[9front] Re: RFNOMNT vs unmount

[Anthony Martin <ality@pbrane.org>]

> This can be done by treating cmount() almost like a union,
> but putting a flag within the union so that names() stops
> traversing the union early -- 'm->shadow'; unmount can
> then prune just the mounts with an newer 'freeze depth'
> than the current rfork depth.

You should make the change in your own kernel if you
have a need for it. Then, after a few weeks or more,
let us know what the consequences were. At that point
we can have a better discussion.

For example, one of my small experiments involves
removing a special case in namec, disallowing #/
from being attached, and manually setting up the
first attach in userinit.

It's a small but subtle change so I want to let it
brew for a while to see if there are any surprises.

(One of the things I've come to appreciate most about
Plan 9 over the last thirteen years is how amenable it
is to experimentation by a single person: it's small
enough so that anyone can have their own.)

Cheers,
  Anthony