1 files changed, 39 insertions, 14 deletions

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 6a8bc6e0643..88511c3805a 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -110,7 +110,7 @@ radix_tree_node_free(struct radix_tree_node *node)
  * success, return zero, with preemption disabled.  On error, return -ENOMEM
  * with preemption not disabled.
  */
-int radix_tree_preload(unsigned int __nocast gfp_mask)
+int radix_tree_preload(gfp_t gfp_mask)
 {
 	struct radix_tree_preload *rtp;
 	struct radix_tree_node *node;
@@ -281,35 +281,60 @@ int radix_tree_insert(struct radix_tree_root *root,
 }
 EXPORT_SYMBOL(radix_tree_insert);
 
-/**
- *	radix_tree_lookup    -    perform lookup operation on a radix tree
- *	@root:		radix tree root
- *	@index:		index key
- *
- *	Lookup the item at the position @index in the radix tree @root.
- */
-void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
+static inline void **__lookup_slot(struct radix_tree_root *root,
+				   unsigned long index)
 {
 	unsigned int height, shift;
-	struct radix_tree_node *slot;
+	struct radix_tree_node **slot;
 
 	height = root->height;
 	if (index > radix_tree_maxindex(height))
 		return NULL;
 
 	shift = (height-1) * RADIX_TREE_MAP_SHIFT;
-	slot = root->rnode;
+	slot = &root->rnode;
 
 	while (height > 0) {
-		if (slot == NULL)
+		if (*slot == NULL)
 			return NULL;
 
-		slot = slot->slots[(index >> shift) & RADIX_TREE_MAP_MASK];
+		slot = (struct radix_tree_node **)
+			((*slot)->slots +
+				((index >> shift) & RADIX_TREE_MAP_MASK));
 		shift -= RADIX_TREE_MAP_SHIFT;
 		height--;
 	}
 
-	return slot;
+	return (void **)slot;
+}
+
+/**
+ *	radix_tree_lookup_slot    -    lookup a slot in a radix tree
+ *	@root:		radix tree root
+ *	@index:		index key
+ *
+ *	Lookup the slot corresponding to the position @index in the radix tree
+ *	@root. This is useful for update-if-exists operations.
+ */
+void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
+{
+	return __lookup_slot(root, index);
+}
+EXPORT_SYMBOL(radix_tree_lookup_slot);
+
+/**
+ *	radix_tree_lookup    -    perform lookup operation on a radix tree
+ *	@root:		radix tree root
+ *	@index:		index key
+ *
+ *	Lookup the item at the position @index in the radix tree @root.
+ */
+void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
+{
+	void **slot;
+
+	slot = __lookup_slot(root, index);
+	return slot != NULL ? *slot : NULL;
 }
 EXPORT_SYMBOL(radix_tree_lookup);