func: static void nbd_client_closed(NBDClient *client)
  
  {
  
      nb_fds--;
  
      if (nb_fds == 0 && !persistent && state == RUNNING) {
  
          state = TERMINATE;
  
      }
  
      nbd_update_server_watch();
  
      nbd_client_put(client);
  
  }
  