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....
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()..
The patch is not needed and isn't clearly an improvement, so I would
rather it were dropped.
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
> > >
> > >
> >
> >
>
