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Re: [Qemu-devel] [PATCH] qcow2: Switch L1 table in a single sequence
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From: |
Eric Blake |
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Subject: |
Re: [Qemu-devel] [PATCH] qcow2: Switch L1 table in a single sequence |
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Date: |
Mon, 30 Sep 2013 11:48:32 -0600 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130923 Thunderbird/17.0.9 |
On 09/30/2013 09:57 AM, Max Reitz wrote:
> Switching the L1 table in memory should be an atomic operation, as far
> as possible. Calling qcow2_free_clusters on the old L1 table on disk is
> not a good idea when the old L1 table is no longer valid and the address
> to the new one hasn't yet been written into the corresponding
> BDRVQcowState field. To be more specific, this can lead to segfaults due
> to qcow2_check_metadata_overlap trying to access the L1 table during the
> free operation.
>
> Signed-off-by: Max Reitz <address@hidden>
> ---
> block/qcow2-cluster.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
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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