debugfs: add rename for debugfs files

Implement debugfs_rename() to allow renaming files/directories in debugfs.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index 5a9c495..104e51e 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -38,6 +38,9 @@
 
 void debugfs_remove(struct dentry *dentry);
 
+struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
+                struct dentry *new_dir, const char *new_name);
+
 struct dentry *debugfs_create_u8(const char *name, mode_t mode,
 				 struct dentry *parent, u8 *value);
 struct dentry *debugfs_create_u16(const char *name, mode_t mode,
@@ -85,6 +88,12 @@
 static inline void debugfs_remove(struct dentry *dentry)
 { }
 
+static inline struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
+                struct dentry *new_dir, char *new_name)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline struct dentry *debugfs_create_u8(const char *name, mode_t mode,
 					       struct dentry *parent,
 					       u8 *value)