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}