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1// SPDX-License-Identifier: GPL-2.0-only
2#include <asm/bug.h>
3#include <linux/rbtree_augmented.h>
4#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#define NODE_END(node) ((node)->sector + ((node)->size >> 9))
17
18RB_DECLARE_CALLBACKS_MAX(static, augment_callbacks,
19 struct drbd_interval, rb, sector_t, end, NODE_END);
20
21/*
22 * drbd_insert_interval - insert a new interval into a tree
23 */
24bool
25drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
26{
27 struct rb_node **new = &root->rb_node, *parent = NULL;
28 sector_t this_end = this->sector + (this->size >> 9);
29
30 BUG_ON(!IS_ALIGNED(this->size, 512));
31
32 while (*new) {
33 struct drbd_interval *here =
34 rb_entry(*new, struct drbd_interval, rb);
35
36 parent = *new;
37 if (here->end < this_end)
38 here->end = this_end;
39 if (this->sector < here->sector)
40 new = &(*new)->rb_left;
41 else if (this->sector > here->sector)
42 new = &(*new)->rb_right;
43 else if (this < here)
44 new = &(*new)->rb_left;
45 else if (this > here)
46 new = &(*new)->rb_right;
47 else
48 return false;
49 }
50
51 this->end = this_end;
52 rb_link_node(&this->rb, parent, new);
53 rb_insert_augmented(&this->rb, root, &augment_callbacks);
54 return true;
55}
56
57/**
58 * drbd_contains_interval - check if a tree contains a given interval
59 * @root: red black tree root
60 * @sector: start sector of @interval
61 * @interval: may be an invalid pointer
62 *
63 * Returns if the tree contains the node @interval with start sector @start.
64 * Does not dereference @interval until @interval is known to be a valid object
65 * in @tree. Returns %false if @interval is in the tree but with a different
66 * sector number.
67 */
68bool
69drbd_contains_interval(struct rb_root *root, sector_t sector,
70 struct drbd_interval *interval)
71{
72 struct rb_node *node = root->rb_node;
73
74 while (node) {
75 struct drbd_interval *here =
76 rb_entry(node, struct drbd_interval, rb);
77
78 if (sector < here->sector)
79 node = node->rb_left;
80 else if (sector > here->sector)
81 node = node->rb_right;
82 else if (interval < here)
83 node = node->rb_left;
84 else if (interval > here)
85 node = node->rb_right;
86 else
87 return true;
88 }
89 return false;
90}
91
92/*
93 * drbd_remove_interval - remove an interval from a tree
94 */
95void
96drbd_remove_interval(struct rb_root *root, struct drbd_interval *this)
97{
98 /* avoid endless loop */
99 if (drbd_interval_empty(this))
100 return;
101
102 rb_erase_augmented(&this->rb, root, &augment_callbacks);
103}
104
105/**
106 * drbd_find_overlap - search for an interval overlapping with [sector, sector + size)
107 * @root: red black tree root
108 * @sector: start sector
109 * @size: size, aligned to 512 bytes
110 *
111 * Returns an interval overlapping with [sector, sector + size), or NULL if
112 * there is none. When there is more than one overlapping interval in the
113 * tree, the interval with the lowest start sector is returned, and all other
114 * overlapping intervals will be on the right side of the tree, reachable with
115 * rb_next().
116 */
117struct drbd_interval *
118drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size)
119{
120 struct rb_node *node = root->rb_node;
121 struct drbd_interval *overlap = NULL;
122 sector_t end = sector + (size >> 9);
123
124 BUG_ON(!IS_ALIGNED(size, 512));
125
126 while (node) {
127 struct drbd_interval *here =
128 rb_entry(node, struct drbd_interval, rb);
129
130 if (node->rb_left &&
131 sector < interval_end(node->rb_left)) {
132 /* Overlap if any must be on left side */
133 node = node->rb_left;
134 } else if (here->sector < end &&
135 sector < here->sector + (here->size >> 9)) {
136 overlap = here;
137 break;
138 } else if (sector >= here->sector) {
139 /* Overlap if any must be on right side */
140 node = node->rb_right;
141 } else
142 break;
143 }
144 return overlap;
145}
146
147struct drbd_interval *
148drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size)
149{
150 sector_t end = sector + (size >> 9);
151 struct rb_node *node;
152
153 for (;;) {
154 node = rb_next(&i->rb);
155 if (!node)
156 return NULL;
157 i = rb_entry(node, struct drbd_interval, rb);
158 if (i->sector >= end)
159 return NULL;
160 if (sector < i->sector + (i->size >> 9))
161 return i;
162 }
163}