1 // SPDX-License-Identifier: GPL-2.0
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 */
9 static inline
interval_end(struct rb_node * node)10 sector_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
18 RB_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 */
24 bool
drbd_insert_interval(struct rb_root * root,struct drbd_interval * this)25 drbd_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 * @sector: start sector of @interval
60 * @interval: may not be a valid pointer
61 *
62 * Returns if the tree contains the node @interval with start sector @start.
63 * Does not dereference @interval until @interval is known to be a valid object
64 * in @tree. Returns %false if @interval is in the tree but with a different
65 * sector number.
66 */
67 bool
drbd_contains_interval(struct rb_root * root,sector_t sector,struct drbd_interval * interval)68 drbd_contains_interval(struct rb_root *root, sector_t sector,
69 struct drbd_interval *interval)
70 {
71 struct rb_node *node = root->rb_node;
72
73 while (node) {
74 struct drbd_interval *here =
75 rb_entry(node, struct drbd_interval, rb);
76
77 if (sector < here->sector)
78 node = node->rb_left;
79 else if (sector > here->sector)
80 node = node->rb_right;
81 else if (interval < here)
82 node = node->rb_left;
83 else if (interval > here)
84 node = node->rb_right;
85 else
86 return true;
87 }
88 return false;
89 }
90
91 /**
92 * drbd_remove_interval - remove an interval from a tree
93 */
94 void
drbd_remove_interval(struct rb_root * root,struct drbd_interval * this)95 drbd_remove_interval(struct rb_root *root, struct drbd_interval *this)
96 {
97 rb_erase_augmented(&this->rb, root, &augment_callbacks);
98 }
99
100 /**
101 * drbd_find_overlap - search for an interval overlapping with [sector, sector + size)
102 * @sector: start sector
103 * @size: size, aligned to 512 bytes
104 *
105 * Returns an interval overlapping with [sector, sector + size), or NULL if
106 * there is none. When there is more than one overlapping interval in the
107 * tree, the interval with the lowest start sector is returned, and all other
108 * overlapping intervals will be on the right side of the tree, reachable with
109 * rb_next().
110 */
111 struct drbd_interval *
drbd_find_overlap(struct rb_root * root,sector_t sector,unsigned int size)112 drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size)
113 {
114 struct rb_node *node = root->rb_node;
115 struct drbd_interval *overlap = NULL;
116 sector_t end = sector + (size >> 9);
117
118 BUG_ON(!IS_ALIGNED(size, 512));
119
120 while (node) {
121 struct drbd_interval *here =
122 rb_entry(node, struct drbd_interval, rb);
123
124 if (node->rb_left &&
125 sector < interval_end(node->rb_left)) {
126 /* Overlap if any must be on left side */
127 node = node->rb_left;
128 } else if (here->sector < end &&
129 sector < here->sector + (here->size >> 9)) {
130 overlap = here;
131 break;
132 } else if (sector >= here->sector) {
133 /* Overlap if any must be on right side */
134 node = node->rb_right;
135 } else
136 break;
137 }
138 return overlap;
139 }
140
141 struct drbd_interval *
drbd_next_overlap(struct drbd_interval * i,sector_t sector,unsigned int size)142 drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size)
143 {
144 sector_t end = sector + (size >> 9);
145 struct rb_node *node;
146
147 for (;;) {
148 node = rb_next(&i->rb);
149 if (!node)
150 return NULL;
151 i = rb_entry(node, struct drbd_interval, rb);
152 if (i->sector >= end)
153 return NULL;
154 if (sector < i->sector + (i->size >> 9))
155 return i;
156 }
157 }
158