Re: [Xen-devel] backport "ext4: serialize unaligned asynchronous DIO" to 2.6.32

[Philipp Hahn <hahn@xxxxxxxxxxxxx>]

Hello Ted, hello Eric,

On Monday February 7th 2011 16:59:36 Ted Ts'o wrote:
> commit 7520bb0f2980ef79d17dcbec2783760b37490ffc
> Author: Eric Sandeen <sandeen@xxxxxxxxxx>
> Date:   Mon Feb 7 10:57:28 2011 -0500
>
>     ext4: serialize unaligned asynchronous DIO
>
>     ext4 has a data corruption case when doing non-block-aligned
>     asynchronous direct IO into a sparse file, as demonstrated
>     by xfstest 240.

I hope you remember that bug, because I encountered this data corruption bug 
on Debians 2.6.32(.51) kernel as well.

On the other hand RedHat seems to have back-ported that fix to RHEL5 (2.6.18)  
and probably RHEL6 (2.6.32) as well, but I don't have a subscription, so I 
can't verify that:
<http://rpmfind.net/linux/RPM/centos/updates/5.7/x86_64/RPMS/kernel-devel-2.6.18-274.12.1.el5.x86_64.html>
<https://bugzilla.redhat.com/show_bug.cgi?id=689830>

The Xen-people also encountered it and asked for someone to backport it:
<http://osdir.com/ml/xen-development/2011-07/msg00474.html>

I tried to backport it from 2.6.38~rc5 to 2.6.32.51 and thus far it seems to 
fix the bug. But several other things were re-named and re-organized between 
those versions, so it was not slreight forward.

Since I'm no ext4 expert, I'd like to ask you to have a look at this backport. 
Is it sound or are there some tests I can throw at it to get it tested more 
thoroughly?
Does is classify for <mailto:stable@xxxxxxxxxxxxxxx>?

Thanks in advance
Philipp Hahn
-- 
Philipp Hahn           Open Source Software Engineer      hahn@xxxxxxxxxxxxx
Univention GmbH        Linux for Your Business        fon: +49 421 22 232- 0
Mary-Somerville-Str.1  D-28359 Bremen                 fax: +49 421 22 232-99
                                                   http://www.univention.de/

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