Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262027AbUC1Ane (ORCPT ); Sat, 27 Mar 2004 19:43:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262040AbUC1Ane (ORCPT ); Sat, 27 Mar 2004 19:43:34 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:31895 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S262027AbUC1Anc (ORCPT ); Sat, 27 Mar 2004 19:43:32 -0500 To: Jamie Lokier , =?iso-8859-1?q?J=F6rn?= Engel , Davide Libenzi , "Patrick J. LoPresti" , Linux Kernel Mailing List Subject: Re: [PATCH] cowlinks v2 References: <20040321125730.GB21844@wohnheim.fh-wedel.de> <20040321181430.GB29440@wohnheim.fh-wedel.de> <20040325174942.GC11236@mail.shareable.org> <20040325194303.GE11236@mail.shareable.org> <20040327102828.GA21884@mail.shareable.org> <20040327214238.GA23893@mail.shareable.org> From: ebiederm@xmission.com (Eric W. Biederman) Date: 27 Mar 2004 17:43:11 -0700 In-Reply-To: Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1173 Lines: 21 ebiederm@xmission.com (Eric W. Biederman) writes: > The addictive thing about the prototype implementation was that you > could do ``ln --cow / /some/other/directory'' and you would have an > atomic snapshot of your filesystem. Definitely not a feature for the > first implementation but certainly something to dream about. Addictive but broken by design. If any of the files inside your directory tree have hard links outside of the tree there is no way short of recursing through all of the subdirectories directories to tell if a given inode has is in use. Except in the special case where you are taking a cow copy of the entire filesystem. At which point a magic mount option is likely a better interface. Ok that simplifies the long term design a little more. cow directories cannot work correctly in all cases even when implemented in the kernel. So the directory walking must still be done in user space. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/