From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CDADFC43613 for ; Fri, 21 Jun 2019 21:57:53 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A0DB720679 for ; Fri, 21 Jun 2019 21:57:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A0DB720679 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38091 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1heRXc-00018h-Pg for qemu-devel@archiver.kernel.org; Fri, 21 Jun 2019 17:57:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49812) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1heRQN-0007tG-Cw for qemu-devel@nongnu.org; Fri, 21 Jun 2019 17:50:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1heRQG-0006oq-SH for qemu-devel@nongnu.org; Fri, 21 Jun 2019 17:50:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57720) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1heRPd-0005MC-A8; Fri, 21 Jun 2019 17:49:41 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B26B6308624B; Fri, 21 Jun 2019 21:48:43 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-204-30.brq.redhat.com [10.40.204.30]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 266F319C4F; Fri, 21 Jun 2019 21:48:38 +0000 (UTC) To: John Snow , Vladimir Sementsov-Ogievskiy , "qemu-devel@nongnu.org" , "qemu-block@nongnu.org" References: <20190620010356.19164-1-jsnow@redhat.com> <20190620010356.19164-8-jsnow@redhat.com> <8fde15e1-9693-9e46-b5c8-0f657b1eebed@virtuozzo.com> <0eba7f8d-d1ed-fd4d-c417-346083cbed9c@virtuozzo.com> <05fd79a3-1828-f65b-118a-952aef26642a@virtuozzo.com> <460b3bf5-23e6-15f5-eb9e-1451ef246af9@virtuozzo.com> <341981f8-9900-2349-023c-ab9b6cf0e6c1@redhat.com> From: Max Reitz Openpgp: preference=signencrypt Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: <0556a380-a2ba-0893-ed22-e6698fea84d7@redhat.com> Date: Fri, 21 Jun 2019 23:48:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <341981f8-9900-2349-023c-ab9b6cf0e6c1@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="UYqT1MO4xtFaYF8hy7FQwdHzoHd4U8kcR" X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Fri, 21 Jun 2019 21:48:44 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 07/12] block/backup: add 'always' bitmap sync policy X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Fam Zheng , Xie Changlong , Markus Armbruster , Wen Congyang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --UYqT1MO4xtFaYF8hy7FQwdHzoHd4U8kcR Content-Type: multipart/mixed; boundary="xZ820jWvhMIIJw0yTDWROEvGwy2QUmMxz"; protected-headers="v1" From: Max Reitz To: John Snow , Vladimir Sementsov-Ogievskiy , "qemu-devel@nongnu.org" , "qemu-block@nongnu.org" Cc: Kevin Wolf , Fam Zheng , Wen Congyang , Xie Changlong , Markus Armbruster Message-ID: <0556a380-a2ba-0893-ed22-e6698fea84d7@redhat.com> Subject: Re: [Qemu-devel] [PATCH 07/12] block/backup: add 'always' bitmap sync policy References: <20190620010356.19164-1-jsnow@redhat.com> <20190620010356.19164-8-jsnow@redhat.com> <8fde15e1-9693-9e46-b5c8-0f657b1eebed@virtuozzo.com> <0eba7f8d-d1ed-fd4d-c417-346083cbed9c@virtuozzo.com> <05fd79a3-1828-f65b-118a-952aef26642a@virtuozzo.com> <460b3bf5-23e6-15f5-eb9e-1451ef246af9@virtuozzo.com> <341981f8-9900-2349-023c-ab9b6cf0e6c1@redhat.com> In-Reply-To: <341981f8-9900-2349-023c-ab9b6cf0e6c1@redhat.com> --xZ820jWvhMIIJw0yTDWROEvGwy2QUmMxz Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 21.06.19 22:58, John Snow wrote: >=20 >=20 > On 6/21/19 9:44 AM, Vladimir Sementsov-Ogievskiy wrote: [...] Just chiming in on this: >> "So on cancel and abort you synchronize bitmap too?" >=20 > I will concede that this means that if you ask for a bitmap backup with= > the 'always' policy and, for whatever reason change your mind about > this, there's no way to "cancel" the job in a manner that does not edit= > the bitmap at this point. >=20 > I do agree that this seems to go against the wishes of the user, becaus= e > we have different "kinds" of cancellations: >=20 > A) Cancellations that actually represent failures in transactions > B) Cancellations that represent genuine user intention >=20 > It might be nice to allow the user to say "No wait, please don't edit > that bitmap, I made a mistake!" So that =E2=80=9Calways=E2=80=9D doesn=E2=80=99t mean =E2=80=9Calways=E2=80= =9D? To me, that seems like not so good an idea. If the user uses always, they have to live with that. I had to live with calling =E2=80=9Crm=E2=80=9D on the wrong file before. Life=E2=80=99= s tough. In all seriousness: =E2=80=9CAlways=E2=80=9D is not something a user woul= d use, is it? It=E2=80=99s something for management tools. Why would they cancel becau= se =E2=80=9CThey made a mistake=E2=80=9D? Second, what=E2=80=99s the worst thing that may come out of such a mistak= e? Having to perform a full backup? If so, that doesn=E2=80=99t seem so bad= to me. It certainly doesn=E2=80=99t seem so bad to make an unrelated mechanic h= ave an influence on whether =E2=80=9Calways=E2=80=9D means =E2=80=9Calways=E2=80= =9D. Also, this cancel idea would only work for jobs where the bitmap mode does not come into play until the job is done, i.e. backup. I suppose if we want to have bitmap modes other than 'always' for mirror, that too would have to make a copy of the user-supplied bitmap, so there the bitmap mode would make a difference only at the end of the job, too, but who knows. And if it only makes a difference at the end of the job, you might as well just add a way to change a running job=E2=80=99s bitmap-mode. Max --xZ820jWvhMIIJw0yTDWROEvGwy2QUmMxz-- --UYqT1MO4xtFaYF8hy7FQwdHzoHd4U8kcR Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl0NULUACgkQ9AfbAGHV z0CGBwgAucM5Cr+czTFbEwniaLHvecS5nlyxzl06RoK5EQvUZ5GaLstrXS4qPSlA /IcRSgevMPZin99L5ZbvpPYeioI9PxYots1VHCgfv96veqlq68sR8n96HCTTCruk pQN6ivEWRntwSpbjijW3r0mp88taP4TV552p5MqYh/bLZvaJiXabHVuyugMuW/C1 asLVqfboNPm2mq5xuT54xfJ2wpG/bOwqwvu5XOPQ6/6LXmySFgyo2NTwb1QPzcFf 10EHQ1RK3sK3TKK1Zwqv3jqRuP46QsgLeVkEJ8uZ/lETbIYFM+tRvq14rhX9/otu bDnKAUQ8QgM9KdVwUg5tlZlCHPzqAQ== =LFIk -----END PGP SIGNATURE----- --UYqT1MO4xtFaYF8hy7FQwdHzoHd4U8kcR--