index_entry
RB_ENTRY(utf8_item) index_entry;
RB_GENERATE_STATIC(utf8_index_tree, utf8_item, index_entry, utf8_index_cmp);
rc = index_entry(ns, &key, elm);
int index_entry(struct namespace *ns, struct btval *dn,
rc = index_entry(ns, &key, root);