linux-kernel - Re: [PATCH 3/3] f2fs: avoid unneeded barrier in do

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Message-ID: <20200224220031.GC77839@google.com>
Date:   Mon, 24 Feb 2020 14:00:31 -0800
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: avoid unneeded barrier in do_checkpoint()

On 02/19, Chao Yu wrote:
> On 2020/2/19 10:51, Jaegeuk Kim wrote:
> > On 02/18, Chao Yu wrote:
> >> We don't need to wait all dirty page submitting IO twice,
> >> remove unneeded wait step.
> > 
> > What happens if checkpoint and other meta writs are reordered?
> 
> checkpoint can be done as following:
> 
> 1. All meta except last cp-park of checkpoint area.
> 2. last cp-park of checkpoint area
> 
> So we only need to keep barrier in between step 1 and 2, we don't need
> to care about the write order of meta in step 1, right?

Ah, let me integrate this patch into Sahitya's patch.

f2fs: fix the panic in do_checkpoint()

> 
> Thanks,
> 
> > 
> >>
> >> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> >> ---
> >>  fs/f2fs/checkpoint.c | 2 --
> >>  1 file changed, 2 deletions(-)
> >>
> >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> >> index 751815cb4c2b..9c88fb3d255a 100644
> >> --- a/fs/f2fs/checkpoint.c
> >> +++ b/fs/f2fs/checkpoint.c
> >> @@ -1384,8 +1384,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>  
> >>  	/* Flush all the NAT/SIT pages */
> >>  	f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO);
> >> -	/* Wait for all dirty meta pages to be submitted for IO */
> >> -	f2fs_wait_on_all_pages(sbi, F2FS_DIRTY_META);
> >>  
> >>  	/*
> >>  	 * modify checkpoint
> >> -- 
> >> 2.18.0.rc1
> > .
> >