linux-ext4 - Re: ext4: Fix data corruption with multi-block writepages support

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Date:	Mon, 7 Feb 2011 18:44:14 +0000
From:	Matt <jackdachef@...il.com>
To:	Milan Broz <mbroz@...hat.com>
Cc:	"Ted Ts'o" <tytso@....edu>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	linux-ext4 <linux-ext4@...r.kernel.org>
Subject: Re: ext4: Fix data corruption with multi-block writepages support

On Mon, Feb 7, 2011 at 6:29 PM, Milan Broz <mbroz@...hat.com> wrote:
> On 02/07/2011 06:45 PM, Ted Ts'o wrote:
>> On Fri, Feb 04, 2011 at 10:40:47PM +0000, Matt wrote:
>>>
>>> So that means that the file-corruption which existed until 2.6.37-rc6
>>> and got triggered (for me) more easily via "dm crypt: scale to
>>> multiple CPUs"
>>> is fixed now ?
>>
>> Well, a patch exists for it that will be merged into 2.6.38.
>>
>>> That should give ext4 a nice speedup for >=2.6.38 :)
>>
>> I'm not going to make it be the default for 2.6.38, since it's fairly
>> late in the -rc features.  People who want it can explicitly enable it
>> using the mount option mblk_io_submit, though.  (And let me know your
>> success stories!  :-) I will be enabling it as the default in
>> 2.6.39-rc1.
>
> So it was ext4 only bug in ext4_end_bio(),
> dm-crypt per-cpu code was just trigger here, right?
>
> Milan
>

Hi Milan,

Well, that was at least the experience that I made

ext4: after Ted had disabled support for multiple page-io submission

I observed no data-corruption anymore (it had only appeared on the
system-partition, /home - where ext4 also is used or on my backup
partitions there was also no problem as far as I can tell)

XFS: no corruption observed

reiserfs: I can't say for sure since I'm only using it on my /boot partition :P

for other filesystems I can't say anything - I didn't use additional
ones at that time

Regards

Matt
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