🚀 go-pugleaf

As has been noted on sun-spots previously, when one dumps an active file
system, one runs (a somewhat low, but non-neglible) risk of various
nasties happening and causing some inconsistencies in the dump tape.

I don't recall anybody mentioning the possibility of briefly downing the
system only to remount the file system being dumped on the file server
READ-ONLY.  We've resorted to doing this a couple of times at Berkeley,
when a conference was scheduled immediately following a school break, so
that the system HAD to be available for reference, but we also HAD to get
full dumps done.  This way, the file system remains unchanged for the
duration of the dump (which does take appreciably longer, multiuser), but
users can have emergency access.