[libvirt] [PATCH 3/3] Add volume zeroing

Paolo Bonzini pbonzini at redhat.com
Tue Feb 16 08:26:12 UTC 2010


On 02/16/2010 05:08 AM, Dave Allan wrote:
>>
>> What about for a sparse file doing just
>>
>> ftruncate (fd, 0);
>> ftruncate (fd, st.st_size);
>
> That's a good point.  The only thing that makes me hesitate is that
> I'm not certain that the file is guaranteed to contain zeros
> following the second call to ftruncate,

I think since it's sparse, it must be a regular file?  If so, it would
be fine as Eric pointed out.

> a volume represented by a regular file on a backend that doesn't
> support volume delete. If that's so, we could just skip the whole
> zeroing operation entirely for regular files.

Looks like it...

Paolo




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