linux-kernel - Re: [PATCH 3/3] f2fs: fix to cover meta flush with cp

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Message-ID: <8e30b18d-bf8e-dd2f-35fa-08bbfd1b507e@huawei.com>
Date:   Thu, 28 May 2020 09:47:15 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>
Subject: Re: [PATCH 3/3] f2fs: fix to cover meta flush with cp_lock

On 2020/5/28 9:26, Jaegeuk Kim wrote:
> On 05/28, Chao Yu wrote:
>> On 2020/5/28 5:02, Jaegeuk Kim wrote:
>>> On 05/27, Chao Yu wrote:
>>>> meta inode page should be flushed under cp_lock, fix it.
>>>
>>> It doesn't matter for this case, yes?
>>
>> It's not related to discard issue.
> 
> I meant we really need this or not. :P

Yes, let's keep that rule: flush meta pages under cp_lock, otherwise
checkpoint flush order may be broken due to race, right? as checkpoint
should write 2rd cp park page after flushing all meta pages.

> 
>>
>> Now, I got some progress, I can reproduce that bug occasionally.
>>
>> Thanks,
>>
>>>
>>>>
>>>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>>>> ---
>>>>  fs/f2fs/file.c | 2 ++
>>>>  1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>> index f7de2a1da528..0fcae4d90074 100644
>>>> --- a/fs/f2fs/file.c
>>>> +++ b/fs/f2fs/file.c
>>>> @@ -2260,7 +2260,9 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
>>>>  		set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
>>>>  		break;
>>>>  	case F2FS_GOING_DOWN_METAFLUSH:
>>>> +		mutex_lock(&sbi->cp_mutex);
>>>>  		f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_META_IO);
>>>> +		mutex_unlock(&sbi->cp_mutex);
>>>>  		f2fs_stop_checkpoint(sbi, false);
>>>>  		set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
>>>>  		break;
>>>> -- 
>>>> 2.18.0.rc1
>>> .
>>>
> .
>