From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755314AbdK1LZ0 (ORCPT ); Tue, 28 Nov 2017 06:25:26 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:33008 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933128AbdK1Kp6 (ORCPT ); Tue, 28 Nov 2017 05:45:58 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ross Zwisler , Theodore Tso , Jan Kara Subject: [PATCH 4.14 085/193] ext4: prevent data corruption with inline data + DAX Date: Tue, 28 Nov 2017 11:25:32 +0100 Message-Id: <20171128100617.284358025@linuxfoundation.org> X-Mailer: git-send-email 2.15.0 In-Reply-To: <20171128100613.638270407@linuxfoundation.org> References: <20171128100613.638270407@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ross Zwisler commit 559db4c6d784ceedc2a5418ced4d357cb843e221 upstream. If an inode has inline data it is currently prevented from using DAX by a check in ext4_set_inode_flags(). When the inode grows inline data via ext4_create_inline_data() or removes its inline data via ext4_destroy_inline_data_nolock(), the value of S_DAX can change. Currently these changes are unsafe because we don't hold off page faults and I/O, write back dirty radix tree entries and invalidate all mappings. There are also issues with mm-level races when changing the value of S_DAX, as well as issues with the VM_MIXEDMAP flag: https://www.spinics.net/lists/linux-xfs/msg09859.html The unsafe transition of S_DAX can reliably cause data corruption, as shown by the following fstest: https://patchwork.kernel.org/patch/9948381/ Fix this issue by preventing the DAX mount option from being used on filesystems that were created to support inline data. Inline data is an option given to mkfs.ext4. Signed-off-by: Ross Zwisler Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara Signed-off-by: Greg Kroah-Hartman --- fs/ext4/inline.c | 10 ---------- fs/ext4/super.c | 5 +++++ 2 files changed, 5 insertions(+), 10 deletions(-) --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -302,11 +302,6 @@ static int ext4_create_inline_data(handl EXT4_I(inode)->i_inline_size = len + EXT4_MIN_INLINE_DATA_SIZE; ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS); ext4_set_inode_flag(inode, EXT4_INODE_INLINE_DATA); - /* - * Propagate changes to inode->i_flags as well - e.g. S_DAX may - * get cleared - */ - ext4_set_inode_flags(inode); get_bh(is.iloc.bh); error = ext4_mark_iloc_dirty(handle, inode, &is.iloc); @@ -451,11 +446,6 @@ static int ext4_destroy_inline_data_nolo } } ext4_clear_inode_flag(inode, EXT4_INODE_INLINE_DATA); - /* - * Propagate changes to inode->i_flags as well - e.g. S_DAX may - * get set. - */ - ext4_set_inode_flags(inode); get_bh(is.iloc.bh); error = ext4_mark_iloc_dirty(handle, inode, &is.iloc); --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3708,6 +3708,11 @@ static int ext4_fill_super(struct super_ } if (sbi->s_mount_opt & EXT4_MOUNT_DAX) { + if (ext4_has_feature_inline_data(sb)) { + ext4_msg(sb, KERN_ERR, "Cannot use DAX on a filesystem" + " that may contain inline data"); + goto failed_mount; + } err = bdev_dax_supported(sb, blocksize); if (err) goto failed_mount;