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  */
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  * @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  */
68 bool
drbd_contains_interval(struct rb_root * root,sector_t sector,struct drbd_interval * interval)69 drbd_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  */
95 void
drbd_remove_interval(struct rb_root * root,struct drbd_interval * this)96 drbd_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  */
117 struct drbd_interval *
drbd_find_overlap(struct rb_root * root,sector_t sector,unsigned int size)118 drbd_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 
147 struct drbd_interval *
drbd_next_overlap(struct drbd_interval * i,sector_t sector,unsigned int size)148 drbd_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