diff options
Diffstat (limited to 'fs/btrfs/extent_map.c')
| -rw-r--r-- | fs/btrfs/extent_map.c | 455 |
1 files changed, 455 insertions, 0 deletions
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c new file mode 100644 index 000000000..6a98bddd8 --- /dev/null +++ b/fs/btrfs/extent_map.c @@ -0,0 +1,455 @@ +#include <linux/err.h> +#include <linux/slab.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("btrfs_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_zalloc(extent_map_cache, GFP_NOFS); + if (!em) + return NULL; + RB_CLEAR_NODE(&em->rb_node); + 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(extent_map_in_tree(em)); + WARN_ON(!list_empty(&em->list)); + if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags)) + kfree(em->bdev); + kmem_cache_free(extent_map_cache, em); + } +} + +/* 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; +} + +static int tree_insert(struct rb_root *root, struct extent_map *em) +{ + struct rb_node **p = &root->rb_node; + struct rb_node *parent = NULL; + struct extent_map *entry = NULL; + struct rb_node *orig_parent = NULL; + u64 end = range_end(em->start, em->len); + + while (*p) { + parent = *p; + entry = rb_entry(parent, struct extent_map, rb_node); + + if (em->start < entry->start) + p = &(*p)->rb_left; + else if (em->start >= extent_map_end(entry)) + p = &(*p)->rb_right; + else + return -EEXIST; + } + + orig_parent = parent; + while (parent && em->start >= extent_map_end(entry)) { + parent = rb_next(parent); + entry = rb_entry(parent, struct extent_map, rb_node); + } + if (parent) + if (end > entry->start && em->start < extent_map_end(entry)) + return -EEXIST; + + parent = orig_parent; + entry = rb_entry(parent, struct extent_map, rb_node); + while (parent && em->start < entry->start) { + parent = rb_prev(parent); + entry = rb_entry(parent, struct extent_map, rb_node); + } + if (parent) + if (end > entry->start && em->start < extent_map_end(entry)) + return -EEXIST; + + rb_link_node(&em->rb_node, orig_parent, p); + rb_insert_color(&em->rb_node, root); + return 0; +} + +/* + * 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; + + 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 (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) || + test_bit(EXTENT_FLAG_LOGGING, &next->flags)) + return 0; + + /* + * We don't want to merge stuff that hasn't been written to the log yet + * since it may not reflect exactly what is on disk, and that would be + * bad. + */ + if (!list_empty(&prev->list) || !list_empty(&next->list)) + 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->orig_start = merge->orig_start; + em->len += merge->len; + em->block_len += merge->block_len; + em->block_start = merge->block_start; + em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start; + em->mod_start = merge->mod_start; + em->generation = max(em->generation, merge->generation); + + rb_erase(&merge->rb_node, &tree->map); + RB_CLEAR_NODE(&merge->rb_node); + 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->block_len; + rb_erase(&merge->rb_node, &tree->map); + RB_CLEAR_NODE(&merge->rb_node); + em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start; + em->generation = max(em->generation, merge->generation); + free_extent_map(merge); + } +} + +/** + * unpin_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 + * + * 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; + + 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_FILLING, &em->flags)) { + prealloc = true; + clear_bit(EXTENT_FLAG_FILLING, &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; + +} + +void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em) +{ + clear_bit(EXTENT_FLAG_LOGGING, &em->flags); + if (extent_map_in_tree(em)) + try_merge_map(tree, em); +} + +static inline void setup_extent_mapping(struct extent_map_tree *tree, + struct extent_map *em, + int modified) +{ + atomic_inc(&em->refs); + em->mod_start = em->start; + em->mod_len = em->len; + + if (modified) + list_move(&em->list, &tree->modified_extents); + else + try_merge_map(tree, em); +} + +/** + * 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 modified) +{ + int ret = 0; + + ret = tree_insert(&tree->map, em); + if (ret) + goto out; + + setup_extent_mapping(tree, em, modified); +out: + return ret; +} + +static 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); + 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); +} |