Re: [PATCH 01/11] SYSCTL: export root and set handling routines

[Stanislav Kinsbursky]

11.01.2012 02:39, Eric W. Biederman ÐÐÑÐÑ:
> Stanislav Kinsbursky<skinsbursky@xxxxxxxxxxxxx>  writes:
>
> > 03.01.2012 07:49, Eric W. Biederman ÐÐÑÐÑ:
> > > Stanislav Kinsbursky<skinsbursky@xxxxxxxxxxxxx>   writes:
> > >
> > > > 19.12.2011 20:37, Eric W. Biederman ÐÐÑÐÑ:
> > > > > Stanislav Kinsbursky<skinsbursky@xxxxxxxxxxxxx>    writes:
> > > > >
> > > > > Doing that independently of the rest of the sysctls is pretty horrible
> > > > > and confusing to users.   What I am planning might suit your needs and
> > > > > if not we need to talk some more about how to get the vfs to do
> > > > > something reasonable.
> > > >
> > > > Ok, Eric. Would be glad to discuss your sysctls plans.
> > > > But actually you already know my needs: I would like to make sysctls work in the
> > > > way like sysfs does: i.e. content of files depends on mount maker -
> > > > not viewer.
> > >
> > > What drives the desire to have sysctls depend on the mount maker?
> >
> > Because we can (will, actually) have nested fs root's for containers. IOW,
> > container's root will be accessible from it's creator context. And I want to
> > tune container's fs from creators context.
>
> Tuning the child context from the parent context is an entirely
> reasonable thing to do.  To affect a namespace that is not yours
> the requirement is simply that we don't use current to lookup the
> sysctl.  So what I am proposing should work for your case.

Could you explain, what are you proposing?
I still don't know any details about it.

> > > Especially what drives that desire not to have it have a /proc/<pid>/sys
> > > directory that reflects the sysctls for a given process.
> >
> > This is not so important for me, where to access sysctl's. But I'm worrying
> > about backward compatibility. IOW, I'm afraid of changing path
> > "/proc/sys/sunprc/*" to "/proc/<pid>/sys/sunrpc". This would break a lot of
> > user-space programs.
>
> The part that keeps it all working is by adding a symlink from /proc/sys
> to /proc/self/sys.  That technique has worked well for /proc/net, and I
> don't expect there will be any problems with /proc/sys either.  It is
> possible but is very rare for the introduction of a symlink in a path
> to cause problems.

Probably I don't understand you, but as I see it now, symlink to "/proc/self/" 
is unacceptable because of the following:
1) will be used current context (any) instead of desired one
1) if CT has other pid namespace - then we just have broken link.

> Eric


--
Best regards,
Stanislav Kinsbursky
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