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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 F07F9C433E0 for ; Wed, 17 Mar 2021 23:50:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE89664F41 for ; Wed, 17 Mar 2021 23:50:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229943AbhCQXuQ (ORCPT ); Wed, 17 Mar 2021 19:50:16 -0400 Received: from mout.gmx.net ([212.227.15.18]:46219 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229472AbhCQXtx (ORCPT ); Wed, 17 Mar 2021 19:49:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1616024975; bh=uQy2IJrGeO8wIQItIx+2y0cV60IFwhc9/SJwP1eDCcg=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=W34pltpX5QRvgFlfI2zqVPVQ5TgTUYmwt9wvPXp4FNh7pXcQqhJs5QxTS2hClgXOH vd1eGmAKcJN77Qgq02zmLKXMDdILX6LegnvhYU0lg/mNLYZtqUGzC/LcmP4tk7V01e kflv/hjGwlutWZLDcXt++aBUsjYF+ZmEgiBbhmT0= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.net (mrgmx005 [212.227.17.184]) with ESMTPSA (Nemesis) id 1N2V0H-1lq4LB2NZf-013vtk; Thu, 18 Mar 2021 00:49:35 +0100 Subject: Re: [RFC] btrfs: Allow read-only mount with corrupted extent tree To: =?UTF-8?B?RMSBdmlzIE1vc8SBbnM=?= Cc: Btrfs BTRFS , clm@fb.com, Josef Bacik , dsterba@suse.com, "linux-kernel@vger.kernel.org" , Zygo Blaxell References: <20210317012054.238334-1-davispuh@gmail.com> <20a5d997-740a-ca57-8cbc-b88c1e34c8fc@gmx.com> From: Qu Wenruo Message-ID: <01129192-1b93-2a93-2edd-f29f544fe340@gmx.com> Date: Thu, 18 Mar 2021 07:49:29 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:cDEum2fnhp1094X7TyNDbCZKiOUpYAfBlfqYkKoVifF3GFQchOx uPIZzYj/BGDIv4HKjwnkxomz/mpQIPkTjS4AYtQZHeiIIIs84GKkBrYeICMEceGsGAjkPHy ysFCxzegVXbHU11EkGVrGeh+Ru8sr5vGqNP+C95VVJgsoquaKRCS19YhoddFFJDo6mkv0mb j1ygW7gH6gs2g/mtb/q8A== X-UI-Out-Filterresults: notjunk:1;V03:K0:RxC0gFOoub0=:LOoa0KPWouP4XZdXSth1wo Ahg3jyG0DAAJHQp9/PPJ8ckQLPpjXkZFpgOuENqJeB3t/u2HPIpddb1I1PINr+s8zyNHs9qho YyvtVpeWAUCO/ddMkk8eqiodu5KBrHYxf9JOahKcI2O61OGCMatnxAs+6F84CQF6yAQyWewZr tq0xBiHrlRz5HyVsW8hLOwxI3fBKcEoTrH8XVJkMh4iut77cLuvkr3JPpyBcx7q4IGB3cOpAF sQD1SVaP1yOG3Lm4W/GashTMJ+ojXAxUB1q8HYhsZ36jVyKtDpU1gSs60cxKYjIeaiWAe0BuO jFUiqods1xKQNVB4iod1xEYrHqW8+Ex7a6uIGHNi6PJYibRugH8MT0591umfFwafiw+1FEyae F+8IeY26MdpTzxA9g0SQuqijM4xbFY4+hrUOTzPNHVm1x9qmyHBvEXPBZS+oBCfYWydB7q/qj AAkcoIWi3U4vysfTIl1hb902WxPWQdIZZZwrl9+rsjLG9q969YXOXXNy32KC6cwlW+gp7w34W DiGjFMezqZYfYluFYaHwPj5PlqDbofDteoLSjIh0wHiIBwnYBoxivJanKYED58uzs0cDamshl SBUUMknxFvXpBoRRfnafJyBL267X8w5YG23UEOP7sxI1dK8/HPKCAd8SnFsB5jbhUmKCuihV9 yD6Dqi8xCPr8g2InlN/xpJrpVD4rGQGGlm0EN8zRzR27p4v3CvS/BuxAnkLF1mVt+pa7UHs4h 4OG27WTXYAdUxCT7yJ2IGonWqJWVQ2wLFMh5GQ111CZM+Ox/JI+emWDTyQtFWTUxQyAW04HM8 UFPfNLaEbldNFsIy7N+Liwcb+y43gp7tkaPMH5dWICZwcbGUN/iBreItN8X3iFQo8haNo33x+ Pxm6UiMXCUjE7LPUjI1jmzmbvkNACzCeyrXT4AewER1I6jwD1wt3xvB43RGlDfmPoIRmQinAZ v1K+TMCd8Qoj0OpxdcnGDD+qs8sp7etS4yNdTaWJHni2/EX4nut+1ndF1Dak51oAgejUPsPOr tgE9hU/uTiV2CMc5EJVISUZMITFrXwCYRvqeQs1keBi4uSTmCqXwdggD/YofwYXKzdHW8ayOZ iuP1fSX1yYTBtlakoxg/7JMr3KKfOLAVfOYT89iwhr+XOluKkmkLXGnusCn2ncSRIlEFz4NFg HfVYs/4bbkDJnZyNd+dfE0cGxlhpkbPhzeTxbjrCn49LQ32t5hJk5UHMfP3YhmM5Sk2WlnLAm XB3Ty924kV8bOYaQp Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/3/18 =E4=B8=8A=E5=8D=885:03, D=C4=81vis Mos=C4=81ns wrote: > tre=C5=A1d., 2021. g. 17. marts, plkst. 12:28 =E2=80=94 lietot=C4=81js Q= u Wenruo > () rakst=C4=ABja: >> >> >> >> On 2021/3/17 =E4=B8=8A=E5=8D=889:29, D=C4=81vis Mos=C4=81ns wrote: >>> tre=C5=A1d., 2021. g. 17. marts, plkst. 03:18 =E2=80=94 lietot=C4=81js= D=C4=81vis Mos=C4=81ns >>> () rakst=C4=ABja: >>>> >>>> Currently if there's any corruption at all in extent tree >>>> (eg. even single bit) then mounting will fail with: >>>> "failed to read block groups: -5" (-EIO) >>>> It happens because we immediately abort on first error when >>>> searching in extent tree for block groups. >>>> >>>> Now with this patch if `ignorebadroots` option is specified >>>> then we handle such case and continue by removing already >>>> created block groups and creating dummy block groups. >>>> >>>> Signed-off-by: D=C4=81vis Mos=C4=81ns >>>> --- >>>> fs/btrfs/block-group.c | 14 ++++++++++++++ >>>> fs/btrfs/disk-io.c | 4 ++-- >>>> fs/btrfs/disk-io.h | 2 ++ >>>> 3 files changed, 18 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c >>>> index 48ebc106a606..827a977614b3 100644 >>>> --- a/fs/btrfs/block-group.c >>>> +++ b/fs/btrfs/block-group.c >>>> @@ -2048,6 +2048,20 @@ int btrfs_read_block_groups(struct btrfs_fs_in= fo *info) >>>> ret =3D check_chunk_block_group_mappings(info); >>>> error: >>>> btrfs_free_path(path); >>>> + >>>> + if (ret =3D=3D -EIO && btrfs_test_opt(info, IGNOREBADROOTS)) = { >>>> + btrfs_put_block_group_cache(info); >>>> + btrfs_stop_all_workers(info); >>>> + btrfs_free_block_groups(info); >>>> + ret =3D btrfs_init_workqueues(info, NULL); >>>> + if (ret) >>>> + return ret; >>>> + ret =3D btrfs_init_space_info(info); >>>> + if (ret) >>>> + return ret; >>>> + return fill_dummy_bgs(info); >> >> When we hit bad things in extent tree, we should ensure we're mounting >> the fs RO, or we can't continue. >> >> And we should also refuse to mount back to RW if we hit such case, so >> that we don't need anything complex, just ignore the whole extent tree >> and create the dummy block groups. >> > > That's what we're doing here, `ignorebadroots` implies RO mount and > without specifying it doesn't mount at all. > >>> >>> This isn't that nice, but I don't really know how to properly clean up >>> everything related to already created block groups so this was easiest >>> way. It seems to work fine. >>> But looks like need to do something about replay log aswell because if >>> it's not disabled then it fails with: >>> >>> [ 1397.246869] BTRFS info (device sde): start tree-log replay >>> [ 1398.218685] BTRFS warning (device sde): sde checksum verify failed >>> on 21057127661568 wanted 0xd1506ed9 found 0x22ab750a level 0 >>> [ 1398.218803] BTRFS warning (device sde): sde checksum verify failed >>> on 21057127661568 wanted 0xd1506ed9 found 0x7dd54bb9 level 0 >>> [ 1398.218813] BTRFS: error (device sde) in __btrfs_free_extent:3054: >>> errno=3D-5 IO failure >>> [ 1398.218828] BTRFS: error (device sde) in >>> btrfs_run_delayed_refs:2124: errno=3D-5 IO failure >>> [ 1398.219002] BTRFS: error (device sde) in btrfs_replay_log:2254: >>> errno=3D-5 IO failure (Failed to recover log tree) >>> [ 1398.229048] BTRFS error (device sde): open_ctree failed >> >> This is because we shouldn't allow to do anything write to the fs if we >> have anything wrong in extent tree. >> > > This is happening when mounting read-only. My assumption is that it > only tries to replay in memory without writing anything to disk. > We lacks the check on log tree. Normally for such forced RO mount, log replay is not allowed. We should output a warning to prompt user to use nologreplay, and reject the mount. Thanks, Qu