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}