bpf: convert bpf_iter_new_fd() to FD_PREPARE()

int bpf_iter_new_fd(struct bpf_link *link)

{

	struct bpf_iter_link *iter_link;

	struct file *file;

	unsigned int flags;

	int err, fd;

	int err;

	if (link->ops != &bpf_iter_link_lops)

		return -EINVAL;

	flags = O_RDONLY | O_CLOEXEC;

	fd = get_unused_fd_flags(flags);

	if (fd < 0)

		return fd;

	file = anon_inode_getfile("bpf_iter", &bpf_iter_fops, NULL, flags);

	if (IS_ERR(file)) {

		err = PTR_ERR(file);

		goto free_fd;

	}

	FD_PREPARE(fdf, flags, anon_inode_getfile("bpf_iter", &bpf_iter_fops, NULL, flags));

	if (fdf.err)

		return fdf.err;

	iter_link = container_of(link, struct bpf_iter_link, link);

	err = prepare_seq_file(file, iter_link);

	err = prepare_seq_file(fd_prepare_file(fdf), iter_link);

	if (err)

		goto free_file;

		return err; /* Automatic cleanup handles fput */

	fd_install(fd, file);

	return fd;

free_file:

	fput(file);

free_fd:

	put_unused_fd(fd);

	return err;

	return fd_publish(fdf);

}

struct bpf_prog *bpf_iter_get_info(struct bpf_iter_meta *meta, bool in_stop)