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