[PATCH v2 1/1] NFSD: register/unregister of nfsd-client shrinker at nfsd startup/shutdown time

[Dai Ngo <dai.ngo@oracle.com>]

Currently the nfsd-client shrinker is registered and unregistered at
the time the nfsd module is loaded and unloaded. This means after the
nfsd service is shutdown, the nfsd-client shrinker is still registered
in the system. This causes the nfsd-client shrinker to be called when
memory is low even thought nfsd service is not running. This is also
true for the nfsd_reply_cache_shrinker.

This patch moves the  register/unregister of nfsd-client shrinker from
module load/unload time to nfsd startup/shutdown time.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
v2: handle error in nfs4_state_create_net when register_shrinker fails.

 fs/nfsd/nfs4state.c | 22 +++++++++++-----------
 fs/nfsd/nfsctl.c    |  7 +------
 fs/nfsd/nfsd.h      |  6 ++----
 3 files changed, 14 insertions(+), 21 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 7b2ee535ade8..a7cfefd7c205 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4421,7 +4421,7 @@ nfsd4_state_shrinker_scan(struct shrinker *shrink, struct shrink_control *sc)
 	return SHRINK_STOP;
 }
 
-int
+void
 nfsd4_init_leases_net(struct nfsd_net *nn)
 {
 	struct sysinfo si;
@@ -4443,16 +4443,6 @@ 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 = nfsd4_state_shrinker_scan;
-	nn->nfsd_client_shrinker.count_objects = nfsd4_state_shrinker_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)
@@ -8077,8 +8067,17 @@ static int nfs4_state_create_net(struct net *net)
 	INIT_DELAYED_WORK(&nn->nfsd_shrinker_work, nfsd4_state_shrinker_worker);
 	get_net(net);
 
+	nn->nfsd_client_shrinker.scan_objects = nfsd4_state_shrinker_scan;
+	nn->nfsd_client_shrinker.count_objects = nfsd4_state_shrinker_count;
+	nn->nfsd_client_shrinker.seeks = DEFAULT_SEEKS;
+
+	if (register_shrinker(&nn->nfsd_client_shrinker, "nfsd-client"))
+		goto err_shrinker;
 	return 0;
 
+err_shrinker:
+	put_net(net);
+	kfree(nn->sessionid_hashtbl);
 err_sessionid:
 	kfree(nn->unconf_id_hashtbl);
 err_unconf_id:
@@ -8171,6 +8170,7 @@ nfs4_state_shutdown_net(struct net *net)
 	struct list_head *pos, *next, reaplist;
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 
+	unregister_shrinker(&nn->nfsd_client_shrinker);
 	cancel_delayed_work_sync(&nn->laundromat_work);
 	locks_end_grace(&nn->nfsd4_manager);
 
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index d1e581a60480..c2577ee7ffb2 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1457,9 +1457,7 @@ 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;
+	nfsd4_init_leases_net(nn);
 	retval = nfsd_reply_cache_init(nn);
 	if (retval)
 		goto out_cache_error;
@@ -1469,8 +1467,6 @@ static __net_init int nfsd_init_net(struct net *net)
 	return 0;
 
 out_cache_error:
-	nfsd4_leases_net_shutdown(nn);
-out_drc_error:
 	nfsd_idmap_shutdown(net);
 out_idmap_error:
 	nfsd_export_shutdown(net);
@@ -1486,7 +1482,6 @@ 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 = {
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 93b42ef9ed91..fa0144a74267 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -504,8 +504,7 @@ extern void unregister_cld_notifier(void);
 extern void nfsd4_ssc_init_umount_work(struct nfsd_net *nn);
 #endif
 
-extern int nfsd4_init_leases_net(struct nfsd_net *nn);
-extern void nfsd4_leases_net_shutdown(struct nfsd_net *nn);
+extern void nfsd4_init_leases_net(struct nfsd_net *nn);
 
 #else /* CONFIG_NFSD_V4 */
 static inline int nfsd4_is_junction(struct dentry *dentry)
@@ -513,8 +512,7 @@ static inline int nfsd4_is_junction(struct dentry *dentry)
 	return 0;
 }
 
-static inline int nfsd4_init_leases_net(struct nfsd_net *nn) { return 0; };
-static inline void nfsd4_leases_net_shutdown(struct nfsd_net *nn) {};
+static inline void nfsd4_init_leases_net(struct nfsd_net *nn) { };
 
 #define register_cld_notifier() 0
 #define unregister_cld_notifier() do { } while(0)
-- 
2.9.5