tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#include <asm/bug.h>
2#include <linux/rbtree_augmented.h>
3#include "drbd_interval.h"
4
5/**
6 * interval_end - return end of @node
7 */
8static inline
9sector_t interval_end(struct rb_node *node)
10{
11 struct drbd_interval *this = rb_entry(node, struct drbd_interval, rb);
12 return this->end;
13}
14
15/**
16 * compute_subtree_last - compute end of @node
17 *
18 * The end of an interval is the highest (start + (size >> 9)) value of this
19 * node and of its children. Called for @node and its parents whenever the end
20 * may have changed.
21 */
22static inline sector_t
23compute_subtree_last(struct drbd_interval *node)
24{
25 sector_t max = node->sector + (node->size >> 9);
26
27 if (node->rb.rb_left) {
28 sector_t left = interval_end(node->rb.rb_left);
29 if (left > max)
30 max = left;
31 }
32 if (node->rb.rb_right) {
33 sector_t right = interval_end(node->rb.rb_right);
34 if (right > max)
35 max = right;
36 }
37 return max;
38}
39
40static void augment_propagate(struct rb_node *rb, struct rb_node *stop)
41{
42 while (rb != stop) {
43 struct drbd_interval *node = rb_entry(rb, struct drbd_interval, rb);
44 sector_t subtree_last = compute_subtree_last(node);
45 if (node->end == subtree_last)
46 break;
47 node->end = subtree_last;
48 rb = rb_parent(&node->rb);
49 }
50}
51
52static void augment_copy(struct rb_node *rb_old, struct rb_node *rb_new)
53{
54 struct drbd_interval *old = rb_entry(rb_old, struct drbd_interval, rb);
55 struct drbd_interval *new = rb_entry(rb_new, struct drbd_interval, rb);
56
57 new->end = old->end;
58}
59
60static void augment_rotate(struct rb_node *rb_old, struct rb_node *rb_new)
61{
62 struct drbd_interval *old = rb_entry(rb_old, struct drbd_interval, rb);
63 struct drbd_interval *new = rb_entry(rb_new, struct drbd_interval, rb);
64
65 new->end = old->end;
66 old->end = compute_subtree_last(old);
67}
68
69static const struct rb_augment_callbacks augment_callbacks = {
70 augment_propagate,
71 augment_copy,
72 augment_rotate,
73};
74
75/**
76 * drbd_insert_interval - insert a new interval into a tree
77 */
78bool
79drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
80{
81 struct rb_node **new = &root->rb_node, *parent = NULL;
82
83 BUG_ON(!IS_ALIGNED(this->size, 512));
84
85 while (*new) {
86 struct drbd_interval *here =
87 rb_entry(*new, struct drbd_interval, rb);
88
89 parent = *new;
90 if (this->sector < here->sector)
91 new = &(*new)->rb_left;
92 else if (this->sector > here->sector)
93 new = &(*new)->rb_right;
94 else if (this < here)
95 new = &(*new)->rb_left;
96 else if (this > here)
97 new = &(*new)->rb_right;
98 else
99 return false;
100 }
101
102 rb_link_node(&this->rb, parent, new);
103 rb_insert_augmented(&this->rb, root, &augment_callbacks);
104 return true;
105}
106
107/**
108 * drbd_contains_interval - check if a tree contains a given interval
109 * @sector: start sector of @interval
110 * @interval: may not be a valid pointer
111 *
112 * Returns if the tree contains the node @interval with start sector @start.
113 * Does not dereference @interval until @interval is known to be a valid object
114 * in @tree. Returns %false if @interval is in the tree but with a different
115 * sector number.
116 */
117bool
118drbd_contains_interval(struct rb_root *root, sector_t sector,
119 struct drbd_interval *interval)
120{
121 struct rb_node *node = root->rb_node;
122
123 while (node) {
124 struct drbd_interval *here =
125 rb_entry(node, struct drbd_interval, rb);
126
127 if (sector < here->sector)
128 node = node->rb_left;
129 else if (sector > here->sector)
130 node = node->rb_right;
131 else if (interval < here)
132 node = node->rb_left;
133 else if (interval > here)
134 node = node->rb_right;
135 else
136 return true;
137 }
138 return false;
139}
140
141/**
142 * drbd_remove_interval - remove an interval from a tree
143 */
144void
145drbd_remove_interval(struct rb_root *root, struct drbd_interval *this)
146{
147 rb_erase_augmented(&this->rb, root, &augment_callbacks);
148}
149
150/**
151 * drbd_find_overlap - search for an interval overlapping with [sector, sector + size)
152 * @sector: start sector
153 * @size: size, aligned to 512 bytes
154 *
155 * Returns an interval overlapping with [sector, sector + size), or NULL if
156 * there is none. When there is more than one overlapping interval in the
157 * tree, the interval with the lowest start sector is returned, and all other
158 * overlapping intervals will be on the right side of the tree, reachable with
159 * rb_next().
160 */
161struct drbd_interval *
162drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size)
163{
164 struct rb_node *node = root->rb_node;
165 struct drbd_interval *overlap = NULL;
166 sector_t end = sector + (size >> 9);
167
168 BUG_ON(!IS_ALIGNED(size, 512));
169
170 while (node) {
171 struct drbd_interval *here =
172 rb_entry(node, struct drbd_interval, rb);
173
174 if (node->rb_left &&
175 sector < interval_end(node->rb_left)) {
176 /* Overlap if any must be on left side */
177 node = node->rb_left;
178 } else if (here->sector < end &&
179 sector < here->sector + (here->size >> 9)) {
180 overlap = here;
181 break;
182 } else if (sector >= here->sector) {
183 /* Overlap if any must be on right side */
184 node = node->rb_right;
185 } else
186 break;
187 }
188 return overlap;
189}
190
191struct drbd_interval *
192drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size)
193{
194 sector_t end = sector + (size >> 9);
195 struct rb_node *node;
196
197 for (;;) {
198 node = rb_next(&i->rb);
199 if (!node)
200 return NULL;
201 i = rb_entry(node, struct drbd_interval, rb);
202 if (i->sector >= end)
203 return NULL;
204 if (sector < i->sector + (i->size >> 9))
205 return i;
206 }
207}