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 static void augment_propagate(struct rb_node *rb, struct rb_node *stop) 41 { 42 while (rb != stop) { 43 struct drbd_interval *node = rb_entry(rb, struct drbd_interval, rb); 44 sector_t subtree_last = compute_subtree_last(node); 45 if (node->end == subtree_last) 46 break; 47 node->end = subtree_last; 48 rb = rb_parent(&node->rb); 49 } 50 } 51 52 static void augment_copy(struct rb_node *rb_old, struct rb_node *rb_new) 53 { 54 struct drbd_interval *old = rb_entry(rb_old, struct drbd_interval, rb); 55 struct drbd_interval *new = rb_entry(rb_new, struct drbd_interval, rb); 56 57 new->end = old->end; 58 } 59 60 static void augment_rotate(struct rb_node *rb_old, struct rb_node *rb_new) 61 { 62 struct drbd_interval *old = rb_entry(rb_old, struct drbd_interval, rb); 63 struct drbd_interval *new = rb_entry(rb_new, struct drbd_interval, rb); 64 65 new->end = old->end; 66 old->end = compute_subtree_last(old); 67 } 68 69 static const struct rb_augment_callbacks augment_callbacks = { 70 augment_propagate, 71 augment_copy, 72 augment_rotate, 73 }; 74 75 /** 76 * drbd_insert_interval - insert a new interval into a tree 77 */ 78 bool 79 drbd_insert_interval(struct rb_root *root, struct drbd_interval *this) 80 { 81 struct rb_node **new = &root->rb_node, *parent = NULL; 82 83 BUG_ON(!IS_ALIGNED(this->size, 512)); 84 85 while (*new) { 86 struct drbd_interval *here = 87 rb_entry(*new, struct drbd_interval, rb); 88 89 parent = *new; 90 if (this->sector < here->sector) 91 new = &(*new)->rb_left; 92 else if (this->sector > here->sector) 93 new = &(*new)->rb_right; 94 else if (this < here) 95 new = &(*new)->rb_left; 96 else if (this > here) 97 new = &(*new)->rb_right; 98 else 99 return false; 100 } 101 102 rb_link_node(&this->rb, parent, new); 103 rb_insert_augmented(&this->rb, root, &augment_callbacks); 104 return true; 105 } 106 107 /** 108 * drbd_contains_interval - check if a tree contains a given interval 109 * @sector: start sector of @interval 110 * @interval: may not be a valid pointer 111 * 112 * Returns if the tree contains the node @interval with start sector @start. 113 * Does not dereference @interval until @interval is known to be a valid object 114 * in @tree. Returns %false if @interval is in the tree but with a different 115 * sector number. 116 */ 117 bool 118 drbd_contains_interval(struct rb_root *root, sector_t sector, 119 struct drbd_interval *interval) 120 { 121 struct rb_node *node = root->rb_node; 122 123 while (node) { 124 struct drbd_interval *here = 125 rb_entry(node, struct drbd_interval, rb); 126 127 if (sector < here->sector) 128 node = node->rb_left; 129 else if (sector > here->sector) 130 node = node->rb_right; 131 else if (interval < here) 132 node = node->rb_left; 133 else if (interval > here) 134 node = node->rb_right; 135 else 136 return true; 137 } 138 return false; 139 } 140 141 /** 142 * drbd_remove_interval - remove an interval from a tree 143 */ 144 void 145 drbd_remove_interval(struct rb_root *root, struct drbd_interval *this) 146 { 147 rb_erase_augmented(&this->rb, root, &augment_callbacks); 148 } 149 150 /** 151 * drbd_find_overlap - search for an interval overlapping with [sector, sector + size) 152 * @sector: start sector 153 * @size: size, aligned to 512 bytes 154 * 155 * Returns an interval overlapping with [sector, sector + size), or NULL if 156 * there is none. When there is more than one overlapping interval in the 157 * tree, the interval with the lowest start sector is returned, and all other 158 * overlapping intervals will be on the right side of the tree, reachable with 159 * rb_next(). 160 */ 161 struct drbd_interval * 162 drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size) 163 { 164 struct rb_node *node = root->rb_node; 165 struct drbd_interval *overlap = NULL; 166 sector_t end = sector + (size >> 9); 167 168 BUG_ON(!IS_ALIGNED(size, 512)); 169 170 while (node) { 171 struct drbd_interval *here = 172 rb_entry(node, struct drbd_interval, rb); 173 174 if (node->rb_left && 175 sector < interval_end(node->rb_left)) { 176 /* Overlap if any must be on left side */ 177 node = node->rb_left; 178 } else if (here->sector < end && 179 sector < here->sector + (here->size >> 9)) { 180 overlap = here; 181 break; 182 } else if (sector >= here->sector) { 183 /* Overlap if any must be on right side */ 184 node = node->rb_right; 185 } else 186 break; 187 } 188 return overlap; 189 } 190 191 struct drbd_interval * 192 drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size) 193 { 194 sector_t end = sector + (size >> 9); 195 struct rb_node *node; 196 197 for (;;) { 198 node = rb_next(&i->rb); 199 if (!node) 200 return NULL; 201 i = rb_entry(node, struct drbd_interval, rb); 202 if (i->sector >= end) 203 return NULL; 204 if (sector < i->sector + (i->size >> 9)) 205 return i; 206 } 207 } 208