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

[Thomas Haynes <[e-mail]>]

> 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 ….