From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cantor2.suse.de ([195.135.220.15]:60326 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752221AbaDORlW (ORCPT ); Tue, 15 Apr 2014 13:41:22 -0400 Date: Tue, 15 Apr 2014 10:41:21 -0700 From: Mark Fasheh To: Filipe David Manana Cc: "linux-btrfs@vger.kernel.org" Subject: Re: [PATCH 1/4] Btrfs: send, bump stream version Message-ID: <20140415174121.GE7901@wotan.suse.de> Reply-To: Mark Fasheh References: <1397580021-26598-1-git-send-email-fdmanana@gmail.com> <20140415172800.GD7901@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Apr 15, 2014 at 06:34:38PM +0100, Filipe David Manana wrote: > On Tue, Apr 15, 2014 at 6:28 PM, Mark Fasheh wrote: > > On Tue, Apr 15, 2014 at 05:40:18PM +0100, Filipe David Borba Manana wrote: > >> This increases the send stream version from version 1 to version 2, adding > >> 2 new commands: > >> > >> 1) total data size - used to tell the receiver how much file data the stream > >> will add or update; > >> > >> 2) fallocate - used to pre-allocate space for files and to punch holes in files. > >> > >> This is preparation work for subsequent changes that implement the new features > >> (computing total data size and use fallocate for better performance). > > > > Are these changes compatible with software using the old stream version? We > > have snapshotting tools that are using send/recieve and it would be bad to > > change the ABI in incompatible ways underneath them. > > --Mark > > New versions of btrfs-progs (send stream v2 support) will still be > able to read and process v1 streams. Older btrfs-progs (v1 only) won't > be able to process the new commands. > Does this answers your question Mark? Yes it does thanks. Unfortunately though this is unacceptable behavior - kernel upgrades are not supposed to break existing userspace interfaces. In particular what will happen here is that the user will grab a new kernel and then find out that their fancy snapshotting software won't work any more. --Mark -- Mark Fasheh