flatten    bool
		oSizes     sizeHistogram
	}{
		{
			path:    "/",
			size:    1322310,
			flatten: true,
			objs:    8,
			oSizes:  sizeHistogram{0: 2, 1: 3, 2: 2, 4: 1},
		},
		{
			path:   "/",
			size:   20000,
			objs:   2,
			oSizes: sizeHistogram{1: 2},
		},
		{
			path:   "/dir1",
			size:   1302010,
			objs:   5,
			oSizes: sizeHistogram{0: 1, 1: 1, 2: 2, 4: 1},
		},
		{

type dataUsageHash string

// sizeHistogramV1 is size histogram V1, which has fewer intervals esp. between
// 1024B and 1MiB.
type sizeHistogramV1 [dataUsageBucketLenV1]uint64

// sizeHistogram is a size histogram.
type sizeHistogram [dataUsageBucketLen]uint64

// versionsHistogram is a histogram of number of versions in an object.
type versionsHistogram [dataUsageVersionLen]uint64

type dataUsageEntry struct {