return errFileCorrupt
		}
		return nil
	}

	h := algo.New()
	hashBuf := make([]byte, h.Size())
	left := wantSize

	// Calculate the size of the bitrot file and compare
	// it with the actual file size.
	if left != bitrotShardFileSize(partSize, shardSize, algo) {
		return errFileCorrupt
	}

	bufp := xioutil.ODirectPoolSmall.Get().(*[]byte)