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

[Paolo Bonzini <pbonzini@redhat.com>]

Il 13/09/2013 21:48, Peter Lieven ha scritto:
> Am 13.09.2013 20:25, schrieb Eric Blake:
>> 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.
>>
> Ok, so do you find the proposed -S 0 bei Paolo a good choice?
> If this is supplied I would go as far as completly setting
> has_zero_init = 0 also for targets which default to 1. This
> would guaranteed exspansion and full allocation for all drivers.

Sounds good.

Paolo