From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out01.mta.xmission.com ([166.70.13.231]:58124 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751011AbcGXFX0 (ORCPT ); Sun, 24 Jul 2016 01:23:26 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Andrey Vagin Cc: LKML , James Bottomley , Serge Hallyn , Linux API , Linux Containers , Alexander Viro , "criu\@openvz.org" , linux-fsdevel , "Michael Kerrisk \(man-pages\)" References: <1468520419-28220-1-git-send-email-avagin@openvz.org> Date: Sun, 24 Jul 2016 00:10:21 -0500 In-Reply-To: (Andrey Vagin's message of "Thu, 14 Jul 2016 15:02:53 -0700") Message-ID: <87poq3liyq.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Andrey Vagin writes: > Hello, > > I forgot to add --cc-cover for git send-email, so everyone who is in > Cc got only a cover letter. All messages were sent in mail lists. > > Sorry for inconvenience. Mostly the code looked sensible. But I had a couple of issues. Resend this in September (when the merge window is closed and I am back from vacation) and I will give this a thorough review and get this merged. Or possibly next week if Linus releases another -rc > On Thu, Jul 14, 2016 at 11:20 AM, Andrey Vagin wrote: >> Each namespace has an owning user namespace and now there is not way >> to discover these relationships. >> >> Pid and user namepaces are hierarchical. There is no way to discover >> parent-child relationships too. >> >> Why we may want to know relationships between namespaces? >> >> One use would be visualization, in order to understand the running system. >> Another would be to answer the question: what capability does process X have to >> perform operations on a resource governed by namespace Y? >> >> One more use-case (which usually called abnormal) is checkpoint/restart. >> In CRIU we age going to dump and restore nested namespaces. >> >> There [1] was a discussion about which interface to choose to determing >> relationships between namespaces. >> >> Eric suggested to add two ioctl-s [2]: >>> Grumble, Grumble. I think this may actually a case for creating ioctls >>> for these two cases. Now that random nsfs file descriptors are bind >>> mountable the original reason for using proc files is not as pressing. >>> >>> One ioctl for the user namespace that owns a file descriptor. >>> One ioctl for the parent namespace of a namespace file descriptor. >> >> Here is an implementaions of these ioctl-s. >> >> [1] https://lkml.org/lkml/2016/7/6/158 >> [2] https://lkml.org/lkml/2016/7/9/101 >> >> Cc: "Eric W. Biederman" >> Cc: James Bottomley >> Cc: "Michael Kerrisk (man-pages)" >> Cc: "W. Trevor King" >> Cc: Alexander Viro >> Cc: Serge Hallyn Eric