From patchwork Tue Aug 25 02:44:57 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 7067871 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 2E9299F402 for ; Tue, 25 Aug 2015 02:47:16 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4D02820719 for ; Tue, 25 Aug 2015 02:47:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 462A520723 for ; Tue, 25 Aug 2015 02:47:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752215AbbHYCrH (ORCPT ); Mon, 24 Aug 2015 22:47:07 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:56569 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751687AbbHYCrD (ORCPT ); Mon, 24 Aug 2015 22:47:03 -0400 X-IronPort-AV: E=Sophos;i="5.15,520,1432569600"; d="scan'208";a="99979528" Received: from bogon (HELO edo.cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 25 Aug 2015 10:50:11 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (localhost.localdomain [127.0.0.1]) by edo.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id t7P2ksdX003851; Tue, 25 Aug 2015 10:46:54 +0800 Received: from localhost.localdomain (10.167.226.33) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.181.6; Tue, 25 Aug 2015 10:46:59 +0800 From: Qu Wenruo To: CC: Subject: [PATCH 2/2] btrfs-progs: find-root: Fix a bug that will cause wrong result Date: Tue, 25 Aug 2015 10:44:57 +0800 Message-ID: <1440470697-21177-2-git-send-email-quwenruo@cn.fujitsu.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1440470697-21177-1-git-send-email-quwenruo@cn.fujitsu.com> References: <1440470697-21177-1-git-send-email-quwenruo@cn.fujitsu.com> MIME-Version: 1.0 X-Originating-IP: [10.167.226.33] Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-8.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP [BUG] btrfs-find-root may not output desire result, as due to search_extent_cache() may return result which doesn't cover the desired range, generation cache can be screwed up if higher generation tree root is found before lower generation tree root. For example: ======= ./btrfs-find-root /dev/sda6 -a Superblock thinks the generation is 8 Superblock thinks the level is 0 adding bytenr: 4194304, gen: 8 <<< Debug output adding bytenr: 24715264, gen: 7 <<< gen is 7 at read_tree_block time Well block 4194304(gen: 8 level: 0) seems good, and it matches superblock Well block 24715264(gen: 8 level: 0) seems good, and it matches superblock <<< But its gen is wrong at result output time ======= [Fix] Add a new judgment to make sure the search_extent_cache() is returning desired result. Reported-by: Marc Merlin Signed-off-by: Qu Wenruo --- find-root.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/find-root.c b/find-root.c index 1af37b5..0eca0ab 100644 --- a/find-root.c +++ b/find-root.c @@ -46,9 +46,14 @@ static int add_eb_to_result(struct extent_buffer *eb, generation < filter->generation) return ret; - /* Get the generation cache or create one */ + /* + * Get the generation cache or create one + * + * NOTE: search_cache_extent() may return cache doesn't cover + * the range. So need extra judgement to make sure it's a match. + */ cache = search_cache_extent(result, generation); - if (!cache) { + if (!cache || cache->start != generation) { gen_cache = malloc(sizeof(*gen_cache)); BUG_ON(!gen_cache); cache = &gen_cache->cache;