Re: [9fans] A proposal regarding # in bind

["Ronald G. Minnich" <rminnich@lanl.gov>]

On Wed, 26 Feb 2003, Boyd Roberts wrote:

> Russ Cox wrote:
>
> >Here's a different proposal, also just an idea rather
> >than a complete proposal, but perhaps worth pursuing.
> >
> >
> Yes I was thinking of a similar (non file-system) interface
> that provided a descriptor to access/modify your namespace.
>
> Your idea certainly seems to be on the right track.
>
> I would imagine that if it's a fd it could then be used
> to pass a namespace to related and un-related processes.

This is actually how I did the old v9fs on Linux. To create a name space
you opened a "thing" that gave you an fd -- essentially the equivalent of
the mount device. To create other things (directories to mount things in,
etc.) in the name space you did ioctl (sorry, it was all I had) that set
up unions, mountpoints, etc., etc. To turn one of these off you closed the
fd for the corresponding thing, and it got removed from your name space.

Inheritance was easy. If you left the fd open for the kid, kid gets
namespace. If you didn't leave the fd open, kid gets clean name space.

It is pretty handy. The only issue is working out "what fd is what thing"
and I never had the time to make that easily figured out by users -- hence
I did not get to an equivalent of the ns command.

It all went away in the name of simplicity when we ported to 2.4, but I
still miss it sometimes!

ron