> some would say that you shouldn't slow down the 'default' FFS at all
> to do this.  i.e. clone the current ffs into a different mount-type,
> e.g. "bufs" (for backwards ufs...  8-), and do it there.
> 
> While compatibility is nice, it's not clear that you want to slow down
> your 'default case' significantly to get it.

That's right.  It should be a kernel option that produces a duplicate
set of vfsops for the reverse-endian filesystem (REFFS?), either with
some glue in ffs_mount that automatically substitutes the second set
of vfsops if it detects a reversed magic number, or with a completely
manual mechanism that has to be invoked from user mode (i.e., mount -t
ffs -o reverse).  I prefer the automagic method because it'd be least
surprising to a naive user.  Obviously this would be an option - most
people probably don't need to be able to do this, but if you do need
to, you *really* need to, as I can attest from personal experience. :'(

			       _MelloN_