ubifs_read_nnode
err = ubifs_read_nnode(c, parent, iip);
err = ubifs_read_nnode(c, NULL, 0);
err = ubifs_read_nnode(c, NULL, 0);
err = ubifs_read_nnode(c, NULL, 0);
err = ubifs_read_nnode(c, NULL, 0);
err = ubifs_read_nnode(c, NULL, 0);
int ubifs_read_nnode(struct ubifs_info *c, struct ubifs_nnode *parent, int iip);