From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 23 May 2001 05:35:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 23 May 2001 05:35:48 -0400 Received: from nat-pool-meridian.redhat.com ([199.183.24.200]:22102 "EHLO devserv.devel.redhat.com") by vger.kernel.org with ESMTP id ; Wed, 23 May 2001 05:35:33 -0400 Date: Wed, 23 May 2001 10:13:32 +0100 From: "Stephen C. Tweedie" To: "Peter J. Braam" Cc: Linus Torvalds , Andreas Dilger , Alexander Viro , Edgar Toernig , Ben LaHaise , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Stephen Tweedie Subject: Re: Why side-effects on open(2) are evil. (was Re: [RFD w/info-PATCH]device arguments from lookup) Message-ID: <20010523101332.B27177@redhat.com> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from braam@mountainviewdata.com on Tue, May 22, 2001 at 01:16:42PM -0600 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Tue, May 22, 2001 at 01:16:42PM -0600, Peter J. Braam wrote: > File system journal recovery can corrupt a snapshot, because it copies > data that needs to be preserved in a snapshot. Journal recovery may move data from the journal to other locations on the device, yes, but that doesn't change the logical contents of the filesystem. I don't see how that results in "corruption": the snapshot is (or at least, ought to be!) fully independent of the original version of the data, so such recovery should only be taking the snapshot from one consistent state to a different but equivalent state. > During journal replay such > data may be copied again, but the source can have new data already. Only if you are recovering a live volume, surely? And that is *guaranteed* to cause problems. --Stephen