kgid_t.  When a request message is finally created convert
the kuid_t and kgid_t values into uids and gids in the initial user
namespace.

Cc: Sage Weil <sage@inktank.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index dd26846..ff4188b 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -184,8 +184,8 @@
 
 	union ceph_mds_request_args r_args;
 	int r_fmode;        /* file mode, if expecting cap */
-	uid_t r_uid;
-	gid_t r_gid;
+	kuid_t r_uid;
+	kgid_t r_gid;
 
 	/* for choosing which mds to send this request to */
 	int r_direct_mode;