Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261556AbVDZOdG (ORCPT ); Tue, 26 Apr 2005 10:33:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261555AbVDZOdG (ORCPT ); Tue, 26 Apr 2005 10:33:06 -0400 Received: from mail.shareable.org ([81.29.64.88]:8617 "EHLO mail.shareable.org") by vger.kernel.org with ESMTP id S261550AbVDZOdA (ORCPT ); Tue, 26 Apr 2005 10:33:00 -0400 Date: Tue, 26 Apr 2005 15:32:47 +0100 From: Jamie Lokier To: "Artem B. Bityuckiy" Cc: Ville Herva , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: filesystem transactions API Message-ID: <20050426143247.GF10833@mail.shareable.org> References: <20050424211942.GN13052@parcelfarce.linux.theplanet.co.uk> <20050426134629.GU16169@viasys.com> <20050426141426.GC10833@mail.shareable.org> <426E4EBD.6070104@oktetlabs.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <426E4EBD.6070104@oktetlabs.ru> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1383 Lines: 34 Artem B. Bityuckiy wrote: > Jamie Lokier wrote: > >I think I've wanted something like that for _years_ in unix. > > > >It's an old, old idea, and I've often wondered why we haven't implemented > >it. > > > > I thought it is possible to rather easily to implement this on top > of non-transactional FS (albeit I didn't try) and there is no need > to overcomplicate an FS. Just implement a specialized user-space > library and utilize it. No. A transaction means that _all_ processes will see the whole transaction or not. It does _not_ mean that only a subset of programs, which happen to link with a particular user-space library, will see it or not. For example, you can use transactions for distro package management: a whole update of a package would be a single transaction, so that at no time does any program see an inconsistent set of files. See why _every_ process in the system must have the same view? [ If you meant that you can implement it with a user-space library that every process in the system links to, that's true. But it would rather misses the point of having filesystems in the kernel at all :) ] -- Jamie - 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/