diff options
Diffstat (limited to 'fs/btrfs/extent-io-tree.c')
| -rw-r--r-- | fs/btrfs/extent-io-tree.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c index b487a9e4aaa7..8dd03ac86d26 100644 --- a/fs/btrfs/extent-io-tree.c +++ b/fs/btrfs/extent-io-tree.c @@ -161,6 +161,113 @@ void free_extent_state(struct extent_state *state) } } +/* + * Search @tree for an entry that contains @offset. Such entry would have + * entry->start <= offset && entry->end >= offset. + * + * @tree: the tree to search + * @offset: offset that should fall within an entry in @tree + * @node_ret: pointer where new node should be anchored (used when inserting an + * entry in the tree) + * @parent_ret: points to entry which would have been the parent of the entry, + * containing @offset + * + * Return a pointer to the entry that contains @offset byte address and don't change + * @node_ret and @parent_ret. + * + * If no such entry exists, return pointer to entry that ends before @offset + * and fill parameters @node_ret and @parent_ret, ie. does not return NULL. + */ +struct rb_node *tree_search_for_insert(struct extent_io_tree *tree, u64 offset, + struct rb_node ***node_ret, + struct rb_node **parent_ret) +{ + struct rb_root *root = &tree->state; + struct rb_node **node = &root->rb_node; + struct rb_node *prev = NULL; + struct tree_entry *entry; + + while (*node) { + prev = *node; + entry = rb_entry(prev, struct tree_entry, rb_node); + + if (offset < entry->start) + node = &(*node)->rb_left; + else if (offset > entry->end) + node = &(*node)->rb_right; + else + return *node; + } + + if (node_ret) + *node_ret = node; + if (parent_ret) + *parent_ret = prev; + + /* Search neighbors until we find the first one past the end */ + while (prev && offset > entry->end) { + prev = rb_next(prev); + entry = rb_entry(prev, struct tree_entry, rb_node); + } + + return prev; +} + +/* + * Search offset in the tree or fill neighbor rbtree node pointers. + * + * @tree: the tree to search + * @offset: offset that should fall within an entry in @tree + * @next_ret: pointer to the first entry whose range ends after @offset + * @prev_ret: pointer to the first entry whose range begins before @offset + * + * Return a pointer to the entry that contains @offset byte address. If no + * such entry exists, then return NULL and fill @prev_ret and @next_ret. + * Otherwise return the found entry and other pointers are left untouched. + */ +struct rb_node *tree_search_prev_next(struct extent_io_tree *tree, u64 offset, + struct rb_node **prev_ret, + struct rb_node **next_ret) +{ + struct rb_root *root = &tree->state; + struct rb_node **node = &root->rb_node; + struct rb_node *prev = NULL; + struct rb_node *orig_prev = NULL; + struct tree_entry *entry; + + ASSERT(prev_ret); + ASSERT(next_ret); + + while (*node) { + prev = *node; + entry = rb_entry(prev, struct tree_entry, rb_node); + + if (offset < entry->start) + node = &(*node)->rb_left; + else if (offset > entry->end) + node = &(*node)->rb_right; + else + return *node; + } + + orig_prev = prev; + while (prev && offset > entry->end) { + prev = rb_next(prev); + entry = rb_entry(prev, struct tree_entry, rb_node); + } + *next_ret = prev; + prev = orig_prev; + + entry = rb_entry(prev, struct tree_entry, rb_node); + while (prev && offset < entry->start) { + prev = rb_prev(prev); + entry = rb_entry(prev, struct tree_entry, rb_node); + } + *prev_ret = prev; + + return NULL; +} + /* Wrappers around set/clear extent bit */ int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end, u32 bits, struct extent_changeset *changeset) |