De man 8 mount no Linux:
If no
-toption is given, or if theautotype is specified, mount will try to guess the desired type. Mount uses theblkidlibrary for guessing the filesystem type; if that does not turn up anything that looks familiar, mount will try to read the file/etc/filesystems, or, if that does not exist,/proc/filesystems. All of the filesystem types listed there will be tried, except for those that are labelednodev(e.g.devpts,procandnfs). If/etc/filesystemsends in a line with a single*,mountwill read/proc/filesystemsafterwards. While trying, all filesystem types will be mounted with the mount optionsilent.
Então, basta criar um arquivo /etc/filesystems contendo algo assim:
ext4
ext3
ext2
vfat
msdos
ntfs
iso9660
ufs
xfs
Adicione mais tipos de arquivos, se precisar. Então você pode usar o tipo auto em fstab .