From: Eric Blake <eblake@redhat.com>
To: Max Reitz <mreitz@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] qcow2: Unset zero_beyond_eof in save_vmstate
Date: Mon, 21 Oct 2013 21:37:05 +0100 [thread overview]
Message-ID: <52659071.4070003@redhat.com> (raw)
In-Reply-To: <1382298755-21383-1-git-send-email-mreitz@redhat.com>
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On 10/20/2013 08:52 PM, Max Reitz wrote:
> Saving the VM state is done using bdrv_pwrite. This function may perform
> a read-modify-write, which in this case results in data being read from
> beyond the end of the virtual disk. Since we are actually trying to
> access an area which is not a part of the virtual disk, zero_beyond_eof
> has to be set to false before performing the partial write, otherwise
> the VM state may become corrupted.
>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
> Follow-up to (depends on):
> - qcow2: Restore total_sectors value in save_vmstate
Reviewed-by: Eric Blake <eblake@redhat.com>
Do you have test cases that demonstrate the corruption pre-patch?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2013-10-21 20:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-20 19:52 [Qemu-devel] [PATCH] qcow2: Unset zero_beyond_eof in save_vmstate Max Reitz
2013-10-21 20:37 ` Eric Blake [this message]
2013-10-23 17:07 ` Max Reitz
2013-10-23 18:27 ` Max Reitz
2013-10-24 9:52 ` Kevin Wolf
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