From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756334AbZBWXtZ (ORCPT ); Mon, 23 Feb 2009 18:49:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752631AbZBWXtQ (ORCPT ); Mon, 23 Feb 2009 18:49:16 -0500 Received: from e31.co.us.ibm.com ([32.97.110.149]:51845 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752042AbZBWXtQ (ORCPT ); Mon, 23 Feb 2009 18:49:16 -0500 Date: Mon, 23 Feb 2009 17:49:11 -0600 From: "Serge E. Hallyn" To: Dave Hansen Cc: Ingo Molnar , containers , "linux-kernel@vger.kernel.org" , Oren Laadan , Alexey Dobriyan Subject: Re: [RFC][PATCH 3/5] check files for checkpointability Message-ID: <20090223234911.GB2590@us.ibm.com> References: <20090219182007.B4B47C1F@kernel> <20090219182009.1A3E8860@kernel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090219182009.1A3E8860@kernel> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting Dave Hansen (dave@linux.vnet.ibm.com): > > Introduce a files_struct counter to indicate whether a particular > file_struct has ever contained a file which can not be > checkpointed. This flag is a one-way trip; once it is set, it may > not be unset. > > We assume at allocation that a new files_struct is clean and may > be checkpointed. However, as soon as it has had its files filled > from its parent's, we check it for real in __scan_files_for_cr(). > At that point, we mark it if it contained any uncheckpointable > files. > > We also check each 'struct file' when it is installed in a fd > slot. This way, if anyone open()s or managed to dup() an > unsuppored file, we can catch it. So what is the point of tagging the files_struct counter and making it a one-way trip? Why not just check every file at checkpoint time? -serge