NFSD: keep track of the number of courtesy clients in the system

Add counter nfs4_courtesy_client_count to nfsd_net to keep track
of the number of courtesy clients in the system.
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/netns.h

@@ -192,6 +192,8 @@ struct nfsd_net {
 
 	atomic_t		nfs4_client_count;
 	int			nfs4_max_clients;
+
+	atomic_t		nfsd_courtesy_clients;
 };
 
 /* Simple check to find out if a given net was properly initialized */

fs/nfsd/nfs4state.c

@@ -160,6 +160,13 @@ static bool is_client_expired(struct nfs4_client *clp)
 	return clp->cl_time == 0;
 }
 
+static void nfsd4_dec_courtesy_client_count(struct nfsd_net *nn,
+					struct nfs4_client *clp)
+{
+	if (clp->cl_state != NFSD4_ACTIVE)
+		atomic_add_unless(&nn->nfsd_courtesy_clients, -1, 0);
+}
+
 static __be32 get_client_locked(struct nfs4_client *clp)
 {
 	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
@@ -169,6 +176,7 @@ static __be32 get_client_locked(struct nfs4_client *clp)
 	if (is_client_expired(clp))
 		return nfserr_expired;
 	atomic_inc(&clp->cl_rpc_users);
+	nfsd4_dec_courtesy_client_count(nn, clp);
 	clp->cl_state = NFSD4_ACTIVE;
 	return nfs_ok;
 }
@@ -190,6 +198,7 @@ renew_client_locked(struct nfs4_client *clp)
 
 	list_move_tail(&clp->cl_lru, &nn->client_lru);
 	clp->cl_time = ktime_get_boottime_seconds();
+	nfsd4_dec_courtesy_client_count(nn, clp);
 	clp->cl_state = NFSD4_ACTIVE;
 }
 
@@ -2235,6 +2244,7 @@ __destroy_client(struct nfs4_client *clp)
 	if (clp->cl_cb_conn.cb_xprt)
 		svc_xprt_put(clp->cl_cb_conn.cb_xprt);
 	atomic_add_unless(&nn->nfs4_client_count, -1, 0);
+	nfsd4_dec_courtesy_client_count(nn, clp);
 	free_client(clp);
 	wake_up_all(&expiry_wq);
 }
@@ -4358,6 +4368,8 @@ void nfsd4_init_leases_net(struct nfsd_net *nn)
 	max_clients = (u64)si.totalram * si.mem_unit / (1024 * 1024 * 1024);
 	max_clients *= NFS4_CLIENTS_PER_GB;
 	nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB);
+
+	atomic_set(&nn->nfsd_courtesy_clients, 0);
 }
 
 static void init_nfs4_replay(struct nfs4_replay *rp)
@@ -5911,8 +5923,11 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
 			goto exp_client;
 		if (!state_expired(lt, clp->cl_time))
 			break;
-		if (!atomic_read(&clp->cl_rpc_users))
+		if (!atomic_read(&clp->cl_rpc_users)) {
+			if (clp->cl_state == NFSD4_ACTIVE)
+				atomic_inc(&nn->nfsd_courtesy_clients);
 			clp->cl_state = NFSD4_COURTESY;
+		}
 		if (!client_has_state(clp))
 			goto exp_client;
 		if (!nfs4_anylock_blockers(clp))