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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 D666CC282C4 for ; Tue, 12 Feb 2019 07:47:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD765206BA for ; Tue, 12 Feb 2019 07:47:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727247AbfBLHrj (ORCPT ); Tue, 12 Feb 2019 02:47:39 -0500 Received: from mx2.suse.de ([195.135.220.15]:40182 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725916AbfBLHrj (ORCPT ); Tue, 12 Feb 2019 02:47:39 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2249CAE60; Tue, 12 Feb 2019 07:47:37 +0000 (UTC) Subject: Re: [PATCH RFC] btrfs: Don't create SINGLE or DUP chunks for degraded rw mount To: Remi Gauvin , linux-btrfs References: <20190212070319.30619-1-wqu@suse.com> <964481b6-e761-8d0d-3ef1-cbe19dbfae9e@suse.de> <79f33db2-f39c-6bd6-4697-d9d9f6a704f1@georgianit.com> From: Qu Wenruo Openpgp: preference=signencrypt Autocrypt: addr=wqu@suse.de; prefer-encrypt=mutual; keydata= mQENBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAG0F1F1IFdlbnJ1byA8d3F1QHN1c2UuZGU+iQFUBBMBCAA+AhsDBQsJCAcCBhUICQoLAgQW AgMBAh4BAheAFiEELd9y5aWlW6idqkLhwj2R86El/qgFAlnVgp0FCQlmAm4ACgkQwj2R86El /qilmgf/cUq9kFQo577ku5gc6rFpVg68ublBwjYpwjw0b//xo+Wo1wm+RRbUGs+djSZAqw12 D4F3r0mBTI7abUCNWAbFkYZSAIFVi0DMkjypIVS7PSaEt04rM9VBTToE+YqU6WENeJ57R2p2 +hI0wZrBwxObdsdaOtxWtsp3bmhIbdqxSKrtXuRawy4KnQYcLuGzOce9okdlbAE0W3KHm1gQ oNAe6FX8nC9qo14m8LqEbThYH+qj4iCMlN8HIfbSx4F3e7nHZ+UAMW+E/lnMRkIB9Df+JyVd /NlXzIjZAggcWsqpx6D4wyAuexKWkiGQeUeArUNihAwXjmyqWPGmjVyIh+oC6LkBDQRZ1YGv AQgAqlPrYeBLMv3PAZ75YhQIwH6c4SNcB++hQ9TCT5gIQNw51+SQzkXIGgmzxMIS49cZcE4K Xk/kHw5hieQeQZa60BWVRNXwoRI4ib8okgDuMkD5Kz1WEyO149+BZ7HD4/yK0VFJGuvDJR8T 7RZwB69uVSLjkuNZZmCmDcDzS0c/SJOg5nkxt1iTtgUETb1wNKV6yR9XzRkrEW/qShChyrS9 fNN8e9c0MQsC4fsyz9Ylx1TOY/IF/c6rqYoEEfwnpdlz0uOM1nA1vK+wdKtXluCa79MdfaeD /dt76Kp/o6CAKLLcjU1Iwnkq1HSrYfY3HZWpvV9g84gPwxwxX0uXquHxLwARAQABiQE8BBgB CAAmFiEELd9y5aWlW6idqkLhwj2R86El/qgFAlnVga8CGwwFCQPCZwAACgkQwj2R86El/qgN 8Qf+M0vM2Idwm5txZZSs+/kSgcPxEwYmxUinnUJGyc0ZWYQXPl0cBetZon9El0naijGzNWvf HxIPB+ZFehk6Otgc78p1a3/xck/s1myFRLrmbbTJNoFiyL25ljcq0J8z5Zp4yuABL2RiLdaZ Pt/jfwjBHwGR+QKp6dD2qMrUWf9b7TFzYDMZXzZ2/eoIgtyjEelNBPrIgOFe24iKMjaGjd97 fJuRcBMHdhUAxvXQF1oRtd83JvYJ5OtwTd8MgkEfl+fo7HwWkuHbzc70L4fFKv2BowqFdaHy mId1ijGPGr46tuZ5a4cw/zbaPYx6fJ4sK9tSv/6V1QPNUdqml6hm6pfs6A== Message-ID: Date: Tue, 12 Feb 2019 15:47:32 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <79f33db2-f39c-6bd6-4697-d9d9f6a704f1@georgianit.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="PgCVyUh7rh7uPOQSMNzNx1ti85qcBP11P" Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --PgCVyUh7rh7uPOQSMNzNx1ti85qcBP11P Content-Type: multipart/mixed; boundary="oJiMkg69zxfsVrh4a2BMXSSgomFhcRojw"; protected-headers="v1" From: Qu Wenruo To: Remi Gauvin , linux-btrfs Message-ID: Subject: Re: [PATCH RFC] btrfs: Don't create SINGLE or DUP chunks for degraded rw mount References: <20190212070319.30619-1-wqu@suse.com> <964481b6-e761-8d0d-3ef1-cbe19dbfae9e@suse.de> <79f33db2-f39c-6bd6-4697-d9d9f6a704f1@georgianit.com> In-Reply-To: <79f33db2-f39c-6bd6-4697-d9d9f6a704f1@georgianit.com> --oJiMkg69zxfsVrh4a2BMXSSgomFhcRojw Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2019/2/12 =E4=B8=8B=E5=8D=883:43, Remi Gauvin wrote: > On 2019-02-12 2:22 a.m., Qu Wenruo wrote: >=20 >>> Does this mean you would rely on scrub/CSUM to repair the missing dat= a >>> if device is restored? >> >> Yes, just as btrfs usually does. >> >=20 > I don't really understand the implications of the problems with mountin= g > fs when single/dup data chunk are allocated on raid1, Consider this use case: One btrfs with 2 devices, RAID1 for data and metadata. One day devid 2 got failure, and before replacement arrives, user can only use devid 1 alone. (Maybe that's the root fs). Then new disk arrived, user replaced the missing device, caused SINGLE or DUP chunks on devid 1, and more importantly, some metadata/data is already in DUP/SINGLE chunks. Then some days later, devid 1 get failure too, now user is unable to mount the fs degraded RW any more, since SINGLE/DUP chunks are all on devid 1, and no way to replace devid 1. Thanks, Qu > but I would think > that would actually be a preferable situation than filling a drive with= > 'data' we know is completely bogus... converting single/dup data to rai= d > should be much faster than tripping on CSUM errors, and less prone to > missed errors? >=20 >=20 --oJiMkg69zxfsVrh4a2BMXSSgomFhcRojw-- --PgCVyUh7rh7uPOQSMNzNx1ti85qcBP11P Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAlxiehQACgkQwj2R86El /qiZhwf+Kc1i8i+TsvGAmwblsuEIsxpNYQ+oQjhZRYfnJpiwBl/Wekb/C125eTrY d88+Pa3BLtS9tk11GN9h4J8K0/ecrdGXyD1nhb87mOa9blx3BcRCiw4UhBuzdZv+ xzFEAralLKRjXTp7inIaOC4UWGkxHnVq9+ex95IqbnY4lwwxTC7/Xgol+knayj95 JryD14wN9A57J+2g+ROArD3b+L0IRN6JYxgnotzlvLLNHF21y8J2aLB+f7HCaEsV N6Ddt/BZZ+M/YSVW+zHGrLwrRROkn96RDd80ktQad3BiwIpJkdjVxb/fRmARzykj RUDXgLAwG0aen5voAL1e2P/5zXeiuw== =yVwQ -----END PGP SIGNATURE----- --PgCVyUh7rh7uPOQSMNzNx1ti85qcBP11P--