Re: [Qemu-devel] [PATCH 4/4] block: avoid creating oversized writes in multiwrite_merge

[Paolo Bonzini]

Il 19/09/2014 00:56, Peter Lieven ha scritto:
>> > So I think if we treat it just as a hint for multiwrite, we can avoid
>> > writing code to split oversized requests.  They always worked so far, we
>> > can certainly wait until we have a real bug fix.
> I would not treat this as a hint. I would use it in cases where we definitely
> know an absolute hard limit for I/O request size. Otherwise the value for
> bs->bl.max_transfer_length should be 0.
> 
> If there comes in an oversized request we fail it as early as possible

That's the part that I'd rather not touch, at least not without doing
request splitting.

Paolo

 and regarding
> the multi write code we avoid that it accidentally generates an oversized 
> request.