From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <42BF9DBA.3000607@yahoo.com.au> Date: Mon, 27 Jun 2005 16:33:30 +1000 From: Nick Piggin MIME-Version: 1.0 Subject: [patch 3] radix tree: lookup_slot References: <42BF9CD1.2030102@yahoo.com.au> <42BF9D67.10509@yahoo.com.au> <42BF9D86.90204@yahoo.com.au> In-Reply-To: <42BF9D86.90204@yahoo.com.au> Content-Type: multipart/mixed; boundary="------------070401060205080306050100" Sender: owner-linux-mm@kvack.org Return-Path: To: linux-kernel , Linux Memory Management List-ID: This is a multi-part message in MIME format. --------------070401060205080306050100 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit -- SUSE Labs, Novell Inc. --------------070401060205080306050100 Content-Type: text/plain; name="radix-tree-lookup_slot.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="radix-tree-lookup_slot.patch" From: Hans Reiser Reiser4 uses radix trees to solve a trouble reiser4_readdir has serving nfs requests. Unfortunately, radix tree api lacks an operation suitable for modifying existing entry. This patch adds radix_tree_lookup_slot which returns pointer to found item within the tree. That location can be then updated. Signed-off-by: Andrew Morton Index: linux-2.6/include/linux/radix-tree.h =================================================================== --- linux-2.6.orig/include/linux/radix-tree.h +++ linux-2.6/include/linux/radix-tree.h @@ -46,6 +46,7 @@ do { \ int radix_tree_insert(struct radix_tree_root *, unsigned long, void *); void *radix_tree_lookup(struct radix_tree_root *, unsigned long); +void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long); void *radix_tree_delete(struct radix_tree_root *, unsigned long); unsigned int radix_tree_gang_lookup(struct radix_tree_root *root, void **results, Index: linux-2.6/lib/radix-tree.c =================================================================== --- linux-2.6.orig/lib/radix-tree.c +++ linux-2.6/lib/radix-tree.c @@ -276,14 +276,8 @@ int radix_tree_insert(struct radix_tree_ } 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; @@ -306,7 +300,36 @@ void *radix_tree_lookup(struct radix_tre 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); --------------070401060205080306050100-- Send instant messages to your online friends http://au.messenger.yahoo.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org