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
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
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
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
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 *
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 *
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