func: static void bdrv_co_drain_bh_cb(void *opaque)
  
  {
  
      BdrvCoDrainData *data = opaque;
  
      Coroutine *co = data->co;
  
  
  
      qemu_bh_delete(data->bh);
  
      bdrv_drain_poll(data->bs);
  
      data->done = true;
  
      qemu_coroutine_enter(co, NULL);
  
  }
  