From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f44.google.com ([209.85.218.44]:33013 "EHLO mail-oi0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754606AbcGHVjY (ORCPT ); Fri, 8 Jul 2016 17:39:24 -0400 Received: by mail-oi0-f44.google.com with SMTP id u201so76389971oie.0 for ; Fri, 08 Jul 2016 14:39:24 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <0e0dcbb3-73a4-0c5f-9978-67109d505b79@freenet.de> References: <96f8022e-4209-2498-62e4-50ccbee46e37@freenet.de> <0e0dcbb3-73a4-0c5f-9978-67109d505b79@freenet.de> From: Chris Murphy Date: Fri, 8 Jul 2016 15:39:23 -0600 Message-ID: Subject: Re: rollback to a snapshot and delete old top volume - missing of "@" To: Kai Herlemann Cc: Chris Murphy , Btrfs BTRFS Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Jul 8, 2016 at 2:08 PM, Kai Herlemann wrote: > If here any developers read along: I'd like to suggest that there's > automatically made a subvolume "@" by default, which is set as default > subvolume, or a tip to the distribution, that it would made sense to do that > with the installation. It would protect other users against confusion and > work like I had it. I think that upstream won't do that or recommend it. There is already a subvolume created at mkfs time, that's subvolid=5 (a.k.a. 0) and it is set as the default subvolume. I don't see the point in having two of them. If you want it, make it. If your distro wants it, it should be done in the installer, not mkfs. Further I think it's inappropriate to take 'btrfs sub set-default' away from the user. That is a user owned setting. It is not OK for some utility to assert domain over that setting, and depend on it for proper booting. It makes the entire boot process undiscoverable, breaks self-describing boot process which are simpler to understand and troubleshoot, in favor of secret decoder ring booting that now requires even more esoteric knowledge on the part of users. So I think it's a bad design. Instead those utilities should employ rootflags=subvol or subvolid to explicitly use a particular fs tree for rootfs, rather that hide this fact by using subvolume set-default. -- Chris Murphy