1 files changed, 30 insertions, 2 deletions

diff --git a/include/linux/nfslocalio.h b/include/linux/nfslocalio.h
index b353abe00357..9202f4b24343 100644
--- a/include/linux/nfslocalio.h
+++ b/include/linux/nfslocalio.h
@@ -32,7 +32,8 @@ typedef struct {
 	struct auth_domain *dom; /* auth_domain for localio */
 } nfs_uuid_t;
 
-void nfs_uuid_begin(nfs_uuid_t *);
+void nfs_uuid_init(nfs_uuid_t *);
+bool nfs_uuid_begin(nfs_uuid_t *);
 void nfs_uuid_end(nfs_uuid_t *);
 void nfs_uuid_is_local(const uuid_t *, struct list_head *,
 		       struct net *, struct auth_domain *, struct module *);
@@ -54,7 +55,7 @@ struct nfsd_localio_operations {
 						const struct cred *,
 						const struct nfs_fh *,
 						const fmode_t);
-	void (*nfsd_file_put_local)(struct nfsd_file *);
+	struct net *(*nfsd_file_put_local)(struct nfsd_file *);
 	struct file *(*nfsd_file_file)(struct nfsd_file *);
 } ____cacheline_aligned;
 
@@ -65,10 +66,37 @@ struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *,
 		   struct rpc_clnt *, const struct cred *,
 		   const struct nfs_fh *, const fmode_t);
 
+static inline void nfs_to_nfsd_net_put(struct net *net)
+{
+	/*
+	 * Once reference to nfsd_serv is dropped, NFSD could be
+	 * unloaded, so ensure safe return from nfsd_file_put_local()
+	 * by always taking RCU.
+	 */
+	rcu_read_lock();
+	nfs_to->nfsd_serv_put(net);
+	rcu_read_unlock();
+}
+
+static inline void nfs_to_nfsd_file_put_local(struct nfsd_file *localio)
+{
+	/*
+	 * Must not hold RCU otherwise nfsd_file_put() can easily trigger:
+	 * "Voluntary context switch within RCU read-side critical section!"
+	 * by scheduling deep in underlying filesystem (e.g. XFS).
+	 */
+	struct net *net = nfs_to->nfsd_file_put_local(localio);
+
+	nfs_to_nfsd_net_put(net);
+}
+
 #else   /* CONFIG_NFS_LOCALIO */
 static inline void nfsd_localio_ops_init(void)
 {
 }
+static inline void nfs_to_nfsd_file_put_local(struct nfsd_file *localio)
+{
+}
 #endif  /* CONFIG_NFS_LOCALIO */
 
 #endif  /* __LINUX_NFSLOCALIO_H */