From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751939AbbAUHFo (ORCPT ); Wed, 21 Jan 2015 02:05:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37998 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750812AbbAUHFm (ORCPT ); Wed, 21 Jan 2015 02:05:42 -0500 Message-ID: <1421823925.2789.3.camel@pluto.fritz.box> Subject: Re: [RFC PATCH 0/5] Second attempt at contained helper execution From: Ian Kent To: "J. Bruce Fields" Cc: Kernel Mailing List , David Howells , Oleg Nesterov , Trond Myklebust , Benjamin Coddington , Al Viro , Jeff Layton , "Eric W. Biederman" Date: Wed, 21 Jan 2015 15:05:25 +0800 In-Reply-To: <20150116152527.GD17315@fieldses.org> References: <20150114092704.30252.60446.stgit@pluto.fritz.box> <20150114215525.GB7071@fieldses.org> <20150114221011.GC7071@fieldses.org> <1421281572.2688.4.camel@pluto.fritz.box> <20150115162741.GA14902@fieldses.org> <1421370073.2630.4.camel@pluto.fritz.box> <20150116152527.GD17315@fieldses.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2015-01-16 at 10:25 -0500, J. Bruce Fields wrote: > On Fri, Jan 16, 2015 at 09:01:13AM +0800, Ian Kent wrote: > > On Thu, 2015-01-15 at 11:27 -0500, J. Bruce Fields wrote: > > > On Thu, Jan 15, 2015 at 08:26:12AM +0800, Ian Kent wrote: > > > > On Wed, 2015-01-14 at 17:10 -0500, J. Bruce Fields wrote: > > > > > > On Wed, Jan 14, 2015 at 05:32:22PM +0800, Ian Kent wrote: > > > > > > > There are other difficulties to tackle as well, such as how to decide > > > > > > > if contained helper execution is needed. For example, if a mount has > > > > > > > been propagated to a container or bound into the container tree (such > > > > > > > as with the --volume option of "docker run") the root init namespace > > > > > > > may need to be used and not the container namespace. > > > > > > > > > > I think you have to go through each of the existing upcall examples and > > > > > decide what's needed for each. > > > > > > > > > > At least for the nfsv4 idmapper I would've thought the namespace the > > > > > mount was done in would be the right choice, hence my previous question. > > > > > > > > Probably but you don't necessarily know what namespace the mount was > > > > done in. It may have been propagated from another namespace or (although > > > > I don't think it works yet) bound from another container using the > > > > volumes-from docker option. > > > > > > Name-id mappings should be associated with the superblock, I guess--so > > > don't you store a pointer to the right thing there? > > > > Quite possibly but my original point was, without an acceptable > > mechanism to execute the helper we can't know what might need to be done > > to use it. > > At least for me it would be easier to review if it came with at least > one example user. Haven't seen any negative responses but perhaps people are still away over Xmas. In the mean time it's probably a good idea to add some use cases to the series in case the approach is OK. I'll have a look at the nfsd code and see if I can spot the places. Ian