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From: Chao Yu <chao@kernel.org>
To: Jaegeuk Kim <jaegeuk@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
Date: Wed, 25 Aug 2021 07:30:22 +0800	[thread overview]
Message-ID: <d0a48947-e4df-9b0f-735e-6b306a64c4fe@kernel.org> (raw)
In-Reply-To: <YSUn1j22s/kc+hWS@google.com>

On 2021/8/25 1:09, Jaegeuk Kim wrote:
> 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

Oh, I doubt that we may failed to flush data of all inodes due to failures during
sync_inodes_sb(), additionally, how about adding retry logic for sync_inodes_sb()
if there is still any F2FS_DIRTY_DATA reference counts in f2fs_enable_checkpoint()
to mitigate this issue, e.g.:

f2fs_enable_checkpoint()

	do {
		sync_inode_sb();
		congestion_wait();
		cond_resched();
	} while (get_pages(sbi, F2FS_DIRTY_DATA) && retry_count--)

	if (get_pages(sbi, F2FS_DIRTY_DATA))
		f2fs_warm("");

Thanks,

> checkpoint=disable test. I don't think this hurts anything but can see
> some mitigation of the issue.
> 
>>
>> Thanks,

  reply	other threads:[~2021-08-24 23:30 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23 17:01 Jaegeuk Kim
2021-08-24  1:08 ` [f2fs-dev] " Chao Yu
2021-08-24 17:09   ` Jaegeuk Kim
2021-08-24 23:30     ` Chao Yu [this message]
2021-08-25 21:31       ` Jaegeuk Kim
2021-08-25 21:33 ` [PATCH v2] " Jaegeuk Kim
2021-08-26  0:16   ` [f2fs-dev] " Chao Yu
2021-08-26 16:52   ` [f2fs-dev] [PATCH v3] " Jaegeuk Kim
2021-08-27 14:36     ` Chao Yu

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