On 09/11/2015 03:56, Fam Zheng wrote: > + if (bs->drv && bs->drv->bdrv_drain) { > + bs->drv->bdrv_drain(bs); > + } > + QLIST_FOREACH(child, &bs->children, next) { > + BlockDriverState *cbs = child->bs; > + if (cbs->drv && cbs->drv->bdrv_drain) { > + cbs->drv->bdrv_drain(bs); > + } > + }
I think this is not enough, because the children could have children as well. Perhaps you can do it like bdrv_flush: one function does the call to bdrv_drain and the recursion on children; bdrv_drain calls that one function and then does the "while (busy)" loop. Paolo