Re: [Qemu-devel] [PATCH 1/5 for-2.11?] qcow2: reject unaligned offsets in write compressed

[Eric Blake]

On 11/14/2017 12:30 PM, Anton Nefedov wrote:
> On 14/11/2017 7:50 PM, Eric Blake wrote:
>> On 11/14/2017 04:16 AM, Anton Nefedov wrote:
>>> Misaligned compressed write is not supported.
>>>
>>> Signed-off-by: Anton Nefedov <address@hidden>
>>> ---
>>>   block/qcow2.c | 4 ++++
>>>   1 file changed, 4 insertions(+)
>>
>> Should this one be applied in 2.11?
>>
> 
> For the record, this one is pretty hard to trigger; backup and qemu-img
> convert currently use compressed write, both make sure they operate in
> clusters.
> 
> qemu-io is almighty though

Okay, then we definitely have a bug, and this patch is definitely 2.11
material, especially if you update the commit message to show the
trigger case:

> 
> qemu-io> write -c -P 7 512 64k
> wrote 65536/65536 bytes at offset 512
> 64 KiB, 1 ops; 0.0187 sec (3.329 MiB/sec and 53.2566 ops/sec)
> qemu-io> read -P 7 512 64k
> Pattern verification failed at offset 512, 65536 bytes
> read 65536/65536 bytes at offset 512
> 64 KiB, 1 ops; 0.0002 sec (248.016 MiB/sec and 3968.2540 ops/sec)
> qemu-io> read -P 7 0 64k
> read 65536/65536 bytes at offset 0
> 64 KiB, 1 ops; 0.0000 sec (1.606 GiB/sec and 26315.7895 ops/sec)
> 
> /Anton
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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