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RE: [Xen-devel] RE: Window VM hit blue screen when dom0 uses ext4 with extent enabled

> Subject: Re: [Xen-devel] RE: Window VM hit blue screen when dom0 uses ext4 with extent enabled
> From: Ian.Campbell@xxxxxxxxxx
> To: tinnycloud@xxxxxxxxxxx
> CC: xen-devel@xxxxxxxxxxxxxxxxxxx; jeremy@xxxxxxxx; konrad.wilk@xxxxxxxxxx
> Date: Thu, 14 Jul 2011 09:02:06 +0100
> On Thu, 2011-07-14 at 06:44 +0100, MaoXiaoyun wrote:
> > I think the ext4 needs to backport this patch much likely.
> > Otherwise it will hit the problem I met.
> >
> > http://patchwork.ozlabs.org/patch/79880/
> That version is still in state NEW but something appears to have been
> committed upstream as e9e3bcecf44c04b9e6b505fd8e2eb9cea58fb94d:
> 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.
> ...
> Seems like a reasonable enough thing to backport to me (for what that's
> worth). Although:
> It is also quite a lot slower
> (14 min for package installs, vs. 8 min for well-aligned)
> but I'll take slow correctness over fast corruption any day.
> Mingming suggested that we can track outstanding
> conversions, and wait on those so that non-sparse
> files won't be affected, and I've implemented that here;
> unaligned AIO to nonsparse files won't take a perf hit.
> Something to bear in mind if you are deploying anything based on sparse
> files on ext4.
That's right. Since we use VHD as our base image.
We are trying to backport this patch, but isn't easy for me.
Meanwhile, there are quite a lot ext4 patches in upstream, I'm afried
some of them are also needed for stable ext4, well, not sure.
Could someone kindly backport e9e3bcecf44c04b9e6b505fd8e2eb9cea58fb94d
for me?
Many thanks.

> Ian.
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