ltree_entry_cmp
RB_PROTOTYPE( ltree_rbtree, chfs_ltree_entry, rb, ltree_entry_cmp);
RB_GENERATE( ltree_rbtree, chfs_ltree_entry, rb, ltree_entry_cmp);
int ltree_entry_cmp(struct chfs_ltree_entry *le1, struct chfs_ltree_entry *le2);