bio_map_user_iov(): get rid of copying iov_iter

	int j;

	struct bio *bio;

	int ret;

	struct iov_iter i;

	struct bio_vec *bvec;

	if (!iov_iter_count(iter))

	if (!bio)

		return ERR_PTR(-ENOMEM);

	i = *iter;

	while (iov_iter_count(&i)) {

	while (iov_iter_count(iter)) {

		struct page **pages;

		ssize_t bytes;

		size_t offs, added = 0;

		int npages;

		bytes = iov_iter_get_pages_alloc(&i, &pages, LONG_MAX, &offs);

		bytes = iov_iter_get_pages_alloc(iter, &pages, LONG_MAX, &offs);

		if (unlikely(bytes <= 0)) {

			ret = bytes ? bytes : -EFAULT;

			goto out_unmap;

				bytes -= n;

				offs = 0;

			}

			iov_iter_advance(&i, added);

			iov_iter_advance(iter, added);

		}

		/*

		 * release the pages we didn't map into the bio, if any

	 * reference to it

	 */

	bio_get(bio);

	iov_iter_advance(iter, bio->bi_iter.bi_size);

	return bio;

 out_unmap: