From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ram Pai Subject: Re: how to show propagation state for mounts Date: Wed, 20 Feb 2008 11:42:28 -0800 Message-ID: <1203536549.28525.24.camel@ram.us.ibm.com> References: <20080220160422.GY27894@ZenIV.linux.org.uk> <20080220163102.GA27736@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Al Viro , Miklos Szeredi , linux-fsdevel@vger.kernel.org To: Matthew Wilcox Return-path: Received: from e32.co.us.ibm.com ([32.97.110.150]:39493 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756576AbYBTTlW (ORCPT ); Wed, 20 Feb 2008 14:41:22 -0500 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e32.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id m1KJevIo011184 for ; Wed, 20 Feb 2008 14:40:57 -0500 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m1KJfCQt101670 for ; Wed, 20 Feb 2008 12:41:12 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m1KJfClZ013055 for ; Wed, 20 Feb 2008 12:41:12 -0700 In-Reply-To: <20080220163102.GA27736@parisc-linux.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, 2008-02-20 at 09:31 -0700, Matthew Wilcox wrote: > On Wed, Feb 20, 2008 at 04:04:22PM +0000, Al Viro wrote: > > It's less about the form of representation (after all, we generate poll > > events when contents of that sucker changes, so one *can* get a consistent > > snapshot of the entire thing) and more about having it self-contained > > when we have namespaces in the play. > > > > IOW, the data in there should give answers to questions that make sense. > > "Do events get propagated from this vfsmount I have to that vfsmount I have?" > > is a meaningful one; ditto for "are events here propagated to somewhere I > > don't see?" or "are events getting propagated here from somewhere I don't > > see?". > > Why do those last two questions deserve an answer? How will a person's > or application's behaviour be affected by whether a change will > propagate to something they don't know about and can't see? Well, I do not want to be surprised to see a mount suddenly show up in my namespace because of some action by some other user in some other namespace. Its going to happen anyway if the namespace is forked of a namespace that had shared mounts in them. However I would rather prefer to know in advance the spots (mounts) where such surprises can happen. Also I would prefer to know how my actions will effect mounts in other namespaces. RP >