Re: [9fans] v9fs question

[erik quanstrom <quanstro@quanstro.net>]

On Mon Jul 13 20:43:21 EDT 2009, newsham@lava.net wrote:
> > Could we solve this by making private mounts the default (or only
> > allowed) behavior?
>
> I've wondered if there's enough context information
> that the fs driver could "fake" per-process mount points
> directly.  For example, I mount v9fs on /n.  Initially
> I have no remote mounts in there, but I have /n/ctl.
> I echo "mount 1.2.3.4 foo" to /n/ctl and now I have
> /n/foo which is served from 1.2.3.4 for my process, but
> other processes dont see /n/foo.  I fork a child and it
> gets /n/foo, too.  In the child I mount another directory
> and the changes are seen in both the child and the parent.
> I then echo "copyns" to /n/ctl and then perform another
> mount and the new mount is visible in the child process but
> not the parent process.

i believe you've described the speaks-for relationship
in plan 9.

>
> This would of course require that the [linux] kernel filesystem
> (probably vfs layer) could distinguish who made a filesystem
> request.  It might also require some hackery to get the
> inheritance on fork working properly (although perhaps some
> existing unix mechanism could be reused for this purpose, such
> as session and process group stuff).

how could the fs record the creat without having the uid/gid?

- erik