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Date:   Mon, 1 Feb 2021 12:11:23 -0800
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Daeho Jeong <daeho43@gmail.com>
Cc:     Chao Yu <chao@kernel.org>, Daeho Jeong <daehojeong@google.com>,
        kernel-team@android.com, linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: fix checkpoint mount option wrong
 combination
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On 02/01, Daeho Jeong wrote:
> Actually, I think we need to select one among them, disable, enable
> and merge. I realized my previous understanding about that was wrong.
> In that case of "checkpoint=merge,checkpoint=enable", the last option
> will override the ones before that.
> This is how the other mount options like fsync_mode, whint_mode and etc.
> So, the answer will be "checkpoint=enable". What do you think?

We need to clarify a bit more. :)

mount checkpoint=disable,checkpoint=merge
remount checkpoint=enable,checkpoint=merge

Then, is it going to enable checkpoint with a thread?

> 
> 
> 
> 2021년 2월 1일 (월) 오후 9:40, Chao Yu <chao@kernel.org>님이 작성:
> >
> > On 2021/2/1 8:06, Daeho Jeong wrote:
> > > From: Daeho Jeong <daehojeong@google.com>
> > >
> > > As checkpoint=merge comes in, mount option setting related to
> > > checkpoint had been mixed up. Fixed it.
> > >
> > > Signed-off-by: Daeho Jeong <daehojeong@google.com>
> > > ---
> > >   fs/f2fs/super.c | 11 +++++------
> > >   1 file changed, 5 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > > index 56696f6cfa86..8231c888c772 100644
> > > --- a/fs/f2fs/super.c
> > > +++ b/fs/f2fs/super.c
> > > @@ -930,20 +930,25 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
> > >                               return -EINVAL;
> > >                       F2FS_OPTION(sbi).unusable_cap_perc = arg;
> > >                       set_opt(sbi, DISABLE_CHECKPOINT);
> > > +                     clear_opt(sbi, MERGE_CHECKPOINT);
> > >                       break;
> > >               case Opt_checkpoint_disable_cap:
> > >                       if (args->from && match_int(args, &arg))
> > >                               return -EINVAL;
> > >                       F2FS_OPTION(sbi).unusable_cap = arg;
> > >                       set_opt(sbi, DISABLE_CHECKPOINT);
> > > +                     clear_opt(sbi, MERGE_CHECKPOINT);
> > >                       break;
> > >               case Opt_checkpoint_disable:
> > >                       set_opt(sbi, DISABLE_CHECKPOINT);
> > > +                     clear_opt(sbi, MERGE_CHECKPOINT);
> > >                       break;
> > >               case Opt_checkpoint_enable:
> > >                       clear_opt(sbi, DISABLE_CHECKPOINT);
> > > +                     clear_opt(sbi, MERGE_CHECKPOINT);
> >
> > What if: -o checkpoint=merge,checkpoint=enable
> >
> > Can you please explain the rule of merge/disable/enable combination and their
> > result? e.g.
> > checkpoint=merge,checkpoint=enable
> > checkpoint=enable,checkpoint=merge
> > checkpoint=merge,checkpoint=disable
> > checkpoint=disable,checkpoint=merge
> >
> > If the rule/result is clear, it should be documented.
> >
> > Thanks,
> >
> >
> > >                       break;
> > >               case Opt_checkpoint_merge:
> > > +                     clear_opt(sbi, DISABLE_CHECKPOINT);
> > >                       set_opt(sbi, MERGE_CHECKPOINT);
> > >                       break;
> > >   #ifdef CONFIG_F2FS_FS_COMPRESSION
> > > @@ -1142,12 +1147,6 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
> > >               return -EINVAL;
> > >       }
> > >
> > > -     if (test_opt(sbi, DISABLE_CHECKPOINT) &&
> > > -                     test_opt(sbi, MERGE_CHECKPOINT)) {
> > > -             f2fs_err(sbi, "checkpoint=merge cannot be used with checkpoint=disable\n");
> > > -             return -EINVAL;
> > > -     }
> > > -
> > >       /* Not pass down write hints if the number of active logs is lesser
> > >        * than NR_CURSEG_PERSIST_TYPE.
> > >        */
> > >
> 
> 
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