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Re: [Qemu-devel] [PATCH 0/2] qcow2: Add two more unalignment checks
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 0/2] qcow2: Add two more unalignment checks |
Date: |
Mon, 19 Jan 2015 14:04:51 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 |
On 01/19/2015 01:49 PM, Max Reitz wrote:
> With the series adding unalignment checks and the series reworking the
> zero cluster expansion code overlapping, the unalignment checks have not
> been implemented in the latter code.
>
> This series fixes it.
>
> There are other places which would require unalignment checks, like the
> offsets of L1 tables, especially for snapshots; but because it would be
> best to add these checks in the function which reads the snapshot table,
> this would make images with broken snapshots completely unusable, which
> is something I opted to avoid for now.
>
> Ideally, we need to make the qcow2 repair function repair such cases,
> but until that is done there is not much we can do about them.
What's the best repair? Read the data from the unaligned location, and
write a fresh copy into a new aligned allocation? At any rate, I agree
that repairing unaligned locations is harder than detecting them, so
your series is fine as is.
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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Re: [Qemu-devel] [PATCH 0/2] qcow2: Add two more unalignment checks, Kevin Wolf, 2015/01/22