[libvirt] [PATCH] storage: Support different wiping algorithms

[Michal Privoznik]

On 03.01.2012 17:39, Daniel P. Berrange wrote:
> On Tue, Jan 03, 2012 at 05:12:47PM +0100, Michal Privoznik wrote:
>> Currently, we support only filling a volume with zeroes on wiping.
>> However, it is not enough as data might still be readable by
>> experienced and equipped attacker. Many technical papers have been
>> written, therefore we should support other wiping algorithms.
>> ---
>> Okay, this is not as complete as I'd like it. Wiping could take ages,
>> therefore we *want* it to be asynchronous. But that would mean:
>>
>> 1) Create new API to answer: "Are we done yet?"
> 
> IMHO, we basically want to duplicate the async job system from
> virDomainPtr, for virStorageVolPtr.
> 
> eg,
>       virStorageVolAbortJob(virStorageVolPtr vol);
>       virStorageVolGetJobInfo(virStorageVolPtr vol,
>                               virStorageVolJobInfoPtr info);
> 
> this would be useful for several other storage vol related
> APIs. We might also want similar APIs against virStoragePoolPtr
> 
>> 2) Create event emitting system - like we have for domains
>>
>> 3) Combination of previous two
>>
>> In fact, I've started writing events, but it turned out to be
>> huge and I am not even in a half yet. I need to find a way of
>> re-using event code we already have. But thats another day and
>> another patch set.
> 
> Yes, the abilty to support async events for other objects like
> virStoragePoolPtr, virStorageVolPtr, virNetworkPtr, etc is a
> well overdue todo item.
> 
> 
> I think it would be acceptable todo option 1 as the first
> impl, and then add option 2 as a follow on patchset, since
> events are merely an optimization.
> 
> Daniel

One thing I am wondering about is - can we separate these steps? I mean,
take this part in and do the rest in follow up patches. Certainly,
writing JobInfo for storage is rather huge code to be written and thus
worth its own patch set. Moreover, this functionality can be desired by
many products based on libvirt that want to be certified (e.g. PCI DSS)
and thus need other wiping algorithms than just zeroing. From this POV
is JobInfo just a "nice to have" feature.

So if we get consensus on this, please review.

Michal