From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751426AbdILFFj (ORCPT ); Tue, 12 Sep 2017 01:05:39 -0400 Received: from mga09.intel.com ([134.134.136.24]:5341 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751292AbdILFFe (ORCPT ); Tue, 12 Sep 2017 01:05:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.42,381,1500966000"; d="scan'208";a="899352296" From: Ross Zwisler To: "Theodore Ts'o" , Jan Kara , linux-kernel@vger.kernel.org Cc: Ross Zwisler , Andreas Dilger , Christoph Hellwig , Dan Williams , Dave Chinner , linux-ext4@vger.kernel.org, linux-nvdimm@lists.01.org Subject: [PATCH v2 2/5] ext4: prevent data corruption with journaling + DAX Date: Mon, 11 Sep 2017 23:05:23 -0600 Message-Id: <20170912050526.7627-3-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20170912050526.7627-1-ross.zwisler@linux.intel.com> References: <20170912050526.7627-1-ross.zwisler@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The current code has the potential for data corruption when changing an inode's journaling mode, as that can result in a subsequent unsafe change in S_DAX. I've captured an instance of this data corruption in the following fstest: https://patchwork.kernel.org/patch/9948377/ Prevent this data corruption from happening by disallowing changes to the journaling mode if the '-o dax' mount option was used. This means that for a given filesystem we could have a mix of inodes using either DAX or data journaling, but whatever state the inodes are in will be held for the duration of the mount. Signed-off-by: Ross Zwisler Suggested-by: Jan Kara --- fs/ext4/inode.c | 5 ----- fs/ext4/ioctl.c | 16 +++++++++++++--- 2 files changed, 13 insertions(+), 8 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index e963508..3207333 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5971,11 +5971,6 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA); } ext4_set_aops(inode); - /* - * Update inode->i_flags after EXT4_INODE_JOURNAL_DATA was updated. - * E.g. S_DAX may get cleared / set. - */ - ext4_set_inode_flags(inode); jbd2_journal_unlock_updates(journal); percpu_up_write(&sbi->s_journal_flag_rwsem); diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index afb66d4..b0b754b 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -290,10 +290,20 @@ static int ext4_ioctl_setflags(struct inode *inode, if (err) goto flags_out; - if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL)) + if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL)) { + /* + * Changes to the journaling mode can cause unsafe changes to + * S_DAX if we are using the DAX mount option. + */ + if (test_opt(inode->i_sb, DAX)) { + err = -EBUSY; + goto flags_out; + } + err = ext4_change_inode_journal_flag(inode, jflag); - if (err) - goto flags_out; + if (err) + goto flags_out; + } if (migrate) { if (flags & EXT4_EXTENTS_FL) err = ext4_ext_migrate(inode); -- 2.9.5