LXR linux/drivers/block/drbd/drbd

   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 * @root:       red black tree root
  60 * @sector:     start sector of @interval
  61 * @interval:   may not be a valid 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        rb_erase_augmented(&this->rb, root, &augment_callbacks);
  99}
 100
 101/**
 102 * drbd_find_overlap  - search for an interval overlapping with [sector, sector + size)
 103 * @root:       red black tree root
 104 * @sector:     start sector
 105 * @size:       size, aligned to 512 bytes
 106 *
 107 * Returns an interval overlapping with [sector, sector + size), or NULL if
 108 * there is none.  When there is more than one overlapping interval in the
 109 * tree, the interval with the lowest start sector is returned, and all other
 110 * overlapping intervals will be on the right side of the tree, reachable with
 111 * rb_next().
 112 */
 113struct drbd_interval *
 114drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size)
 115{
 116        struct rb_node *node = root->rb_node;
 117        struct drbd_interval *overlap = NULL;
 118        sector_t end = sector + (size >> 9);
 119
 120        BUG_ON(!IS_ALIGNED(size, 512));
 121
 122        while (node) {
 123                struct drbd_interval *here =
 124                        rb_entry(node, struct drbd_interval, rb);
 125
 126                if (node->rb_left &&
 127                    sector < interval_end(node->rb_left)) {
 128                        /* Overlap if any must be on left side */
 129                        node = node->rb_left;
 130                } else if (here->sector < end &&
 131                           sector < here->sector + (here->size >> 9)) {
 132                        overlap = here;
 133                        break;
 134                } else if (sector >= here->sector) {
 135                        /* Overlap if any must be on right side */
 136                        node = node->rb_right;
 137                } else
 138                        break;
 139        }
 140        return overlap;
 141}
 142
 143struct drbd_interval *
 144drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size)
 145{
 146        sector_t end = sector + (size >> 9);
 147        struct rb_node *node;
 148
 149        for (;;) {
 150                node = rb_next(&i->rb);
 151                if (!node)
 152                        return NULL;
 153                i = rb_entry(node, struct drbd_interval, rb);
 154                if (i->sector >= end)
 155                        return NULL;
 156                if (sector < i->sector + (i->size >> 9))
 157                        return i;
 158        }
 159}
 160