[NFS-Ganesha-Devel] Re: [nfsv4] Re: Clarification on delegation behavior for same-client conflicting OPEN

On Fri, Oct 31, 2025 at 7:29 AM Jeff Layton <jlayton(a)poochiereds.net&gt; wrote: > > On Thu, 2025-10-30 at 17:35 +0000, Suhas Athani via Devel wrote: > > > > Hello NFS community, > > > > We’re seeking clarification on server behavior for OPEN > > delegations when the same client issues a potentially conflicting > > OPEN on a file for which it already holds a delegation. > > > > Context and RFC references > > > >  * > >    RFC 8881(10.4 Open Delegation) > >     - > >       “There must be no current OPEN conflicting with the > > requested delegation.” > >     - > >       “There should be no current delegation that conflicts with > > the delegation being requested.” > > > >  * > >    RFC 8881(10.4.1 Open Delegation and Data Caching) > >     - > >       For delegation handling, READs/WRITEs without OPEN are > > treated as the functional equivalents of a corresponding type of > > OPEN, and the server “can use the client ID associated with the > > current session to determine if the operation has been done by > > the holder of the delegation (in which case, no recall is > > necessary) or by another client (in which case, the delegation > > must be recalled and I/O not proceed until the delegation is > > returned or revoked).” > > > >  * > >    Historical reference: RFC 5661 (obsoleted by RFC 8881) carries > > the same sections 10.4 and 10.4.1 > > Questions > > 1) Same-client conflicting OPEN: > > > >  * > >    If a client holds an OPEN_DELEGATE_READ on a file and then the > > same client issues an OPEN that requires write access (or > > otherwise conflicts), should the server: > >  * > > > > > > > > > >     - > >       Allow the OPEN to complete immediately without recalling > > the delegation (i.e., no recall necessary for same-client), per > > RFC 8881 10.4.1; or > > > >  * > >    Recall the delegation anyway and delay the operation until > > DELEGRETURN? The only thing I'll add to what Jeff said is.. for the case of CLAIM_DELEGATE_CUR or CLAIM_DELEG_CUR_FH you do not want to recall and wait for a DELEGRETURN, since these Opens need to be done before the client can DELEGRETURN. Also, a client is being dumb if it does any Opens on the FH other than the above 2 Claim types while it holds a Write delegation. However, I don't the the RFC forbids it, so I'd say just do it. (A Write delegation allows Reading/Writing, opening for any acces/deny case locally in the client. The server recalls the write delegation when another client requests any Open for the FH.