On 02/22, Chao Yu wrote:
> On 2019/2/22 10:40, Jaegeuk Kim wrote:
> > On 02/20, Chao Yu wrote:
> >> On 2019/2/20 15:25, Chao Yu wrote:
> >>> On 2019/2/20 15:08, Jaegeuk Kim wrote:
> >>>> 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 <jaeg...@kernel.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
> >>>
> >>> Cpu pipeline / compiler can make code out-of-order execution, which means:
> >>>
> >>> a = 1;
> >>> b = 2;
> >>>
> >>> may actually be executed as the order of:
> >>>
> >>> b = 2;
> >>> a = 1;
> >>>
> >>> So I doubt that below two line codes can be executed out-of-order:
> >>>
> >>> else
> >>> __clear_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); --- clear flag later
> >>>
> >>> if ()
> >>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); --- set flag first
> >
> > In spin_lock_irqsave()?
>
> Not sure in coverage of spin_lock, system can guarantee codes being
> executed orderly.
>
> >
> >>>
> >>>> flag, CP_QUOTA_NEED_FSCK_FLAG.
> >>>
> >>> Agreed, I've checked each operation in f2fs_quota_operations yesterday,
> >>> and
> >>> didn't find any missing places yet...
> >>
> >> Oh, I mean the place where set SBI_QUOTA_NEED_REPAIR, I also doubt we
> >> missed to set the flag.
> >
> > So, I may need to keep this patch untill we find the missing case. I'll
> > keep an
> > eye on this.
>
> Agreed, do you mind adding one line comment there to notice that?
/*
* TODO: we count on fsck.f2fs to clear this flag until we figure out
* missing cases which clear it incorrectly.
*/
I added like this.
Thanks,
>
> Thanks,
>
> >
> >>
> >> Thanks,
> >>
> >>>
> >>> Thanks,
> >>>
> >>>>
> >>>>>
> >>>>> Thanks,
> >>>>>
> >>>>>>
> >>>>>>>
> >>>>>>> Thanks,
> >>>>>>>
> >>>>>>>>
> >>>>>>>> if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR))
> >>>>>>>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
> >>>>>>>>
> >>>>>>
> >>>>>> .
> >>>>>>
> >>>>
> >>>> .
> >>>>
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Linux-f2fs-devel mailing list
> >>> linux-f2fs-de...@lists.sourceforge.net
> >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> >>>
> >>> .
> >>>
> >
> > .
> >
