[libvirt] [PATCH 1/2] storage: Don't delete Ploop volumes twice

[Olga Krishtal]

On 15/07/16 11:37, Martin Kletzander wrote:
> On Fri, Jul 15, 2016 at 09:41:11AM +0200, Ján Tomko wrote:
>> On Thu, Jul 14, 2016 at 02:27:40PM +0200, Martin Kletzander wrote:
>>> When reinitializing Ploop volumes we also went through the rutine of 
>>> the
>>> normal wipe, effectively removing the root.hds file twice.
>>
>> The file was wiped with the selected algorithm first (without deletion),
>> then reinitialized to make sure you can delete it via libvirt later.
>>
>
> You're right, I missed that what I was describing only happened with
> VIR_STORAGE_VOL_WIPE_ALG_ZERO.  Anyway since the description for
> vol-wipe is:
>
>  "Ensure data previously on a volume is not accessible to future reads"
>
> wiping algorithm does not really make sense for file-based storage.
> That's kind of the whole point of this series.
Actually, virStorageBackendVolWipePloop only deletes root.hds and 
DiscDescriptor.xml.
So the data on block device can still be accessible.
To prevent this we used little path/to/volume manipulation and wiped 
root.hds firstly and
only then called virStorageBackendVolWipePloop. It is incorrect to call 
only this function
for ploop.
>
>> We could get rid of the reinitialization if we make sure libvirt can
>> operate on the volume (after wiping, pretty much only delete makes
>> sense), but removing the actual wiping is wrong.
>>
>> Jan
>>
>>
>>> Since we'll
>>> hopefully add support for other formats as well, split the function 
>>> with
>>> a switch into which we can cleanly add formats in the future.
>>>
>>> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
>>> ---
>>> src/storage/storage_backend.c | 49 
>>> ++++++++++++++++++++++++-------------------
>>> 1 file changed, 27 insertions(+), 22 deletions(-)
>
>
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