From patchwork Fri Jun 3 19:08:38 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liu Bo X-Patchwork-Id: 9153927 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 2E3A060751 for ; Fri, 3 Jun 2016 19:07:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 16E42282ED for ; Fri, 3 Jun 2016 19:07:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 07DAC28336; Fri, 3 Jun 2016 19:07:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 92426282ED for ; Fri, 3 Jun 2016 19:07:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964777AbcFCTHI (ORCPT ); Fri, 3 Jun 2016 15:07:08 -0400 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 Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id u53J74H1024156 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 3 Jun 2016 19:07:05 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserv0022.oracle.com (8.13.8/8.13.8) with ESMTP id u53J732K022752 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 3 Jun 2016 19:07:04 GMT Received: from abhmp0010.oracle.com (abhmp0010.oracle.com [141.146.116.16]) by userv0121.oracle.com (8.13.8/8.13.8) with ESMTP id u53J72KA017433; Fri, 3 Jun 2016 19:07:03 GMT Received: from localhost.us.oracle.com (/10.211.47.181) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 03 Jun 2016 12:07:02 -0700 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> X-Mailer: git-send-email 2.5.5 X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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); }