static bool is_zero_cluster(BlockDriverState *bs, int64_t start) { BDRVQcow2State *s = bs->opaque; int nr; BlockDriverState *file; int64_t res = bdrv_get_block_status_above(bs, NULL, start, s->cluster_sectors, &nr, &file); return res >= 0 && ((res & BDRV_BLOCK_ZERO) || !(res & BDRV_BLOCK_DATA)); }