drivers/block/drbd/drbd_interval.c

   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  */
   9 static inline
  10 sector_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
  18 RB_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  */
  24 bool
  25 drbd_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  */
  67 bool
  68 drbd_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  */
  94 void
  95 drbd_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  */
 111 struct drbd_interval *
 112 drbd_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
 141 struct drbd_interval *
 142 drbd_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 }