[PATCH 04/10] btrfs-progs: reform the function block_group_cache_tree_search()

[damenly.su@gmail.com]

From: Su Yue <Damenly_Su@gmx.com>

Add the new value 2 of @contains in block_group_cache_tree_search().
The new values means the function will return the block group that
contains bytenr, otherwise return the next one that starts after
@bytenr. Will be used in later commit.

Signed-off-by: Su Yue <Damenly_Su@gmx.com>
---
 extent-tree.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/extent-tree.c b/extent-tree.c
index ab576f8732a2..1d8535049eaf 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -196,13 +196,16 @@ static int btrfs_add_block_group_cache(struct btrfs_fs_info *info,
 }
 
 /*
- * This will return the block group at or after bytenr if contains is 0, else
- * it will return the block group that contains the bytenr
+ * @contains:
+ *   if 0, return the block group at or after bytenr if contains is 0.
+ *   if 1, return the block group that contains the bytenr.
+ *   if 2, return the block group that contains bytenr, otherwise return the
+ *     next one that starts after @bytenr.
  */
 static struct btrfs_block_group_cache *block_group_cache_tree_search(
 		struct btrfs_fs_info *info, u64 bytenr, int contains)
 {
-	struct btrfs_block_group_cache *cache, *ret = NULL;
+	struct btrfs_block_group_cache *cache, *ret = NULL, *tmp = NULL;
 	struct rb_node *n;
 	u64 end, start;
 
@@ -215,8 +218,8 @@ static struct btrfs_block_group_cache *block_group_cache_tree_search(
 		start = cache->key.objectid;
 
 		if (bytenr < start) {
-			if (!contains && (!ret || start < ret->key.objectid))
-				ret = cache;
+			if (!tmp || start < tmp->key.objectid)
+				tmp = cache;
 			n = n->rb_left;
 		} else if (bytenr > start) {
 			if (contains && bytenr <= end) {
@@ -229,6 +232,13 @@ static struct btrfs_block_group_cache *block_group_cache_tree_search(
 			break;
 		}
 	}
+
+	/*
+	 * If ret is NULL, means not found any block group cotanins @bytenr.
+	 * So just except the case that cotanins equals 1.
+	 */
+	if (!ret && contains != 1)
+		ret = tmp;
 	return ret;
 }
 
-- 
2.21.0 (Apple Git-122)