List all the filesystems mounted on the system.

def EnumerateFilesystemsFromClient(args):
  """List all the filesystems mounted on the system."""
  del args  # Unused.

  filenames = ["/proc/mounts", "/etc/mtab"]

  for filename in filenames:
    for device, fs_type, mnt_point in CheckMounts(filename):
      yield rdf_client_fs.Filesystem(
          mount_point=mnt_point, type=fs_type, device=device)