467 lines
12 KiB
C
467 lines
12 KiB
C
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/hardirq.h>
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#include "ctree.h"
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#include "extent_map.h"
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#include "compression.h"
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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 = kmem_cache_create("btrfs_extent_map",
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sizeof(struct extent_map), 0,
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SLAB_MEM_SPREAD, 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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kmem_cache_destroy(extent_map_cache);
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}
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/**
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* extent_map_tree_init - initialize extent map tree
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* @tree: tree to initialize
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*
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* Initialize the extent tree @tree. Should be called for each new inode
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* or other user of the extent_map interface.
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*/
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void extent_map_tree_init(struct extent_map_tree *tree)
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{
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tree->map = RB_ROOT;
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INIT_LIST_HEAD(&tree->modified_extents);
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rwlock_init(&tree->lock);
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}
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/**
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* alloc_extent_map - allocate new extent map structure
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*
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* Allocate a new extent_map structure. The new structure is
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* returned with a reference count of one and needs to be
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* freed using free_extent_map()
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*/
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struct extent_map *alloc_extent_map(void)
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{
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struct extent_map *em;
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em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
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if (!em)
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return NULL;
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RB_CLEAR_NODE(&em->rb_node);
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em->flags = 0;
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em->compress_type = BTRFS_COMPRESS_NONE;
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em->generation = 0;
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atomic_set(&em->refs, 1);
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INIT_LIST_HEAD(&em->list);
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return em;
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}
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/**
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* free_extent_map - drop reference count of an extent_map
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* @em: extent map being released
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*
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* Drops the reference out on @em by one and free the structure
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* if the reference count hits zero.
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*/
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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(extent_map_in_tree(em));
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WARN_ON(!list_empty(&em->list));
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if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags))
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kfree(em->map_lookup);
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kmem_cache_free(extent_map_cache, em);
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}
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}
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/* simple helper to do math around the end of an extent, handling wrap */
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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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static int tree_insert(struct rb_root *root, struct extent_map *em)
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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 = NULL;
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struct rb_node *orig_parent = NULL;
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u64 end = range_end(em->start, em->len);
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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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if (em->start < entry->start)
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p = &(*p)->rb_left;
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else if (em->start >= extent_map_end(entry))
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p = &(*p)->rb_right;
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else
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return -EEXIST;
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}
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orig_parent = parent;
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while (parent && em->start >= extent_map_end(entry)) {
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parent = rb_next(parent);
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entry = rb_entry(parent, struct extent_map, rb_node);
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}
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if (parent)
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if (end > entry->start && em->start < extent_map_end(entry))
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return -EEXIST;
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parent = orig_parent;
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entry = rb_entry(parent, struct extent_map, rb_node);
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while (parent && em->start < entry->start) {
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parent = rb_prev(parent);
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entry = rb_entry(parent, struct extent_map, rb_node);
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}
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if (parent)
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if (end > entry->start && em->start < extent_map_end(entry))
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return -EEXIST;
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rb_link_node(&em->rb_node, orig_parent, p);
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rb_insert_color(&em->rb_node, root);
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return 0;
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}
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/*
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* search through the tree for an extent_map with a given offset. If
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* it can't be found, try to find some neighboring extents
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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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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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/* check to see if two extent_map structs are adjacent and safe to merge */
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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 (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
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return 0;
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/*
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* don't merge compressed extents, we need to know their
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* actual size
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*/
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if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
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return 0;
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if (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) ||
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test_bit(EXTENT_FLAG_LOGGING, &next->flags))
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return 0;
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/*
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* We don't want to merge stuff that hasn't been written to the log yet
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* since it may not reflect exactly what is on disk, and that would be
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* bad.
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*/
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if (!list_empty(&prev->list) || !list_empty(&next->list))
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return 0;
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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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static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
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{
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struct extent_map *merge = NULL;
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struct rb_node *rb;
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/*
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* We can't modify an extent map that is in the tree and that is being
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* used by another task, as it can cause that other task to see it in
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* inconsistent state during the merging. We always have 1 reference for
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* the tree and 1 for this task (which is unpinning the extent map or
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* clearing the logging flag), so anything > 2 means it's being used by
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* other tasks too.
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*/
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if (atomic_read(&em->refs) > 2)
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return;
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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->orig_start = merge->orig_start;
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em->len += merge->len;
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em->block_len += merge->block_len;
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em->block_start = merge->block_start;
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em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
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em->mod_start = merge->mod_start;
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em->generation = max(em->generation, merge->generation);
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rb_erase(&merge->rb_node, &tree->map);
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RB_CLEAR_NODE(&merge->rb_node);
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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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em->block_len += merge->block_len;
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rb_erase(&merge->rb_node, &tree->map);
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RB_CLEAR_NODE(&merge->rb_node);
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em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
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em->generation = max(em->generation, merge->generation);
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free_extent_map(merge);
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}
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}
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/**
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* unpin_extent_cache - unpin an extent from the cache
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* @tree: tree to unpin the extent in
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* @start: logical offset in the file
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* @len: length of the extent
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* @gen: generation that this extent has been modified in
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*
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* Called after an extent has been written to disk properly. Set the generation
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* to the generation that actually added the file item to the inode so we know
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* we need to sync this extent when we call fsync().
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*/
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int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
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u64 gen)
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{
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int ret = 0;
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struct extent_map *em;
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bool prealloc = false;
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write_lock(&tree->lock);
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em = lookup_extent_mapping(tree, start, len);
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WARN_ON(!em || em->start != start);
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if (!em)
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goto out;
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em->generation = gen;
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clear_bit(EXTENT_FLAG_PINNED, &em->flags);
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em->mod_start = em->start;
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em->mod_len = em->len;
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if (test_bit(EXTENT_FLAG_FILLING, &em->flags)) {
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prealloc = true;
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clear_bit(EXTENT_FLAG_FILLING, &em->flags);
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}
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try_merge_map(tree, em);
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if (prealloc) {
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em->mod_start = em->start;
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em->mod_len = em->len;
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}
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free_extent_map(em);
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out:
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write_unlock(&tree->lock);
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return ret;
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}
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void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
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{
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clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
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if (extent_map_in_tree(em))
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try_merge_map(tree, em);
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}
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static inline void setup_extent_mapping(struct extent_map_tree *tree,
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struct extent_map *em,
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int modified)
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{
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atomic_inc(&em->refs);
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em->mod_start = em->start;
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em->mod_len = em->len;
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if (modified)
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list_move(&em->list, &tree->modified_extents);
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else
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try_merge_map(tree, em);
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}
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/**
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* add_extent_mapping - add new extent map to the extent tree
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* @tree: tree to insert new map in
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* @em: map to insert
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*
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* Insert @em into @tree or perform a simple forward/backward merge with
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* existing mappings. The extent_map struct passed in will be inserted
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* into the tree directly, with an additional reference taken, or a
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* reference dropped if the merge attempt was successful.
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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, int modified)
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{
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int ret = 0;
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ret = tree_insert(&tree->map, em);
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if (ret)
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goto out;
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setup_extent_mapping(tree, em, modified);
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out:
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return ret;
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}
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static struct extent_map *
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__lookup_extent_mapping(struct extent_map_tree *tree,
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u64 start, u64 len, int strict)
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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;
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|
struct rb_node *next = NULL;
|
||
|
|
u64 end = range_end(start, len);
|
||
|
|
|
||
|
|
rb_node = __tree_search(&tree->map, start, &prev, &next);
|
||
|
|
if (!rb_node) {
|
||
|
|
if (prev)
|
||
|
|
rb_node = prev;
|
||
|
|
else if (next)
|
||
|
|
rb_node = next;
|
||
|
|
else
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
em = rb_entry(rb_node, struct extent_map, rb_node);
|
||
|
|
|
||
|
|
if (strict && !(end > em->start && start < extent_map_end(em)))
|
||
|
|
return NULL;
|
||
|
|
|
||
|
|
atomic_inc(&em->refs);
|
||
|
|
return em;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* lookup_extent_mapping - lookup extent_map
|
||
|
|
* @tree: tree to lookup in
|
||
|
|
* @start: byte offset to start the search
|
||
|
|
* @len: length of the lookup range
|
||
|
|
*
|
||
|
|
* Find and return the first extent_map struct in @tree that intersects the
|
||
|
|
* [start, len] range. There may be additional objects in the tree that
|
||
|
|
* intersect, so check the object returned carefully to make sure that no
|
||
|
|
* additional lookups are needed.
|
||
|
|
*/
|
||
|
|
struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
|
||
|
|
u64 start, u64 len)
|
||
|
|
{
|
||
|
|
return __lookup_extent_mapping(tree, start, len, 1);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* search_extent_mapping - find a nearby extent map
|
||
|
|
* @tree: tree to lookup in
|
||
|
|
* @start: byte offset to start the search
|
||
|
|
* @len: length of the lookup range
|
||
|
|
*
|
||
|
|
* Find and return the first extent_map struct in @tree that intersects the
|
||
|
|
* [start, len] range.
|
||
|
|
*
|
||
|
|
* If one can't be found, any nearby extent may be returned
|
||
|
|
*/
|
||
|
|
struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
|
||
|
|
u64 start, u64 len)
|
||
|
|
{
|
||
|
|
return __lookup_extent_mapping(tree, start, len, 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* remove_extent_mapping - removes an extent_map from the extent tree
|
||
|
|
* @tree: extent tree to remove from
|
||
|
|
* @em: extent map being removed
|
||
|
|
*
|
||
|
|
* Removes @em from @tree. No reference counts are dropped, and no checks
|
||
|
|
* are done to see if the range is in use
|
||
|
|
*/
|
||
|
|
int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
|
||
|
|
{
|
||
|
|
int ret = 0;
|
||
|
|
|
||
|
|
WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
|
||
|
|
rb_erase(&em->rb_node, &tree->map);
|
||
|
|
if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
|
||
|
|
list_del_init(&em->list);
|
||
|
|
RB_CLEAR_NODE(&em->rb_node);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
void replace_extent_mapping(struct extent_map_tree *tree,
|
||
|
|
struct extent_map *cur,
|
||
|
|
struct extent_map *new,
|
||
|
|
int modified)
|
||
|
|
{
|
||
|
|
WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags));
|
||
|
|
ASSERT(extent_map_in_tree(cur));
|
||
|
|
if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags))
|
||
|
|
list_del_init(&cur->list);
|
||
|
|
rb_replace_node(&cur->rb_node, &new->rb_node, &tree->map);
|
||
|
|
RB_CLEAR_NODE(&cur->rb_node);
|
||
|
|
|
||
|
|
setup_extent_mapping(tree, new, modified);
|
||
|
|
}
|