From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DA8EC43381 for ; Wed, 27 Mar 2019 19:04:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A8D5206B7 for ; Wed, 27 Mar 2019 19:04:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553713444; bh=Ve3AJ4oJBbQPmvhNe61aB7yojfLhY8+qUDf2+HkRmvk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qMchMBb5Qed3jqWQvaVStj5eJYPj8nO+cwevZ9QjD/GqC7HN0Hpjm8/w0dyDyd/iW ornpsXPMGLhxH7/jF0E49OoH6uCs2rKR0XuDaTN8W5WWTNc5dOd+8egYHSBg6G1bHz 5WikXQcRtwesO503CqB1dv0uGVa9b9UL70Tzpfkw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389376AbfC0SNO (ORCPT ); Wed, 27 Mar 2019 14:13:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:55762 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389362AbfC0SNM (ORCPT ); Wed, 27 Mar 2019 14:13:12 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CC48E2184C; Wed, 27 Mar 2019 18:13:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553710390; bh=Ve3AJ4oJBbQPmvhNe61aB7yojfLhY8+qUDf2+HkRmvk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OKt99bdPsO41JqfdzFzw1OfKEgwsvPiGe48xxT5PrWcaPJ4UC6FoIwEk0s8pnoWnd XkyrmZkJQRC8FpzecwUFecx/rNGAVRQNQ3yosGa3XwehxhB3OF7yR20uIsN0tEAUw3 dEBNgK6UNrcQsqRad6XoHGsILM4aT6CpZmlhO/dI= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Theodore Ts'o , Sasha Levin , linux-ext4@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 097/192] jbd2: fix race when writing superblock Date: Wed, 27 Mar 2019 14:08:49 -0400 Message-Id: <20190327181025.13507-97-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190327181025.13507-1-sashal@kernel.org> References: <20190327181025.13507-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Theodore Ts'o [ Upstream commit 538bcaa6261b77e71d37f5596c33127c1a3ec3f7 ] The jbd2 superblock is lockless now, so there is probably a race condition between writing it so disk and modifing contents of it, which may lead to checksum error. The following race is the one case that we have captured. jbd2 fsstress jbd2_journal_commit_transaction jbd2_journal_update_sb_log_tail jbd2_write_superblock jbd2_superblock_csum_set jbd2_journal_revoke jbd2_journal_set_features(revork) modify superblock submit_bh(checksum incorrect) Fix this by locking the buffer head before modifing it. We always write the jbd2 superblock after we modify it, so this just means calling the lock_buffer() a little earlier. This checksum corruption problem can be reproduced by xfstests generic/475. Reported-by: zhangyi (F) Suggested-by: Jan Kara Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/jbd2/journal.c | 52 ++++++++++++++++++++++++----------------------- 1 file changed, 27 insertions(+), 25 deletions(-) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index 8ef6b6daaa7a..88f2a49338a1 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1356,6 +1356,10 @@ static int journal_reset(journal_t *journal) return jbd2_journal_start_thread(journal); } +/* + * This function expects that the caller will have locked the journal + * buffer head, and will return with it unlocked + */ static int jbd2_write_superblock(journal_t *journal, int write_flags) { struct buffer_head *bh = journal->j_sb_buffer; @@ -1365,7 +1369,6 @@ static int jbd2_write_superblock(journal_t *journal, int write_flags) trace_jbd2_write_superblock(journal, write_flags); if (!(journal->j_flags & JBD2_BARRIER)) write_flags &= ~(REQ_FUA | REQ_PREFLUSH); - lock_buffer(bh); if (buffer_write_io_error(bh)) { /* * Oh, dear. A previous attempt to write the journal @@ -1424,6 +1427,7 @@ int jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid, jbd_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n", tail_block, tail_tid); + lock_buffer(journal->j_sb_buffer); sb->s_sequence = cpu_to_be32(tail_tid); sb->s_start = cpu_to_be32(tail_block); @@ -1454,18 +1458,17 @@ static void jbd2_mark_journal_empty(journal_t *journal, int write_op) journal_superblock_t *sb = journal->j_superblock; BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex)); - read_lock(&journal->j_state_lock); - /* Is it already empty? */ - if (sb->s_start == 0) { - read_unlock(&journal->j_state_lock); + lock_buffer(journal->j_sb_buffer); + if (sb->s_start == 0) { /* Is it already empty? */ + unlock_buffer(journal->j_sb_buffer); return; } + jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n", journal->j_tail_sequence); sb->s_sequence = cpu_to_be32(journal->j_tail_sequence); sb->s_start = cpu_to_be32(0); - read_unlock(&journal->j_state_lock); jbd2_write_superblock(journal, write_op); @@ -1488,9 +1491,8 @@ void jbd2_journal_update_sb_errno(journal_t *journal) journal_superblock_t *sb = journal->j_superblock; int errcode; - read_lock(&journal->j_state_lock); + lock_buffer(journal->j_sb_buffer); errcode = journal->j_errno; - read_unlock(&journal->j_state_lock); if (errcode == -ESHUTDOWN) errcode = 0; jbd_debug(1, "JBD2: updating superblock error (errno %d)\n", errcode); @@ -1894,28 +1896,27 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat, sb = journal->j_superblock; + /* Load the checksum driver if necessary */ + if ((journal->j_chksum_driver == NULL) && + INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V3)) { + journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0); + if (IS_ERR(journal->j_chksum_driver)) { + printk(KERN_ERR "JBD2: Cannot load crc32c driver.\n"); + journal->j_chksum_driver = NULL; + return 0; + } + /* Precompute checksum seed for all metadata */ + journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid, + sizeof(sb->s_uuid)); + } + + lock_buffer(journal->j_sb_buffer); + /* If enabling v3 checksums, update superblock */ if (INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V3)) { sb->s_checksum_type = JBD2_CRC32C_CHKSUM; sb->s_feature_compat &= ~cpu_to_be32(JBD2_FEATURE_COMPAT_CHECKSUM); - - /* Load the checksum driver */ - if (journal->j_chksum_driver == NULL) { - journal->j_chksum_driver = crypto_alloc_shash("crc32c", - 0, 0); - if (IS_ERR(journal->j_chksum_driver)) { - printk(KERN_ERR "JBD2: Cannot load crc32c " - "driver.\n"); - journal->j_chksum_driver = NULL; - return 0; - } - - /* Precompute checksum seed for all metadata */ - journal->j_csum_seed = jbd2_chksum(journal, ~0, - sb->s_uuid, - sizeof(sb->s_uuid)); - } } /* If enabling v1 checksums, downgrade superblock */ @@ -1927,6 +1928,7 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat, sb->s_feature_compat |= cpu_to_be32(compat); sb->s_feature_ro_compat |= cpu_to_be32(ro); sb->s_feature_incompat |= cpu_to_be32(incompat); + unlock_buffer(journal->j_sb_buffer); return 1; #undef COMPAT_FEATURE_ON -- 2.19.1