// this disk is a root disk. treat those disks with
				// size less than or equal to the threshold as rootDrives.
				rootDrive = di.Total <= globalRootDiskThreshold
			} else {
				rootDrive, err = disk.IsRootDisk(drivePath, SlashSeparator)
			}
		}
	}

	switch {
	case osIsNotExist(err):
		err = errDiskNotFound
	case isSysErrTooLong(err):
		err = errFileNameTooLong
	case isSysErrIO(err):