1 files changed, 54 insertions, 9 deletions

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 8fdbba7cad96..8e8a76a44ff0 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -36,19 +36,30 @@
  * second map contains a reference to the entry in the first map.
  */
 
+static struct workqueue_struct *nfsd_export_wq;
+
 #define	EXPKEY_HASHBITS		8
 #define	EXPKEY_HASHMAX		(1 << EXPKEY_HASHBITS)
 #define	EXPKEY_HASHMASK		(EXPKEY_HASHMAX -1)
 
-static void expkey_put(struct kref *ref)
+static void expkey_release(struct work_struct *work)
 {
-	struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
+	struct svc_expkey *key = container_of(to_rcu_work(work),
+					      struct svc_expkey, ek_rwork);
 
 	if (test_bit(CACHE_VALID, &key->h.flags) &&
 	    !test_bit(CACHE_NEGATIVE, &key->h.flags))
 		path_put(&key->ek_path);
 	auth_domain_put(key->ek_client);
-	kfree_rcu(key, ek_rcu);
+	kfree(key);
+}
+
+static void expkey_put(struct kref *ref)
+{
+	struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
+
+	INIT_RCU_WORK(&key->ek_rwork, expkey_release);
+	queue_rcu_work(nfsd_export_wq, &key->ek_rwork);
 }
 
 static int expkey_upcall(struct cache_detail *cd, struct cache_head *h)
@@ -353,11 +364,13 @@ static void export_stats_destroy(struct export_stats *stats)
 					    EXP_STATS_COUNTERS_NUM);
 }
 
-static void svc_export_release(struct rcu_head *rcu_head)
+static void svc_export_release(struct work_struct *work)
 {
-	struct svc_export *exp = container_of(rcu_head, struct svc_export,
-			ex_rcu);
+	struct svc_export *exp = container_of(to_rcu_work(work),
+					      struct svc_export, ex_rwork);
 
+	path_put(&exp->ex_path);
+	auth_domain_put(exp->ex_client);
 	nfsd4_fslocs_free(&exp->ex_fslocs);
 	export_stats_destroy(exp->ex_stats);
 	kfree(exp->ex_stats);
@@ -369,9 +382,8 @@ static void svc_export_put(struct kref *ref)
 {
 	struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
 
-	path_put(&exp->ex_path);
-	auth_domain_put(exp->ex_client);
-	call_rcu(&exp->ex_rcu, svc_export_release);
+	INIT_RCU_WORK(&exp->ex_rwork, svc_export_release);
+	queue_rcu_work(nfsd_export_wq, &exp->ex_rwork);
 }
 
 static int svc_export_upcall(struct cache_detail *cd, struct cache_head *h)
@@ -1479,6 +1491,36 @@ const struct seq_operations nfs_exports_op = {
 	.show	= e_show,
 };
 
+/**
+ * nfsd_export_wq_init - allocate the export release workqueue
+ *
+ * Called once at module load. The workqueue runs deferred svc_export and
+ * svc_expkey release work scheduled by queue_rcu_work() in the cache put
+ * callbacks.
+ *
+ * Return values:
+ *   %0: workqueue allocated
+ *   %-ENOMEM: allocation failed
+ */
+int nfsd_export_wq_init(void)
+{
+	nfsd_export_wq = alloc_workqueue("nfsd_export", WQ_UNBOUND, 0);
+	if (!nfsd_export_wq)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
+ * nfsd_export_wq_shutdown - drain and free the export release workqueue
+ *
+ * Called once at module unload. Per-namespace teardown in
+ * nfsd_export_shutdown() has already drained all deferred work.
+ */
+void nfsd_export_wq_shutdown(void)
+{
+	destroy_workqueue(nfsd_export_wq);
+}
+
 /*
  * Initialize the exports module.
  */
@@ -1540,6 +1582,9 @@ nfsd_export_shutdown(struct net *net)
 
 	cache_unregister_net(nn->svc_expkey_cache, net);
 	cache_unregister_net(nn->svc_export_cache, net);
+	/* Drain deferred export and expkey release work. */
+	rcu_barrier();
+	flush_workqueue(nfsd_export_wq);
 	cache_destroy_net(nn->svc_expkey_cache, net);
 	cache_destroy_net(nn->svc_export_cache, net);
 	svcauth_unix_purge(net);