From patchwork Thu Sep 13 08:20:26 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lu Fengqi X-Patchwork-Id: 10598841 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B5E2C14BD for ; Thu, 13 Sep 2018 08:20:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A7CC72A4DD for ; Thu, 13 Sep 2018 08:20:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9C15B2A50E; Thu, 13 Sep 2018 08:20:41 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI 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 F35CB2A4DD for ; Thu, 13 Sep 2018 08:20:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726855AbeIMN3C (ORCPT ); Thu, 13 Sep 2018 09:29:02 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:11650 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726308AbeIMN3C (ORCPT ); Thu, 13 Sep 2018 09:29:02 -0400 X-IronPort-AV: E=Sophos;i="5.43,368,1503331200"; d="scan'208";a="44863036" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 13 Sep 2018 16:20:37 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (unknown [10.167.33.80]) by cn.fujitsu.com (Postfix) with ESMTP id F151C4B6EC75 for ; Thu, 13 Sep 2018 16:20:33 +0800 (CST) Received: from fnst.localdomain (10.167.226.155) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.408.0; Thu, 13 Sep 2018 16:20:40 +0800 From: Lu Fengqi To: Subject: [PATCH] btrfs-progs: lowmem: fix false alert about the existence of gaps in the check_file_extent Date: Thu, 13 Sep 2018 16:20:26 +0800 Message-ID: <20180913082026.16996-1-lufq.fnst@cn.fujitsu.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-Originating-IP: [10.167.226.155] X-yoursite-MailScanner-ID: F151C4B6EC75.AD79B X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: lufq.fnst@cn.fujitsu.com 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 In the check_inode_item function, the extent_end variable used to store the end of the last file extent that has checked. When it passes to check_file_extent, if the offset of the next file extent is not equal to it, there is a gap between the two file extents. In the case of a gap existing, it is wrong that only add the extent_num_bytes of this file extent to the invalid extent_end variable as before. Therefore, lowmem check will false alert that there are gaps between the subsequent file extents of this inode due to the wrong extent_end variable. Solution: The extent_end variable should set to the sum of the offset and the extent_num_bytes of the file extent. Example: Suppose that lowmem check the following file extent of inode 257. item 6 key (257 EXTENT_DATA 0) itemoff 15813 itemsize 53 generation 6 type 1 (regular) extent data disk byte 13631488 nr 4096 extent data offset 0 nr 4096 ram 4096 extent compression 0 (none) item 7 key (257 EXTENT_DATA 8192) itemoff 15760 itemsize 53 generation 6 type 1 (regular) extent data disk byte 13631488 nr 4096 extent data offset 0 nr 4096 ram 4096 extent compression 0 (none) item 8 key (257 EXTENT_DATA 12288) itemoff 15707 itemsize 53 generation 6 type 1 (regular) extent data disk byte 13631488 nr 4096 extent data offset 0 nr 4096 ram 4096 extent compression 0 (none) For inode 257, check_inode_item set extent_end to 0, then call check_file_extent to check item {6,7,8}. item 6) offset(0) == extent_end(0) extent_end = extent_end(0) + extent_num_bytes(4096) item 7) offset(8192) != extent_end(4096) extent_end = extent_end(4096) + extent_num_bytes(4096) ^^^ The old extent_end should replace by offset(8192). item 8) offset(12288) != extent_end(8192) ^^^ But there is no gap between item {7,8}. Fixes: d88da10ddd42 ("btrfs-progs: check: introduce function to check file extent") Signed-off-by: Lu Fengqi --- check/mode-lowmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c index 1bce44f5658a..370318f0e631 100644 --- a/check/mode-lowmem.c +++ b/check/mode-lowmem.c @@ -1974,7 +1974,7 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_path *path, } } - *end += extent_num_bytes; + *end = fkey.offset + extent_num_bytes; if (!is_hole) *size += extent_num_bytes;