From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1032270Ab2CPWvV (ORCPT ); Fri, 16 Mar 2012 18:51:21 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:36948 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031562Ab2CPWvS (ORCPT ); Fri, 16 Mar 2012 18:51:18 -0400 From: John Stultz To: linux-kernel@vger.kernel.org Cc: John Stultz , Andrew Morton , Android Kernel Team , Robert Love , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Dmitry Adamushko , Dave Chinner , Neil Brown , Andrea Righi , "Aneesh Kumar K.V" Subject: [PATCH 1/2] [RFC] Range tree implementation Date: Fri, 16 Mar 2012 15:51:06 -0700 Message-Id: <1331938267-13583-2-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 1.7.3.2.146.gca209 In-Reply-To: <1331938267-13583-1-git-send-email-john.stultz@linaro.org> References: <1331938267-13583-1-git-send-email-john.stultz@linaro.org> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12031622-5518-0000-0000-0000030393F2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After Andrew suggested something like his mumbletree idea to better store a list of ranges, I worked on a few different approaches, and this is what I've finally managed to get working. I suspect range-tree isn't a totally accurate name, but I couldn't quite make out the difference between range trees and interval trees, so I just picked one to call it. Do let me know if you have a better name. The idea of storing ranges in a tree is nice, but has a number of complications. When adding a range, its possible that a large range will consume and merge a number of smaller ranges. When removing a range, its possible you may end up splitting an existing range, causing one range to become two. This makes it very difficult to provide generic list_head like behavior, as the parent structures would need to be duplicated and removed, and that has lots of memory ownership issues. So, this is a much simplified and more list_head like implementation. You can add a node to a tree, or remove a node to a tree, but the generic implementation doesn't do the merging or splitting for you. But it does provide helpers to find overlapping and adjacent ranges. Andrew also really wanted this range-tree implementation to be resuable so we don't duplicate the file locking logic. I'm not totally convinced that the requirements between the volatile ranges and file locking are really equivelent, but this reduced impelementation may make it possible. Do let me know what you think or if you have other ideas for better ways to do the same. Changelog: v2: * Reworked code to use an rbtree instead of splaying CC: Andrew Morton CC: Android Kernel Team CC: Robert Love CC: Mel Gorman CC: Hugh Dickins CC: Dave Hansen CC: Rik van Riel CC: Dmitry Adamushko CC: Dave Chinner CC: Neil Brown CC: Andrea Righi CC: Aneesh Kumar K.V Signed-off-by: John Stultz --- include/linux/rangetree.h | 53 +++++++++++++++++++++++ lib/Makefile | 2 +- lib/rangetree.c | 105 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 159 insertions(+), 1 deletions(-) create mode 100644 include/linux/rangetree.h create mode 100644 lib/rangetree.c diff --git a/include/linux/rangetree.h b/include/linux/rangetree.h new file mode 100644 index 0000000..ca03821 --- /dev/null +++ b/include/linux/rangetree.h @@ -0,0 +1,53 @@ +#ifndef _LINUX_RANGETREE_H +#define _LINUX_RANGETREE_H + +#include +#include + +struct range_tree_node { + struct rb_node rb; + u64 start; + u64 end; +}; + +struct range_tree_root { + struct rb_root head; +}; + +static inline void range_tree_init(struct range_tree_root *root) +{ + root->head = RB_ROOT; +} + +static inline void range_tree_node_init(struct range_tree_node *node) +{ + rb_init_node(&node->rb); + node->start = 0; + node->end = 0; +} + +static inline int range_tree_empty(struct range_tree_root *root) +{ + return RB_EMPTY_ROOT(&root->head); +} + +static inline +struct range_tree_node *range_tree_root_node(struct range_tree_root *root) +{ + struct range_tree_node *ret; + ret = container_of(root->head.rb_node, struct range_tree_node, rb); + return ret; +} + +extern struct range_tree_node *range_tree_in_range(struct range_tree_root *root, + u64 start, u64 end); +extern struct range_tree_node *range_tree_in_range_adjacent( + struct range_tree_root *root, + u64 start, u64 end); +extern void range_tree_add(struct range_tree_root *root, + struct range_tree_node *node); +extern void range_tree_remove(struct range_tree_root *root, + struct range_tree_node *node); +#endif + + diff --git a/lib/Makefile b/lib/Makefile index 18515f0..f43ef0d 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -12,7 +12,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \ idr.o int_sqrt.o extable.o prio_tree.o \ sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \ proportions.o prio_heap.o ratelimit.o show_mem.o \ - is_single_threaded.o plist.o decompress.o + is_single_threaded.o plist.o decompress.o rangetree.o lib-$(CONFIG_MMU) += ioremap.o lib-$(CONFIG_SMP) += cpumask.o diff --git a/lib/rangetree.c b/lib/rangetree.c new file mode 100644 index 0000000..0f6208a --- /dev/null +++ b/lib/rangetree.c @@ -0,0 +1,105 @@ +#include +#include +#include + + +/** + * range_tree_in_range - Returns the first node that overlaps with the + * given range + * @root: range_tree root + * @start: range start + * @end: range end + * + */ +struct range_tree_node *range_tree_in_range(struct range_tree_root *root, + u64 start, u64 end) +{ + struct rb_node **p = &root->head.rb_node; + struct range_tree_node *candidate; + + while (*p) { + candidate = rb_entry(*p, struct range_tree_node, rb); + if (end < candidate->start) + p = &(*p)->rb_left; + else if (start > candidate->end) + p = &(*p)->rb_right; + else + return candidate; + } + + return 0; +} + + +/** + * range_tree_in_range - Returns the first node that overlaps or is adjacent + * with the given range + * @root: range_tree root + * @start: range start + * @end: range end + * + */ +struct range_tree_node *range_tree_in_range_adjacent( + struct range_tree_root *root, + u64 start, u64 end) +{ + struct rb_node **p = &root->head.rb_node; + struct range_tree_node *candidate; + + while (*p) { + candidate = rb_entry(*p, struct range_tree_node, rb); + if (end+1 < candidate->start) + p = &(*p)->rb_left; + else if (start > candidate->end + 1) + p = &(*p)->rb_right; + else + return candidate; + } + return 0; +} + +/** + * range_tree_add - Add a node to a range tree + * @root: range tree to be added to + * @node: range_tree_node to be added + * + * Adds a node to the range tree. + */ +void range_tree_add(struct range_tree_root *root, + struct range_tree_node *node) +{ + struct rb_node **p = &root->head.rb_node; + struct rb_node *parent = NULL; + struct range_tree_node *ptr; + + WARN_ON_ONCE(!RB_EMPTY_NODE(&node->rb)); + + while (*p) { + parent = *p; + ptr = rb_entry(parent, struct range_tree_node, rb); + if (node->start < ptr->start) + p = &(*p)->rb_left; + else + p = &(*p)->rb_right; + } + rb_link_node(&node->rb, parent, p); + rb_insert_color(&node->rb, &root->head); + +} + + +/** + * range_tree_remove: Removes a given node from the tree + * @root: root of tree + * @node: Node to be removed + * + * Removes a node and splays the tree + */ +void range_tree_remove(struct range_tree_root *root, + struct range_tree_node *node) +{ + WARN_ON_ONCE(RB_EMPTY_NODE(&node->rb)); + + rb_erase(&node->rb, &root->head); + RB_CLEAR_NODE(&node->rb); +} -- 1.7.3.2.146.gca209