ceph: close stopped mds' session

If a mds has stopped, close its session and clean up its session
requests/caps. The process is similar to handling SESSION_CLOSE
initiated by mds.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/mds_client.c

@@ -3136,6 +3136,22 @@ static void check_new_map(struct ceph_mds_client *mdsc,
 				__unregister_session(mdsc, s);
 				__wake_requests(mdsc, &s->s_waiting);
 				ceph_put_mds_session(s);
+			} else if (i >= newmap->m_num_mds) {
+				/* force close session for stopped mds */
+				get_session(s);
+				__unregister_session(mdsc, s);
+				__wake_requests(mdsc, &s->s_waiting);
+				kick_requests(mdsc, i);
+				mutex_unlock(&mdsc->mutex);
+
+				mutex_lock(&s->s_mutex);
+				cleanup_session_requests(mdsc, s);
+				remove_session_caps(s);
+				mutex_unlock(&s->s_mutex);
+
+				ceph_put_mds_session(s);
+
+				mutex_lock(&mdsc->mutex);
 			} else {
 				/* just close it */
 				mutex_unlock(&mdsc->mutex);