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-t, --types fstype
The argument following the -t is used to indicate the filesystem
type. The filesystem types which are currently supported depend
on the running kernel. See /proc/filesystems and /lib/mod‐
ules/$(uname -r)/kernel/fs for a complete list of the filesys‐
tems. The most common are ext2, ext3, ext4, xfs, btrfs, vfat,
sysfs, proc, nfs and cifs.

The programs mount and umount support filesystem subtypes. The
subtype is defined by a '.subtype' suffix. For example
'fuse.sshfs'. It's recommended to use subtype notation rather
than add any prefix to the mount source (for example
'sshfs#example.com' is deprecated).

If no -t option is given, or if the auto type is specified,
mount will try to guess the desired type. Mount uses the blkid
library 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 labeled "nodev" (e.g. devpts, proc and nfs).
If /etc/filesystems ends in a line with a single *, mount will
read /proc/filesystems afterwards. While trying, all filesystem
types will be mounted with the mount option silent.

The auto type may be useful for user-mounted floppies. Creating
a file /etc/filesystems can be useful to change the probe order
(e.g., to try vfat before msdos or ext3 before ext2) or if you
use a kernel module autoloader.

More than one type may be specified in a comma-separated list,
for option -t as well as in an /etc/fstab entry. The list of
filesystem types for option -t can be prefixed with no to spec‐
ify the filesystem types on which no action should be taken.
The prefix no has no effect when specified in an /etc/fstab
entry.

The prefix no can be meaningful with the -a option. For exam‐
ple, the command

mount -a -t nomsdos,smbfs

mounts all filesystems except those of type msdos and smbfs.

For most types all the mount program has to do is issue a simple
mount(2) system call, and no detailed knowledge of the filesys‐
tem type is required. For a few types however (like nfs, nfs4,
cifs, smbfs, ncpfs) an ad hoc code is necessary. The nfs, nfs4,
cifs, smbfs, and ncpfs filesystems have a separate mount pro‐
gram. In order to make it possible to treat all types in a uni‐
form way, mount will execute the program /sbin/mount.type (if
that exists) when called with type type. Since different ver‐
sions of the smbmount program have different calling conven‐
tions, /sbin/mount.smbfs may have to be a shell script that sets
up the desired call.