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author | Lachlan McIlroy <lachlan@redback.melbourne.sgi.com> | 2009-01-14 16:29:51 +1100 |
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committer | Lachlan McIlroy <lachlan@redback.melbourne.sgi.com> | 2009-01-14 16:29:51 +1100 |
commit | cb7a97d01521797cad9f63e8478403c3e51fea49 (patch) | |
tree | 84cddf20369f82f10c1c3712e6cce20dd1b9d863 /fs/btrfs/extent_map.c | |
parent | 0335cb76aa3fa913a2164bc9b669e5aef9d56fa3 (diff) | |
parent | a6525042bfdfcab128bd91fad264de10fd24a55e (diff) | |
download | linux-cb7a97d01521797cad9f63e8478403c3e51fea49.tar.bz2 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 into for-linus
Diffstat (limited to 'fs/btrfs/extent_map.c')
-rw-r--r-- | fs/btrfs/extent_map.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c new file mode 100644 index 000000000000..4a83e33ada32 --- /dev/null +++ b/fs/btrfs/extent_map.c @@ -0,0 +1,351 @@ +#include <linux/err.h> +#include <linux/gfp.h> +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/spinlock.h> +#include <linux/version.h> +#include <linux/hardirq.h> +#include "extent_map.h" + +/* temporary define until extent_map moves out of btrfs */ +struct kmem_cache *btrfs_cache_create(const char *name, size_t size, + unsigned long extra_flags, + void (*ctor)(void *, struct kmem_cache *, + unsigned long)); + +static struct kmem_cache *extent_map_cache; + +int __init extent_map_init(void) +{ + extent_map_cache = btrfs_cache_create("extent_map", + sizeof(struct extent_map), 0, + 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 + * @mask: flags for memory allocations during tree operations + * + * 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, gfp_t mask) +{ + tree->map.rb_node = NULL; + spin_lock_init(&tree->lock); +} +EXPORT_SYMBOL(extent_map_tree_init); + +/** + * alloc_extent_map - allocate new extent map structure + * @mask: memory allocation flags + * + * 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(gfp_t mask) +{ + struct extent_map *em; + em = kmem_cache_alloc(extent_map_cache, mask); + if (!em || IS_ERR(em)) + return em; + em->in_tree = 0; + em->flags = 0; + atomic_set(&em->refs, 1); + return em; +} +EXPORT_SYMBOL(alloc_extent_map); + +/** + * 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); + kmem_cache_free(extent_map_cache, em); + } +} +EXPORT_SYMBOL(free_extent_map); + +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; +} + +/* + * look for an offset in the tree, and if it can't be found, return + * the first offset we can find smaller than 'offset'. + */ +static inline struct rb_node *tree_search(struct rb_root *root, u64 offset) +{ + struct rb_node *prev; + struct rb_node *ret; + ret = __tree_search(root, offset, &prev, NULL); + if (!ret) + return prev; + return ret; +} + +/* 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; +} + +/** + * 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 sucessfull. + */ +int add_extent_mapping(struct extent_map_tree *tree, + struct extent_map *em) +{ + int ret = 0; + struct extent_map *merge = NULL; + 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; + } + assert_spin_locked(&tree->lock); + rb = tree_insert(&tree->map, em->start, &em->rb_node); + if (rb) { + ret = -EEXIST; + free_extent_map(merge); + goto out; + } + atomic_inc(&em->refs); + 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; + 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; + free_extent_map(merge); + } +out: + return ret; +} +EXPORT_SYMBOL(add_extent_mapping); + +/* 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; +} + +/** + * 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) +{ + 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); + + assert_spin_locked(&tree->lock); + rb_node = __tree_search(&tree->map, start, &prev, &next); + if (!rb_node && prev) { + em = rb_entry(prev, struct extent_map, rb_node); + if (end > em->start && start < extent_map_end(em)) + goto found; + } + if (!rb_node && next) { + em = rb_entry(next, struct extent_map, rb_node); + if (end > em->start && start < extent_map_end(em)) + goto found; + } + if (!rb_node) { + em = NULL; + goto out; + } + if (IS_ERR(rb_node)) { + em = ERR_PTR(PTR_ERR(rb_node)); + goto out; + } + em = rb_entry(rb_node, struct extent_map, rb_node); + if (end > em->start && start < extent_map_end(em)) + goto found; + + em = NULL; + goto out; + +found: + atomic_inc(&em->refs); +out: + return em; +} +EXPORT_SYMBOL(lookup_extent_mapping); + +/** + * 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)); + assert_spin_locked(&tree->lock); + rb_erase(&em->rb_node, &tree->map); + em->in_tree = 0; + return ret; +} +EXPORT_SYMBOL(remove_extent_mapping); |