Btrfs: cleanup reserved space when freeing tree log on error

On error we will wait and free the tree log at unmount without a transaction.
This means that the actual freeing of the blocks doesn't happen which means we
complain about space leaks on unmount.  So to fix this just skip the transaction
specific cleanup part of the tree log free'ing if we don't have a transaction
and that way we can free up our reserved space and our counters stay happy.
Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/tree-log.c

@@ -2151,11 +2151,13 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 					return ret;
 				}
 
+				if (trans) {
 					btrfs_tree_lock(next);
 					btrfs_set_lock_blocking(next);
 					clean_tree_block(trans, root, next);
 					btrfs_wait_tree_block_writeback(next);
 					btrfs_tree_unlock(next);
+				}
 
 				WARN_ON(root_owner !=
 					BTRFS_TREE_LOG_OBJECTID);
@@ -2227,11 +2229,13 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
 
 				next = path->nodes[*level];
 
+				if (trans) {
 					btrfs_tree_lock(next);
 					btrfs_set_lock_blocking(next);
 					clean_tree_block(trans, root, next);
 					btrfs_wait_tree_block_writeback(next);
 					btrfs_tree_unlock(next);
+				}
 
 				WARN_ON(root_owner != BTRFS_TREE_LOG_OBJECTID);
 				ret = btrfs_free_and_pin_reserved_extent(root,
@@ -2301,11 +2305,13 @@ static int walk_log_tree(struct btrfs_trans_handle *trans,
 
 			next = path->nodes[orig_level];
 
+			if (trans) {
 				btrfs_tree_lock(next);
 				btrfs_set_lock_blocking(next);
 				clean_tree_block(trans, log, next);
 				btrfs_wait_tree_block_writeback(next);
 				btrfs_tree_unlock(next);
+			}
 
 			WARN_ON(log->root_key.objectid !=
 				BTRFS_TREE_LOG_OBJECTID);
@@ -2608,13 +2614,10 @@ static void free_log_tree(struct btrfs_trans_handle *trans,
 		.process_func = process_one_buffer
 	};
 
-	if (trans) {
 	ret = walk_log_tree(trans, log, &wc);
-
 	/* I don't think this can happen but just in case */
 	if (ret)
 		btrfs_abort_transaction(trans, log, ret);
-	}
 
 	while (1) {
 		ret = find_first_extent_bit(&log->dirty_log_pages,