285 lines
6.9 KiB
C
285 lines
6.9 KiB
C
#include <linux/err.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/version.h>
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#include <linux/hardirq.h>
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#include "extent_map.h"
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/* temporary define until extent_map moves out of btrfs */
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struct kmem_cache *btrfs_cache_create(const char *name, size_t size,
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unsigned long extra_flags,
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void (*ctor)(void *, struct kmem_cache *,
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unsigned long));
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static struct kmem_cache *extent_map_cache;
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int __init extent_map_init(void)
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{
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extent_map_cache = btrfs_cache_create("extent_map",
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sizeof(struct extent_map), 0,
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NULL);
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if (!extent_map_cache)
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return -ENOMEM;
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return 0;
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}
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void extent_map_exit(void)
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{
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if (extent_map_cache)
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kmem_cache_destroy(extent_map_cache);
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}
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void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
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{
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tree->map.rb_node = NULL;
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tree->last = NULL;
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spin_lock_init(&tree->lock);
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}
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EXPORT_SYMBOL(extent_map_tree_init);
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struct extent_map *alloc_extent_map(gfp_t mask)
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{
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struct extent_map *em;
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em = kmem_cache_alloc(extent_map_cache, mask);
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if (!em || IS_ERR(em))
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return em;
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em->in_tree = 0;
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em->flags = 0;
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atomic_set(&em->refs, 1);
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return em;
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}
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EXPORT_SYMBOL(alloc_extent_map);
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void free_extent_map(struct extent_map *em)
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{
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if (!em)
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return;
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WARN_ON(atomic_read(&em->refs) == 0);
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if (atomic_dec_and_test(&em->refs)) {
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WARN_ON(em->in_tree);
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kmem_cache_free(extent_map_cache, em);
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}
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}
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EXPORT_SYMBOL(free_extent_map);
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static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
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struct rb_node *node)
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{
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struct rb_node ** p = &root->rb_node;
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struct rb_node * parent = NULL;
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struct extent_map *entry;
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while(*p) {
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parent = *p;
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entry = rb_entry(parent, struct extent_map, rb_node);
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WARN_ON(!entry->in_tree);
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if (offset < entry->start)
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p = &(*p)->rb_left;
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else if (offset >= extent_map_end(entry))
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p = &(*p)->rb_right;
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else
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return parent;
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}
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entry = rb_entry(node, struct extent_map, rb_node);
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entry->in_tree = 1;
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rb_link_node(node, parent, p);
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rb_insert_color(node, root);
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return NULL;
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}
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static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
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struct rb_node **prev_ret,
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struct rb_node **next_ret)
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{
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struct rb_node * n = root->rb_node;
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struct rb_node *prev = NULL;
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struct rb_node *orig_prev = NULL;
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struct extent_map *entry;
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struct extent_map *prev_entry = NULL;
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while(n) {
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entry = rb_entry(n, struct extent_map, rb_node);
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prev = n;
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prev_entry = entry;
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WARN_ON(!entry->in_tree);
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if (offset < entry->start)
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n = n->rb_left;
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else if (offset >= extent_map_end(entry))
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n = n->rb_right;
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else
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return n;
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}
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if (prev_ret) {
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orig_prev = prev;
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while(prev && offset >= extent_map_end(prev_entry)) {
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prev = rb_next(prev);
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prev_entry = rb_entry(prev, struct extent_map, rb_node);
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}
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*prev_ret = prev;
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prev = orig_prev;
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}
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if (next_ret) {
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prev_entry = rb_entry(prev, struct extent_map, rb_node);
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while(prev && offset < prev_entry->start) {
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prev = rb_prev(prev);
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prev_entry = rb_entry(prev, struct extent_map, rb_node);
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}
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*next_ret = prev;
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}
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return NULL;
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}
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static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
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{
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struct rb_node *prev;
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struct rb_node *ret;
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ret = __tree_search(root, offset, &prev, NULL);
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if (!ret)
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return prev;
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return ret;
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}
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static int mergable_maps(struct extent_map *prev, struct extent_map *next)
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{
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if (extent_map_end(prev) == next->start &&
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prev->flags == next->flags &&
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prev->bdev == next->bdev &&
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((next->block_start == EXTENT_MAP_HOLE &&
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prev->block_start == EXTENT_MAP_HOLE) ||
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(next->block_start == EXTENT_MAP_INLINE &&
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prev->block_start == EXTENT_MAP_INLINE) ||
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(next->block_start == EXTENT_MAP_DELALLOC &&
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prev->block_start == EXTENT_MAP_DELALLOC) ||
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(next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
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next->block_start == extent_map_block_end(prev)))) {
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return 1;
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}
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return 0;
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}
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/*
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* add_extent_mapping tries a simple forward/backward merge with existing
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* mappings. The extent_map struct passed in will be inserted into
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* the tree directly (no copies made, just a reference taken).
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*/
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int add_extent_mapping(struct extent_map_tree *tree,
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struct extent_map *em)
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{
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int ret = 0;
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struct extent_map *merge = NULL;
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struct rb_node *rb;
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rb = tree_insert(&tree->map, em->start, &em->rb_node);
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if (rb) {
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merge = rb_entry(rb, struct extent_map, rb_node);
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ret = -EEXIST;
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goto out;
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}
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atomic_inc(&em->refs);
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if (em->start != 0) {
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rb = rb_prev(&em->rb_node);
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if (rb)
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merge = rb_entry(rb, struct extent_map, rb_node);
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if (rb && mergable_maps(merge, em)) {
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em->start = merge->start;
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em->len += merge->len;
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em->block_start = merge->block_start;
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merge->in_tree = 0;
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rb_erase(&merge->rb_node, &tree->map);
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free_extent_map(merge);
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}
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}
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rb = rb_next(&em->rb_node);
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if (rb)
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merge = rb_entry(rb, struct extent_map, rb_node);
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if (rb && mergable_maps(em, merge)) {
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em->len += merge->len;
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rb_erase(&merge->rb_node, &tree->map);
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merge->in_tree = 0;
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free_extent_map(merge);
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}
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tree->last = em;
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out:
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return ret;
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}
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EXPORT_SYMBOL(add_extent_mapping);
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static u64 range_end(u64 start, u64 len)
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{
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if (start + len < start)
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return (u64)-1;
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return start + len;
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}
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/*
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* lookup_extent_mapping returns the first extent_map struct in the
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* tree that intersects the [start, len] range. There may
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* be additional objects in the tree that intersect, so check the object
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* returned carefully to make sure you don't need additional lookups.
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*/
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struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
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u64 start, u64 len)
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{
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struct extent_map *em;
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struct rb_node *rb_node;
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struct rb_node *prev = NULL; struct rb_node *next = NULL; u64 end = range_end(start, len); em = tree->last; if (em && end > em->start && start < extent_map_end(em)) goto found;
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rb_node = __tree_search(&tree->map, start, &prev, &next);
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if (!rb_node && prev) {
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em = rb_entry(prev, struct extent_map, rb_node);
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if (end > em->start && start < extent_map_end(em))
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goto found;
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}
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if (!rb_node && next) {
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em = rb_entry(next, struct extent_map, rb_node);
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if (end > em->start && start < extent_map_end(em))
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goto found;
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}
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if (!rb_node) {
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em = NULL;
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goto out;
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}
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if (IS_ERR(rb_node)) {
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em = ERR_PTR(PTR_ERR(rb_node));
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goto out;
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}
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em = rb_entry(rb_node, struct extent_map, rb_node);
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if (end > em->start && start < extent_map_end(em))
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goto found;
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em = NULL;
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goto out;
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found:
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atomic_inc(&em->refs);
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tree->last = em;
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out:
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return em;
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}
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EXPORT_SYMBOL(lookup_extent_mapping);
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/*
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* removes an extent_map struct from the tree. No reference counts are
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* dropped, and no checks are done to see if the range is in use
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*/
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int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
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{
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int ret = 0;
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rb_erase(&em->rb_node, &tree->map);
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em->in_tree = 0;
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if (tree->last == em)
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tree->last = NULL;
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return ret;
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}
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EXPORT_SYMBOL(remove_extent_mapping);
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