diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 62ae35f..7dfe062 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -25,6 +25,12 @@
 	unsigned long		subdirs;
 	/* children rbtree starts here and goes through sd->s_rb */
 	struct rb_root		children;
+
+	/*
+	 * The kernfs hierarchy this directory belongs to.  This fits
+	 * better directly in sysfs_dirent but is here to save space.
+	 */
+	struct kernfs_root	*root;
 };
 
 struct sysfs_elem_symlink {
@@ -104,6 +110,20 @@
 	return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
+/**
+ * kernfs_root - find out the kernfs_root a sysfs_dirent belongs to
+ * @sd: sysfs_dirent of interest
+ *
+ * Return the kernfs_root @sd belongs to.
+ */
+static inline struct kernfs_root *kernfs_root(struct sysfs_dirent *sd)
+{
+	/* if parent exists, it's always a dir; otherwise, @sd is a dir */
+	if (sd->s_parent)
+		sd = sd->s_parent;
+	return sd->s_dir.root;
+}
+
 /*
  * Context structure to be used while adding/removing nodes.
  */