sysfs, kernfs: introduce kernfs_rename[_ns]()

Introduce kernfs rename interface, krenfs_rename[_ns]().

This is just rename of sysfs_rename().  No functional changes.
Function comment is added to kernfs_rename_ns() and @new_parent_sd is
renamed to @new_parent for consistency with other kernfs interfaces.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index fe6290d..803d960 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -20,6 +20,8 @@
 void kernfs_remove(struct sysfs_dirent *sd);
 int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
+int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
+		     const char *new_name, const void *new_ns);
 
 #else	/* CONFIG_SYSFS */
 
@@ -34,6 +36,11 @@
 					   const char *name, const void *ns)
 { return -ENOSYS; }
 
+static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
+				   struct sysfs_dirent *new_parent,
+				   const char *new_name, const void *new_ns)
+{ return -ENOSYS; }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,