This add_merge_cache_extent() function will try to merge adjusted
cache_extent.
This is used for later btrfs-convert ext2 free space cache.
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
extent-cache.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
extent-cache.h | 8 ++++++++
2 files changed, 65 insertions(+)
diff --git a/extent-cache.c b/extent-cache.c
index d80aead..38bed8b 100644
--- a/extent-cache.c
+++ b/extent-cache.c
@@ -282,3 +282,60 @@ void free_extent_cache_tree(struct cache_tree *tree)
{
cache_tree_free_extents(tree, free_extent_cache);
}
+
+int add_merge_cache_extent(struct cache_tree *tree, u64 start, u64 size)
+{
+ struct cache_extent *cache;
+ struct cache_extent *next = NULL;
+ struct cache_extent *prev = NULL;
+ int next_merged = 0;
+ int prev_merged = 0;
+ int ret = 0;
+
+ if (cache_tree_empty(tree))
+ goto insert;
+
+ cache = search_cache_extent(tree, start);
+ if (!cache) {
+ /*
+ * Either the tree is completely empty, or the no range after
+ * start.
+ * Either way, the last cache_extent should be prev.
+ */
+ prev = last_cache_extent(tree);
+ } else if (start <= cache->start) {
+ next = cache;
+ prev = prev_cache_extent(cache);
+ } else {
+ prev = cache;
+ next = next_cache_extent(cache);
+ }
+
+ /*
+ * Ensure the range to be inserted won't cover with existings
+ * Or we will need extra loop to do merge
+ */
+ BUG_ON(next && start + size > next->start);
+ BUG_ON(prev && prev->start + prev->size > start);
+
+ if (next && start + size == next->start) {
+ next_merged = 1;
+ next->size = next->start + next->size - start;
+ next->start = start;
+ }
+ if (prev && prev->start + prev->size == start) {
+ prev_merged = 1;
+ if (next_merged) {
+ next->size = next->start + next->size - prev->start;
+ next->start = prev->start;
+ remove_cache_extent(tree, prev);
+ free(prev);
+ } else {
+ prev->size = start + size - prev->start;
+ }
+ }
+insert:
+ if (!prev_merged && !next_merged)
+ ret = add_cache_extent(tree, start, size);
+ return ret;
+}
diff --git a/extent-cache.h b/extent-cache.h
index 1ce68ef..f031fbf 100644
--- a/extent-cache.h
+++ b/extent-cache.h
@@ -110,4 +110,12 @@ int add_cache_extent2(struct cache_tree *tree,
u64 objectid, u64 start, u64 size);
int insert_cache_extent2(struct cache_tree *tree, struct cache_extent *pe);
+/*
+ * Insert a cache_extent range [start, start + size).
+ *
+ * This function may merge with existing cache_extent.
+ * NOTE: caller must ensure the inserted range won't cover with any existing
+ * range.
+ */
+int add_merge_cache_extent(struct cache_tree *tree, u64 start, u64 size);
#endif
--
2.6.2
--
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