linux-kernel - Re: [PATCH] f2fs: let fill_super handle roll-forward errors

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Message-ID: <20170815164212.GA4293@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Tue, 15 Aug 2017 09:42:12 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, stable@...r.kernel.org
Subject: Re: [PATCH] f2fs: let fill_super handle roll-forward errors

On 08/15, Chao Yu wrote:
> On 2017/8/15 11:22, Jaegeuk Kim wrote:
> > On 08/15, Chao Yu wrote:
> >> Hi Jaegeuk,
> >>
> >> On 2017/8/11 8:42, Jaegeuk Kim wrote:
> >>> If we set CP_ERROR_FLAG in roll-forward error, f2fs is no longer to proceed
> >>> any IOs due to f2fs_cp_error(). But, for example, if some stale data is involved
> >>> on roll-forward process, we're able to get -ENOENT, getting fs stuck.
> >>> If we get any error, let fill_super set SBI_NEED_FSCK and try to recover back
> >>> to stable point.
> >>
> >> Before that, we have cleaned up all node/meta page cache, so we will get back to
> >> last checkpoint status, means losing fsynced datas for ever.
> >>
> >> Would it be better to just leave message reminding user to mount with
> >> disable_roll_forward or run fsck offline.
> > 
> > We can't rely on user for this, since fsck cannot recover this, resulting in
> 
> If fsck has no ability to recover this, it could tag superblock in somewhere,
> then kernel could skip recovery. Comparing to fail recovery directly, it give
> user another chance to rescuer his datas.

Huh, what do you mean? This patch let f2fs_fill_super set SBI_NEED_FSCK in
superblock and skip roll-forward in second round.

> 
> Thanks,
> 
> > infinite mount failure. The only way is to disable roll-forward recovery, which
> > is same as returning error here.
> > 
> > Thanks,
> > 
> >>
> >> Thanks,
> >>
> >>>
> >>> Cc: <stable@...r.kernel.org>
> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> >>> ---
> >>>  fs/f2fs/recovery.c | 2 --
> >>>  1 file changed, 2 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> >>> index a3d02613934a..f707d810c87d 100644
> >>> --- a/fs/f2fs/recovery.c
> >>> +++ b/fs/f2fs/recovery.c
> >>> @@ -649,8 +649,6 @@ int recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
> >>>  	}
> >>>  
> >>>  	clear_sbi_flag(sbi, SBI_POR_DOING);
> >>> -	if (err)
> >>> -		set_ckpt_flags(sbi, CP_ERROR_FLAG);
> >>>  	mutex_unlock(&sbi->cp_mutex);
> >>>  
> >>>  	/* let's drop all the directory inodes for clean checkpoint */
> >>>
> > 
> > .
> >