Re: [Qemu-block] [PATCH 1/1] nbd: implement bdrv_get_info callback

[Eric Blake]

On 02/02/2018 08:06 AM, Edgar Kaziakhmedov wrote:

>>>> However, it would be nice to remove can_write_zeroes_with_unmap from
>>>> BlockDriverInfo, and make bdrv_can_write_zeroes_with_unmap just return
>>>> !!(bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP).  Kevin, what do you
>>>> think?
>> Actually, I may even just give a shot at writing this alternative patch,
>> to make Kevin's decision easier.
> But actually qcow2 performs some checks for version inside get_info
> callback before setting can_write_zeroes_with_unmap flag,
> so we can't take into account such checks in
> bdrv_can_write_zeroes_with_unmap subroutine. Therefore, I don't think it
> is possible to do it like that.

Here's the patch I proposed (it looks like I forgot to CC you):

https://lists.gnu.org/archive/html/qemu-devel/2018-01/msg06471.html

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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