1 #include <asm/bug.h> 2 #include <linux/rbtree_augmented.h> 3 #include "drbd_interval.h" 4 5 /** 6 * interval_end - return end of @node 7 */ 8 static inline 9 sector_t interval_end(struct rb_node *node) 10 { 11 struct drbd_interval *this = rb_entry(node, struct drbd_interval, rb); 12 return this->end; 13 } 14 15 /** 16 * compute_subtree_last - compute end of @node 17 * 18 * The end of an interval is the highest (start + (size >> 9)) value of this 19 * node and of its children. Called for @node and its parents whenever the end 20 * may have changed. 21 */ 22 static inline sector_t 23 compute_subtree_last(struct drbd_interval *node) 24 { 25 sector_t max = node->sector + (node->size >> 9); 26 27 if (node->rb.rb_left) { 28 sector_t left = interval_end(node->rb.rb_left); 29 if (left > max) 30 max = left; 31 } 32 if (node->rb.rb_right) { 33 sector_t right = interval_end(node->rb.rb_right); 34 if (right > max) 35 max = right; 36 } 37 return max; 38 } 39 40 RB_DECLARE_CALLBACKS(static, augment_callbacks, struct drbd_interval, rb, 41 sector_t, end, compute_subtree_last); 42 43 /** 44 * drbd_insert_interval - insert a new interval into a tree 45 */ 46 bool 47 drbd_insert_interval(struct rb_root *root, struct drbd_interval *this) 48 { 49 struct rb_node **new = &root->rb_node, *parent = NULL; 50 sector_t this_end = this->sector + (this->size >> 9); 51 52 BUG_ON(!IS_ALIGNED(this->size, 512)); 53 54 while (*new) { 55 struct drbd_interval *here = 56 rb_entry(*new, struct drbd_interval, rb); 57 58 parent = *new; 59 if (here->end < this_end) 60 here->end = this_end; 61 if (this->sector < here->sector) 62 new = &(*new)->rb_left; 63 else if (this->sector > here->sector) 64 new = &(*new)->rb_right; 65 else if (this < here) 66 new = &(*new)->rb_left; 67 else if (this > here) 68 new = &(*new)->rb_right; 69 else 70 return false; 71 } 72 73 this->end = this_end; 74 rb_link_node(&this->rb, parent, new); 75 rb_insert_augmented(&this->rb, root, &augment_callbacks); 76 return true; 77 } 78 79 /** 80 * drbd_contains_interval - check if a tree contains a given interval 81 * @sector: start sector of @interval 82 * @interval: may not be a valid pointer 83 * 84 * Returns if the tree contains the node @interval with start sector @start. 85 * Does not dereference @interval until @interval is known to be a valid object 86 * in @tree. Returns %false if @interval is in the tree but with a different 87 * sector number. 88 */ 89 bool 90 drbd_contains_interval(struct rb_root *root, sector_t sector, 91 struct drbd_interval *interval) 92 { 93 struct rb_node *node = root->rb_node; 94 95 while (node) { 96 struct drbd_interval *here = 97 rb_entry(node, struct drbd_interval, rb); 98 99 if (sector < here->sector) 100 node = node->rb_left; 101 else if (sector > here->sector) 102 node = node->rb_right; 103 else if (interval < here) 104 node = node->rb_left; 105 else if (interval > here) 106 node = node->rb_right; 107 else 108 return true; 109 } 110 return false; 111 } 112 113 /** 114 * drbd_remove_interval - remove an interval from a tree 115 */ 116 void 117 drbd_remove_interval(struct rb_root *root, struct drbd_interval *this) 118 { 119 rb_erase_augmented(&this->rb, root, &augment_callbacks); 120 } 121 122 /** 123 * drbd_find_overlap - search for an interval overlapping with [sector, sector + size) 124 * @sector: start sector 125 * @size: size, aligned to 512 bytes 126 * 127 * Returns an interval overlapping with [sector, sector + size), or NULL if 128 * there is none. When there is more than one overlapping interval in the 129 * tree, the interval with the lowest start sector is returned, and all other 130 * overlapping intervals will be on the right side of the tree, reachable with 131 * rb_next(). 132 */ 133 struct drbd_interval * 134 drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size) 135 { 136 struct rb_node *node = root->rb_node; 137 struct drbd_interval *overlap = NULL; 138 sector_t end = sector + (size >> 9); 139 140 BUG_ON(!IS_ALIGNED(size, 512)); 141 142 while (node) { 143 struct drbd_interval *here = 144 rb_entry(node, struct drbd_interval, rb); 145 146 if (node->rb_left && 147 sector < interval_end(node->rb_left)) { 148 /* Overlap if any must be on left side */ 149 node = node->rb_left; 150 } else if (here->sector < end && 151 sector < here->sector + (here->size >> 9)) { 152 overlap = here; 153 break; 154 } else if (sector >= here->sector) { 155 /* Overlap if any must be on right side */ 156 node = node->rb_right; 157 } else 158 break; 159 } 160 return overlap; 161 } 162 163 struct drbd_interval * 164 drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size) 165 { 166 sector_t end = sector + (size >> 9); 167 struct rb_node *node; 168 169 for (;;) { 170 node = rb_next(&i->rb); 171 if (!node) 172 return NULL; 173 i = rb_entry(node, struct drbd_interval, rb); 174 if (i->sector >= end) 175 return NULL; 176 if (sector < i->sector + (i->size >> 9)) 177 return i; 178 } 179 } 180