Bug#637234: linux-image-3.0.0-1-686-pae: I/O errors using ext4 under xen (also affects ext3 as of linux-image-3.1.0-1-amd64 et al)

[Dominic Hargreaves <dom@earth.li>]

retitle 637234 linux-image-3.0.0-1-686-pae: I/O errors using ext4 under xen (also affects ext3 as of linux-image-3.1.0-1-amd64 et al)
thanks

[note that I've stripped off the CC to xen-devel in this comment, but
have no objection to it being put back if it makes sense]

On Wed, Sep 07, 2011 at 08:29:38AM -0400, Konrad Rzeszutek Wilk wrote:
> On Wed, Sep 07, 2011 at 02:51:04AM +0100, Ben Hutchings wrote:
> > On Mon, 2011-08-29 at 10:08 -0400, Konrad Rzeszutek Wilk wrote:
> > [...]
> > > Oh, I think I know _exactly_ what bug that is:
> > > 
> > > This git commit:
> > > 280802657fb95c52bb5a35d43fea60351883b2af "xen/blkback: When writting barriers set the sector number to zero"
> > > has to be reverted. Specifically:
> > > 
> > > commit 3f963cae3ef35d26fdd899c08797a598c5ca3e9b
> > > Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> > > Date:   Tue Jul 19 16:44:42 2011 -0700
> > > 
> > >     Revert "xen/blkback: When writting barriers set the sector number to zero..."
> > [...]
> > > and this one added:
> > > 
> > > 25266338a41470a21e9b3974445be09e0640dda7
> > > xen/blkback: don't fail empty barrier requests
> > [...]
> > 
> > Which repository are these in?
> 
> Jeremy's: git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git

This problem is also present with ext3 by default now, following the
barriers-by-default change in Linux 3.1 (I'm seeing the problems with
3.1.4-1 domU and squeeze dom0; the barrier=0 workaround works).

If I'm not confused, this message from Konrad is about the same problem,
and points to another possible fix:

<http://lists.xen.org/archives/html/xen-devel/2011-12/msg00306.html>

I suspect that over time this will hit a lot of people on domU upgrades
from squeeze to wheezy - and it needs to be fixed in the dom0 kernel, which
presumably means a point release update.

Cheers,
Dominic.

-- 
Dominic Hargreaves | http://www.larted.org.uk/~dom/
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