181 lines
4.5 KiB
C
181 lines
4.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <asm/bug.h>
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#include <linux/rbtree_augmented.h>
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#include "drbd_interval.h"
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/**
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* interval_end - return end of @node
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*/
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static inline
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sector_t interval_end(struct rb_node *node)
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{
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struct drbd_interval *this = rb_entry(node, struct drbd_interval, rb);
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return this->end;
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}
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/**
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* compute_subtree_last - compute end of @node
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*
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* The end of an interval is the highest (start + (size >> 9)) value of this
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* node and of its children. Called for @node and its parents whenever the end
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* may have changed.
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*/
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static inline sector_t
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compute_subtree_last(struct drbd_interval *node)
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{
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sector_t max = node->sector + (node->size >> 9);
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if (node->rb.rb_left) {
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sector_t left = interval_end(node->rb.rb_left);
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if (left > max)
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max = left;
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}
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if (node->rb.rb_right) {
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sector_t right = interval_end(node->rb.rb_right);
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if (right > max)
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max = right;
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}
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return max;
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}
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RB_DECLARE_CALLBACKS(static, augment_callbacks, struct drbd_interval, rb,
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sector_t, end, compute_subtree_last);
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/**
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* drbd_insert_interval - insert a new interval into a tree
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*/
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bool
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drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
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{
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struct rb_node **new = &root->rb_node, *parent = NULL;
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sector_t this_end = this->sector + (this->size >> 9);
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BUG_ON(!IS_ALIGNED(this->size, 512));
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while (*new) {
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struct drbd_interval *here =
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rb_entry(*new, struct drbd_interval, rb);
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parent = *new;
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if (here->end < this_end)
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here->end = this_end;
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if (this->sector < here->sector)
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new = &(*new)->rb_left;
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else if (this->sector > here->sector)
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new = &(*new)->rb_right;
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else if (this < here)
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new = &(*new)->rb_left;
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else if (this > here)
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new = &(*new)->rb_right;
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else
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return false;
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}
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this->end = this_end;
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rb_link_node(&this->rb, parent, new);
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rb_insert_augmented(&this->rb, root, &augment_callbacks);
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return true;
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}
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/**
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* drbd_contains_interval - check if a tree contains a given interval
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* @sector: start sector of @interval
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* @interval: may not be a valid pointer
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*
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* Returns if the tree contains the node @interval with start sector @start.
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* Does not dereference @interval until @interval is known to be a valid object
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* in @tree. Returns %false if @interval is in the tree but with a different
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* sector number.
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*/
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bool
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drbd_contains_interval(struct rb_root *root, sector_t sector,
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struct drbd_interval *interval)
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{
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struct rb_node *node = root->rb_node;
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while (node) {
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struct drbd_interval *here =
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rb_entry(node, struct drbd_interval, rb);
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if (sector < here->sector)
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node = node->rb_left;
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else if (sector > here->sector)
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node = node->rb_right;
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else if (interval < here)
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node = node->rb_left;
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else if (interval > here)
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node = node->rb_right;
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else
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return true;
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}
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return false;
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}
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/**
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* drbd_remove_interval - remove an interval from a tree
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*/
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void
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drbd_remove_interval(struct rb_root *root, struct drbd_interval *this)
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{
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rb_erase_augmented(&this->rb, root, &augment_callbacks);
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}
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/**
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* drbd_find_overlap - search for an interval overlapping with [sector, sector + size)
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* @sector: start sector
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* @size: size, aligned to 512 bytes
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*
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* Returns an interval overlapping with [sector, sector + size), or NULL if
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* there is none. When there is more than one overlapping interval in the
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* tree, the interval with the lowest start sector is returned, and all other
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* overlapping intervals will be on the right side of the tree, reachable with
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* rb_next().
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*/
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struct drbd_interval *
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drbd_find_overlap(struct rb_root *root, sector_t sector, unsigned int size)
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{
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struct rb_node *node = root->rb_node;
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struct drbd_interval *overlap = NULL;
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sector_t end = sector + (size >> 9);
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BUG_ON(!IS_ALIGNED(size, 512));
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while (node) {
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struct drbd_interval *here =
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rb_entry(node, struct drbd_interval, rb);
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if (node->rb_left &&
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sector < interval_end(node->rb_left)) {
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/* Overlap if any must be on left side */
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node = node->rb_left;
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} else if (here->sector < end &&
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sector < here->sector + (here->size >> 9)) {
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overlap = here;
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break;
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} else if (sector >= here->sector) {
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/* Overlap if any must be on right side */
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node = node->rb_right;
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} else
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break;
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}
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return overlap;
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}
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struct drbd_interval *
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drbd_next_overlap(struct drbd_interval *i, sector_t sector, unsigned int size)
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{
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sector_t end = sector + (size >> 9);
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struct rb_node *node;
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for (;;) {
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node = rb_next(&i->rb);
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if (!node)
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return NULL;
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i = rb_entry(node, struct drbd_interval, rb);
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if (i->sector >= end)
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return NULL;
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if (sector < i->sector + (i->size >> 9))
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return i;
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}
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}
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