ubifs_tnc_levelorder_next
znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, NULL);
znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, znode);
znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, znode);
znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, NULL);
struct ubifs_znode *ubifs_tnc_levelorder_next(const struct ubifs_info *c,