Commit 16c523dd authored by Jens Axboe's avatar Jens Axboe
Browse files

[PATCH] splice: cleanup __generic_file_splice_read() 



The whole shadow/pages logic got overly complex, and this simpler
approach is actually faster in testing.

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent c0bd1f65

fs/splice.c

+10 −49
Original line number Diff line number Diff line
@@ -220,10 +220,10 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe, 
{

	struct address_space *mapping = in->f_mapping;

	unsigned int offset, nr_pages;

	struct page *pages[PIPE_BUFFERS], *shadow[PIPE_BUFFERS];

	struct page *pages[PIPE_BUFFERS];

	struct page *page;

	pgoff_t index, pidx;

	int i, j;

	pgoff_t index;

	int i;



	index = in->f_pos >> PAGE_CACHE_SHIFT;

	offset = in->f_pos & ~PAGE_CACHE_MASK;
@@ -237,42 +237,14 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe, 
	 */

	do_page_cache_readahead(mapping, in, index, nr_pages);



	/*

	 * Get as many pages from the page cache as possible..

	 * Start IO on the page cache entries we create (we

	 * can assume that any pre-existing ones we find have

	 * already had IO started on them).

	 */

	i = find_get_pages(mapping, index, nr_pages, pages);



	/*

	 * common case - we found all pages and they are contiguous,

	 * kick them off

	 */

	if (i && (pages[i - 1]->index == index + i - 1))

		goto splice_them;



	/*

	 * fill shadow[] with pages at the right locations, so we only

	 * have to fill holes

	 */

	memset(shadow, 0, nr_pages * sizeof(struct page *));

	for (j = 0; j < i; j++)

		shadow[pages[j]->index - index] = pages[j];



	/*

	 * now fill in the holes

	 */

	for (i = 0, pidx = index; i < nr_pages; pidx++, i++) {

		int error;



		if (shadow[i])

			continue;



	for (i = 0; i < nr_pages; i++, index++) {

		/*

		 * no page there, look one up / create it

		 */

		page = find_or_create_page(mapping, pidx,

		page = find_or_create_page(mapping, index,

						   mapping_gfp_mask(mapping));

		if (!page)

			break;
@@ -280,31 +252,20 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe, 
		if (PageUptodate(page))

			unlock_page(page);

		else {

			error = mapping->a_ops->readpage(in, page);

			int error = mapping->a_ops->readpage(in, page);



			if (unlikely(error)) {

				page_cache_release(page);

				break;

			}

		}

		shadow[i] = page;

	}



	if (!i) {

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

			 if (shadow[i])

				page_cache_release(shadow[i]);

		}

		return 0;

		pages[i] = page;

	}



	memcpy(pages, shadow, i * sizeof(struct page *));



	/*

	 * Now we splice them into the pipe..

	 */

splice_them:

	if (i)

		return move_to_pipe(pipe, pages, i, offset, len, flags);



	return 0;

}



/**