drbd: Add interval tree data structure
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>hifive-unleashed-5.1
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c3afd8f568
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@ -1,5 +1,6 @@
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drbd-y := drbd_bitmap.o drbd_proc.o
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drbd-y := drbd_bitmap.o drbd_proc.o
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drbd-y += drbd_worker.o drbd_receiver.o drbd_req.o drbd_actlog.o
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drbd-y += drbd_worker.o drbd_receiver.o drbd_req.o drbd_actlog.o
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drbd-y += drbd_main.o drbd_strings.o drbd_nl.o
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drbd-y += drbd_main.o drbd_strings.o drbd_nl.o
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drbd-y += drbd_interval.o
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obj-$(CONFIG_BLK_DEV_DRBD) += drbd.o
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obj-$(CONFIG_BLK_DEV_DRBD) += drbd.o
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@ -0,0 +1,156 @@
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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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* update_interval_end - recompute 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 void
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update_interval_end(struct rb_node *node, void *__unused)
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{
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struct drbd_interval *this = rb_entry(node, struct drbd_interval, rb);
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sector_t end;
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end = this->sector + (this->size >> 9);
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if (node->rb_left) {
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sector_t left = interval_end(node->rb_left);
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if (left > end)
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end = left;
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}
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if (node->rb_right) {
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sector_t right = interval_end(node->rb_right);
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if (right > end)
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end = right;
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}
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this->end = end;
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}
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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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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 (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->sector > here->sector)
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new = &(*new)->rb_right;
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return false;
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}
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rb_link_node(&this->rb, parent, new);
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rb_insert_color(&this->rb, root);
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rb_augment_insert(&this->rb, update_interval_end, NULL);
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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 interval->sector == sector;
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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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struct rb_node *deepest;
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deepest = rb_augment_erase_begin(&this->rb);
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rb_erase(&this->rb, root);
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rb_augment_erase_end(deepest, update_interval_end, NULL);
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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 the interval overlapping with [sector, sector + size), or NULL.
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* When there is more than one overlapping interval in the tree, the interval
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* with the lowest start sector is returned.
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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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@ -0,0 +1,31 @@
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#ifndef __DRBD_INTERVAL_H
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#define __DRBD_INTERVAL_H
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#include <linux/types.h>
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#include <linux/rbtree.h>
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struct drbd_interval {
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struct rb_node rb;
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sector_t sector; /* start sector of the interval */
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unsigned int size; /* size in bytes */
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sector_t end; /* highest interval end in subtree */
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};
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static inline void drbd_clear_interval(struct drbd_interval *i)
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{
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RB_CLEAR_NODE(&i->rb);
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}
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static inline bool drbd_interval_empty(struct drbd_interval *i)
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{
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return RB_EMPTY_NODE(&i->rb);
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}
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bool drbd_insert_interval(struct rb_root *, struct drbd_interval *);
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struct drbd_interval *drbd_find_interval(struct rb_root *, sector_t,
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struct drbd_interval *);
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void drbd_remove_interval(struct rb_root *, struct drbd_interval *);
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struct drbd_interval *drbd_find_overlap(struct rb_root *, sector_t,
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unsigned int);
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#endif /* __DRBD_INTERVAL_H */
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