Re: [PATCH 03/11] block/raw-format: implement .bdrv_cancel_in_flight handler

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

21.01.2021 02:15, Eric Blake wrote:
> On 11/18/20 12:04 PM, Vladimir Sementsov-Ogievskiy wrote:
>> We are going to cancel in-flight requests on mirror nbd target on job
>> cancel. Still nbd is often used not directly but as raw-format child.
>> So, add pass-through handler here.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>   block/raw-format.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
> 
> Should all filters do this automatically (or rather, should the block
> layer do this automatically for all filters)?  But I understand that it
> does NOT make sense for format drivers in general (cancelling a guest
> request may still require metadata updates), where raw-format is the
> exception, so doing it in raw-format instead of the block layer makes sense.
> 

Hmm.. probably not for backup_top filter. But of course OK for throttling

> 
>>   BlockDriver bdrv_raw = {
>>       .format_name          = "raw",
>>       .instance_size        = sizeof(BDRVRawState),
>> @@ -608,6 +613,7 @@ BlockDriver bdrv_raw = {
>>       .bdrv_has_zero_init   = &raw_has_zero_init,
>>       .strong_runtime_opts  = raw_strong_runtime_opts,
>>       .mutable_opts         = mutable_opts,
>> +    .bdrv_cancel_in_flight = raw_cancel_in_flight,
> 
> A demonstration of why I don't like aligning the =.  But it's merely
> cosmetic, so doesn't affect:
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 


-- 
Best regards,
Vladimir