Commit 9e0267c2 authored by Jens Axboe's avatar Jens Axboe
Browse files

[PATCH] splice: fixup writeout path after ->map changes 



Since ->map() no longer locks the page, we need to adjust the handling
of those pages (and stealing) a little. This now passes full regressions
again.

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent a4514ebd

fs/splice.c

+30 −19
Original line number Diff line number Diff line
@@ -50,7 +50,8 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info, 
	struct page *page = buf->page;

	struct address_space *mapping = page_mapping(page);



	WARN_ON(!PageLocked(page));

	lock_page(page);



	WARN_ON(!PageUptodate(page));



	/*
@@ -65,8 +66,10 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info, 
	if (PagePrivate(page))

		try_to_release_page(page, mapping_gfp_mask(mapping));



	if (!remove_mapping(mapping, page))

	if (!remove_mapping(mapping, page)) {

		unlock_page(page);

		return 1;

	}



	buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;

	return 0;
@@ -507,14 +510,12 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, 
	if (sd->flags & SPLICE_F_MOVE) {

		/*

		 * If steal succeeds, buf->page is now pruned from the vm

		 * side (LRU and page cache) and we can reuse it.

		 * side (LRU and page cache) and we can reuse it. The page

		 * will also be looked on successful return.

		 */

		if (buf->ops->steal(info, buf))

			goto find_page;



		/*

		 * this will also set the page locked

		 */

		page = buf->page;

		if (add_to_page_cache(page, mapping, index, gfp_mask))

			goto find_page;
@@ -523,15 +524,27 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, 
			lru_cache_add(page);

	} else {

find_page:

		page = find_lock_page(mapping, index);

		if (!page) {

			ret = -ENOMEM;

		page = find_or_create_page(mapping, index, gfp_mask);

		if (!page)

			page = page_cache_alloc_cold(mapping);

			if (unlikely(!page))

				goto out_nomem;



			/*

		 * If the page is uptodate, it is also locked. If it isn't

		 * uptodate, we can mark it uptodate if we are filling the

		 * full page. Otherwise we need to read it in first...

			 * This will also lock the page

			 */

			ret = add_to_page_cache_lru(page, mapping, index,

						    gfp_mask);

			if (unlikely(ret))

				goto out;

		}



		/*

		 * We get here with the page locked. If the page is also

		 * uptodate, we don't need to do more. If it isn't, we

		 * may need to bring it in if we are not going to overwrite

		 * the full page.

		 */

		if (!PageUptodate(page)) {

			if (sd->len < PAGE_CACHE_SIZE) {
@@ -553,12 +566,10 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, 
					ret = -EIO;

					goto out;

				}

			} else {

				WARN_ON(!PageLocked(page));

			} else

				SetPageUptodate(page);

		}

	}

	}



	ret = mapping->a_ops->prepare_write(file, page, 0, sd->len);

	if (ret == AOP_TRUNCATED_PAGE) {
@@ -585,10 +596,10 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, 
	mark_page_accessed(page);

	balance_dirty_pages_ratelimited(mapping);

out:

	if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {

	if (!(buf->flags & PIPE_BUF_FLAG_STOLEN))

		page_cache_release(page);



	unlock_page(page);

	}

out_nomem:

	buf->ops->unmap(info, buf);

	return ret;