On Wed, Aug 20, 2025 at 7:15 PM NeilBrown <neil@xxxxxxxxxx> wrote:
>
> On Thu, 14 Aug 2025, Olga Kornievskaia wrote:
> > On Tue, Aug 12, 2025 at 8:05 PM NeilBrown <neil@xxxxxxxxxx> wrote:
> > >
> > > On Wed, 13 Aug 2025, Olga Kornievskaia wrote:
> > > > When nfsd is in grace and receives an NLM LOCK request which turns
> > > > out to have a conflicting delegation, return that the server is in
> > > > grace.
> > > >
> > > > Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > > > Signed-off-by: Olga Kornievskaia <okorniev@xxxxxxxxxx>
> > > > ---
> > > > fs/lockd/svc4proc.c | 15 +++++++++++++--
> > > > 1 file changed, 13 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
> > > > index 109e5caae8c7..7ac4af5c9875 100644
> > > > --- a/fs/lockd/svc4proc.c
> > > > +++ b/fs/lockd/svc4proc.c
> > > > @@ -141,8 +141,19 @@ __nlm4svc_proc_lock(struct svc_rqst *rqstp, struct nlm_res *resp)
> > > > resp->cookie = argp->cookie;
> > > >
> > > > /* Obtain client and file */
> > > > - if ((resp->status = nlm4svc_retrieve_args(rqstp, argp, &host, &file)))
> > > > - return resp->status == nlm_drop_reply ? rpc_drop_reply :rpc_success;
> > > > + resp->status = nlm4svc_retrieve_args(rqstp, argp, &host, &file);
> > > > + switch (resp->status) {
> > > > + case 0:
> > > > + break;
> > > > + case nlm_drop_reply:
> > > > + if (locks_in_grace(SVC_NET(rqstp))) {
> > > > + resp->status = nlm_lck_denied_grace_period;
> > >
> > > I think this is wrong. If the lock request has the "reclaim" flag set,
> > > then nlm_lck_denied_grace_period is not a meaningful error.
> > > nlm4svc_retrieve_args() returns nlm_drop_reply when there is a delay
> > > getting a response to an upcall to mountd. For NLM the request really
> > > must be dropped.
> >
> > Thank you for pointing out this case so we are suggesting to.
> >
> > if (locks_in_grace(SVC_NET(rqstp)) && !argp->reclaim)
> >
> > However, I've been looking and looking but I cannot figure out how
> > nlm4svc_retrieve_args() would ever get nlm_drop_reply. You say it can
> > happen during the upcall to mountd. So that happens within nfsd_open()
> > call and a part of fh_verify().
> > To return nlm_drop_reply, nlm_fopen() must have gotten nfserr_dropit
> > from the nfsd_open(). I have searched and searched but I don't see
> > anything that ever sets nfserr_dropit (NFSERR_DROPIT).
> >
> > I searched the logs and nfserr_dropit was an error that was EAGAIN
> > translated into but then removed by the following patch.
>
> Oh. I didn't know that.
> We now use RQ_DROPME instead.
> I guess we should remove NFSERR_DROPIT completely as it not used at all
> any more.
>
> Though returning nfserr_jukebox to an v2 client isn't a good idea....
I'll take your word for you.
> So I guess my main complaint isn't valid, but I still don't like this
> patch. It seems an untidy place to put the locks_in_grace test.
> Other callers of nlm4svc_retrieve_args() check locks_in_grace() before
> making that call. __nlm4svc_proc_lock probably should too. Or is there
> a reason that it is delayed until the middle of nlmsvc_lock()..
I thought the same about why not adding the in_grace check and decided
that it was probably because you dont want to deny a lock if there are
no conflicts. If we add it, somebody might notice and will complain
that they can't get their lock when there are no conflicts.
> The patch is not needed and isn't clearly an improvement, so I would
> rather it were dropped.
I'm not against dropping this patch if the conclusion is that dropping
the packet is no worse than returning in_grace error.
>
> Thanks,
> NeilBrown
>
>
> >
> > commit 062304a815fe10068c478a4a3f28cf091c55cb82
> > Author: J. Bruce Fields <bfields@xxxxxxxxxxxx>
> > Date: Sun Jan 2 22:05:33 2011 -0500
> >
> > nfsd: stop translating EAGAIN to nfserr_dropit
> >
> > diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
> > index dc9c2e3fd1b8..fd608a27a8d5 100644
> > --- a/fs/nfsd/nfsproc.c
> > +++ b/fs/nfsd/nfsproc.c
> > @@ -735,7 +735,8 @@ nfserrno (int errno)
> > { nfserr_stale, -ESTALE },
> > { nfserr_jukebox, -ETIMEDOUT },
> > { nfserr_jukebox, -ERESTARTSYS },
> > - { nfserr_dropit, -EAGAIN },
> > + { nfserr_jukebox, -EAGAIN },
> > + { nfserr_jukebox, -EWOULDBLOCK },
> > { nfserr_jukebox, -ENOMEM },
> > { nfserr_badname, -ESRCH },
> > { nfserr_io, -ETXTBSY },
> >
> > so if fh_verify is failing whatever it is returning, it is not
> > nfserr_dropit nor is it nfserr_jukebox which means nlm_fopen() would
> > translate it to nlm_failed which with my patch would not trigger
> > nlm_lck_denied_grace_period error but resp->status would be set to
> > nlm_failed.
> >
> > So I circle back to I hope that convinces you that we don't need a
> > check for the reclaim lock.
> >
> > I believe nlm_drop_reply is nfsd_open's jukebox error, one of which is
> > delegation recall. it can be a memory failure. But I'm sure when
> > EWOULDBLOCK occurs.
> >
> > > At the very least we need to guard against the reclaim flag being set in
> > > the above test. But I would much rather a more clear distinction were
> > > made between "drop because of a conflicting delegation" and "drop
> > > because of a delay getting upcall response".
> > > Maybe a new "nlm_conflicting_delegtion" return from ->fopen which nlm4
> > > (and ideally nlm2) handles appropriately.
> >
> >
> > > NeilBrown
> > >
> > >
> > > > + return rpc_success;
> > > > + }
> > > > + return nlm_drop_reply;
> > > > + default:
> > > > + return rpc_success;
> > > > + }
> > > >
> > > > /* Now try to lock the file */
> > > > resp->status = nlmsvc_lock(rqstp, file, host, &argp->lock,
> > > > --
> > > > 2.47.1
> > > >
> > > >
> > >
> > >
> >
>
