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![Qu Wenruo](/assets/img/avatar_default.png)
This patch implements an infrastructure to insert/search/merge an extent range (with variable length). This provides the basis for later extent buffer cache used in btrfs. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Marek Behún <marek.behun@nic.cz>
319 lines
7.1 KiB
C
319 lines
7.1 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Crossported from the same named file of btrfs-progs.
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*
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* Minor modification to include headers.
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*/
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#include <linux/kernel.h>
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#include <linux/rbtree.h>
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#include <linux/errno.h>
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#include <linux/bug.h>
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#include <stdlib.h>
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#include "extent-cache.h"
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#include "common/rbtree-utils.h"
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struct cache_extent_search_range {
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u64 objectid;
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u64 start;
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u64 size;
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};
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static int cache_tree_comp_range(struct rb_node *node, void *data)
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{
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struct cache_extent *entry;
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struct cache_extent_search_range *range;
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range = (struct cache_extent_search_range *)data;
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entry = rb_entry(node, struct cache_extent, rb_node);
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if (entry->start + entry->size <= range->start)
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return 1;
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else if (range->start + range->size <= entry->start)
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return -1;
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else
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return 0;
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}
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static int cache_tree_comp_nodes(struct rb_node *node1, struct rb_node *node2)
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{
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struct cache_extent *entry;
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struct cache_extent_search_range range;
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entry = rb_entry(node2, struct cache_extent, rb_node);
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range.start = entry->start;
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range.size = entry->size;
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return cache_tree_comp_range(node1, (void *)&range);
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}
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static int cache_tree_comp_range2(struct rb_node *node, void *data)
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{
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struct cache_extent *entry;
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struct cache_extent_search_range *range;
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range = (struct cache_extent_search_range *)data;
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entry = rb_entry(node, struct cache_extent, rb_node);
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if (entry->objectid < range->objectid)
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return 1;
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else if (entry->objectid > range->objectid)
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return -1;
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else if (entry->start + entry->size <= range->start)
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return 1;
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else if (range->start + range->size <= entry->start)
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return -1;
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else
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return 0;
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}
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static int cache_tree_comp_nodes2(struct rb_node *node1, struct rb_node *node2)
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{
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struct cache_extent *entry;
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struct cache_extent_search_range range;
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entry = rb_entry(node2, struct cache_extent, rb_node);
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range.objectid = entry->objectid;
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range.start = entry->start;
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range.size = entry->size;
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return cache_tree_comp_range2(node1, (void *)&range);
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}
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void cache_tree_init(struct cache_tree *tree)
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{
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tree->root = RB_ROOT;
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}
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static struct cache_extent *alloc_cache_extent(u64 start, u64 size)
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{
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struct cache_extent *pe = malloc(sizeof(*pe));
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if (!pe)
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return pe;
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pe->objectid = 0;
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pe->start = start;
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pe->size = size;
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return pe;
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}
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int add_cache_extent(struct cache_tree *tree, u64 start, u64 size)
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{
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struct cache_extent *pe = alloc_cache_extent(start, size);
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int ret;
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if (!pe)
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return -ENOMEM;
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ret = insert_cache_extent(tree, pe);
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if (ret)
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free(pe);
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return ret;
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}
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int insert_cache_extent(struct cache_tree *tree, struct cache_extent *pe)
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{
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return rb_insert(&tree->root, &pe->rb_node, cache_tree_comp_nodes);
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}
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int insert_cache_extent2(struct cache_tree *tree, struct cache_extent *pe)
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{
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return rb_insert(&tree->root, &pe->rb_node, cache_tree_comp_nodes2);
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}
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struct cache_extent *lookup_cache_extent(struct cache_tree *tree,
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u64 start, u64 size)
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{
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struct rb_node *node;
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struct cache_extent *entry;
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struct cache_extent_search_range range;
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range.start = start;
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range.size = size;
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node = rb_search(&tree->root, &range, cache_tree_comp_range, NULL);
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if (!node)
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return NULL;
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entry = rb_entry(node, struct cache_extent, rb_node);
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return entry;
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}
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struct cache_extent *lookup_cache_extent2(struct cache_tree *tree,
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u64 objectid, u64 start, u64 size)
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{
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struct rb_node *node;
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struct cache_extent *entry;
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struct cache_extent_search_range range;
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range.objectid = objectid;
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range.start = start;
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range.size = size;
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node = rb_search(&tree->root, &range, cache_tree_comp_range2, NULL);
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if (!node)
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return NULL;
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entry = rb_entry(node, struct cache_extent, rb_node);
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return entry;
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}
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struct cache_extent *search_cache_extent(struct cache_tree *tree, u64 start)
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{
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struct rb_node *next;
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struct rb_node *node;
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struct cache_extent *entry;
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struct cache_extent_search_range range;
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range.start = start;
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range.size = 1;
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node = rb_search(&tree->root, &range, cache_tree_comp_range, &next);
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if (!node)
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node = next;
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if (!node)
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return NULL;
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entry = rb_entry(node, struct cache_extent, rb_node);
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return entry;
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}
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struct cache_extent *search_cache_extent2(struct cache_tree *tree,
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u64 objectid, u64 start)
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{
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struct rb_node *next;
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struct rb_node *node;
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struct cache_extent *entry;
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struct cache_extent_search_range range;
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range.objectid = objectid;
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range.start = start;
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range.size = 1;
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node = rb_search(&tree->root, &range, cache_tree_comp_range2, &next);
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if (!node)
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node = next;
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if (!node)
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return NULL;
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entry = rb_entry(node, struct cache_extent, rb_node);
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return entry;
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}
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struct cache_extent *first_cache_extent(struct cache_tree *tree)
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{
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struct rb_node *node = rb_first(&tree->root);
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if (!node)
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return NULL;
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return rb_entry(node, struct cache_extent, rb_node);
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}
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struct cache_extent *last_cache_extent(struct cache_tree *tree)
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{
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struct rb_node *node = rb_last(&tree->root);
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if (!node)
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return NULL;
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return rb_entry(node, struct cache_extent, rb_node);
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}
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struct cache_extent *prev_cache_extent(struct cache_extent *pe)
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{
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struct rb_node *node = rb_prev(&pe->rb_node);
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if (!node)
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return NULL;
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return rb_entry(node, struct cache_extent, rb_node);
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}
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struct cache_extent *next_cache_extent(struct cache_extent *pe)
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{
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struct rb_node *node = rb_next(&pe->rb_node);
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if (!node)
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return NULL;
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return rb_entry(node, struct cache_extent, rb_node);
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}
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void remove_cache_extent(struct cache_tree *tree, struct cache_extent *pe)
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{
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rb_erase(&pe->rb_node, &tree->root);
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}
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void cache_tree_free_extents(struct cache_tree *tree,
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free_cache_extent free_func)
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{
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struct cache_extent *ce;
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while ((ce = first_cache_extent(tree))) {
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remove_cache_extent(tree, ce);
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free_func(ce);
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}
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}
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static void free_extent_cache(struct cache_extent *pe)
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{
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free(pe);
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}
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void free_extent_cache_tree(struct cache_tree *tree)
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{
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cache_tree_free_extents(tree, free_extent_cache);
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}
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int add_merge_cache_extent(struct cache_tree *tree, u64 start, u64 size)
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{
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struct cache_extent *cache;
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struct cache_extent *next = NULL;
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struct cache_extent *prev = NULL;
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int next_merged = 0;
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int prev_merged = 0;
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int ret = 0;
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if (cache_tree_empty(tree))
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goto insert;
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cache = search_cache_extent(tree, start);
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if (!cache) {
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/*
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* Either the tree is completely empty, or the no range after
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* start.
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* Either way, the last cache_extent should be prev.
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*/
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prev = last_cache_extent(tree);
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} else if (start <= cache->start) {
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next = cache;
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prev = prev_cache_extent(cache);
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} else {
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prev = cache;
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next = next_cache_extent(cache);
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}
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/*
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* Ensure the range to be inserted won't cover with existings
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* Or we will need extra loop to do merge
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*/
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BUG_ON(next && start + size > next->start);
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BUG_ON(prev && prev->start + prev->size > start);
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if (next && start + size == next->start) {
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next_merged = 1;
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next->size = next->start + next->size - start;
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next->start = start;
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}
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if (prev && prev->start + prev->size == start) {
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prev_merged = 1;
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if (next_merged) {
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next->size = next->start + next->size - prev->start;
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next->start = prev->start;
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remove_cache_extent(tree, prev);
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free(prev);
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} else {
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prev->size = start + size - prev->start;
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}
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}
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insert:
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if (!prev_merged && !next_merged)
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ret = add_cache_extent(tree, start, size);
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return ret;
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}
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