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

[Peter Lieven <pl@kamp.de>]

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.

Peter