Commit 7480a904 authored by Jens Axboe's avatar Jens Axboe
Browse files

[PATCH] splice: speedup __generic_file_splice_read 



Using find_get_page() is a lot faster than find_or_create_page(). This
gets splice a lot closer to sendfile() for fd -> socket transfers.

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent b92ce558

fs/splice.c

+63 −11
Original line number Diff line number Diff line
@@ -240,7 +240,7 @@ __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe, 
	struct page *pages[PIPE_BUFFERS];

	struct page *page;

	pgoff_t index;

	int i;

	int i, error;



	index = in->f_pos >> PAGE_CACHE_SHIFT;

	offset = in->f_pos & ~PAGE_CACHE_MASK;
@@ -260,32 +260,84 @@ __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe, 
	/*

	 * now fill in the holes

	 */

	error = 0;

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

find_page:

		/*

		 * no page there, look one up / create it

		 * lookup the page for this index

		 */

		page = find_or_create_page(mapping, index,

						   mapping_gfp_mask(mapping));

		page = find_get_page(mapping, index);

		if (!page) {

			/*

			 * If in nonblock mode then dont block on

			 * readpage (we've kicked readahead so there

			 * will be asynchronous progress):

			 */

			if (flags & SPLICE_F_NONBLOCK)

				break;



			/*

			 * page didn't exist, allocate one

			 */

			page = page_cache_alloc_cold(mapping);

			if (!page)

				break;



		if (PageUptodate(page))

			error = add_to_page_cache_lru(page, mapping, index,

						mapping_gfp_mask(mapping));

			if (unlikely(error)) {

				page_cache_release(page);

				break;

			}



			goto readpage;

		}



		/*

		 * If the page isn't uptodate, we may need to start io on it

		 */

		if (!PageUptodate(page)) {

			lock_page(page);



			/*

			 * page was truncated, stop here. if this isn't the

			 * first page, we'll just complete what we already

			 * added

			 */

			if (!page->mapping) {

				unlock_page(page);

		else {

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

				page_cache_release(page);

				break;

			}

			/*

			 * page was already under io and is now done, great

			 */

			if (PageUptodate(page)) {

				unlock_page(page);

				goto fill_it;

			}



readpage:

			/*

			 * need to read in the page

			 */

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



			if (unlikely(error)) {

				page_cache_release(page);

				if (error == AOP_TRUNCATED_PAGE)

					goto find_page;

				break;

			}

		}

fill_it:

		pages[i] = page;

	}



	if (i)

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



	return 0;

	return error;

}



/**