On Mon, 2025-08-11 at 15:10 -0400, Jeff Layton wrote:
> On Mon, 2025-08-11 at 14:18 -0400, Olga Kornievskaia wrote:
> > When v3 NLM request finds a conflicting delegation, it triggers
> > a delegation recall and nfsd_open fails with EAGAIN. nfsd_open
> > then translates EAGAIN into nfserr_jukebox. In nlm_fopen, instead
> > of returning nlm_failed for when there is a conflicting delegation,
> > drop this NLM request so that the client retries. Once delegation
> > is recalled and if a local lock is claimed, a retry would lead to
> > nfsd returning a nlm_lck_blocked error or a successful nlm lock.
> >
> > Signed-off-by: Olga Kornievskaia <okorniev@xxxxxxxxxx>
> > ---
> > fs/nfsd/lockd.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
> > index edc9f75dc75c..ad3e461f30c0 100644
> > --- a/fs/nfsd/lockd.c
> > +++ b/fs/nfsd/lockd.c
> > @@ -57,6 +57,7 @@ nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp,
> > switch (nfserr) {
> > case nfs_ok:
> > return 0;
> > + case nfserr_jukebox:
> > case nfserr_dropit:
> > return nlm_drop_reply;
> > case nfserr_stale:
>
> This works by triggering a RPC retransmission. That could time out on
> soft mounts if it takes a while to return a delegation. Looking at the
> NLM spec here:
>
> https://pubs.opengroup.org/onlinepubs/9629799/chap14.htm
>
> What about returning NLM4_DENIED instead? The description there is:
>
> NLM4_DENIED
> The call failed. For attempts to set a lock, this status implies
> that if the client retries the call later, it may succeed.
>
> Presumably the client should redrive this effectively indefinitely that
> way?
Scratch that idea. The client treats that as a fatal error in
nlmclnt_lock():
/*
* EAGAIN doesn't make sense for sleeping locks, and in some
* cases NLM_LCK_DENIED is returned for a permanent error. So
* turn it into an ENOLCK.
*/
if (resp->status == nlm_lck_denied && (flags & FL_SLEEP))
status = -ENOLCK;
else
status = nlm_stat_to_errno(resp->status);
Dropping the call might be next best option then.
--
Jeff Layton <jlayton@xxxxxxxxxx>
