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 */
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 * @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 */
67bool
68drbd_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 */
94void
95drbd_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 */
111struct drbd_interval *
112drbd_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
141struct drbd_interval *
142drbd_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