ceph: make sure request isn't in any waiting list when kicking request.

commit 03974e81 upstream.

we may corrupt waiting list if a request in the waiting list is kicked.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

fs/ceph/mds_client.c

@@ -1985,6 +1985,7 @@ static void kick_requests(struct ceph_mds_client *mdsc, int mds)
 		if (req->r_session &&
 		    req->r_session->s_mds == mds) {
 			dout(" kicking tid %llu\n", req->r_tid);
+			list_del_init(&req->r_wait);
 			__do_request(mdsc, req);
 		}
 	}