From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Darrick J. Wong" Subject: Re: [PATCH 3/3] ext4: Fix fsync error handling after filesystem abort. Date: Mon, 10 Jun 2013 14:22:09 -0700 Message-ID: <20130610212209.GA6021@blackbox.djwong.org> References: <1370882461-12786-1-git-send-email-dmonakhov@openvz.org> <1370882461-12786-3-git-send-email-dmonakhov@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org, tytso@mit.edu, jack@suse.cz To: Dmitry Monakhov Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:48559 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752205Ab3FJVWV (ORCPT ); Mon, 10 Jun 2013 17:22:21 -0400 Content-Disposition: inline In-Reply-To: <1370882461-12786-3-git-send-email-dmonakhov@openvz.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, Jun 10, 2013 at 08:41:01PM +0400, Dmitry Monakhov wrote: > If filesystem was aborted after inode's write back is complete > but before its metadata was updated we may return success > results in data loss. > In order to handle fs abort correctly we have to check > fs state once we discover that it is in MS_RDONLY state > > Test case: http://patchwork.ozlabs.org/patch/244297 > > Changes from V2: > - more spelling fixes > > Changes from V1: > - fix spelling > > Reviewed-by: Jan Kara > Signed-off-by: Dmitry Monakhov > --- > fs/ext4/fsync.c | 7 ++++++- > fs/ext4/super.c | 12 +++++++++++- > 2 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c > index fc938eb..a8bc47f 100644 > --- a/fs/ext4/fsync.c > +++ b/fs/ext4/fsync.c > @@ -98,8 +98,13 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) > > trace_ext4_sync_file_enter(file, datasync); > > - if (inode->i_sb->s_flags & MS_RDONLY) > + if (inode->i_sb->s_flags & MS_RDONLY) { > + /* Make sure that we read updated s_mount_flags value */ > + smp_rmb(); > + if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED) > + ret = -EROFS; > goto out; > + } > > if (!journal) { > ret = generic_file_fsync(file, start, end, datasync); > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 0f77c2e..f23daaa 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -399,6 +399,11 @@ static void ext4_handle_error(struct super_block *sb) > } > if (test_opt(sb, ERRORS_RO)) { > ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only"); > + /* > + * Make shure updated value of ->s_mount_flags will be visible > + * before ->s_flags update > + */ > + smp_wmb(); > sb->s_flags |= MS_RDONLY; > } > if (test_opt(sb, ERRORS_PANIC)) > @@ -571,8 +576,13 @@ void __ext4_abort(struct super_block *sb, const char *function, > > if ((sb->s_flags & MS_RDONLY) == 0) { > ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only"); > - sb->s_flags |= MS_RDONLY; > EXT4_SB(sb)->s_mount_flags |= EXT4_MF_FS_ABORTED; > + /* > + * Make shure updated value of ->s_mount_flags will be visiable I think you meant 'sure' and 'visible' here and in the previous hunk. --D > + * before ->s_flags update > + */ > + smp_wmb(); > + sb->s_flags |= MS_RDONLY; > if (EXT4_SB(sb)->s_journal) > jbd2_journal_abort(EXT4_SB(sb)->s_journal, -EIO); > save_error_info(sb, function, line); > -- > 1.7.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html