Re: [Qemu-devel] [PATCH 08/12] qemu-img: conditionally zero out target on convert

[Eric Blake <eblake@redhat.com>]

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On 09/13/2013 04:36 AM, Paolo Bonzini wrote:
> Il 13/09/2013 12:25, Peter Lieven ha scritto:
>> if the target has_zero_init = 0, but supports efficiently
>> writing zeroes by unmapping we call bdrv_zeroize to
>> avoid fully allocating the target. this currently
>> is designed especially for iscsi.
>>
>> Signed-off-by: Peter Lieven <pl@kamp.de>
>> ---
>>  qemu-img.c |   22 ++++++++++++++++------
>>  1 file changed, 16 insertions(+), 6 deletions(-)
>>
>> diff --git a/qemu-img.c b/qemu-img.c
>> index 3e5e388..6eaddc6 100644
>> --- a/qemu-img.c
>> +++ b/qemu-img.c
>> @@ -1354,7 +1354,8 @@ static int img_convert(int argc, char **argv)
>>          }
>>      }
>>  
>> -    flags = BDRV_O_RDWR;
>> +    flags = BDRV_O_RDWR | BDRV_O_UNMAP;
> 
> I think this should be a new command-line flag.

I agree - while 'sparse by default' may be reasonable, it is also
feasible to want a mode that guarantees expansion rather than unmapped
or sparse.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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