From: Ted Ts'o <tytso@mit.edu>
To: Ding Dinghua <dingdinghua85@gmail.com>
Cc: Yongqiang Yang <xiaoqiangnk@gmail.com>,
Niraj Kulkarni <kulkarniniraj14@gmail.com>,
linux-ext4@vger.kernel.org
Subject: Re: Need of revoke mechanism in JBD
Date: Tue, 26 Apr 2011 08:25:58 -0400 [thread overview]
Message-ID: <20110426122558.GF9486@thunk.org> (raw)
In-Reply-To: <BANLkTikV4nU4Zc4OxNa6q8wDtM7cLUF_ig@mail.gmail.com>
On Tue, Apr 26, 2011 at 05:23:21PM +0800, Ding Dinghua wrote:
> I think it's not only a performance issue but more important, a
> correctness issue.
> Revoke table is used for preventing the wrong replay of journal which
> cause data corruption:
> If block A has been journalled its modification, committed to journal
> and hasn't been checkpointed,
> and in later transactions block A is freed and reused for data in
> no-journalled-data mode, then If
> we don't have revoke table which recording the releasing event, replay
> of journal will overwrite the new data,
> which causing data corruption.
Yes, this is correct. It should be covered fairly well in Stephen
Tweedie's, "Journaling the ext2fs file system" paper, which you can
find at:
https://ext4.wiki.kernel.org/index.php/Publications
if you'd like more details.
Hope this helps!
- Ted
next prev parent reply other threads:[~2011-04-26 12:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-26 8:29 Need of revoke mechanism in JBD Niraj Kulkarni
2011-04-26 8:56 ` Yongqiang Yang
2011-04-26 9:23 ` Ding Dinghua
2011-04-26 10:47 ` Niraj Kulkarni
2011-04-26 10:57 ` Amir Goldstein
2011-04-26 17:27 ` Andreas Dilger
2011-04-27 0:52 ` Ding Dinghua
2011-04-26 12:25 ` Ted Ts'o [this message]
2011-04-29 19:45 ` Amir Goldstein
2011-04-30 2:06 ` Niraj Kulkarni
2011-05-01 22:28 ` Ted Ts'o
2011-05-02 10:42 ` Amir Goldstein
2011-05-02 14:43 ` Ted Ts'o
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