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From:   Chuck Lever <chuck.lever@oracle.com>
To:     Bruce Fields <bfields@fieldses.org>
CC:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Olga Kornievskaia <kolga@netapp.com>
Subject: Re: [PATCH] nfsd: don't abort copies early
Thread-Topic: [PATCH] nfsd: don't abort copies early
Thread-Index: AQHXCtx0cs5d9peX+k+/c+JLDyWeq6pnsZqAgAAAt4A=
Date:   Wed, 24 Feb 2021 19:34:10 +0000
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> On Feb 24, 2021, at 2:31 PM, J. Bruce Fields <bfields@fieldses.org> wrote=
:
>=20
> I confess I always have to stare at these comparisons for a minute to
> figure out which way they should go.  And the logic in each of these
> loops is a little repetitive.
>=20
> Would it be worth creating a little state_expired() helper to work out
> the comparison and the new timeout?

That's better, but aren't there already operators on time64_t data objects
that can be used for this?


> --b.
>=20
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 61552e89bd89..00fb3603c29e 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -5363,6 +5363,22 @@ static bool clients_still_reclaiming(struct nfsd_n=
et *nn)
> 	return true;
> }
>=20
> +struct laundry_time {
> +	time64_t cutoff;
> +	time64_t new_timeo;
> +};
> +
> +bool state_expired(struct laundry_time *lt, time64_t last_refresh)
> +{
> +	time64_t time_remaining;
> +
> +	if (last_refresh > lt->cutoff)
> +		return true;
> +	time_remaining =3D lt->cutoff - last_refresh;
> +	lt->new_timeo =3D min(lt->new_timeo, time_remaining);
> +	return false;
> +}
> +
> static time64_t
> nfs4_laundromat(struct nfsd_net *nn)
> {
> @@ -5372,14 +5388,16 @@ nfs4_laundromat(struct nfsd_net *nn)
> 	struct nfs4_ol_stateid *stp;
> 	struct nfsd4_blocked_lock *nbl;
> 	struct list_head *pos, *next, reaplist;
> -	time64_t cutoff =3D ktime_get_boottime_seconds() - nn->nfsd4_lease;
> -	time64_t t, new_timeo =3D nn->nfsd4_lease;
> +	struct laundry_time lt =3D {
> +		.cutoff =3D ktime_get_boottime_seconds() - nn->nfsd4_lease,
> +		.new_timeo =3D nn->nfsd4_lease
> +	};
> 	struct nfs4_cpntf_state *cps;
> 	copy_stateid_t *cps_t;
> 	int i;
>=20
> 	if (clients_still_reclaiming(nn)) {
> -		new_timeo =3D 0;
> +		lt.new_timeo =3D 0;
> 		goto out;
> 	}
> 	nfsd4_end_grace(nn);
> @@ -5389,7 +5407,7 @@ nfs4_laundromat(struct nfsd_net *nn)
> 	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
> 		cps =3D container_of(cps_t, struct nfs4_cpntf_state, cp_stateid);
> 		if (cps->cp_stateid.sc_type =3D=3D NFS4_COPYNOTIFY_STID &&
> -				cps->cpntf_time < cutoff)
> +				state_expired(&lt, cps->cpntf_time))
> 			_free_cpntf_state_locked(nn, cps);
> 	}
> 	spin_unlock(&nn->s2s_cp_lock);
> @@ -5397,11 +5415,8 @@ nfs4_laundromat(struct nfsd_net *nn)
> 	spin_lock(&nn->client_lock);
> 	list_for_each_safe(pos, next, &nn->client_lru) {
> 		clp =3D list_entry(pos, struct nfs4_client, cl_lru);
> -		if (clp->cl_time > cutoff) {
> -			t =3D clp->cl_time - cutoff;
> -			new_timeo =3D min(new_timeo, t);
> +		if (!state_expired(&lt, clp->cl_time))
> 			break;
> -		}
> 		if (mark_client_expired_locked(clp)) {
> 			trace_nfsd_clid_expired(&clp->cl_clientid);
> 			continue;
> @@ -5418,11 +5433,8 @@ nfs4_laundromat(struct nfsd_net *nn)
> 	spin_lock(&state_lock);
> 	list_for_each_safe(pos, next, &nn->del_recall_lru) {
> 		dp =3D list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> -		if (dp->dl_time > cutoff) {
> -			t =3D dp->dl_time - cutoff;
> -			new_timeo =3D min(new_timeo, t);
> +		if (!state_expired(&lt, clp->cl_time))
> 			break;
> -		}
> 		WARN_ON(!unhash_delegation_locked(dp));
> 		list_add(&dp->dl_recall_lru, &reaplist);
> 	}
> @@ -5438,11 +5450,8 @@ nfs4_laundromat(struct nfsd_net *nn)
> 	while (!list_empty(&nn->close_lru)) {
> 		oo =3D list_first_entry(&nn->close_lru, struct nfs4_openowner,
> 					oo_close_lru);
> -		if (oo->oo_time > cutoff) {
> -			t =3D oo->oo_time - cutoff;
> -			new_timeo =3D min(new_timeo, t);
> +		if (!state_expired(&lt, oo->oo_time))
> 			break;
> -		}
> 		list_del_init(&oo->oo_close_lru);
> 		stp =3D oo->oo_last_closed_stid;
> 		oo->oo_last_closed_stid =3D NULL;
> @@ -5468,11 +5477,8 @@ nfs4_laundromat(struct nfsd_net *nn)
> 	while (!list_empty(&nn->blocked_locks_lru)) {
> 		nbl =3D list_first_entry(&nn->blocked_locks_lru,
> 					struct nfsd4_blocked_lock, nbl_lru);
> -		if (nbl->nbl_time > cutoff) {
> -			t =3D nbl->nbl_time - cutoff;
> -			new_timeo =3D min(new_timeo, t);
> +		if (!state_expired(&lt, oo->oo_time))
> 			break;
> -		}
> 		list_move(&nbl->nbl_lru, &reaplist);
> 		list_del_init(&nbl->nbl_list);
> 	}
> @@ -5485,8 +5491,7 @@ nfs4_laundromat(struct nfsd_net *nn)
> 		free_blocked_lock(nbl);
> 	}
> out:
> -	new_timeo =3D max_t(time64_t, new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
> -	return new_timeo;
> +	return max_t(time64_t, lt.new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
> }
>=20
> static struct workqueue_struct *laundry_wq;

--
Chuck Lever