linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: don't clear CP_QUOTA_NEED_FSCK

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Message-ID: <20190220070855.GA91331@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Tue, 19 Feb 2019 23:08:55 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: don't clear CP_QUOTA_NEED_FSCK_FLAG

On 02/18, Chao Yu wrote:
> On 2019/2/16 12:55, Jaegeuk Kim wrote:
> > On 02/13, Chao Yu wrote:
> >> On 2019/2/12 10:33, Jaegeuk Kim wrote:
> >>> If we met this once, let fsck.f2fs clear this only.
> >>> Note that, this addresses all the subtle fault injection test.
> >>>
> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> >>> ---
> >>>  fs/f2fs/checkpoint.c | 2 --
> >>>  1 file changed, 2 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> >>> index 03fea4efd64b..10a3ada28715 100644
> >>> --- a/fs/f2fs/checkpoint.c
> >>> +++ b/fs/f2fs/checkpoint.c
> >>> @@ -1267,8 +1267,6 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>>  
> >>>  	if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH))
> >>>  		__set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
> >>> -	else
> >>> -		__clear_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
> >>
> >> I didn't get it, previously, if we didn't persist all quota file's data in
> >> checkpoint, then we will tag CP_QUOTA_NEED_FSCK_FLAG in CP area, but in current
> >> checkpoint, we have persisted all quota file's data, quota files are consistent
> >> with all other files in filesystem, why we can't remove this NEED_FSCK flag..?
> > 
> > I said it's subtle. So, I guessed 1) set CP_QUOTA_NEED_FSCK_FLAG, 2) clear
> 
> I know it's subtle... and I agreed we can fix it like this in upstream
> first, but in our product, it's not rare that we hit the
> QUOTA_SKIP_FLUSH(its value is 4) case, later we may encounter long latency
> caused by quota repairing of fsck.
> 
> > SBI_QUOTA_SKIP_FLUSH by checkpoint, 3) clear CP_QUOTA_NEED_FSCK_FLAG by another
> > checkpoint?
> 
> But later if QUOTA_NEED_REPAIR is set, we will set QUOTA_NEED_FSCK_FLAG
> again, right?
> 
> if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR))
> 	__set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
> 
> 
> So in order to figure out whether this is caused by out-of-order execution
> of below assignments:
> 
> 	if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH))
> 		__set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
> 	else
> 		__clear_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); --- clear flag later
> 
> 	if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR))
> 		__set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); --- set flag first
> 
> 
> Could you have a try:
> 
> 	if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR) ||
> 			is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH))
> 		__set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
> 	else
> 		__clear_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);

What does this mean? I'm in doubt we have a missing case where we clear this
flag, CP_QUOTA_NEED_FSCK_FLAG.

> 
> Thanks,
> 
> > 
> >>
> >> Thanks,
> >>
> >>>  
> >>>  	if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR))
> >>>  		__set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
> >>>
> > 
> > .
> >