ubifs_tnc_postorder_first
znode = ubifs_tnc_postorder_first(c->zroot.znode);
return ubifs_tnc_postorder_first(zn);
struct ubifs_znode *zn = ubifs_tnc_postorder_first(znode);
struct ubifs_znode *ubifs_tnc_postorder_first(struct ubifs_znode *znode);