From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: Kai Li <li.kai4@h3c.com>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
joseph.qi@linux.alibaba.com, gechangwei@live.cn,
wang.yongd@h3c.com, wang.xibo@h3c.com
Subject: Re: [PATCH] jbd2: clear JBD2_ABORT flag before journal_reset to update log tail info when load journal
Date: Fri, 17 Jan 2020 16:26:57 -0500 [thread overview]
Message-ID: <20200117212657.GF448999@mit.edu> (raw)
In-Reply-To: <20200114103119.GE6466@quack2.suse.cz>
On Tue, Jan 14, 2020 at 11:31:19AM +0100, Jan Kara wrote:
> Thanks for the patch! Just some small comments below:
>
> On Sat 11-01-20 10:25:42, Kai Li wrote:
> > Fixes: 85e0c4e89c1b "jbd2: if the journal is aborted then don't allow update of the log tail"
>
> This tag should come at the bottom of the changelog (close to your
> Signed-off-by).
>
> > If journal is dirty when mount, it will be replayed but jbd2 sb
> > log tail cannot be updated to mark a new start because
> > journal->j_flags has already been set with JBD2_ABORT first
> > in journal_init_common.
> > When a new transaction is committed, it will be recorded in block 1
> > first(journal->j_tail is set to 1 in journal_reset). If emergency
> > restart again before journal super block is updated unfortunately,
> > the new recorded trans will not be replayed in the next mount.
> > It is danerous which may lead to metadata corruption for file system.
>
> I'd slightly rephrase the text here so that it is more easily readable and
> correct some grammar mistakes. Something like:
>
> If the journal is dirty when the filesystem is mounted, jbd2 will replay
> the journal but the journal superblock will not be updated by
> journal_reset() because JBD2_ABORT flag is still set (it was set in
> journal_init_common()). This is problematic because when a new transaction
> is then committed, it will be recorded in block 1 (journal->j_tail was set
> to 1 in journal_reset()). If unclean shutdown happens again before the
> journal superblock is updated, the new recorded transaction will not be
> replayed during the next mount (because of stale sb->s_start and
> sb->s_sequence values) which can lead to filesystem corruption.
>
> Otherwise the patch looks good to me so feel free to add:
>
> Reviewed-by: Jan Kara <jack@suse.cz>
>
> (again this is added to the bottom of the changelog like the 'Fixes' tag or
> 'Signed-off-by' tag).
Thanks, applied with a fixed up commit description.
- Ted
next prev parent reply other threads:[~2020-01-17 21:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-11 2:25 [PATCH] jbd2: clear JBD2_ABORT flag before journal_reset to update log tail info when load journal Kai Li
2020-01-14 10:31 ` Jan Kara
2020-01-17 21:26 ` Theodore Y. Ts'o [this message]
2020-01-20 6:30 ` Likai
2020-12-02 12:01 ` yebin
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