From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:25688 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752272AbcFCTHH (ORCPT ); Fri, 3 Jun 2016 15:07:07 -0400 From: Liu Bo To: linux-btrfs@vger.kernel.org Cc: Josef Bacik Subject: [PATCH v2] Btrfs: fix eb memory leak due to readpage failure Date: Fri, 3 Jun 2016 12:08:38 -0700 Message-Id: <1464980918-8365-1-git-send-email-bo.li.liu@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: eb->io_pages is set in read_extent_buffer_pages(). In case of readpage failure, for pages that have been added to bio, it calls bio_endio and later readpage_io_failed_hook() does the work. When this eb's page (couldn't be the 1st page) fails to add itself to bio due to failure in merge_bio(), it cannot decrease eb->io_pages via bio_endio, and ends up with a memory leak eventually. This lets __do_readpage propagate errors to callers and adds the 'atomic_dec(&eb->io_pages)'. Signed-off-by: Liu Bo --- v2: - Move 'dec io_pages' to the caller so that we're consistent with write_one_eb() fs/btrfs/extent_io.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index d247fc0..0309388 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2869,6 +2869,7 @@ __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset, * into the tree that are removed when the IO is done (by the end_io * handlers) * XXX JDM: This needs looking at to ensure proper page locking + * return 0 on success, otherwise return error */ static int __do_readpage(struct extent_io_tree *tree, struct page *page, @@ -2890,7 +2891,7 @@ static int __do_readpage(struct extent_io_tree *tree, sector_t sector; struct extent_map *em; struct block_device *bdev; - int ret; + int ret = 0; int nr = 0; size_t pg_offset = 0; size_t iosize; @@ -3081,7 +3082,7 @@ out: SetPageUptodate(page); unlock_page(page); } - return 0; + return ret; } static inline void __do_contiguous_readpages(struct extent_io_tree *tree, @@ -5204,8 +5205,17 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, get_extent, &bio, mirror_num, &bio_flags, READ | REQ_META); - if (err) + if (err) { ret = err; + /* + * We use &bio in above __extent_read_full_page, + * so we ensure that if it returns error, the + * current page fails to add itself to bio. + * + * We must dec io_pages by ourselves. + */ + atomic_dec(&eb->io_pages); + } } else { unlock_page(page); } -- 2.5.5