size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
			 struct iov_iter *i)
{
	if (i->type & (ITER_BVEC|ITER_KVEC)) {
		void *kaddr = kmap_atomic(page);
		size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
		kunmap_atomic(kaddr);
		return wanted;
	} else if (likely(!(i->type & ITER_PIPE)))
		return copy_page_to_iter_iovec(page, offset, bytes, i);
	else
		return copy_page_to_iter_pipe(page, offset, bytes, i);
}
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
			 struct iov_iter *i)
{
	if (i->type & (ITER_BVEC|ITER_KVEC)) {
		void *kaddr = kmap_atomic(page);
		size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
		kunmap_atomic(kaddr);
		return wanted;
	} else if (likely(!(i->type & ITER_PIPE)))
		return copy_page_to_iter_iovec(page, offset, bytes, i);
	else
		return copy_page_to_iter_pipe(page, offset, bytes, i);
}