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}
164