| #include <linux/err.h> |
| #include <linux/slab.h> |
| #include <linux/module.h> |
| #include <linux/spinlock.h> |
| #include <linux/hardirq.h> |
| #include "ctree.h" |
| #include "extent_map.h" |
| |
| |
| static struct kmem_cache *extent_map_cache; |
| |
| int __init extent_map_init(void) |
| { |
| extent_map_cache = kmem_cache_create("extent_map", |
| sizeof(struct extent_map), 0, |
| SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL); |
| if (!extent_map_cache) |
| return -ENOMEM; |
| return 0; |
| } |
| |
| void extent_map_exit(void) |
| { |
| if (extent_map_cache) |
| kmem_cache_destroy(extent_map_cache); |
| } |
| |
| /** |
| * extent_map_tree_init - initialize extent map tree |
| * @tree: tree to initialize |
| * |
| * Initialize the extent tree @tree. Should be called for each new inode |
| * or other user of the extent_map interface. |
| */ |
| void extent_map_tree_init(struct extent_map_tree *tree) |
| { |
| tree->map = RB_ROOT; |
| INIT_LIST_HEAD(&tree->modified_extents); |
| rwlock_init(&tree->lock); |
| } |
| |
| /** |
| * alloc_extent_map - allocate new extent map structure |
| * |
| * Allocate a new extent_map structure. The new structure is |
| * returned with a reference count of one and needs to be |
| * freed using free_extent_map() |
| */ |
| struct extent_map *alloc_extent_map(void) |
| { |
| struct extent_map *em; |
| em = kmem_cache_alloc(extent_map_cache, GFP_NOFS); |
| if (!em) |
| return NULL; |
| em->in_tree = 0; |
| em->flags = 0; |
| em->compress_type = BTRFS_COMPRESS_NONE; |
| em->generation = 0; |
| atomic_set(&em->refs, 1); |
| INIT_LIST_HEAD(&em->list); |
| return em; |
| } |
| |
| /** |
| * free_extent_map - drop reference count of an extent_map |
| * @em: extent map beeing releasead |
| * |
| * Drops the reference out on @em by one and free the structure |
| * if the reference count hits zero. |
| */ |
| void free_extent_map(struct extent_map *em) |
| { |
| if (!em) |
| return; |
| WARN_ON(atomic_read(&em->refs) == 0); |
| if (atomic_dec_and_test(&em->refs)) { |
| WARN_ON(em->in_tree); |
| WARN_ON(!list_empty(&em->list)); |
| kmem_cache_free(extent_map_cache, em); |
| } |
| } |
| |
| static struct rb_node *tree_insert(struct rb_root *root, u64 offset, |
| struct rb_node *node) |
| { |
| struct rb_node **p = &root->rb_node; |
| struct rb_node *parent = NULL; |
| struct extent_map *entry; |
| |
| while (*p) { |
| parent = *p; |
| entry = rb_entry(parent, struct extent_map, rb_node); |
| |
| WARN_ON(!entry->in_tree); |
| |
| if (offset < entry->start) |
| p = &(*p)->rb_left; |
| else if (offset >= extent_map_end(entry)) |
| p = &(*p)->rb_right; |
| else |
| return parent; |
| } |
| |
| entry = rb_entry(node, struct extent_map, rb_node); |
| entry->in_tree = 1; |
| rb_link_node(node, parent, p); |
| rb_insert_color(node, root); |
| return NULL; |
| } |
| |
| /* |
| * search through the tree for an extent_map with a given offset. If |
| * it can't be found, try to find some neighboring extents |
| */ |
| static struct rb_node *__tree_search(struct rb_root *root, u64 offset, |
| struct rb_node **prev_ret, |
| struct rb_node **next_ret) |
| { |
| struct rb_node *n = root->rb_node; |
| struct rb_node *prev = NULL; |
| struct rb_node *orig_prev = NULL; |
| struct extent_map *entry; |
| struct extent_map *prev_entry = NULL; |
| |
| while (n) { |
| entry = rb_entry(n, struct extent_map, rb_node); |
| prev = n; |
| prev_entry = entry; |
| |
| WARN_ON(!entry->in_tree); |
| |
| if (offset < entry->start) |
| n = n->rb_left; |
| else if (offset >= extent_map_end(entry)) |
| n = n->rb_right; |
| else |
| return n; |
| } |
| |
| if (prev_ret) { |
| orig_prev = prev; |
| while (prev && offset >= extent_map_end(prev_entry)) { |
| prev = rb_next(prev); |
| prev_entry = rb_entry(prev, struct extent_map, rb_node); |
| } |
| *prev_ret = prev; |
| prev = orig_prev; |
| } |
| |
| if (next_ret) { |
| prev_entry = rb_entry(prev, struct extent_map, rb_node); |
| while (prev && offset < prev_entry->start) { |
| prev = rb_prev(prev); |
| prev_entry = rb_entry(prev, struct extent_map, rb_node); |
| } |
| *next_ret = prev; |
| } |
| return NULL; |
| } |
| |
| /* check to see if two extent_map structs are adjacent and safe to merge */ |
| static int mergable_maps(struct extent_map *prev, struct extent_map *next) |
| { |
| if (test_bit(EXTENT_FLAG_PINNED, &prev->flags)) |
| return 0; |
| |
| /* |
| * don't merge compressed extents, we need to know their |
| * actual size |
| */ |
| if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags)) |
| return 0; |
| |
| if (extent_map_end(prev) == next->start && |
| prev->flags == next->flags && |
| prev->bdev == next->bdev && |
| ((next->block_start == EXTENT_MAP_HOLE && |
| prev->block_start == EXTENT_MAP_HOLE) || |
| (next->block_start == EXTENT_MAP_INLINE && |
| prev->block_start == EXTENT_MAP_INLINE) || |
| (next->block_start == EXTENT_MAP_DELALLOC && |
| prev->block_start == EXTENT_MAP_DELALLOC) || |
| (next->block_start < EXTENT_MAP_LAST_BYTE - 1 && |
| next->block_start == extent_map_block_end(prev)))) { |
| return 1; |
| } |
| return 0; |
| } |
| |
| static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em) |
| { |
| struct extent_map *merge = NULL; |
| struct rb_node *rb; |
| |
| if (em->start != 0) { |
| rb = rb_prev(&em->rb_node); |
| if (rb) |
| merge = rb_entry(rb, struct extent_map, rb_node); |
| if (rb && mergable_maps(merge, em)) { |
| em->start = merge->start; |
| em->len += merge->len; |
| em->block_len += merge->block_len; |
| em->block_start = merge->block_start; |
| merge->in_tree = 0; |
| if (merge->generation > em->generation) { |
| em->mod_start = em->start; |
| em->mod_len = em->len; |
| em->generation = merge->generation; |
| list_move(&em->list, &tree->modified_extents); |
| } |
| |
| list_del_init(&merge->list); |
| rb_erase(&merge->rb_node, &tree->map); |
| free_extent_map(merge); |
| } |
| } |
| |
| rb = rb_next(&em->rb_node); |
| if (rb) |
| merge = rb_entry(rb, struct extent_map, rb_node); |
| if (rb && mergable_maps(em, merge)) { |
| em->len += merge->len; |
| em->block_len += merge->len; |
| rb_erase(&merge->rb_node, &tree->map); |
| merge->in_tree = 0; |
| if (merge->generation > em->generation) { |
| em->mod_len = em->len; |
| em->generation = merge->generation; |
| list_move(&em->list, &tree->modified_extents); |
| } |
| list_del_init(&merge->list); |
| free_extent_map(merge); |
| } |
| } |
| |
| /** |
| * unpint_extent_cache - unpin an extent from the cache |
| * @tree: tree to unpin the extent in |
| * @start: logical offset in the file |
| * @len: length of the extent |
| * @gen: generation that this extent has been modified in |
| * @prealloc: if this is set we need to clear the prealloc flag |
| * |
| * Called after an extent has been written to disk properly. Set the generation |
| * to the generation that actually added the file item to the inode so we know |
| * we need to sync this extent when we call fsync(). |
| */ |
| int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len, |
| u64 gen) |
| { |
| int ret = 0; |
| struct extent_map *em; |
| bool prealloc = false; |
| |
| write_lock(&tree->lock); |
| em = lookup_extent_mapping(tree, start, len); |
| |
| WARN_ON(!em || em->start != start); |
| |
| if (!em) |
| goto out; |
| |
| list_move(&em->list, &tree->modified_extents); |
| em->generation = gen; |
| clear_bit(EXTENT_FLAG_PINNED, &em->flags); |
| em->mod_start = em->start; |
| em->mod_len = em->len; |
| |
| if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) { |
| prealloc = true; |
| clear_bit(EXTENT_FLAG_PREALLOC, &em->flags); |
| } |
| |
| try_merge_map(tree, em); |
| |
| if (prealloc) { |
| em->mod_start = em->start; |
| em->mod_len = em->len; |
| } |
| |
| free_extent_map(em); |
| out: |
| write_unlock(&tree->lock); |
| return ret; |
| |
| } |
| |
| /** |
| * add_extent_mapping - add new extent map to the extent tree |
| * @tree: tree to insert new map in |
| * @em: map to insert |
| * |
| * Insert @em into @tree or perform a simple forward/backward merge with |
| * existing mappings. The extent_map struct passed in will be inserted |
| * into the tree directly, with an additional reference taken, or a |
| * reference dropped if the merge attempt was successful. |
| */ |
| int add_extent_mapping(struct extent_map_tree *tree, |
| struct extent_map *em) |
| { |
| int ret = 0; |
| struct rb_node *rb; |
| struct extent_map *exist; |
| |
| exist = lookup_extent_mapping(tree, em->start, em->len); |
| if (exist) { |
| free_extent_map(exist); |
| ret = -EEXIST; |
| goto out; |
| } |
| rb = tree_insert(&tree->map, em->start, &em->rb_node); |
| if (rb) { |
| ret = -EEXIST; |
| goto out; |
| } |
| atomic_inc(&em->refs); |
| |
| em->mod_start = em->start; |
| em->mod_len = em->len; |
| |
| try_merge_map(tree, em); |
| out: |
| return ret; |
| } |
| |
| /* simple helper to do math around the end of an extent, handling wrap */ |
| static u64 range_end(u64 start, u64 len) |
| { |
| if (start + len < start) |
| return (u64)-1; |
| return start + len; |
| } |
| |
| struct extent_map *__lookup_extent_mapping(struct extent_map_tree *tree, |
| u64 start, u64 len, int strict) |
| { |
| struct extent_map *em; |
| struct rb_node *rb_node; |
| struct rb_node *prev = NULL; |
| 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 beeing 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); |
| list_del_init(&em->list); |
| em->in_tree = 0; |
| return ret; |
| } |