[nfsv4] Re: OPEN_XOR_DELEGATION when there is existing OPEN stateid

[Thomas Haynes <[e-mail]>]

> On Oct 2, 2024, at 5:51 AM, Jeff Layton <[e-mail]> wrote:
> 
> On Tue, 2024-10-01 at 22:24 -0700, Thomas Haynes wrote:
>> 
>>> On Oct 1, 2024, at 6:11 AM, Jeff Layton <[e-mail]> wrote:
>>> 
>>> Another delstid question. Consider the following situation. All opens
>>> have WANT_OPEN_XOR_DELEGATION set:
>>> 
>>> 1/ Client opens a file r/o. Server doesn't assign a delegation, so an
>>> open stateid (with seq=1) is returned.
>>> 
>>> 2/ Client opens the file again for r/w. Server assigns a delegation and
>>> skips updating the OPEN stateid's seqid and sending the result back to
>>> the client.
>>> 
>>> Is that wrong behavior? It seems like that would morph the open stateid
>>> for this openowner without updating the client as to the new stateid.
>>> The delegation does cover it in that case, but it seems less than
>>> optimal if the client ends up returning that delegation later.
>>> 
>>> If the client already holds an open stateid, should we ignore
>>> WANT_OPEN_XOR_DELEGATION?
>>> -- 
>>> Jeff Layton <[e-mail]>
>> 
>> 
>> It seems to me we can’t break the upgrade, so we have to honor the WANT_OPEN_XOR_DELEGATION by returning an upgraded open stateid.
>> 
>> I.e., if the client already has an open stateid and presents an WANT_OPEN_XOR_DELEGATION, then cannot return just a delegation. Either we just upgrade the existing open stateid or we upgrade it and also return the delegation.
>> 
>> Likewise, if we had already returned a delegation stateid, we should just return a delegation stateid.
>> 
>> Feel free to argue with me ….
> 
> No, that makes sense I think.
> 
> Would it be OK to just ignore WANT_OPEN_XOR_DELEGATION in this case,
> and return both an updated open stateid and the delegation stateid?
> That's probably the more desirable outcome (regardless of the "XOR" in
> the name).
> -- 
> Jeff Layton <[e-mail]>


It is a hint, none of the language states it MUST return one or the other.

So yes, it is okay.

Let me see if I can still add this text.