diff --git a/fs/libfs.c b/fs/libfs.c
index e2de5401abca..e9b29c6ffccb 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -481,6 +481,7 @@ EXPORT_SYMBOL(simple_rename);
 
 /**
  * simple_setattr - setattr for simple filesystem
+ * @mnt_userns: user namespace of the target mount
  * @dentry: dentry
  * @iattr: iattr structure
  *