linux-ext4 - Re: Need of revoke mechanism in JBD

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 30 Apr 2011 07:36:49 +0530
From:	Niraj Kulkarni <kulkarniniraj14@...il.com>
To:	Amir Goldstein <amir73il@...il.com>
CC:	Ted Ts'o <tytso@....edu>, Ding Dinghua <dingdinghua85@...il.com>,
	Yongqiang Yang <xiaoqiangnk@...il.com>,
	linux-ext4@...r.kernel.org
Subject: Re: Need of revoke mechanism in JBD

On Saturday 30 April 2011 01:15 AM, Amir Goldstein wrote:
> On Tue, Apr 26, 2011 at 3:25 PM, Ted Ts'o<tytso@....edu>  wrote:
>> 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
> Actually, the original paper has no mention of revoke records.
> I went out to look for useful documentation on journal forget/revoke
> and came back empty handed as well.
>
>> if you'd like more details.
>>
>> Hope this helps!
>>
>>                                                 - Ted
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
>> the body of a message to majordomo@...r.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
Yes, I tried some other papers too, but no use. Anyway I've figured out 
that for my change, I dont need any kind of journalling related 
facilities, so I am going to bypass it completely.

Niraj
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html