From 466e066837898ec047165b8f1081c529092c6d0a Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 1 Dec 2015 15:11:21 +0800 Subject: btrfs-progs: extent-cache: Add comments for search/lookup functions There are quite a lot search/lookup functions with different behavior, add comments for them, as it will take extra time to view source to understand the behavior difference. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- extent-cache.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'extent-cache.h') diff --git a/extent-cache.h b/extent-cache.h index cb1f77c2..1ce68efb 100644 --- a/extent-cache.h +++ b/extent-cache.h @@ -45,11 +45,31 @@ struct cache_extent *last_cache_extent(struct cache_tree *tree); struct cache_extent *prev_cache_extent(struct cache_extent *pe); struct cache_extent *next_cache_extent(struct cache_extent *pe); +/* + * Find a cache_extent which covers start. + * + * If not found, return next cache_extent if possible. + */ struct cache_extent *search_cache_extent(struct cache_tree *tree, u64 start); + +/* + * Find a cahce_extent which restrictly covers start. + * + * If not found, return NULL. + */ struct cache_extent *lookup_cache_extent(struct cache_tree *tree, u64 start, u64 size); +/* + * Add an non-overlap extent into cache tree + * + * If [start, start+size) overlap with existing one, it will return -EEXIST. + */ int add_cache_extent(struct cache_tree *tree, u64 start, u64 size); + +/* + * Same with add_cache_extent, but with cache_extent strcut. + */ int insert_cache_extent(struct cache_tree *tree, struct cache_extent *pe); void remove_cache_extent(struct cache_tree *tree, struct cache_extent *pe); @@ -71,8 +91,19 @@ static void free_##name##_tree(struct cache_tree *tree) \ void free_extent_cache_tree(struct cache_tree *tree); +/* + * Search a cache_extent with same objectid, and covers start. + * + * If not found, return next if possible. + */ struct cache_extent *search_cache_extent2(struct cache_tree *tree, u64 objectid, u64 start); +/* + * Search a cache_extent with same objectid, and covers the range + * [start, start + size) + * + * If not found, return next cache_extent if possible. + */ struct cache_extent *lookup_cache_extent2(struct cache_tree *tree, u64 objectid, u64 start, u64 size); int add_cache_extent2(struct cache_tree *tree, -- cgit v1.2.3