types. when using mount(8) with '-a', do _NOT_ remount file systems
that have been mounted once already. (This cannot be 100% precisely
determined (thanks to mfs, union fs, and similar file systems which
don't use a 'real' mounted-from node), and changed options cannot be updated
with mount -a. however, options wouldn't be updated with the old mount -a
anyway, and this solves several annoyances.
cgd