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Re: [Nbd] [PATCH v4 04/11] nbd: Improve server handling of bogus commands

> On 14 Jun 2016, at 16:11, Paolo Bonzini <pbonzini@...696...> wrote:
>> To illustrate the problem, look consider what qemu itself would do as
>> a server if it can't buffer the entire read issued to it.
> Return ENOMEM?

Well OK, qemu then 'works' on the basis it breaks another
part of the spec, which is coping with long reads.

> However, it looks like the
> de facto status prior to structured replies is that the error is in the
> spec, and this patch introduces a regression.

Well, I guess the patch makes it work the same as the
reference server implementation and the spec, which I'd
consider a fix. My view is that the error is in the
kernel client. I think Erik CC'd in nbd-general
re the comment that the spec was broken; I don't think
it is, and don't propose to change it. Wouter might or
might not feel differently.

It's been reasonably well known (I wrote about it
at least 3 years ago), that the current implementation
(reference + kernel) does not cope well with errors
on reads, so I'm guessing one is just trading one
set of brokenness for another. So I'm pretty relaxed
about what goes in qemu.

Alex Bligh

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