On Wed, 2021-12-08 at 07:54 -0800, dai.ngo@xxxxxxxxxx wrote:
> On 12/6/21 11:55 AM, Chuck Lever III wrote:
>
> >
> > > +
> > > +/*
> > > + * Function to check if the nfserr_share_denied error for 'fp'
> > > resulted
> > > + * from conflict with courtesy clients then release their state to
> > > resolve
> > > + * the conflict.
> > > + *
> > > + * Function returns:
> > > + * 0 - no conflict with courtesy clients
> > > + * >0 - conflict with courtesy clients resolved, try
> > > access/deny check again
> > > + * -1 - conflict with courtesy clients being resolved in
> > > background
> > > + * return nfserr_jukebox to NFS client
> > > + */
> > > +static int
> > > +nfs4_destroy_clnts_with_sresv_conflict(struct svc_rqst *rqstp,
> > > + struct nfs4_file *fp, struct
> > > nfs4_ol_stateid *stp,
> > > + u32 access, bool share_access)
> > > +{
> > > + int cnt = 0;
> > > + int async_cnt = 0;
> > > + bool no_retry = false;
> > > + struct nfs4_client *cl;
> > > + struct list_head *pos, *next, reaplist;
> > > + struct nfsd_net *nn = net_generic(SVC_NET(rqstp),
> > > nfsd_net_id);
> > > +
> > > + INIT_LIST_HEAD(&reaplist);
> > > + spin_lock(&nn->client_lock);
> > > + list_for_each_safe(pos, next, &nn->client_lru) {
> > > + cl = list_entry(pos, struct nfs4_client, cl_lru);
> > > + /*
> > > + * check all nfs4_ol_stateid of this client
> > > + * for conflicts with 'access'mode.
> > > + */
> > > + if (nfs4_check_deny_bmap(cl, fp, stp, access,
> > > share_access)) {
> > > + if (!test_bit(NFSD4_COURTESY_CLIENT, &cl-
> > > >cl_flags)) {
> > > + /* conflict with non-courtesy
> > > client */
> > > + no_retry = true;
> > > + cnt = 0;
> > > + goto out;
> > > + }
> > > + /*
> > > + * if too many to resolve synchronously
> > > + * then do the rest in background
> > > + */
> > > + if (cnt > 100) {
> > > + set_bit(NFSD4_DESTROY_COURTESY_CLIE
> > > NT, &cl->cl_flags);
> > > + async_cnt++;
> > > + continue;
> > > + }
> > > + if (mark_client_expired_locked(cl))
> > > + continue;
> > > + cnt++;
> > > + list_add(&cl->cl_lru, &reaplist);
> > > + }
> > > + }
> > Bruce suggested simply returning NFS4ERR_DELAY for all cases.
> > That would simplify this quite a bit for what is a rare edge
> > case.
>
> If we always do this asynchronously by returning NFS4ERR_DELAY
> for all cases then the following pynfs tests need to be modified
> to handle the error:
>
> RENEW3 st_renew.testExpired :
> FAILURE
> LKU10 st_locku.testTimedoutUnlock :
> FAILURE
> CLOSE9 st_close.testTimedoutClose2 :
> FAILURE
>
> and any new tests that opens file have to be prepared to handle
> NFS4ERR_DELAY due to the lack of destroy_clientid in 4.0.
>
> Do we still want to take this approach?
NFS4ERR_DELAY is a valid error for both CLOSE and LOCKU (see RFC7530
section 13.2 https://datatracker.ietf.org/doc/html/rfc7530#section-13.2
) so if pynfs complains, then it needs fixing regardless.
RENEW, on the other hand, cannot return NFS4ERR_DELAY, but why would it
need to? Either the lease is still valid, or else someone is already
trying to tear it down due to an expiration event. I don't see why
courtesy locks need to add any further complexity to that test.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
