Remove dead code from AVL tree

The avl_update_* functions are never used by ZFS and are therefore
being removed.  They're barely even used in Illumos.  Additionally,
simplify avl_add() by using a VERIFY which produces exactly the same
behavior under Linux.

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Giuseppe Di Natale <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #6716 

2 files changed, 4 insertions, 82 deletions

diff --git a/include/sys/avl.h b/include/sys/avl.h
index ba51e2a79..206b539fa 100644
--- a/include/sys/avl.h
+++ b/include/sys/avl.h
@@ -260,17 +260,6 @@ extern void avl_add(avl_tree_t *tree, void *node);
 extern void avl_remove(avl_tree_t *tree, void *node);
 
 /*
- * Reinsert a node only if its order has changed relative to its nearest
- * neighbors. To optimize performance avl_update_lt() checks only the previous
- * node and avl_update_gt() checks only the next node. Use avl_update_lt() and
- * avl_update_gt() only if you know the direction in which the order of the
- * node may change.
- */
-extern boolean_t avl_update(avl_tree_t *, void *);
-extern boolean_t avl_update_lt(avl_tree_t *, void *);
-extern boolean_t avl_update_gt(avl_tree_t *, void *);
-
-/*
  * Swaps the contents of the two trees.
  */
 extern void avl_swap(avl_tree_t *tree1, avl_tree_t *tree2);
diff --git a/module/avl/avl.c b/module/avl/avl.c
index 7a79f3785..f024cdf61 100644
--- a/module/avl/avl.c
+++ b/module/avl/avl.c
@@ -626,25 +626,16 @@ avl_insert_here(
 }
 
 /*
- * Add a new node to an AVL tree.
+ * Add a new node to an AVL tree.  Strictly enforce that no duplicates can
+ * be added to the tree with a VERIFY which is enabled for non-DEBUG builds.
  */
 void
 avl_add(avl_tree_t *tree, void *new_node)
 {
 	avl_index_t where = 0;
 
-	/*
-	 * This is unfortunate.  We want to call panic() here, even for
-	 * non-DEBUG kernels.  In userland, however, we can't depend on anything
-	 * in libc or else the rtld build process gets confused.  So, all we can
-	 * do in userland is resort to a normal ASSERT().
-	 */
-	if (avl_find(tree, new_node, &where) != NULL)
-#ifdef _KERNEL
-		panic("avl_find() succeeded inside avl_add()");
-#else
-		ASSERT(0);
-#endif
+	VERIFY(avl_find(tree, new_node, &where) == NULL);
+
 	avl_insert(tree, new_node, where);
 }
 
@@ -817,64 +808,6 @@ avl_remove(avl_tree_t *tree, void *data)
 	} while (parent != NULL);
 }
 
-#define	AVL_REINSERT(tree, obj)		\
-	avl_remove((tree), (obj));	\
-	avl_add((tree), (obj))
-
-boolean_t
-avl_update_lt(avl_tree_t *t, void *obj)
-{
-	void *neighbor;
-
-	ASSERT(((neighbor = AVL_NEXT(t, obj)) == NULL) ||
-	    (t->avl_compar(obj, neighbor) <= 0));
-
-	neighbor = AVL_PREV(t, obj);
-	if ((neighbor != NULL) && (t->avl_compar(obj, neighbor) < 0)) {
-		AVL_REINSERT(t, obj);
-		return (B_TRUE);
-	}
-
-	return (B_FALSE);
-}
-
-boolean_t
-avl_update_gt(avl_tree_t *t, void *obj)
-{
-	void *neighbor;
-
-	ASSERT(((neighbor = AVL_PREV(t, obj)) == NULL) ||
-	    (t->avl_compar(obj, neighbor) >= 0));
-
-	neighbor = AVL_NEXT(t, obj);
-	if ((neighbor != NULL) && (t->avl_compar(obj, neighbor) > 0)) {
-		AVL_REINSERT(t, obj);
-		return (B_TRUE);
-	}
-
-	return (B_FALSE);
-}
-
-boolean_t
-avl_update(avl_tree_t *t, void *obj)
-{
-	void *neighbor;
-
-	neighbor = AVL_PREV(t, obj);
-	if ((neighbor != NULL) && (t->avl_compar(obj, neighbor) < 0)) {
-		AVL_REINSERT(t, obj);
-		return (B_TRUE);
-	}
-
-	neighbor = AVL_NEXT(t, obj);
-	if ((neighbor != NULL) && (t->avl_compar(obj, neighbor) > 0)) {
-		AVL_REINSERT(t, obj);
-		return (B_TRUE);
-	}
-
-	return (B_FALSE);
-}
-
 void
 avl_swap(avl_tree_t *tree1, avl_tree_t *tree2)
 {