From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932428AbVHKMZX (ORCPT ); Thu, 11 Aug 2005 08:25:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932503AbVHKMZX (ORCPT ); Thu, 11 Aug 2005 08:25:23 -0400 Received: from smtp205.mail.sc5.yahoo.com ([216.136.129.95]:25721 "HELO smtp205.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S932428AbVHKMZW (ORCPT ); Thu, 11 Aug 2005 08:25:22 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type; b=r/+yeOBuM4QEcHsqOaNGktGXM0e1jt2+k8kFh0ooV9bmriyw5DVzK9ixEhcg6V8Ef5/NqOFO7gLN03VsfMt9trx3CDtgRyoKyFTEXeCG8oAQ+H61Qtd3Tgn+SchnkkzeWan1oXm5vT8ThsaVz9jYjoLqChhm9j3XhDdMwNVuuKQ= ; Message-ID: <42FB43A8.8060902@yahoo.com.au> Date: Thu, 11 Aug 2005 22:25:12 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.8) Gecko/20050513 Debian/1.7.8-1 X-Accept-Language: en MIME-Version: 1.0 To: Paul McKenney CC: Dipankar Sarma , Ingo Molnar , linux-kernel Subject: [patch 4/7] radix-tree: lookup_slot References: <42FB4201.7080304@yahoo.com.au> <42FB42BD.6020808@yahoo.com.au> <42FB42EF.1040401@yahoo.com.au> <42FB4311.2070807@yahoo.com.au> In-Reply-To: <42FB4311.2070807@yahoo.com.au> Content-Type: multipart/mixed; boundary="------------060909090306000901090508" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------060909090306000901090508 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit 4/7 Required by lockless pagecache in order to get a pointer to a pagecache struct page. -- SUSE Labs, Novell Inc. --------------060909090306000901090508 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. 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); --------------060909090306000901090508-- Send instant messages to your online friends http://au.messenger.yahoo.com