ceph: fix uid/gid on resent mds requests

MDS requests can be rebuilt and resent in non-process context, but were
filling in uid/gid from current_fsuid/gid.  Put that information in the
request struct on request setup.

This fixes incorrect (and root) uid/gid getting set for requests that
are forwarded between MDSs, usually due to metadata migrations.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index d66d63c..9341fd4 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -170,6 +170,8 @@
 
 	union ceph_mds_request_args r_args;
 	int r_fmode;        /* file mode, if expecting cap */
+	uid_t r_uid;
+	gid_t r_gid;
 
 	/* for choosing which mds to send this request to */
 	int r_direct_mode;