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 874A5C433DB for ; Thu, 25 Mar 2021 02:00:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5416C61A1B for ; Thu, 25 Mar 2021 02:00:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233672AbhCYB7y (ORCPT ); Wed, 24 Mar 2021 21:59:54 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:13682 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231374AbhCYB7t (ORCPT ); Wed, 24 Mar 2021 21:59:49 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4F5SsR4NqLznTTn; Thu, 25 Mar 2021 09:57:15 +0800 (CST) Received: from [10.136.110.154] (10.136.110.154) by smtp.huawei.com (10.3.19.209) with Microsoft SMTP Server (TLS) id 14.3.498.0; Thu, 25 Mar 2021 09:59:43 +0800 Subject: Re: [PATCH] Revert "f2fs: give a warning only for readonly partition" To: Jaegeuk Kim CC: , , References: <20210323064155.12582-1-yuchao0@huawei.com> <107e671d-68ea-1a74-521e-ab2b6fe36416@huawei.com> From: Chao Yu Message-ID: <8b0b0782-a667-9edc-5ee9-98ac9f67b7b7@huawei.com> Date: Thu, 25 Mar 2021 09:59:43 +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: 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 2021/3/25 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. 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 >>>>> . >>>>> >>> . >>> > . >