Re: [Qemu-devel] [PATCH 1/2] iotests: 030 TestParallelOps non-shared base node

[Vladimir Sementsov-Ogievskiy]

20.03.2019 20:25, Alberto Garcia wrote:
> On Wed 20 Mar 2019 10:35:27 AM CET, Vladimir Sementsov-Ogievskiy wrote:
>>> Maybe at least this kind of freezing isn't the right tool for block
>>> jobs, after all.
>>
>> I think, the correct way, which will support these correct cases
>> (which however don't look like real use cases) is removing base from
>> stream view. Stream should operate instead using bottom-node.
> 
> What is bottom-node?

I mean bottom intermediate node, or a node which backing is base.

> 
>> And this all looks really more complicated than what we already have
>> with frozen backing chain.
>>
>> Do we really need such cases with parallel streams, sharing same node
>> as base for one and top for another? Will someone be upset if we drop
>> usage for such scenarios?
> 
> That would mean that 'base' is blocked and therefore cannot be used by a
> different block job.
> 
> I don't think it's terrible to restrict that scenario, although it's
> technically a regression so someone could complain about it. As I said
> ealier I would prefer not to do it if there's a simple solution (we
> would need to think about it), but I wouldn't want to make the code more
> complicated just for this use case.
> 
> Berto
> 


-- 
Best regards,
Vladimir