btrfs: error on missing block group when unaccounting log tree extent buffers

Currently we only log an error message if we can't find the block group
for a log tree extent buffer when unaccounting it (while freeing a log
tree). A missing block group means something is seriously wrong and we
end up leaking space from the metadata space info. So return -ENOENT in
case we don't find the block group.

Reviewed-by: Boris Burkov <[email protected]>
Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Filipe Manana <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: fdmanana

fs/btrfs/tree-log.c

@@ -2593,14 +2593,14 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
 /*
  * Correctly adjust the reserved bytes occupied by a log tree extent buffer
  */
-static void unaccount_log_buffer(struct btrfs_fs_info *fs_info, u64 start)
+static int unaccount_log_buffer(struct btrfs_fs_info *fs_info, u64 start)
 {
 	struct btrfs_block_group *cache;
 
 	cache = btrfs_lookup_block_group(fs_info, start);
 	if (!cache) {
 		btrfs_err(fs_info, "unable to find block group for %llu", start);
-		return;
+		return -ENOENT;
 	}
 
 	spin_lock(&cache->space_info->lock);
@@ -2611,27 +2611,22 @@ static void unaccount_log_buffer(struct btrfs_fs_info *fs_info, u64 start)
 	spin_unlock(&cache->space_info->lock);
 
 	btrfs_put_block_group(cache);
+
+	return 0;
 }
 
 static int clean_log_buffer(struct btrfs_trans_handle *trans,
 			    struct extent_buffer *eb)
 {
-	int ret;
-
 	btrfs_tree_lock(eb);
 	btrfs_clear_buffer_dirty(trans, eb);
 	wait_on_extent_buffer_writeback(eb);
 	btrfs_tree_unlock(eb);
 
-	if (trans) {
-		ret = btrfs_pin_reserved_extent(trans, eb);
-		if (ret)
-			return ret;
-	} else {
-		unaccount_log_buffer(eb->fs_info, eb->start);
-	}
+	if (trans)
+		return btrfs_pin_reserved_extent(trans, eb);
 
-	return 0;
+	return unaccount_log_buffer(eb->fs_info, eb->start);
 }
 
 static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,