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Subject: Re: [Qemu-devel] qcow2 - safe on kill?  safe on power fail?
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To: qemu-devel@nongnu.org

Anthony Liguori wrote:
> Andreas Schwab wrote:
>> Anthony Liguori <anthony@codemonkey.ws> writes:
>>
>>  
>>> The only ways that you can cause corruption is if the QCOW2 sector
>>> allocation code is faulty (and you would be screwed no matter what 
>>> here)
>>> or if you issue a SIGTERM/SIGKILL that interrupts the code while it's
>>> allocating a new sector.
>>>     
>>
>> Blocking SIGTERM until the allocation is finished could close that hole.
>>   
>
> Seems like a band-aid to me as SIGKILL is still an issue.  Plus it 
> would involve modifying all disk formats, not just QCOW2.  I'd rather 
> see proper journal support added to QCOW2 myself.

Journalling is so out of fashion.  It's better to sequence the 
operations so that failure results in a leak instead of corruption.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.