kernel/util: Clean-ups to DoublyLinkedList insertion routines.

* Make some code common in Insert.

 * Remove unneeded logic from InsertAfter and just call the base Insert.
   InsertBefore does this, already.

 * Synchronize Insert code and APIs in the fs_shell DoublyLinkedList.

headers/private/fs_shell/DoublyLinkedList.h

@@ -327,8 +327,9 @@ public:
 
 	inline bool IsEmpty() const			{ return (fFirst == NULL); }
 
+	inline void InsertBefore(Element* insertBefore, Element* element);
+	inline void InsertAfter(Element* insertAfter, Element* element);
 	inline void Insert(Element* element, bool back = true);
-	inline void Insert(Element *before, Element *element);
 	inline void Add(Element *element, bool back = true);
 	inline void Remove(Element *element);
 
@@ -361,6 +362,10 @@ public:
 	inline ConstReverseIterator GetReverseIterator() const
 		{ return ConstReverseIterator(this); }
 
+private:
+	inline void Insert(Element* before, Element* element);
+		// TODO: Obsolete! Use InsertBefore() instead!
+
 private:
 	Element	*fFirst;
 	Element	*fLast;
@@ -401,10 +406,10 @@ DOUBLY_LINKED_LIST_CLASS_NAME::Insert(Element *element, bool back)
 	}
 }
 
-// Insert
+
 DOUBLY_LINKED_LIST_TEMPLATE_LIST
 void
-DOUBLY_LINKED_LIST_CLASS_NAME::Insert(Element *before, Element *element)
+DOUBLY_LINKED_LIST_CLASS_NAME::InsertBefore(Element* before, Element* element)
 {
 	if (before == NULL) {
 		Insert(element);
@@ -426,6 +431,40 @@ DOUBLY_LINKED_LIST_CLASS_NAME::Insert(Element *before, Element *element)
 		fFirst = element;
 }
 
+
+DOUBLY_LINKED_LIST_TEMPLATE_LIST
+void
+DOUBLY_LINKED_LIST_CLASS_NAME::InsertAfter(Element* after, Element* element)
+{
+	ASSERT(element != NULL);
+
+	if (after == NULL) {
+		Insert(element, false);
+		return;
+	}
+
+	Link* afterLink = sGetLink(after);
+	Link* link = sGetLink(element);
+
+	link->previous = after;
+	link->next = afterLink->next;
+	afterLink->next = element;
+
+	if (link->next != NULL)
+		sGetLink(link->next)->previous = element;
+	else
+		fLast = element;
+}
+
+
+DOUBLY_LINKED_LIST_TEMPLATE_LIST
+void
+DOUBLY_LINKED_LIST_CLASS_NAME::Insert(Element* before, Element* element)
+{
+	InsertBefore(before, element);
+}
+
+
 // Add
 DOUBLY_LINKED_LIST_TEMPLATE_LIST
 void

headers/private/kernel/util/DoublyLinkedList.h

@@ -400,9 +400,9 @@ DOUBLY_LINKED_LIST_CLASS_NAME::Insert(Element* element, bool back)
 			"list: %p\n", this);
 #endif
 
+		Link* elLink = sGetLink(element);
 		if (back) {
 			// append
-			Link* elLink = sGetLink(element);
 			elLink->previous = fLast;
 			elLink->next = NULL;
 			if (fLast)
@@ -412,7 +412,6 @@ DOUBLY_LINKED_LIST_CLASS_NAME::Insert(Element* element, bool back)
 			fLast = element;
 		} else {
 			// prepend
-			Link* elLink = sGetLink(element);
 			elLink->previous = NULL;
 			elLink->next = fFirst;
 			if (fFirst)
@@ -457,31 +456,24 @@ DOUBLY_LINKED_LIST_CLASS_NAME::InsertBefore(Element* before, Element* element)
 
 DOUBLY_LINKED_LIST_TEMPLATE_LIST
 void
-DOUBLY_LINKED_LIST_CLASS_NAME::InsertAfter(Element* insertAfter,
+DOUBLY_LINKED_LIST_CLASS_NAME::InsertAfter(Element* after, Element* element)
-	Element* element)
 {
 	ASSERT(element != NULL);
 
+	if (after == NULL) {
+		Insert(element, false);
+		return;
+	}
+
 #if DEBUG_DOUBLY_LINKED_LIST
 	ASSERT_PRINT(fFirst == NULL ? fLast == NULL : fLast != NULL,
 		"list: %p\n", this);
 #endif
 
-	if (insertAfter == NULL) {
+	Link* afterLink = sGetLink(after);
-		// insert at the head
-		Link* elLink = sGetLink(element);
-		elLink->previous = NULL;
-		elLink->next = fFirst;
-		if (fFirst != NULL)
-			sGetLink(fFirst)->previous = element;
-		else
-			fLast = element;
-		fFirst = element;
-	} else {
-		Link* afterLink = sGetLink(insertAfter);
 	Link* link = sGetLink(element);
 
-		link->previous = insertAfter;
+	link->previous = after;
 	link->next = afterLink->next;
 	afterLink->next = element;
 
@@ -490,7 +482,6 @@ DOUBLY_LINKED_LIST_CLASS_NAME::InsertAfter(Element* insertAfter,
 	else
 		fLast = element;
 }
-}
 
 
 DOUBLY_LINKED_LIST_TEMPLATE_LIST