From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264719AbUEEQ2H (ORCPT ); Wed, 5 May 2004 12:28:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264722AbUEEQ2H (ORCPT ); Wed, 5 May 2004 12:28:07 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:54489 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S264719AbUEEQ2F (ORCPT ); Wed, 5 May 2004 12:28:05 -0400 Date: Wed, 5 May 2004 17:28:03 +0100 From: viro@parcelfarce.linux.theplanet.co.uk To: Nikita Danilov Cc: linux kernel mailing list Subject: Re: [PATCH-RFC] code for raceless /sys/fs/foofs/* Message-ID: <20040505162802.GN17014@parcelfarce.linux.theplanet.co.uk> References: <16536.61900.721224.492325@laputa.namesys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16536.61900.721224.492325@laputa.namesys.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 05, 2004 at 05:53:16PM +0400, Nikita Danilov wrote: > Hello, > > attached patch adds code necessary to safely export per-super-block > information in /sys/fs and /proc/fs. > > Common problem with exporting file system information in procfs or sysfs > is a race between method that inputs/outputs data and concurrent umount > of the super-block involved. Aside of the implementation questions (will comment later), there is an interface problem here. We end up allowing anyone who has sysfs mounted (in chroot jail, in limited namespace, etc.) to pin down _any_ reiser4 superblock, whether they have the thing itself mounted or not.