On 22/05/2015 05:40, Fam Zheng wrote:
> + ret = bdrv_get_block_status(source, NULL, sector_num, nb_sectors, &pnum);
> + if (ret < 0 || pnum < nb_sectors ||
> + (ret & BDRV_BLOCK_ALLOCATED && !(ret & BDRV_BLOCK_ZERO))) {
> + bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors,
> + mirror_read_complete, op);
> + } else if (ret & BDRV_BLOCK_ZERO) {
> + bdrv_aio_write_zeroes(s->target, sector_num, op->nb_sectors,
> + s->unmap ? BDRV_REQ_MAY_UNMAP : 0,
> + mirror_write_complete, op);
> + } else {
> + assert(!(ret & BDRV_BLOCK_ALLOCATED));
> + bdrv_aio_discard(s->target, sector_num, op->nb_sectors,
> + mirror_write_complete, op);
> + }
This doesn't work if you have a backing file. You want to test
BDRV_BLOCK_DATA, not BDRV_BLOCK_ALLOCATED.
On the other hand, if BDRV_BLOCK_ALLOCATED is nonzero, you need to
recurse on bs->backing_hd. The logic is very similar to
bdrv_is_allocated_above, but you need to write bdrv_get_block_status_above.
Paolo
