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

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Message-ID: <20200528190010.GA162605@google.com>
Date:   Thu, 28 May 2020 12:00:10 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
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 05/28, Chao Yu wrote:
> 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.

Well, this is for shutdown test, and thus we don't need to sync up here.

> 
> > 
> >>
> >> 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
> >>> .
> >>>
> > .
> >