linux-kernel - Re: [PATCH] f2fs: fix to redirty page if fail to gc data page

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Message-ID: <20160603051734.GA25068@jaegeuk>
Date:	Thu, 2 Jun 2016 22:17:34 -0700
From:	Jaegeuk Kim <jaegeuk@...nel.org>
To:	Chao Yu <yuchao0@...wei.com>
Cc:	Chao Yu <chao@...nel.org>, linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: fix to redirty page if fail to gc data page

On Fri, Jun 03, 2016 at 01:13:21PM +0800, Chao Yu wrote:
> On 2016/6/3 13:08, Jaegeuk Kim wrote:
> > On Tue, May 31, 2016 at 02:10:50PM +0800, Chao Yu wrote:
> >> Hi Jaegeuk,
> >>
> >> On 2016/5/30 10:37, Jaegeuk Kim wrote:
> >>> Hi Chao,
> >>>
> >>> On Sat, May 21, 2016 at 01:19:11PM +0800, Chao Yu wrote:
> >>>> From: Chao Yu <yuchao0@...wei.com>
> >>>>
> >>>> If we fail to move data page during foreground GC, we should give another
> >>>> chance to writeback that page which was set dirty previously by writer.
> >>>>
> >>>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> >>>> ---
> >>>>  fs/f2fs/gc.c | 5 ++++-
> >>>>  1 file changed, 4 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> >>>> index 38d56f6..ee213a8 100644
> >>>> --- a/fs/f2fs/gc.c
> >>>> +++ b/fs/f2fs/gc.c
> >>>> @@ -653,12 +653,15 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type)
> >>>>  			.page = page,
> >>>>  			.encrypted_page = NULL,
> >>>>  		};
> >>>> +		bool is_dirty = PageDirty(page);
> >>>> +
> >>>>  		set_page_dirty(page);
> >>>>  		f2fs_wait_on_page_writeback(page, DATA, true);
> >>>>  		if (clear_page_dirty_for_io(page))
> >>>>  			inode_dec_dirty_pages(inode);
> >>>>  		set_cold_data(page);
> >>>> -		do_write_data_page(&fio);
> >>>> +		if (do_write_data_page(&fio) && is_dirty)
> >>>> +			set_page_dirty(page);
> >>>
> >>> If this page is truncated with -ENOENT, we don't need to set it dirty again.
> >>
> >> Agree
> >>
> >>> I expect that, if we get an error here, do_garbage_collect() would retry FG_GC
> >>
> >> IIRC, you have reworked the FG_GC flows changed from an infinite loop to trying
> >> do the movement just one time. Here, I think if there are just few of blocks are
> >> failed to be moved, we can give one more time for retrying. How do you think?
> > 
> > Mostly I expected here -ENOENT caused by race condition.
> 
> If we hit ENOENT case, we can pass get_valid_blocks check, so we don't need to
> worry about this case, right?
> 
> > Do we have another expectation?
> 
> ENOMEM or EIO?

EIO will stop everything.
ENOMEM would be better to wait for a while from page reclaim?

> 
> Thanks,
> 
> > 
> > Thanks,
> > 
> >>
> >>> again.
> >>>
> >>> Thanks,
> >>>
> >>>>  		clear_cold_data(page);
> >>>>  	}
> >>>>  out:
> >>>> -- 
> >>>> 2.7.2
> >>> .
> >>>
> > .
> >