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[209.132.180.67]) by mx.google.com with ESMTP id e8-v6si4462829plb.83.2018.08.03.14.27.52; Fri, 03 Aug 2018 14:28:07 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732104AbeHCXYn (ORCPT + 99 others); Fri, 3 Aug 2018 19:24:43 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58256 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729828AbeHCXYn (ORCPT ); Fri, 3 Aug 2018 19:24:43 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A1AA04219DD8; Fri, 3 Aug 2018 21:26:41 +0000 (UTC) Received: from agk-dp.fab.redhat.com (agk-dp.fab.redhat.com [10.33.15.10]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BD6F52026D65; Fri, 3 Aug 2018 21:26:39 +0000 (UTC) Received: from agk by agk-dp.fab.redhat.com with local (Exim 4.69) (envelope-from ) id 1flhao-0008JK-DT; Fri, 03 Aug 2018 22:26:38 +0100 Date: Fri, 3 Aug 2018 22:26:38 +0100 From: Alasdair G Kergon To: Linus Torvalds Cc: Theodore Ts'o , Mike Snitzer , Jens Axboe , Sagi Grimberg , Linux Kernel Mailing List , linux-block , dm-devel@redhat.com, Ilya Dryomov , wgh@torlan.ru, Zdenek Kabelac Subject: Re: [dm-devel] LVM snapshot broke between 4.14 and 4.16 Message-ID: <20180803212638.GC31444@agk-dp.fab.redhat.com> Mail-Followup-To: Linus Torvalds , Theodore Ts'o , Mike Snitzer , Jens Axboe , Sagi Grimberg , Linux Kernel Mailing List , linux-block , dm-devel@redhat.com, Ilya Dryomov , wgh@torlan.ru, Zdenek Kabelac References: <1ec0a220-d5b0-1c27-e63b-c4d3f4ce9d77@torlan.ru> <20180803133102.GA3092@redhat.com> <20180803152034.GD32066@thunk.org> <20180803195636.GA31444@agk-dp.fab.redhat.com> <20180803200817.GB31444@agk-dp.fab.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Red Hat UK Ltd. Registered in England and Wales, number 03798903. Registered Office: Peninsular House, 30-36 Monument Street, 4th Floor, London, England, EC3R 8NB. User-Agent: Mutt/1.5.18 (2008-05-17) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Fri, 03 Aug 2018 21:26:41 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Fri, 03 Aug 2018 21:26:41 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'agk@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 03, 2018 at 01:42:52PM -0700, Linus Torvalds wrote: > So even in case 2, we do try to avoid versioning. More often we add a > new flag, and say "hey, if you want the new behavior, use the new flag > to say so". Not versioning, but explicit "I want the new behavior" There are spare flags available in dm-ioctl - one could indeed turn on the new more-restrictive behaviour. Alasdair