From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261861AbVF0GjT (ORCPT ); Mon, 27 Jun 2005 02:39:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261876AbVF0Ghl (ORCPT ); Mon, 27 Jun 2005 02:37:41 -0400 Received: from smtp209.mail.sc5.yahoo.com ([216.136.130.117]:13646 "HELO smtp209.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S261861AbVF0Gdf (ORCPT ); Mon, 27 Jun 2005 02:33:35 -0400 Message-ID: <42BF9DBA.3000607@yahoo.com.au> Date: Mon, 27 Jun 2005 16:33:30 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.6) Gecko/20050324 Debian/1.7.6-1 X-Accept-Language: en MIME-Version: 1.0 To: linux-kernel , Linux Memory Management 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: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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