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=-15.3 required=3.0 tests=BAYES_00, 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 9FE91C433C1 for ; Sat, 27 Mar 2021 10:05:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61A15619F9 for ; Sat, 27 Mar 2021 10:05:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231173AbhC0KEh (ORCPT ); Sat, 27 Mar 2021 06:04:37 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:15075 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230427AbhC0KDZ (ORCPT ); Sat, 27 Mar 2021 06:03:25 -0400 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4F6vW03P3dz1BHQR; Sat, 27 Mar 2021 18:01:16 +0800 (CST) Received: from [10.136.110.154] (10.136.110.154) by smtp.huawei.com (10.3.19.210) with Microsoft SMTP Server (TLS) id 14.3.498.0; Sat, 27 Mar 2021 18:03:16 +0800 Subject: Re: [f2fs-dev] [PATCH] Revert "f2fs: give a warning only for readonly partition" From: Chao Yu To: Jaegeuk Kim CC: , References: <20210323064155.12582-1-yuchao0@huawei.com> <107e671d-68ea-1a74-521e-ab2b6fe36416@huawei.com> <8b0b0782-a667-9edc-5ee9-98ac9f67b7b7@huawei.com> <84688aac-75da-1226-df4d-47ac97087c51@huawei.com> <4b64099b-064d-43a8-461d-b54007f2c16c@huawei.com> Message-ID: Date: Sat, 27 Mar 2021 18:03:16 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <4b64099b-064d-43a8-461d-b54007f2c16c@huawei.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.136.110.154] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/3/27 9:52, Chao Yu wrote: > On 2021/3/27 1:30, Jaegeuk Kim wrote: >> On 03/26, Chao Yu wrote: >>> On 2021/3/26 9:19, Jaegeuk Kim wrote: >>>> On 03/26, Chao Yu wrote: >>>>> On 2021/3/25 9:59, Chao Yu wrote: >>>>>> On 2021/3/25 6:44, Jaegeuk Kim wrote: >>>>>>> On 03/24, Chao Yu wrote: >>>>>>>> On 2021/3/24 12:22, Jaegeuk Kim wrote: >>>>>>>>> On 03/24, Chao Yu wrote: >>>>>>>>>> On 2021/3/24 2:39, Jaegeuk Kim wrote: >>>>>>>>>>> On 03/23, Chao Yu wrote: >>>>>>>>>>>> This reverts commit 938a184265d75ea474f1c6fe1da96a5196163789. >>>>>>>>>>>> >>>>>>>>>>>> Because that commit fails generic/050 testcase which expect failure >>>>>>>>>>>> during mount a recoverable readonly partition. >>>>>>>>>>> >>>>>>>>>>> I think we need to change generic/050, since f2fs can recover this partition, >>>>>>>>>> >>>>>>>>>> Well, not sure we can change that testcase, since it restricts all generic >>>>>>>>>> filesystems behavior. At least, ext4's behavior makes sense to me: >>>>>>>>>> >>>>>>>>>> journal_dev_ro = bdev_read_only(journal->j_dev); >>>>>>>>>> really_read_only = bdev_read_only(sb->s_bdev) | journal_dev_ro; >>>>>>>>>> >>>>>>>>>> if (journal_dev_ro && !sb_rdonly(sb)) { >>>>>>>>>> ext4_msg(sb, KERN_ERR, >>>>>>>>>> "journal device read-only, try mounting with '-o ro'"); >>>>>>>>>> err = -EROFS; >>>>>>>>>> goto err_out; >>>>>>>>>> } >>>>>>>>>> >>>>>>>>>> if (ext4_has_feature_journal_needs_recovery(sb)) { >>>>>>>>>> if (sb_rdonly(sb)) { >>>>>>>>>> ext4_msg(sb, KERN_INFO, "INFO: recovery " >>>>>>>>>> "required on readonly filesystem"); >>>>>>>>>> if (really_read_only) { >>>>>>>>>> ext4_msg(sb, KERN_ERR, "write access " >>>>>>>>>> "unavailable, cannot proceed " >>>>>>>>>> "(try mounting with noload)"); >>>>>>>>>> err = -EROFS; >>>>>>>>>> goto err_out; >>>>>>>>>> } >>>>>>>>>> ext4_msg(sb, KERN_INFO, "write access will " >>>>>>>>>> "be enabled during recovery"); >>>>>>>>>> } >>>>>>>>>> } >>>>>>>>>> >>>>>>>>>>> even though using it as readonly. And, valid checkpoint can allow for user to >>>>>>>>>>> read all the data without problem. >>>>>>>>>> >>>>>>>>>>>> if (f2fs_hw_is_readonly(sbi)) { >>>>>>>>>> >>>>>>>>>> Since device is readonly now, all write to the device will fail, checkpoint can >>>>>>>>>> not persist recovered data, after page cache is expired, user can see stale data. >>>>>>>>> >>>>>>>>> My point is, after mount with ro, there'll be no data write which preserves the >>>>>>>>> current status. So, in the next time, we can recover fsync'ed data later, if >>>>>>>>> user succeeds to mount as rw. Another point is, with the current checkpoint, we >>>>>>>>> should not have any corrupted metadata. So, why not giving a chance to show what >>>>>>>>> data remained to user? I think this can be doable only with CoW filesystems. >>>>>>>> >>>>>>>> I guess we're talking about the different things... >>>>>>>> >>>>>>>> Let me declare two different readonly status: >>>>>>>> >>>>>>>> 1. filesystem readonly: file system is mount with ro mount option, and >>>>>>>> app from userspace can not modify any thing of filesystem, but filesystem >>>>>>>> itself can modify data on device since device may be writable. >>>>>>>> >>>>>>>> 2. device readonly: device is set to readonly status via 'blockdev --setro' >>>>>>>> command, and then filesystem should never issue any write IO to the device. >>>>>>>> >>>>>>>> So, what I mean is, *when device is readonly*, rather than f2fs mountpoint >>>>>>>> is readonly (f2fs_hw_is_readonly() returns true as below code, instead of >>>>>>>> f2fs_readonly() returns true), in this condition, we should not issue any >>>>>>>> write IO to device anyway, because, AFAIK, write IO will fail due to >>>>>>>> bio_check_ro() check. >>>>>>> >>>>>>> In that case, mount(2) will try readonly, no? >>>>>> >>>>>> Yes, if device is readonly, mount (2) can not mount/remount device to rw >>>>>> mountpoint. >>>>> >>>>> Any other concern about this patch? >>>> >>>> Indeed we're talking about different things. :) >>>> >>>> This case is mount(ro) with device(ro) having some data to recover. >>>> My point is why not giving a chance to mount(ro) to show the current data >>>> covered by a valid checkpoint. This doesn't change anything in the disk, >>> Got your idea. >>> >>> IMO, it has potential issue in above condition: >>> >>>>>>>>>> Since device is readonly now, all write to the device will fail, checkpoint can >>>>>>>>>> not persist recovered data, after page cache is expired, user can see stale data. >>> >>> e.g. >>> >>> Recovery writes one inode and then triggers a checkpoint, all writes fail >> >> I'm confused. Currently we don't trigger the roll-forward recovery. > > Oh, my miss, sorry. :-P > > My point is in this condition we can return error and try to notice user to > mount with disable_roll_forward or norecovery option, then at least user can > know he should not expect last fsynced data in newly mounted image. > > Or we can use f2fs_recover_fsync_data() to check whether there is fsynced data, > if there is no such data, then let mount() succeed. Something like this, maybe: --- fs/f2fs/super.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 954b1fe97d67..5e1a1caf412d 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -3966,10 +3966,19 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) * previous checkpoint was not done by clean system shutdown. */ if (f2fs_hw_is_readonly(sbi)) { - if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) - f2fs_err(sbi, "Need to recover fsync data, but write access unavailable"); - else - f2fs_info(sbi, "write access unavailable, skipping recovery"); + if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) { + err = f2fs_recover_fsync_data(sbi, true); + if (!err) + goto reset_checkpoint; + else if (err < 0) + goto free_meta; + err = -EROFS; + f2fs_err(sbi, "Need to recover fsync data, but " + "write access unavailable, please try " + "mount w/ disable_roll_forward or norecovery"); + goto free_meta; + } + f2fs_info(sbi, "write access unavailable, skipping recovery"); goto reset_checkpoint; } -- 2.29.2 Thanks, > > Thanks, > >> >>> due to device is readonly, once inode cache is reclaimed by vm, user will see >>> old inode when reloading it, or even see corrupted fs if partial meta inode's >>> cache is expired. >>> >>> Thoughts? >>> >>> Thanks, >>> >>>> and in the next time, it allows mount(rw|ro) with device(rw) to recover >>>> the data seamlessly. >>>> >>>>> >>>>> Thanks, >>>>> >>>>>> >>>>>> Thanks, >>>>>> >>>>>>> >>>>>>> # blockdev --setro /dev/vdb >>>>>>> # mount -t f2fs /dev/vdb /mnt/test/ >>>>>>> mount: /mnt/test: WARNING: source write-protected, mounted read-only. >>>>>>> >>>>>>>> >>>>>>>> if (f2fs_hw_is_readonly(sbi)) { >>>>>>>> - if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) { >>>>>>>> - err = -EROFS; >>>>>>>> + if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) >>>>>>>> f2fs_err(sbi, "Need to recover fsync data, but write access unavailable"); >>>>>>>> - goto free_meta; >>>>>>>> - } >>>>>>>> - f2fs_info(sbi, "write access unavailable, skipping recovery"); >>>>>>>> + else >>>>>>>> + f2fs_info(sbi, "write access unavailable, skipping recovery"); >>>>>>>> goto reset_checkpoint; >>>>>>>> } >>>>>>>> >>>>>>>> For the case of filesystem is readonly and device is writable, it's fine >>>>>>>> to do recovery in order to let user to see fsynced data. >>>>>>>> >>>>>>>> Thanks, >>>>>>>> >>>>>>>>> >>>>>>>>>> >>>>>>>>>> Am I missing something? >>>>>>>>>> >>>>>>>>>> Thanks, >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Fixes: 938a184265d7 ("f2fs: give a warning only for readonly partition") >>>>>>>>>>>> Signed-off-by: Chao Yu >>>>>>>>>>>> --- >>>>>>>>>>>> fs/f2fs/super.c | 8 +++++--- >>>>>>>>>>>> 1 file changed, 5 insertions(+), 3 deletions(-) >>>>>>>>>>>> >>>>>>>>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c >>>>>>>>>>>> index b48281642e98..2b78ee11f093 100644 >>>>>>>>>>>> --- a/fs/f2fs/super.c >>>>>>>>>>>> +++ b/fs/f2fs/super.c >>>>>>>>>>>> @@ -3952,10 +3952,12 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) >>>>>>>>>>>> * previous checkpoint was not done by clean system shutdown. >>>>>>>>>>>> */ >>>>>>>>>>>> if (f2fs_hw_is_readonly(sbi)) { >>>>>>>>>>>> - if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) >>>>>>>>>>>> + if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) { >>>>>>>>>>>> + err = -EROFS; >>>>>>>>>>>> f2fs_err(sbi, "Need to recover fsync data, but write access unavailable"); >>>>>>>>>>>> - else >>>>>>>>>>>> - f2fs_info(sbi, "write access unavailable, skipping recovery"); >>>>>>>>>>>> + goto free_meta; >>>>>>>>>>>> + } >>>>>>>>>>>> + f2fs_info(sbi, "write access unavailable, skipping recovery"); >>>>>>>>>>>> goto reset_checkpoint; >>>>>>>>>>>> } >>>>>>>>>>>> -- >>>>>>>>>>>> 2.29.2 >>>>>>>>>>> . >>>>>>>>>>> >>>>>>>>> . >>>>>>>>> >>>>>>> . >>>>>>> >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> Linux-f2fs-devel mailing list >>>>>> Linux-f2fs-devel@lists.sourceforge.net >>>>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >>>>>> . >>>>>> >>>> . >>>> >> . >> > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > . >