Commit f0f6b614 authored by Al Viro's avatar Al Viro
Browse files

copy_page_to_iter(): don't split high-order page in case of ITER_PIPE 



... just shove it into one pipe_buffer.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 310d9d5a

lib/iov_iter.c

+6 −15
Original line number Diff line number Diff line
@@ -706,30 +706,21 @@ static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) 
	return false;

}



static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes,

			 struct iov_iter *i)

{

	if (unlikely(iov_iter_is_pipe(i))) {

		return copy_page_to_iter_pipe(page, offset, bytes, i);

	} else {

		void *kaddr = kmap_local_page(page);

		size_t wanted = _copy_to_iter(kaddr + offset, bytes, i);

		kunmap_local(kaddr);

		return wanted;

	}

}



size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,

			 struct iov_iter *i)

{

	size_t res = 0;

	if (unlikely(!page_copy_sane(page, offset, bytes)))

		return 0;

	if (unlikely(iov_iter_is_pipe(i)))

		return copy_page_to_iter_pipe(page, offset, bytes, i);

	page += offset / PAGE_SIZE; // first subpage

	offset %= PAGE_SIZE;

	while (1) {

		size_t n = __copy_page_to_iter(page, offset,

				min(bytes, (size_t)PAGE_SIZE - offset), i);

		void *kaddr = kmap_local_page(page);

		size_t n = min(bytes, (size_t)PAGE_SIZE - offset);

		n = _copy_to_iter(kaddr + offset, n, i);

		kunmap_local(kaddr);

		res += n;

		bytes -= n;

		if (!bytes || !n)