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Date:   Tue, 24 Aug 2021 10:09:42 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <chao@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: don't ignore writing pages on fsync
 during checkpoint=disable
Message-ID: <YSUn1j22s/kc+hWS@google.com>
References: <20210823170151.1434772-1-jaegeuk@kernel.org>
 <baa8a361-1a22-76a0-423d-4378178f7073@kernel.org>
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On 08/24, Chao Yu wrote:
> On 2021/8/24 1:01, Jaegeuk Kim wrote:
> > We must flush dirty pages when calling fsync() during checkpoint=disable.
> > Returning zero makes inode being clear, which fails to flush them when
> > enabling checkpoint back even by sync_inodes_sb().
> 
> Without this patch, file can be persisted via checkpoint=enable as well, my
> testcase:
> 
> - mount -t f2fs -o checkpoint=disable,checkpoint_nomerge /dev/pmem0 /mnt/f2fs/
> - cp file /mnt/f2fs/
> - xfs_io /mnt/f2fs/file -c "fdatasync"
> - mount -o remount,checkpoint=enable /dev/pmem0 /mnt/f2fs/
> - umount /mnt/f2fs
> - mount /dev/pmem0 /mnt/f2fs
> - md5sum file /mnt/f2fs/file
> chksum values are the same.
> 
> Am I missing something?

I'm trying to address one subtle issue where a file has only NEW_ADDR by the
checkpoint=disable test. I don't think this hurts anything but can see
some mitigation of the issue.

> 
> Thanks,