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 /** 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 */ 23 static inline sector_t 24 compute_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 41 RB_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 */ 47 bool 48 drbd_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 */ 90 bool 91 drbd_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 */ 117 void 118 drbd_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 */ 134 struct drbd_interval * 135 drbd_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 } 163 164 struct drbd_interval * 165 drbd_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