While there are very few limitations on directory names, ZFS dataset names seem to support only alphanumeric characters and the space character. This is extremely annoying when trying to create the occasional dataset where the intended directory name has a punctuation mark such as an exclamation point. It also does not seem to support non-ASCII characters either. With the exception of @, I cannot see why a ZFS dataset name cannot support any character that is allowed in a directory name.
With this limitation, there are two workarounds: limit directory names to the character set allowed in dataset names, or create different dataset names and explicitly set the mountpoint to have the correct name of the directory. The former is kind of absurd, but more or less manageable, depending on how badly you want/need the directory name to be correct. The latter creates the need for more complicated scripts and workflows, and extra permissions are needed for creating and mounting datasets with explicitly set mountpoints.


# zfs create storage/文字化け
cannot create 'storage/文字化け': invalid character ' in name
# zfs create storage/touché
cannot create 'storage/touché': invalid character ' in name
# zfs create "storage/Here Today, Gone Tomorrow"
cannot create 'storage/Here Today, Gone Tomorrow': invalid character ',' in name
# zfs create "storage/Why?"
cannot create 'storage/Why?': invalid character '?' in name


I am quite curious why such a limitation exists. I would also like to know if this is a limitation of ZFS as a whole or just zfs(8) in particular.