Commit 7746b32f authored by Dai Ngo's avatar Dai Ngo Committed by Chuck Lever
Browse files

NFSD: add shrinker to reap courtesy clients on low memory condition 



Add courtesy_client_reaper to react to low memory condition triggered
by the system memory shrinker.

The delayed_work for the courtesy_client_reaper is scheduled on
the shrinker's count callback using the laundry_wq.

The shrinker's scan callback is not used for expiring the courtesy
clients due to potential deadlocks.

Signed-off-by: default avatarDai Ngo <dai.ngo@oracle.com>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 3a4ea23d

fs/nfsd/netns.h

+2 −0
Original line number Diff line number Diff line
@@ -194,6 +194,8 @@ struct nfsd_net { 
	int			nfs4_max_clients;



	atomic_t		nfsd_courtesy_clients;

	struct shrinker		nfsd_client_shrinker;

	struct delayed_work	nfsd_shrinker_work;

};



/* Simple check to find out if a given net was properly initialized */

fs/nfsd/nfs4state.c

+86 −8
Original line number Diff line number Diff line
@@ -4349,7 +4349,27 @@ nfsd4_init_slabs(void) 
	return -ENOMEM;

}



void nfsd4_init_leases_net(struct nfsd_net *nn)

static unsigned long

nfsd_courtesy_client_count(struct shrinker *shrink, struct shrink_control *sc)

{

	int cnt;

	struct nfsd_net *nn = container_of(shrink,

			struct nfsd_net, nfsd_client_shrinker);



	cnt = atomic_read(&nn->nfsd_courtesy_clients);

	if (cnt > 0)

		mod_delayed_work(laundry_wq, &nn->nfsd_shrinker_work, 0);

	return (unsigned long)cnt;

}



static unsigned long

nfsd_courtesy_client_scan(struct shrinker *shrink, struct shrink_control *sc)

{

	return SHRINK_STOP;

}



int

nfsd4_init_leases_net(struct nfsd_net *nn)

{

	struct sysinfo si;

	u64 max_clients;
@@ -4370,6 +4390,16 @@ void nfsd4_init_leases_net(struct nfsd_net *nn) 
	nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB);



	atomic_set(&nn->nfsd_courtesy_clients, 0);

	nn->nfsd_client_shrinker.scan_objects = nfsd_courtesy_client_scan;

	nn->nfsd_client_shrinker.count_objects = nfsd_courtesy_client_count;

	nn->nfsd_client_shrinker.seeks = DEFAULT_SEEKS;

	return register_shrinker(&nn->nfsd_client_shrinker, "nfsd-client");

}



void

nfsd4_leases_net_shutdown(struct nfsd_net *nn)

{

	unregister_shrinker(&nn->nfsd_client_shrinker);

}



static void init_nfs4_replay(struct nfs4_replay *rp)
@@ -5942,10 +5972,49 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist, 
	spin_unlock(&nn->client_lock);

}



static void

nfs4_get_courtesy_client_reaplist(struct nfsd_net *nn,

				struct list_head *reaplist)

{

	unsigned int maxreap = 0, reapcnt = 0;

	struct list_head *pos, *next;

	struct nfs4_client *clp;



	maxreap = NFSD_CLIENT_MAX_TRIM_PER_RUN;

	INIT_LIST_HEAD(reaplist);



	spin_lock(&nn->client_lock);

	list_for_each_safe(pos, next, &nn->client_lru) {

		clp = list_entry(pos, struct nfs4_client, cl_lru);

		if (clp->cl_state == NFSD4_ACTIVE)

			break;

		if (reapcnt >= maxreap)

			break;

		if (!mark_client_expired_locked(clp)) {

			list_add(&clp->cl_lru, reaplist);

			reapcnt++;

		}

	}

	spin_unlock(&nn->client_lock);

}



static void

nfs4_process_client_reaplist(struct list_head *reaplist)

{

	struct list_head *pos, *next;

	struct nfs4_client *clp;



	list_for_each_safe(pos, next, reaplist) {

		clp = list_entry(pos, struct nfs4_client, cl_lru);

		trace_nfsd_clid_purged(&clp->cl_clientid);

		list_del_init(&clp->cl_lru);

		expire_client(clp);

	}

}



static time64_t

nfs4_laundromat(struct nfsd_net *nn)

{

	struct nfs4_client *clp;

	struct nfs4_openowner *oo;

	struct nfs4_delegation *dp;

	struct nfs4_ol_stateid *stp;
@@ -5974,12 +6043,8 @@ nfs4_laundromat(struct nfsd_net *nn) 
	}

	spin_unlock(&nn->s2s_cp_lock);

	nfs4_get_client_reaplist(nn, &reaplist, &lt);

	list_for_each_safe(pos, next, &reaplist) {

		clp = list_entry(pos, struct nfs4_client, cl_lru);

		trace_nfsd_clid_purged(&clp->cl_clientid);

		list_del_init(&clp->cl_lru);

		expire_client(clp);

	}

	nfs4_process_client_reaplist(&reaplist);



	spin_lock(&state_lock);

	list_for_each_safe(pos, next, &nn->del_recall_lru) {

		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
@@ -6062,6 +6127,18 @@ laundromat_main(struct work_struct *laundry) 
	queue_delayed_work(laundry_wq, &nn->laundromat_work, t*HZ);

}



static void

courtesy_client_reaper(struct work_struct *reaper)

{

	struct list_head reaplist;

	struct delayed_work *dwork = to_delayed_work(reaper);

	struct nfsd_net *nn = container_of(dwork, struct nfsd_net,

					nfsd_shrinker_work);



	nfs4_get_courtesy_client_reaplist(nn, &reaplist);

	nfs4_process_client_reaplist(&reaplist);

}



static inline __be32 nfs4_check_fh(struct svc_fh *fhp, struct nfs4_stid *stp)

{

	if (!fh_match(&fhp->fh_handle, &stp->sc_file->fi_fhandle))
@@ -7879,6 +7956,7 @@ static int nfs4_state_create_net(struct net *net) 
	INIT_LIST_HEAD(&nn->blocked_locks_lru);



	INIT_DELAYED_WORK(&nn->laundromat_work, laundromat_main);

	INIT_DELAYED_WORK(&nn->nfsd_shrinker_work, courtesy_client_reaper);

	get_net(net);



	return 0;

fs/nfsd/nfsctl.c

+4 −2
Original line number Diff line number Diff line
@@ -1481,11 +1481,12 @@ static __net_init int nfsd_init_net(struct net *net) 
		goto out_idmap_error;

	nn->nfsd_versions = NULL;

	nn->nfsd4_minorversions = NULL;

	retval = nfsd4_init_leases_net(nn);

	if (retval)

		goto out_drc_error;

	retval = nfsd_reply_cache_init(nn);

	if (retval)

		goto out_drc_error;

	nfsd4_init_leases_net(nn);



	get_random_bytes(&nn->siphash_key, sizeof(nn->siphash_key));

	seqlock_init(&nn->writeverf_lock);
@@ -1507,6 +1508,7 @@ static __net_exit void nfsd_exit_net(struct net *net) 
	nfsd_idmap_shutdown(net);

	nfsd_export_shutdown(net);

	nfsd_netns_free_versions(net_generic(net, nfsd_net_id));

	nfsd4_leases_net_shutdown(nn);

}



static struct pernet_operations nfsd_net_ops = {

fs/nfsd/nfsd.h

+4 −2
Original line number Diff line number Diff line
@@ -505,7 +505,8 @@ extern void unregister_cld_notifier(void); 
extern void nfsd4_ssc_init_umount_work(struct nfsd_net *nn);

#endif



extern void nfsd4_init_leases_net(struct nfsd_net *nn);

extern int nfsd4_init_leases_net(struct nfsd_net *nn);

extern void nfsd4_leases_net_shutdown(struct nfsd_net *nn);



#else /* CONFIG_NFSD_V4 */

static inline int nfsd4_is_junction(struct dentry *dentry)
@@ -513,7 +514,8 @@ static inline int nfsd4_is_junction(struct dentry *dentry) 
	return 0;

}



static inline void nfsd4_init_leases_net(struct nfsd_net *nn) {};

static inline int nfsd4_init_leases_net(struct nfsd_net *nn) { return 0; };

static inline void nfsd4_leases_net_shutdown(struct nfsd_net *nn) {};



#define register_cld_notifier() 0

#define unregister_cld_notifier() do { } while(0)