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654 lines
17 KiB
654 lines
17 KiB
// SPDX-License-Identifier: GPL-2.0 |
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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 "ctree.h" |
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#include "volumes.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 __cold 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_CACHED; |
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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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refcount_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(refcount_read(&em->refs) == 0); |
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if (refcount_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_cached *root, struct extent_map *em) |
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{ |
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struct rb_node **p = &root->rb_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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bool leftmost = true; |
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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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leftmost = false; |
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} else { |
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return -EEXIST; |
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} |
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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_cached(&em->rb_node, root, leftmost); |
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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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ASSERT(next->block_start != EXTENT_MAP_DELALLOC && |
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prev->block_start != EXTENT_MAP_DELALLOC); |
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if (prev->map_lookup || next->map_lookup) |
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ASSERT(test_bit(EXTENT_FLAG_FS_MAPPING, &prev->flags) && |
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test_bit(EXTENT_FLAG_FS_MAPPING, &next->flags)); |
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if (extent_map_end(prev) == next->start && |
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prev->flags == next->flags && |
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prev->map_lookup == next->map_lookup && |
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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_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 (refcount_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_cached(&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_cached(&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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refcount_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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static void extent_map_device_set_bits(struct extent_map *em, unsigned bits) |
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{ |
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struct map_lookup *map = em->map_lookup; |
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u64 stripe_size = em->orig_block_len; |
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int i; |
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for (i = 0; i < map->num_stripes; i++) { |
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struct btrfs_bio_stripe *stripe = &map->stripes[i]; |
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struct btrfs_device *device = stripe->dev; |
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set_extent_bits_nowait(&device->alloc_state, stripe->physical, |
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stripe->physical + stripe_size - 1, bits); |
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} |
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} |
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static void extent_map_device_clear_bits(struct extent_map *em, unsigned bits) |
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{ |
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struct map_lookup *map = em->map_lookup; |
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u64 stripe_size = em->orig_block_len; |
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int i; |
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for (i = 0; i < map->num_stripes; i++) { |
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struct btrfs_bio_stripe *stripe = &map->stripes[i]; |
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struct btrfs_device *device = stripe->dev; |
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__clear_extent_bit(&device->alloc_state, stripe->physical, |
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stripe->physical + stripe_size - 1, bits, |
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0, 0, NULL, GFP_NOWAIT, NULL); |
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} |
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} |
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/** |
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* Add new extent map to the extent tree |
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* |
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* @tree: tree to insert new map in |
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* @em: map to insert |
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* @modified: indicate whether the given @em should be added to the |
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* modified list, which indicates the extent needs to be logged |
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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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lockdep_assert_held_write(&tree->lock); |
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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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if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags)) { |
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extent_map_device_set_bits(em, CHUNK_ALLOCATED); |
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extent_map_device_clear_bits(em, CHUNK_TRIMMED); |
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} |
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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; |
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u64 end = range_end(start, len); |
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rb_node = __tree_search(&tree->map.rb_root, start, &prev, &next); |
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if (!rb_node) { |
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if (prev) |
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rb_node = prev; |
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else if (next) |
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rb_node = next; |
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else |
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return NULL; |
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} |
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em = rb_entry(rb_node, struct extent_map, rb_node); |
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if (strict && !(end > em->start && start < extent_map_end(em))) |
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return NULL; |
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refcount_inc(&em->refs); |
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return em; |
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} |
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/** |
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* lookup_extent_mapping - lookup extent_map |
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* @tree: tree to lookup in |
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* @start: byte offset to start the search |
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* @len: length of the lookup range |
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* |
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* Find and return the first extent_map struct in @tree that intersects the |
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* [start, len] range. There may be additional objects in the tree that |
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* intersect, so check the object returned carefully to make sure that no |
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* additional lookups are needed. |
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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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return __lookup_extent_mapping(tree, start, len, 1); |
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} |
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/** |
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* search_extent_mapping - find a nearby extent map |
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* @tree: tree to lookup in |
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* @start: byte offset to start the search |
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* @len: length of the lookup range |
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* |
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* Find and return the first extent_map struct in @tree that intersects the |
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* [start, len] range. |
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* |
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* If one can't be found, any nearby extent may be returned |
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*/ |
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struct extent_map *search_extent_mapping(struct extent_map_tree *tree, |
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u64 start, u64 len) |
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{ |
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return __lookup_extent_mapping(tree, start, len, 0); |
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} |
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/** |
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* remove_extent_mapping - removes an extent_map from the extent tree |
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* @tree: extent tree to remove from |
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* @em: extent map being removed |
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* |
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* Removes @em from @tree. No reference counts are dropped, and no checks |
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* are done to see if the range is in use |
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*/ |
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void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em) |
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{ |
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WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags)); |
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rb_erase_cached(&em->rb_node, &tree->map); |
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if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags)) |
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list_del_init(&em->list); |
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if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags)) |
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extent_map_device_clear_bits(em, CHUNK_ALLOCATED); |
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RB_CLEAR_NODE(&em->rb_node); |
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} |
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void replace_extent_mapping(struct extent_map_tree *tree, |
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struct extent_map *cur, |
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struct extent_map *new, |
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int modified) |
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{ |
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WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags)); |
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ASSERT(extent_map_in_tree(cur)); |
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if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags)) |
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list_del_init(&cur->list); |
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rb_replace_node_cached(&cur->rb_node, &new->rb_node, &tree->map); |
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RB_CLEAR_NODE(&cur->rb_node); |
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setup_extent_mapping(tree, new, modified); |
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} |
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static struct extent_map *next_extent_map(struct extent_map *em) |
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{ |
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struct rb_node *next; |
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next = rb_next(&em->rb_node); |
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if (!next) |
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return NULL; |
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return container_of(next, struct extent_map, rb_node); |
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} |
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static struct extent_map *prev_extent_map(struct extent_map *em) |
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{ |
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struct rb_node *prev; |
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prev = rb_prev(&em->rb_node); |
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if (!prev) |
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return NULL; |
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return container_of(prev, struct extent_map, rb_node); |
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} |
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|
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/* |
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* Helper for btrfs_get_extent. Given an existing extent in the tree, |
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* the existing extent is the nearest extent to map_start, |
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* and an extent that you want to insert, deal with overlap and insert |
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* the best fitted new extent into the tree. |
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*/ |
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static noinline int merge_extent_mapping(struct extent_map_tree *em_tree, |
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struct extent_map *existing, |
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struct extent_map *em, |
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u64 map_start) |
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{ |
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struct extent_map *prev; |
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struct extent_map *next; |
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u64 start; |
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u64 end; |
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u64 start_diff; |
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|
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BUG_ON(map_start < em->start || map_start >= extent_map_end(em)); |
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|
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if (existing->start > map_start) { |
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next = existing; |
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prev = prev_extent_map(next); |
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} else { |
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prev = existing; |
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next = next_extent_map(prev); |
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} |
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|
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start = prev ? extent_map_end(prev) : em->start; |
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start = max_t(u64, start, em->start); |
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end = next ? next->start : extent_map_end(em); |
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end = min_t(u64, end, extent_map_end(em)); |
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start_diff = start - em->start; |
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em->start = start; |
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em->len = end - start; |
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if (em->block_start < EXTENT_MAP_LAST_BYTE && |
|
!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) { |
|
em->block_start += start_diff; |
|
em->block_len = em->len; |
|
} |
|
return add_extent_mapping(em_tree, em, 0); |
|
} |
|
|
|
/** |
|
* Add extent mapping into em_tree |
|
* |
|
* @fs_info: the filesystem |
|
* @em_tree: extent tree into which we want to insert the extent mapping |
|
* @em_in: extent we are inserting |
|
* @start: start of the logical range btrfs_get_extent() is requesting |
|
* @len: length of the logical range btrfs_get_extent() is requesting |
|
* |
|
* Note that @em_in's range may be different from [start, start+len), |
|
* but they must be overlapped. |
|
* |
|
* Insert @em_in into @em_tree. In case there is an overlapping range, handle |
|
* the -EEXIST by either: |
|
* a) Returning the existing extent in @em_in if @start is within the |
|
* existing em. |
|
* b) Merge the existing extent with @em_in passed in. |
|
* |
|
* Return 0 on success, otherwise -EEXIST. |
|
* |
|
*/ |
|
int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info, |
|
struct extent_map_tree *em_tree, |
|
struct extent_map **em_in, u64 start, u64 len) |
|
{ |
|
int ret; |
|
struct extent_map *em = *em_in; |
|
|
|
ret = add_extent_mapping(em_tree, em, 0); |
|
/* it is possible that someone inserted the extent into the tree |
|
* while we had the lock dropped. It is also possible that |
|
* an overlapping map exists in the tree |
|
*/ |
|
if (ret == -EEXIST) { |
|
struct extent_map *existing; |
|
|
|
ret = 0; |
|
|
|
existing = search_extent_mapping(em_tree, start, len); |
|
|
|
trace_btrfs_handle_em_exist(fs_info, existing, em, start, len); |
|
|
|
/* |
|
* existing will always be non-NULL, since there must be |
|
* extent causing the -EEXIST. |
|
*/ |
|
if (start >= existing->start && |
|
start < extent_map_end(existing)) { |
|
free_extent_map(em); |
|
*em_in = existing; |
|
ret = 0; |
|
} else { |
|
u64 orig_start = em->start; |
|
u64 orig_len = em->len; |
|
|
|
/* |
|
* The existing extent map is the one nearest to |
|
* the [start, start + len) range which overlaps |
|
*/ |
|
ret = merge_extent_mapping(em_tree, existing, |
|
em, start); |
|
if (ret) { |
|
free_extent_map(em); |
|
*em_in = NULL; |
|
WARN_ONCE(ret, |
|
"unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n", |
|
ret, existing->start, existing->len, |
|
orig_start, orig_len); |
|
} |
|
free_extent_map(existing); |
|
} |
|
} |
|
|
|
ASSERT(ret == 0 || ret == -EEXIST); |
|
return ret; |
|
}
|
|
|