From patchwork Tue Dec 20 15:05:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhihao Cheng X-Patchwork-Id: 1717918 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org (client-ip=2404:9400:2221:ea00::3; helo=gandalf.ozlabs.org; envelope-from=srs0=03jo=4s=vger.kernel.org=linux-ext4-owner@ozlabs.org; receiver=) Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384) server-digest SHA384) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4Nbzrk0NJ6z1ydZ for ; Wed, 21 Dec 2022 01:45:25 +1100 (AEDT) Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by gandalf.ozlabs.org (Postfix) with ESMTP id 4Nbzrj5rbFz4x3w for ; Wed, 21 Dec 2022 01:45:25 +1100 (AEDT) Received: by gandalf.ozlabs.org (Postfix) id 4Nbzrj5nszz4xZ3; Wed, 21 Dec 2022 01:45:25 +1100 (AEDT) Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: gandalf.ozlabs.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com Authentication-Results: gandalf.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-ext4-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by gandalf.ozlabs.org (Postfix) with ESMTP id 4Nbzrj0Cnkz4x3w for ; Wed, 21 Dec 2022 01:45:25 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233879AbiLTOpX (ORCPT ); Tue, 20 Dec 2022 09:45:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233722AbiLTOpW (ORCPT ); Tue, 20 Dec 2022 09:45:22 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A5601AA19; Tue, 20 Dec 2022 06:45:20 -0800 (PST) Received: from kwepemm600013.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4NbzqC5tsLzRq0V; Tue, 20 Dec 2022 22:44:07 +0800 (CST) Received: from huawei.com (10.175.127.227) by kwepemm600013.china.huawei.com (7.193.23.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.34; Tue, 20 Dec 2022 22:45:17 +0800 From: Zhihao Cheng To: , CC: , , , , , , Subject: [PATCH] [RFC] Fix data missing when reusing bh which is ready to be checkpointed Date: Tue, 20 Dec 2022 23:05:51 +0800 Message-ID: <20221220150551.653925-1-chengzhihao1@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600013.china.huawei.com (7.193.23.68) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org From: zhanchengbin Following process will make data lost and could lead to a filesystem corrupted problem: 1. jh(bh) is inserted into T1->t_checkpoint_list, bh is dirty, and jh->b_transaction = NULL 2. T1 is added into journal->j_checkpoint_transactions. 3. Get bh prepare to write while doing checkpoing: PA PB do_get_write_access jbd2_log_do_checkpoint spin_lock(&jh->b_state_lock) if (buffer_dirty(bh)) clear_buffer_dirty(bh) // clear buffer dirty set_buffer_jbddirty(bh) transaction = journal->j_checkpoint_transactions jh = transaction->t_checkpoint_list if (!buffer_dirty(bh)) __jbd2_journal_remove_checkpoint(jh) // bh won't be flushed jbd2_cleanup_journal_tail __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved) 4. Aborting journal/Power-cut before writing latest bh on journal area. In this way we get a corrupted filesystem with bh'data lost. Fix it by wrapping clear_buffer_dirty(bh) and jh->b_transaction setting into journal->j_list_lock, so that jbd2_log_do_checkpoint() will wait until jh's new transaction fininshed even bh is currently not dirty. Cc: Signed-off-by: zhanchengbin Signed-off-by: Baokun Li Signed-off-by: Zhihao Cheng --- This is a quick fix, I need some suggestions about this patch, whether it will import new problems if this patch is applied. Yi suggests that the formal solution could be splitting journal->j_list_lock into two locks: one protects checkpoint list and the other one for other lists. Besides, jh->b_state_lock should be held while traversing transaction->t_checkpoint_list in jbd2_log_do_checkpoint()/journal_shrink_one_cp_list(). fs/jbd2/transaction.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 6a404ac1c178..d22460001d6b 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -990,6 +990,7 @@ do_get_write_access(handle_t *handle, struct journal_head *jh, start_lock = jiffies; lock_buffer(bh); spin_lock(&jh->b_state_lock); + spin_lock(&journal->j_list_lock); /* If it takes too long to lock the buffer, trace it */ time_lock = jbd2_time_diff(start_lock, jiffies); @@ -1039,6 +1040,7 @@ do_get_write_access(handle_t *handle, struct journal_head *jh, error = -EROFS; if (is_handle_aborted(handle)) { + spin_unlock(&journal->j_list_lock); spin_unlock(&jh->b_state_lock); goto out; } @@ -1049,8 +1051,10 @@ do_get_write_access(handle_t *handle, struct journal_head *jh, * b_next_transaction points to it */ if (jh->b_transaction == transaction || - jh->b_next_transaction == transaction) + jh->b_next_transaction == transaction) { + spin_unlock(&journal->j_list_lock); goto done; + } /* * this is the first time this transaction is touching this buffer, @@ -1073,11 +1077,11 @@ do_get_write_access(handle_t *handle, struct journal_head *jh, * Paired with barrier in jbd2_write_access_granted() */ smp_wmb(); - spin_lock(&journal->j_list_lock); __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved); spin_unlock(&journal->j_list_lock); goto done; } + spin_unlock(&journal->j_list_lock); /* * If there is already a copy-out version of this buffer, then we don't * need to make another one