namespace documentation.

From: Eric W. Biederman
Date: Fri Dec 21 2012 - 17:58:55 EST


Rob Landley <rob@xxxxxxxxxxx> writes:

> On 12/21/2012 11:51:03 AM, Eric W. Biederman wrote:
>> Oleg Nesterov <oleg@xxxxxxxxxx> writes:
>>
>> > Eric. I understand that it is too late to discuss this. And yes, I
>> simply
>> > do not understand the problem space, I never used containers.
>> >
>> > But, stupid question. Let's ignore the pid_ns-specific oddities.
>> >
>> > 1. Ignoring setns(), why do we need /proc/pid/ns/ ?
>> >
>> > 2. Why setns() requires /proc/pid/ns/ ? IOW, why it can't be
>> >
>> > sys_setns(pid_t pid, int clone_flags)
>> > {
>> > truct task_struct *tsk = find_task_by_vpid(pid);
>> > struct nsproxy *target = get_nsproxy(tsk->nsproxy);
>> >
>> > new_nsproxy = create_new_namespaces(...);
>> >
>> > if (clone_flags & CLONE_NEWNS)
>> > mntns_install(...);
>> > if (clone_flags & CLONE_NEWIPC)
>> > ipcns_install(...);
>> > ...
>> > }
>> >
>> > I feel I missed something trivial, but what?
>>
>> It is a question of naming.
>>
>> The problem I set out to solve when all of this was introduced was how
>> to name namespaces without introducing yet another namespace.
>>
>> The solution to the naming problem that I finally found was to
>> introduce
>> something I could mount.
>
> Where might I find documentation on this? I'm aware of
> Documentation/namespaces but it's only got one file in it (about
> conflicts between namespace types). I'm aware of
> http://lxc.sourceforge.net/index.php/about/kernel-namespaces/ and
> http://lxc.sourceforge.net/man/ but that's mixed in with the
> implementation details of a particular userspace tool, and tends to lag
> the kernel significantly. (Those man pages were last updated in 2010,
> which if I recall was the last time I poked them about it.)

I'm not certain what you are asking about.

The man pages that I endeavour to keep reasonably current are.

man 5 proc
man 2 setns
man 2 unshare
man 2 clone

You won't get a design discussion but you will get a description of how
the existing pieces work. Of course now that I look it appears my
patches have not merged yet. But that is reasonable since my recent
changes did not merge until a few days ago.

There is also iproute2 it's man pages and source.

There is the kernel source.

There are the occassional lwn articles.

I believe there should be a reasonable amount of email in the mailing
list archives when talking about the design descision, and when I
introduced setns.

Eric
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/