Commit e69f37bc authored by David Howells's avatar David Howells Committed by Jens Axboe
Browse files

splice: Clean up copy_splice_read() a bit 



Do a couple of cleanups to copy_splice_read():

 (1) Cast to struct page **, not void *.

 (2) Simplify the calculation of the number of pages to keep/reclaim in
     copy_splice_read().

Suggested-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarChristian Brauner <brauner@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: David Hildenbrand <david@redhat.com>
cc: John Hubbard <jhubbard@nvidia.com>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20230522135018.2742245-5-dhowells@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 69df79a4

fs/splice.c

+7 −12
Original line number Diff line number Diff line
@@ -311,7 +311,7 @@ ssize_t copy_splice_read(struct file *in, loff_t *ppos, 
	struct kiocb kiocb;

	struct page **pages;

	ssize_t ret;

	size_t used, npages, chunk, remain, reclaim;

	size_t used, npages, chunk, remain, keep = 0;

	int i;



	/* Work out how much data we can actually add into the pipe */
@@ -325,7 +325,7 @@ ssize_t copy_splice_read(struct file *in, loff_t *ppos, 
	if (!bv)

		return -ENOMEM;



	pages = (void *)(bv + npages);

	pages = (struct page **)(bv + npages);

	npages = alloc_pages_bulk_array(GFP_USER, npages, pages);

	if (!npages) {

		kfree(bv);
@@ -348,11 +348,8 @@ ssize_t copy_splice_read(struct file *in, loff_t *ppos, 
	kiocb.ki_pos = *ppos;

	ret = call_read_iter(in, &kiocb, &to);



	reclaim = npages * PAGE_SIZE;

	remain = 0;

	if (ret > 0) {

		reclaim -= ret;

		remain = ret;

		keep = DIV_ROUND_UP(ret, PAGE_SIZE);

		*ppos = kiocb.ki_pos;

		file_accessed(in);

	} else if (ret < 0) {
@@ -365,14 +362,12 @@ ssize_t copy_splice_read(struct file *in, loff_t *ppos, 
	}



	/* Free any pages that didn't get touched at all. */

	reclaim /= PAGE_SIZE;

	if (reclaim) {

		npages -= reclaim;

		release_pages(pages + npages, reclaim);

	}

	if (keep < npages)

		release_pages(pages + keep, npages - keep);



	/* Push the remaining pages into the pipe. */

	for (i = 0; i < npages; i++) {

	remain = ret;

	for (i = 0; i < keep; i++) {

		struct pipe_buffer *buf = pipe_head_buf(pipe);



		chunk = min_t(size_t, remain, PAGE_SIZE);