Re: [Qemu-devel] [PATCH] Add -f option to qemu-nbd

[Zhi Yong Wu]

On Wed, Nov 16, 2011 at 10:27 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Wed, Nov 16, 2011 at 11:49 AM, Zhi Yong Wu <address@hidden> wrote:
>> On Wed, Nov 16, 2011 at 6:34 PM, Stefan Hajnoczi <address@hidden> wrote:
>>> On Wed, Nov 16, 2011 at 6:57 AM, Chunyan Liu <address@hidden> wrote:
>>>> Currently qemu-nbd does not support finding free nbd device for users like
>>>> "losetup -f" and issuing "qemu-nbd -c /dev/nbdX disk.img" won't report 
>>>> error
>>>> message when /dev/nbd is already in use. It makes things a little 
>>>> confusing.
>>>> This patch adds "-f" option to qemu-nbd to support finding a free nbd 
>>>> device
>>>> for users. Please review and share your comments. Thanks.
>>>>
>>>> Signed-off-by: Chunyan Liu <address@hidden>
>>>> ---
>>>>  qemu-nbd.c |   65 
>>>> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>>>>  1 files changed, 64 insertions(+), 1 deletions(-)
>>>
>>> This patch finds a free device but does not immediately attach to it
>>> and use it.  Interfaces like this are prone to race conditions, I
>>> think it would make more sense to combine the -f option with running
>>> the actual NBD server.
>>>
>>> I suggest:
>>> qemu-nbd -f disk.img
>> Why must we add one new option? I prefer to not adding new option,
>> only enhance existing function of qemu-nbd -c disk.img.
>
> That would change the command-line interface and break existing users.
>  There might be scripts or tools that call out to qemu-nbd, they would
> break if we changed the meaning of -c.
Sound reasonable, thanks
>
> Stefan
>



-- 
Regards,

Zhi Yong Wu