Re: [Nbd] [PATCH v4 04/11] nbd: Improve server handling of bogus commands
- To: Alex Bligh <alex@...872...>
- Cc: "nbd-general@lists.sourceforge.net" <nbd-general@lists.sourceforge.net>, "qemu-devel@...530..." <qemu-devel@...530...>, qemu block <qemu-block@...530...>
- Subject: Re: [Nbd] [PATCH v4 04/11] nbd: Improve server handling of bogus commands
- From: Paolo Bonzini <pbonzini@...696...>
- Date: Wed, 15 Jun 2016 00:05:18 +0200
- Message-id: <2967191c-0204-f99c-0dca-169cdfbcc419@...696...>
- In-reply-to: <B82C8FF7-FB05-4B46-BCEE-A6C41CBA0C45@...872...>
- References: <1463006384-7734-1-git-send-email-eblake@...696...> <1463006384-7734-5-git-send-email-eblake@...696...> <852e526a-5235-499a-741e-a695f5e74f83@...696...> <575EA656.80508@...696...> <6DD06745-C91C-4BFB-BFE5-92E5982ACB42@...872...> <11f620d2-a51d-5235-5abd-4ced314c9090@...696...> <38ABE56B-CA23-4372-A413-CDA72BDAE86A@...872...> <3f9a5b12-67eb-d2f3-f736-22ced5bbf638@...696...> <B82C8FF7-FB05-4B46-BCEE-A6C41CBA0C45@...872...>
On 14/06/2016 17:59, Alex Bligh wrote:
>
>> 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.
ENOMEM is a documented error code, and the limits extension will help
with that as well.
>> 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.
... and QEMU and BSD. What good is a server that doesn't interoperate
(albeit only in error cases) with any client?
Paolo
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