Re: [nfsv4] Can NFSv4.2 operations be optional on a per server file system basis?

[Rick Macklem <[e-mail]>]

Thomas Haynes wrote:
>> On Oct 10, 2021, at 7:07 AM, Rick Macklem <[e-mail]> wrote:
>>
>> Hi,
>>
>> I'm guessing the answer is "no", but I figured I'd ask just to make sure,
>> since RFC7862 states that operations are optional, but does not clarify
>> beyond that.
>>
>> So, if an NFSv4.2 server exports two file systems, where one of them can
>> perform the operation and the other cannot, is the server allowed to
>> reply NFS4ERR_NOTSUPP for the operation when attempted on files
>> in the file system that cannot perform the operation?
>>
>> Thanks, rick
>> ps: In FreeBSD, UFS can do Allocate, but ZFS cannot.
>>
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>
>
>Hi Rick,
>
>The answer is “no”.
That's what I thought.

>But the question is very interesting. NFS4ERR_INVAL might be the most appropriate of the allowed errors, but >pretty sure you do not want to be returning that.
Yea, EINVAL is the correct response for posix_fallocate(), but the Linux fallocate() uses ENOTSUPP and uses
EINVAL for lots of other things. Since returning EINVAL for a ZFS export was flagged as a bug by testers
during last week's Bakeathon, I'd agree that EINVAL wouldn't work.

>Of the not allowed errors, I think that NFS4ERR_OFFLOAD_DENIED is closest to what you want. You actually want an >NFS4ERR_ALLOCATE_DENIED. It would mean that ALLOCATE was supported, but not allowed for the given file.
>
>And I have no clue how easy it would be to drive that into the standard’s body any more. :-)
I think I'll just have to NFS4ERR_NOTSUPP for Allocate unless the server knows that all file systems
(and DSs for the pNFS case) can do it.

Thanks, rick
ps: Tom, is hs-anvil going to stick around on the Bat VPN for a while? I have a client side race/deadlock
      when testing against it and, if I come up with a fix, it would be nice to be able to test against it?

Tom