"tfs" and other filesystems with very short names

[Alan Barrett <apb%iafrica.com@localhost>]

> Added Files:
>       src/sys/lib/libsa: tfs.c tfs.h
> Log Message:
> Add `tfs', a USTAR-format FS, featuring fast floppy loads, 5% better
> space efficiency, and (the real reason) multiple-volume files.

Is it a good idea to add new filesystems with such short names?  We just
went through a process of renameing "cfs" to "coda" because of a name
clash.  I'd prefer to see see "tfs" renamed to "ustarfs" now, rather than
wait for another name clash later.

--apb (Alan Barrett)