// Updates must be closed before we return.
	defer xioutil.SafeClose(updates)

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	var wg sync.WaitGroup
	var mu sync.Mutex
	var results []dataUsageCache
	var firstErr error

	allBuckets, err := z.ListBuckets(ctx, BucketOptions{})
	if err != nil {