Re: [PATCH v3 2/2] quorum: Implement bdrv_co_pwrite_zeroes()

[Alberto Garcia <berto@igalia.com>]

On Fri 13 Nov 2020 12:49:04 PM CET, Max Reitz wrote:
> On 11.11.20 17:53, Alberto Garcia wrote:
>> This simply calls bdrv_co_pwrite_zeroes() in all children
>> 
>> Signed-off-by: Alberto Garcia <berto@igalia.com>
>> ---
>>   block/quorum.c             | 18 ++++++++++++++++--
>>   tests/qemu-iotests/312     |  7 +++++++
>>   tests/qemu-iotests/312.out |  4 ++++
>>   3 files changed, 27 insertions(+), 2 deletions(-)
>
> Should we set supported_zero_flags to something?  I think we can at 
> least set BDRV_REQ_NO_FALLBACK.  We could also try BDRV_REQ_FUA.

We could set all supported_zero_flags as long as all children support
them, right? 

>> +    if (acb->flags & BDRV_REQ_ZERO_WRITE) {
>> +        sacb->ret = bdrv_co_pwrite_zeroes(s->children[i], acb->offset,
>> +                                          acb->bytes, acb->flags);
>> +    } else {
>> +        sacb->ret = bdrv_co_pwritev(s->children[i], acb->offset, acb->bytes,
>> +                                    acb->qiov, acb->flags);
>> +    }
>
> Seems unnecessary (bdrv_co_pwritev() can handle BDRV_REQ_ZERO_WRITE), 
> but perhaps it’s good to be explicit.

pwrite_zeroes() does this additionaly:

    if (!(child->bs->open_flags & BDRV_O_UNMAP)) {
        flags &= ~BDRV_REQ_MAY_UNMAP;
    }

Berto