space_reftree_add_map
void space_reftree_add_map(avl_tree_t *t, range_tree_t *rt, int64_t refcnt);
space_reftree_add_map(&reftree,
space_reftree_add_map(&reftree,
space_reftree_add_map(&reftree, cvd->vdev_dtl[s], 1);