client: flush the dirty caps immediately when the MDS is stopping

Trigger to flush the dirty caps when the MDS is stopping, or the
caps could be dropped if the MDS stopped before the client could
receiving the mdsmap.

Fixes: https://tracker.ceph.com/issues/61914
Signed-off-by: Xiubo Li <xiubli@redhat.com>

src/client/Client.cc

@@ -3091,7 +3091,19 @@ void Client::handle_mds_map(const MConstRef<MMDSMap>& m)
 	continue;
       }
       if (newstate >= MDSMap::STATE_ACTIVE) {
-	if (oldstate < MDSMap::STATE_ACTIVE) {
+	if (oldstate <= MDSMap::STATE_ACTIVE) {
+	  ceph_assert(newstate != oldstate);
+
+          // flush the delayed caps in case this MDS is stopping
+          for (auto p = delayed_list.begin(); p != delayed_list.end(); ) {
+            Inode *in = *p;
+            ++p;
+            if (!mount_aborted && in->auth_cap->session == session.get()) {
+              in->delay_cap_item.remove_myself();
+              check_caps(in, CHECK_CAPS_NODELAY);
+	    }
+          }
+
 	  // kick new requests
 	  kick_requests(session.get());
 	  kick_flushing_caps(session.get());