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Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Philipp Reisner98683652012-11-09 14:18:43 +01002#include <asm/bug.h>
3#include <linux/rbtree_augmented.h>
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +01004#include "drbd_interval.h"
5
6/**
7 * interval_end - return end of @node
8 */
9static inline
10sector_t interval_end(struct rb_node *node)
11{
12 struct drbd_interval *this = rb_entry(node, struct drbd_interval, rb);
13 return this->end;
14}
15
16/**
Philipp Reisner98683652012-11-09 14:18:43 +010017 * compute_subtree_last - compute end of @node
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010018 *
19 * The end of an interval is the highest (start + (size >> 9)) value of this
20 * node and of its children. Called for @node and its parents whenever the end
21 * may have changed.
22 */
Philipp Reisner98683652012-11-09 14:18:43 +010023static inline sector_t
24compute_subtree_last(struct drbd_interval *node)
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010025{
Philipp Reisner98683652012-11-09 14:18:43 +010026 sector_t max = node->sector + (node->size >> 9);
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010027
Philipp Reisner98683652012-11-09 14:18:43 +010028 if (node->rb.rb_left) {
29 sector_t left = interval_end(node->rb.rb_left);
30 if (left > max)
31 max = left;
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010032 }
Philipp Reisner98683652012-11-09 14:18:43 +010033 if (node->rb.rb_right) {
34 sector_t right = interval_end(node->rb.rb_right);
35 if (right > max)
36 max = right;
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010037 }
Philipp Reisner98683652012-11-09 14:18:43 +010038 return max;
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010039}
40
Lai Jiangshane9f05b42014-09-18 16:49:42 +020041RB_DECLARE_CALLBACKS(static, augment_callbacks, struct drbd_interval, rb,
42 sector_t, end, compute_subtree_last);
Philipp Reisner98683652012-11-09 14:18:43 +010043
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010044/**
45 * drbd_insert_interval - insert a new interval into a tree
46 */
47bool
48drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
49{
50 struct rb_node **new = &root->rb_node, *parent = NULL;
Lai Jiangshan82cfb902014-09-18 16:49:41 +020051 sector_t this_end = this->sector + (this->size >> 9);
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010052
53 BUG_ON(!IS_ALIGNED(this->size, 512));
54
55 while (*new) {
56 struct drbd_interval *here =
57 rb_entry(*new, struct drbd_interval, rb);
58
59 parent = *new;
Lai Jiangshan82cfb902014-09-18 16:49:41 +020060 if (here->end < this_end)
61 here->end = this_end;
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010062 if (this->sector < here->sector)
63 new = &(*new)->rb_left;
64 else if (this->sector > here->sector)
65 new = &(*new)->rb_right;
66 else if (this < here)
67 new = &(*new)->rb_left;
Andreas Gruenbacher6618bf12011-01-26 13:06:08 +010068 else if (this > here)
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010069 new = &(*new)->rb_right;
Andreas Gruenbacher6618bf12011-01-26 13:06:08 +010070 else
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010071 return false;
72 }
73
Lai Jiangshan82cfb902014-09-18 16:49:41 +020074 this->end = this_end;
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010075 rb_link_node(&this->rb, parent, new);
Philipp Reisner98683652012-11-09 14:18:43 +010076 rb_insert_augmented(&this->rb, root, &augment_callbacks);
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +010077 return true;
78}
79
80/**
81 * drbd_contains_interval - check if a tree contains a given interval
82 * @sector: start sector of @interval
83 * @interval: may not be a valid pointer
84 *
85 * Returns if the tree contains the node @interval with start sector @start.
86 * Does not dereference @interval until @interval is known to be a valid object
87 * in @tree. Returns %false if @interval is in the tree but with a different
88 * sector number.
89 */
90bool
91drbd_contains_interval(struct rb_root *root, sector_t sector,
92 struct drbd_interval *interval)
93{
94 struct rb_node *node = root->rb_node;
95
96 while (node) {
97 struct drbd_interval *here =
98 rb_entry(node, struct drbd_interval, rb);
99
100 if (sector < here->sector)
101 node = node->rb_left;
102 else if (sector > here->sector)
103 node = node->rb_right;
104 else if (interval < here)
105 node = node->rb_left;
106 else if (interval > here)
107 node = node->rb_right;
108 else
Andreas Gruenbacher3e051462011-01-27 16:20:57 +0100109 return true;
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +0100110 }
111 return false;
112}
113
114/**
115 * drbd_remove_interval - remove an interval from a tree
116 */
117void
118drbd_remove_interval(struct rb_root *root, struct drbd_interval *this)
119{
Philipp Reisner98683652012-11-09 14:18:43 +0100120 rb_erase_augmented(&this->rb, root, &augment_callbacks);
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +0100121}
122
123/**
124 * drbd_find_overlap - search for an interval overlapping with [sector, sector + size)
125 * @sector: start sector
126 * @size: size, aligned to 512 bytes
127 *
Andreas Gruenbacher70b19872011-02-04 12:11:05 +0100128 * Returns an interval overlapping with [sector, sector + size), or NULL if
129 * there is none. When there is more than one overlapping interval in the
130 * tree, the interval with the lowest start sector is returned, and all other
131 * overlapping intervals will be on the right side of the tree, reachable with
132 * rb_next().
Andreas Gruenbacher0939b0e2011-01-03 17:42:00 +0100133 */
134struct drbd_interval *
135drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size)
136{
137 struct rb_node *node = root->rb_node;
138 struct drbd_interval *overlap = NULL;
139 sector_t end = sector + (size >> 9);
140
141 BUG_ON(!IS_ALIGNED(size, 512));
142
143 while (node) {
144 struct drbd_interval *here =
145 rb_entry(node, struct drbd_interval, rb);
146
147 if (node->rb_left &&
148 sector < interval_end(node->rb_left)) {
149 /* Overlap if any must be on left side */
150 node = node->rb_left;
151 } else if (here->sector < end &&
152 sector < here->sector + (here->size >> 9)) {
153 overlap = here;
154 break;
155 } else if (sector >= here->sector) {
156 /* Overlap if any must be on right side */
157 node = node->rb_right;
158 } else
159 break;
160 }
161 return overlap;
162}
Andreas Gruenbacherd0e22a22011-02-17 18:11:24 +0100163
164struct drbd_interval *
165drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size)
166{
167 sector_t end = sector + (size >> 9);
168 struct rb_node *node;
169
170 for (;;) {
171 node = rb_next(&i->rb);
172 if (!node)
173 return NULL;
174 i = rb_entry(node, struct drbd_interval, rb);
175 if (i->sector >= end)
176 return NULL;
177 if (sector < i->sector + (i->size >> 9))
178 return i;
179 }
180}