On Tue, Jul 29, 2014 at 12:41:43PM -0400, Jeff Layton wrote:
> On Tue, 29 Jul 2014 10:53:31 -0400
> "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
>
> > On Fri, Jul 25, 2014 at 07:34:20AM -0400, Jeff Layton wrote:
> > > @@ -698,11 +699,10 @@ static void revoke_delegation(struct nfs4_delegation *dp)
> > > struct nfs4_client *clp = dp->dl_stid.sc_client;
> > >
> > > if (clp->cl_minorversion == 0)
> > > - destroy_delegation(dp);
> > > + destroy_revoked_delegation(dp);
> >
> > I don't understand this one--in the NFSv4.0 case, when is the delegation
> > unhashed?
> >
> > (And, apologies if that's a repeat question. I remember wondering about
> > this before but can't find mail in the archives....)
> >
> > --b.
> >
>
> It's unhashed by the laundromat (or the fault injection code). The
> deltas that change that are later in this patch, but it doesn't have
> much context so it's a little tricky to spot. Here's the relevant code
> chunk from nfs4_laundromat:
>
> ---------------[snip]-----------------
> spin_lock(&state_lock);
> list_for_each_safe(pos, next, &nn->del_recall_lru) {
> dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> if (net_generic(dp->dl_stid.sc_client->net, nfsd_net_id) != nn)
> continue;
> if (time_after((unsigned long)dp->dl_time, (unsigned long)cutoff)) {
> t = dp->dl_time - cutoff;
> new_timeo = min(new_timeo, t);
> break;
> }
> unhash_delegation_locked(dp);
> list_add(&dp->dl_recall_lru, &reaplist);
> }
> spin_unlock(&state_lock);
> list_for_each_safe(pos, next, &reaplist) {
> dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> revoke_delegation(dp);
> }
> ---------------[snip]-----------------
>
> ...so the laundromat walks the nn->del_recall_lru list, unhashes any
> delegation that has expired and gathers them up onto the list. Then, it
> calls revoke_delegation on each outside of the lock.
Got it, thanks.
> As a side note, that net_generic comparison there looks bogus to me.
> How could you ever end up with an entry from a different namespace on
> this list? I left it in for now since it didn't seem relevant (or
> terribly expensive), but I suspect that it can be removed (or turned
> into a WARN or something).
Looks like this was an oversight from e8c69d17d1ef. I'd be fine with
just removing it.
--b.
>
> > > else {
> > > - unhash_delegation(dp);
> > > dp->dl_stid.sc_type = NFS4_REVOKED_DELEG_STID;
> > > - list_add(&dp->dl_recall_lru, &clp->cl_revoked);
> > > + list_move(&dp->dl_recall_lru, &clp->cl_revoked);
> > > }
> > > }
> > >
> > > @@ -1458,15 +1458,14 @@ destroy_client(struct nfs4_client *clp)
> > > spin_lock(&state_lock);
> > > while (!list_empty(&clp->cl_delegations)) {
> > > dp = list_entry(clp->cl_delegations.next, struct
> > > nfs4_delegation, dl_perclnt);
> > > - list_del_init(&dp->dl_perclnt);
> > > - /* Ensure that deleg break won't try to requeue it
> > > */
> > > - ++dp->dl_time;
> > > - list_move(&dp->dl_recall_lru, &reaplist);
> > > + unhash_delegation_locked(dp);
> > > + list_add(&dp->dl_recall_lru, &reaplist);
> > > }
> > > spin_unlock(&state_lock);
> > > while (!list_empty(&reaplist)) {
> > > dp = list_entry(reaplist.next, struct
> > > nfs4_delegation, dl_recall_lru);
> > > - destroy_delegation(dp);
> > > + list_del_init(&dp->dl_recall_lru);
> > > + nfs4_put_delegation(dp);
> > > }
> > > list_splice_init(&clp->cl_revoked, &reaplist);
> > > while (!list_empty(&reaplist)) {
> > > @@ -3662,7 +3661,7 @@ nfs4_open_delegation(struct net *net, struct
> > > svc_fh *fh, open->op_delegate_type = NFS4_OPEN_DELEGATE_READ;
> > > return;
> > > out_free:
> > > - destroy_delegation(dp);
> > > + nfs4_put_delegation(dp);
> > > out_no_deleg:
> > > open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE;
> > > if (open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS &&
> > > @@ -3900,7 +3899,8 @@ nfs4_laundromat(struct nfsd_net *nn)
> > > new_timeo = min(new_timeo, t);
> > > break;
> > > }
> > > - list_move(&dp->dl_recall_lru, &reaplist);
> > > + unhash_delegation_locked(dp);
> > > + list_add(&dp->dl_recall_lru, &reaplist);
> > > }
> > > spin_unlock(&state_lock);
> > > list_for_each_safe(pos, next, &reaplist) {
> > > @@ -5382,12 +5382,8 @@ static u64 nfsd_find_all_delegations(struct
> > > nfs4_client *clp, u64 max, if (dp->dl_time != 0)
> > > continue;
> > >
> > > - /*
> > > - * Increment dl_time to ensure that
> > > delegation breaks
> > > - * don't monkey with it now that we are.
> > > - */
> > > - ++dp->dl_time;
> > > - list_move(&dp->dl_recall_lru, victims);
> > > + unhash_delegation_locked(dp);
> > > + list_add(&dp->dl_recall_lru, victims);
> > > }
> > > if (++count == max)
> > > break;
> > > @@ -5642,12 +5638,14 @@ nfs4_state_shutdown_net(struct net *net)
> > > spin_lock(&state_lock);
> > > list_for_each_safe(pos, next, &nn->del_recall_lru) {
> > > dp = list_entry (pos, struct nfs4_delegation,
> > > dl_recall_lru);
> > > - list_move(&dp->dl_recall_lru, &reaplist);
> > > + unhash_delegation_locked(dp);
> > > + list_add(&dp->dl_recall_lru, &reaplist);
> > > }
> > > spin_unlock(&state_lock);
> > > list_for_each_safe(pos, next, &reaplist) {
> > > dp = list_entry (pos, struct nfs4_delegation,
> > > dl_recall_lru);
> > > - destroy_delegation(dp);
> > > + list_del_init(&dp->dl_recall_lru);
> > > + nfs4_put_delegation(dp);
> > > }
> > >
> > > nfsd4_client_tracking_exit(net);
> > > --
> > > 1.9.3
> > >
>
>
> --
> Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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