code: def get_file_systems(self):
          
          result = {}
          if os.access('/proc/mounts', os.R_OK):
              file = open('/proc/mounts')
              for line in file:
                  try:
                      mount = line.split()
                      device = mount[0]
                      mount_point = mount[1]
                      fs_type = mount[2]
                  except (IndexError, ValueError):
                      continue
  
                  # Skip the filesystem if it is not in the list of valid
                  # filesystems
                  if fs_type not in self.filesystems:
                      self.log.debug("Ignoring %s since it is of type %s " +
                                     " which is not in the list of filesystems.",
                                     mount_point, fs_type)
                      continue
  
                  # Process the filters
                  if self.exclude_reg.search(mount_point):
                      self.log.debug("Ignoring %s since it is in the " +
                                     "exclude_filter list.", mount_point)
                      continue
  
                  if ((('/' in device or device == 'tmpfs') and
                       mount_point.startswith('/'))):
                      try:
                          stat = os.stat(mount_point)
                      except OSError:
                          self.log.debug("Path %s is not mounted - skipping.",
                                         mount_point)
                          continue
  
                      if stat.st_dev in result:
                          continue
  
                      result[stat.st_dev] = {
                          'device': os.path.realpath(device),
                          'mount_point': mount_point,
                          'fs_type': fs_type
                      }
  
              file.close()
  
          else:
              if not psutil:
                  self.log.error('Unable to import psutil')
                  return None
  
              partitions = psutil.disk_partitions(False)
              for partition in partitions:
                  result[len(result)] = {
                      'device': os.path.realpath(partition.device),
                      'mount_point': partition.mountpoint,
                      'fs_type': partition.fstype
                  }
              pass
  
          return result
docs: Creates a map of mounted filesystems on the machine.
  
          iostat(1): Each sector has size of 512 bytes.
  
          Returns:
            st_dev -> FileSystem(device, mount_point)