From: ebiederm@xmission•com (Eric W. Biederman)
To: Stanislav Kinsbursky <skinsbursky@parallels•com>
Cc: "Trond.Myklebust\@netapp.com" <Trond.Myklebust@netapp•com>,
"linux-nfs\@vger.kernel.org" <linux-nfs@vger•kernel.org>,
Pavel Emelianov <xemul@parallels•com>,
"neilb\@suse.de" <neilb@suse•de>,
"netdev\@vger.kernel.org" <netdev@vger•kernel.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger•kernel.org>,
James Bottomley <jbottomley@parallels•com>,
"bfields\@fieldses.org" <bfields@fieldses•org>,
"davem\@davemloft.net" <davem@davemloft•net>,
"devel\@openvz.org" <devel@openvz•org>
Subject: Re: [PATCH 01/11] SYSCTL: export root and set handling routines
Date: Wed, 11 Jan 2012 09:21:43 -0800 [thread overview]
Message-ID: <m1sjjm40k8.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <4F0D5A9E.5030501@parallels.com> (Stanislav Kinsbursky's message of "Wed, 11 Jan 2012 13:47:10 +0400")
Stanislav Kinsbursky <skinsbursky@parallels•com> writes:
> 11.01.2012 02:39, Eric W. Biederman пишет:
>> Stanislav Kinsbursky<skinsbursky@parallels•com> writes:
>>
>>> 03.01.2012 07:49, Eric W. Biederman пишет:
>>>> Stanislav Kinsbursky<skinsbursky@parallels•com> writes:
>>>>
>>>>> 19.12.2011 20:37, Eric W. Biederman пишет:
>>>>>> Stanislav Kinsbursky<skinsbursky@parallels•com> 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.
I am proposing treating /proc/sys like /proc/net is currently treated.
See below.
>>>> 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
(Using the current context is the desirable outcome for existing tools).
> 1) if CT has other pid namespace - then we just have broken link.
Assuming the process in question is not in the pid namespace available
to proc then yes you will indeed have a broken link. But a broken
link is only a problem for new applications that are doing something strange.
I am proposing treating /proc/sys like /proc/net has already been
treated. Aka move have the version of /proc/sys that relative to a
process be visible at: /proc/<pid>/sys, and with a compat symlink
from /proc/sys -> /proc/self/sys.
Just like has already been done with /proc/net.
Semantically this should be easy to understand, and about as backwards
compatible as it gets.
Eric
next prev parent reply other threads:[~2012-01-11 17:21 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-14 11:44 [PATCH 00/11] SUNRPC: make sysctl per network namespcase context Stanislav Kinsbursky
2011-12-14 11:44 ` [PATCH 01/11] SYSCTL: export root and set handling routines Stanislav Kinsbursky
[not found] ` <20111214104449.3991.61989.stgit-bi+AKbBUZKagILUCTcTcHdKyNwTtLsGr@public.gmane.org>
2011-12-17 22:25 ` Eric W. Biederman
[not found] ` <m1bor6rg39.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2011-12-19 8:56 ` Stanislav Kinsbursky
2011-12-19 10:15 ` Eric W. Biederman
[not found] ` <m18vm8g951.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2011-12-19 12:22 ` Stanislav Kinsbursky
[not found] ` <4EEF2C9A.8000403-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2011-12-19 16:37 ` Eric W. Biederman
[not found] ` <m1pqfkecw0.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2011-12-19 17:24 ` Stanislav Kinsbursky
[not found] ` <4EEF7364.8000407-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2012-01-03 3:49 ` Eric W. Biederman
[not found] ` <m1vcotigyb.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2012-01-10 10:38 ` Stanislav Kinsbursky
[not found] ` <4F0C150F.1020007-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2012-01-10 22:39 ` Eric W. Biederman
2012-01-11 9:47 ` Stanislav Kinsbursky
2012-01-11 17:21 ` Eric W. Biederman [this message]
[not found] ` <m1sjjm40k8.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2012-01-11 18:02 ` Stanislav Kinsbursky
2012-01-11 19:36 ` Eric W. Biederman
2012-01-12 9:17 ` Stanislav Kinsbursky
2011-12-14 11:44 ` [PATCH 02/11] SUNRPC: use syctl path instead of dummy parent table Stanislav Kinsbursky
[not found] ` <20111214103602.3991.20990.stgit-bi+AKbBUZKagILUCTcTcHdKyNwTtLsGr@public.gmane.org>
2011-12-14 11:45 ` [PATCH 03/11] SUNRPC: sysctl root for debug table introduced Stanislav Kinsbursky
2011-12-14 11:45 ` [PATCH 09/11] SUNRPC: remove xs_tcp_fin_timeout variable Stanislav Kinsbursky
2011-12-14 11:45 ` [PATCH 04/11] SUNRPC: per-net sysctl's set introduced Stanislav Kinsbursky
2011-12-14 11:45 ` [PATCH 05/11] SUNRPC: register debug sysctl table per network namespace Stanislav Kinsbursky
2011-12-14 11:45 ` [PATCH 06/11] SUNRPC: register xs_tunables " Stanislav Kinsbursky
2011-12-14 11:45 ` [PATCH 07/11] SUNRPC: xs tunables per network namespace introduced Stanislav Kinsbursky
2011-12-14 11:45 ` [PATCH 08/11] SUNRPC: use per-net xs tunables instead of static ones Stanislav Kinsbursky
2011-12-14 11:46 ` [PATCH 10/11] SUNRPC: allow debug flags modifications only from init_net Stanislav Kinsbursky
2011-12-14 11:46 ` [PATCH 11/11] SUNRPC: sysctl table for rpc_debug introduced Stanislav Kinsbursky
2012-02-07 11:44 ` [PATCH 00/11] SUNRPC: make sysctl per network namespcase context Stanislav Kinsbursky
[not found] ` <4F310E8E.5040608-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2012-02-07 13:21 ` Myklebust, Trond
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