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 * @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}
 158