2 files changed, 66 insertions, 0 deletions

diff --git a/fs/locks.c b/fs/locks.c
index 686eae21daf6..1913481bfbf7 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1990,6 +1990,64 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
 }
 EXPORT_SYMBOL(generic_setlease);
 
+#if IS_ENABLED(CONFIG_SRCU)
+/*
+ * Kernel subsystems can register to be notified on any attempt to set
+ * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
+ * to close files that it may have cached when there is an attempt to set a
+ * conflicting lease.
+ */
+static struct srcu_notifier_head lease_notifier_chain;
+
+static inline void
+lease_notifier_chain_init(void)
+{
+        srcu_init_notifier_head(&lease_notifier_chain);
+}
+
+static inline void
+setlease_notifier(long arg, struct file_lock *lease)
+{
+        if (arg != F_UNLCK)
+                srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
+}
+
+int lease_register_notifier(struct notifier_block *nb)
+{
+        return srcu_notifier_chain_register(&lease_notifier_chain, nb);
+}
+EXPORT_SYMBOL_GPL(lease_register_notifier);
+
+void lease_unregister_notifier(struct notifier_block *nb)
+{
+        srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
+}
+EXPORT_SYMBOL_GPL(lease_unregister_notifier);
+
+#else /* !IS_ENABLED(CONFIG_SRCU) */
+static inline void
+lease_notifier_chain_init(void)
+{
+}
+
+static inline void
+setlease_notifier(long arg, struct file_lock *lease)
+{
+}
+
+int lease_register_notifier(struct notifier_block *nb)
+{
+        return 0;
+}
+EXPORT_SYMBOL_GPL(lease_register_notifier);
+
+void lease_unregister_notifier(struct notifier_block *nb)
+{
+}
+EXPORT_SYMBOL_GPL(lease_unregister_notifier);
+
+#endif /* IS_ENABLED(CONFIG_SRCU) */
+
 /**
  * vfs_setlease        -       sets a lease on an open file
  * @filp:       file pointer
@@ -2010,6 +2068,8 @@ EXPORT_SYMBOL(generic_setlease);
 int
 vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
 {
+        if (lease)
+                setlease_notifier(arg, *lease);
         if (filp->f_op->setlease)
                 return filp->f_op->setlease(filp, arg, lease, priv);
         else
@@ -2923,6 +2983,7 @@ static int __init filelock_init(void)
                 INIT_HLIST_HEAD(&fll->hlist);
         }
 
+        lease_notifier_chain_init();
         return 0;
 }
 core_initcall(filelock_init);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 56b8e358af5c..0f106c7f4bb9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1155,6 +1155,11 @@ extern void lease_get_mtime(struct inode *, struct timespec64 *time);
 extern int generic_setlease(struct file *, long, struct file_lock **, void **priv);
 extern int vfs_setlease(struct file *, long, struct file_lock **, void **);
 extern int lease_modify(struct file_lock *, int, struct list_head *);
+
+struct notifier_block;
+extern int lease_register_notifier(struct notifier_block *);
+extern void lease_unregister_notifier(struct notifier_block *);
+
 struct files_struct;
 extern void show_fd_locks(struct seq_file *f,
                          struct file *filp, struct files_struct *files);