dva_get_dsize_sync
dsize += dva_get_dsize_sync(spa, &ddp->ddp_dva[d]);
dsize += dva_get_dsize_sync(spa, &bp->blk_dva[d]);
dsize += dva_get_dsize_sync(spa, &bp->blk_dva[d]);
extern uint64_t dva_get_dsize_sync(spa_t *spa, const dva_t *dva);