From patchwork Mon Dec 2 16:16:54 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wang Shilong X-Patchwork-Id: 3266051 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 2E768C0D4A for ; Mon, 2 Dec 2013 16:17:19 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 0377B2026F for ; Mon, 2 Dec 2013 16:17:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6778C2024F for ; Mon, 2 Dec 2013 16:17:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752619Ab3LBQRM (ORCPT ); Mon, 2 Dec 2013 11:17:12 -0500 Received: from mail-pb0-f43.google.com ([209.85.160.43]:64624 "EHLO mail-pb0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751432Ab3LBQRL (ORCPT ); Mon, 2 Dec 2013 11:17:11 -0500 Received: by mail-pb0-f43.google.com with SMTP id rq2so19182698pbb.2 for ; Mon, 02 Dec 2013 08:17:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=VGEeFGgpsMZBsmwYEQroNDiTqqSfsax+YJiLeA/Pu/k=; b=FKDMegCVfKLa4Qlx1Xm9pbEcOw2w3fnaQXgb6r/cRGP3zoga3Mf8xKzjBVyXEjckCi S4EEgSSn9/B4BNQDy0eOB9kV74dogzwzG/1RYZ1Lv8IYMbSwFzuhBJuKQNAcfQTEmu3k UUySuWm69VCwoFOgQzNUCueuCF71u/iJFBRGsvrACpmByEnRpZOlgYb3FtxbHMNTiXvN 96/rfsD+eJp+haSOooHln7IPvna4AyIHYYuqVWuFYw8hv2G+DFmt2rbXXyXx/GqvAu0n YQ+vG4NCxIgAGqWmjkvYZ9Vp7bHPjdU6Jnp3WXlJqdN6T0XUSLPNOSCYRT5Ugz/S8IPr asNw== X-Received: by 10.66.163.164 with SMTP id yj4mr69534479pab.91.1386001030847; Mon, 02 Dec 2013 08:17:10 -0800 (PST) Received: from linux-b0ol.localdomain ([223.65.141.255]) by mx.google.com with ESMTPSA id wd6sm140042065pab.3.2013.12.02.08.17.07 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Dec 2013 08:17:09 -0800 (PST) From: Wang Shilong To: linux-btrfs@vger.kernel.org Cc: ochmann@informatik.uni-bonn.de, wangshilong1991@gmail.com, Wang Shilong Subject: [PATCH] Btrfs: fix generation mismatch when scrubbing supers Date: Tue, 3 Dec 2013 00:16:54 +0800 Message-Id: <1386001014-8226-1-git-send-email-wangshilong1991@gmail.com> X-Mailer: git-send-email 1.8.4 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_DKIM_INVALID, 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 From: Wang Shilong We came a race condition when scrubbing superblocks, the story is: In commiting transaction, we will update last_trans_commited after writting superblocks. if a scrub start after writting superblocks and before last_trans_commited, generation mismatch happens! We fix it by protecting writting superblock and updating last_trans_commited with tree_log_mutex. Reported-by: Sebastian Ochmann Signed-off-by: Wang Shilong --- fs/btrfs/scrub.c | 11 +++++++---- fs/btrfs/transaction.c | 13 ++++++++++--- 2 files changed, 17 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 561e2f1..afa2f01 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -2932,12 +2932,15 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, atomic_inc(&fs_info->scrubs_running); mutex_unlock(&fs_info->scrub_lock); + /* + * by holding tree_log_mutex while scrubbing supers + * we can avoid generation mismatch. See comments in commiting + * transaction when updating last_trans_commited. + */ if (!is_dev_replace) { - /* - * by holding device list mutex, we can - * kick off writing super in log tree sync. - */ + mutex_lock(&fs_info->tree_log_mutex); ret = scrub_supers(sctx, dev); + mutex_unlock(&fs_info->tree_log_mutex); } mutex_unlock(&fs_info->fs_devices->device_list_mutex); diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index c6a872a..052eb22 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1898,15 +1898,22 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, goto cleanup_transaction; } + btrfs_finish_extent_commit(trans, root); + + /* + * we must gurantee last_trans_commited update is protected by + * tree_log_mutex with write_ctree_super together, otherwise, + * scubbing super will come in before updating last_trans_commited + * and we will get generation mismatch when scrubbing superblocks. + */ + root->fs_info->last_trans_committed = cur_trans->transid; + /* * the super is written, we can safely allow the tree-loggers * to go about their business */ mutex_unlock(&root->fs_info->tree_log_mutex); - btrfs_finish_extent_commit(trans, root); - - root->fs_info->last_trans_committed = cur_trans->transid; /* * We needn't acquire the lock here because there is no other task * which can change it.