Re: [PATCH v11 00/20] nfs/nfsd: add support for localio

Chuck Lever III
2024-07-05T13:35:30Z

> On Jul 5, 2024, at 1:18 AM, Christoph Hellwig <hch@infradead.org> wrote:
>
> On Thu, Jul 04, 2024 at 02:31:46PM -0400, Mike Snitzer wrote:
>> Some new layout misses the entire point of having localio work for
>> NFSv3 and NFSv4. NFSv3 is very ubiquitous.
>
> I'm getting tird of bringing up this "oh NFSv3" again and again without
> any explanation of why that matters for communication insides the
> same Linux kernel instance with a kernel that obviously requires
> patching. Why is running an obsolete protocol inside the same OS
> instance required. Maybe it is, but if so it needs a very good
> explanation.

I agree: I think the requirement for NFSv3 in this situation
needs a clear justification. Both peers are recent vintage
Linux kernels; both peers can use NFSv4.x, there's no
explicit need for backwards compatibility in the use cases
that have been provided so far.

Generally I do agree with Neil's "why not NFSv3, we still
support it" argument. But with NFSv4, you get better locking
semantics, delegation, pNFS (possibly), and proper protocol
extensibility. There are really strong reasons to restrict
this facility to NFSv4.

--
Chuck Lever