linux-kernel - Re: [f2fs-dev] [PATCH 1/4] f2fs: flush journal nat entries for nat

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Message-ID: <20180709204306.GD24534@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Mon, 9 Jul 2018 13:43:06 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 1/4] f2fs: flush journal nat entries for
 nat_bits during unmount

On 07/09, Chao Yu wrote:
> On 2018/7/7 5:09, Jaegeuk Kim wrote:
> > Let's flush journal nat entries for speed up in the next run.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> > ---
> >  fs/f2fs/node.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index 29237aeca041..0f076fb0d828 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -2613,6 +2613,13 @@ void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >  	nid_t set_idx = 0;
> >  	LIST_HEAD(sets);
> >  
> > +	/* during unmount, let's flush nat_bits before checking dirty_nat_cnt */
> > +	if (enabled_nat_bits(sbi, cpc)) {
> > +		down_write(&nm_i->nat_tree_lock);
> > +		remove_nats_in_journal(sbi);
> > +		up_write(&nm_i->nat_tree_lock);
> > +	}
> 
> The case will cover that nm_i->dirty_nat_cnt is zero and there is cached nats in
> journal?

Yes.

> 
> So enabled_nat_bits() below should be removed?

It's out of lock, nm_i->nat_tree_lock, logically..

> 
> 	if (enabled_nat_bits(sbi, cpc) ||
> 		!__has_cursum_space(journal, nm_i->dirty_nat_cnt, NAT_JOURNAL))
> 		remove_nats_in_journal(sbi);
> 
> Thanks,
> 
> > +
> >  	if (!nm_i->dirty_nat_cnt)
> >  		return;
> >  
> >