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Fri, 26 Mar 2021 01:20:00 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 915F161A2B; Fri, 26 Mar 2021 01:19:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616721585; bh=aUjj7g5wXra24mXyN2v00BSWGgNE2xAbToirjTuSRyQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qaBKcxHKSJOULmojprkywXDnbsrBPpEVfGysVTGuubOcRCUsnfYISDK/XjI974ran qUAoCpqSNM3NRS7ipjIrR800VGhubMqlai3o6toiTx51DvN5Keyt6tJ68nUKImhd1/ B5gwU5M5YutxdNujlWjPiDT+Hz+fV1irGIlti3lK9sL40isVZZ7Bo+D+jB1VTTLi/S nGIqgvFALnb3jHEgC6XKBcu9K0olxGKzOiwwcGo3guXE1D4WocEKoFRX6/YzdgKHvv GHFTU/6s1xdKTmLJUjZYa/bOpz5CzxTwQxu9MWaVvpr0u61sQyqY3xXtwNfzBE6XZb fsX5nYj7PYbIg== Date: Thu, 25 Mar 2021 18:19:44 -0700 From: Jaegeuk Kim To: Chao Yu Message-ID: References: <20210323064155.12582-1-yuchao0@huawei.com> <107e671d-68ea-1a74-521e-ab2b6fe36416@huawei.com> <8b0b0782-a667-9edc-5ee9-98ac9f67b7b7@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Headers-End: 1lPb8l-00Bzk2-Vt Subject: Re: [f2fs-dev] [PATCH] Revert "f2fs: give a warning only for readonly partition" X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net 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, 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