Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

From: Jaegeuk Kim
Date: Thu Oct 13 2016 - 13:15:08 EST


On Thu, Oct 13, 2016 at 06:33:19PM +0800, Chao Yu wrote:
> Hi Jaegeuk,
>
> On 2016/10/13 7:23, Jaegeuk Kim wrote:
> > This patch fixes using a wrong pointer for sum_page in f2fs_gc.
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> > ---
> > fs/f2fs/gc.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index e48142f..9c18917 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
> >
> > for (segno = start_segno; segno < end_segno; segno++) {
> >
> > - if (get_valid_blocks(sbi, segno, 1) == 0 ||
> > - unlikely(f2fs_cp_error(sbi)))
> > - goto next;
> > -
> > /* find segment summary of victim */
> > sum_page = find_get_page(META_MAPPING(sbi),
> > GET_SUM_BLOCK(sbi, segno));
> > - f2fs_bug_on(sbi, !PageUptodate(sum_page));
> > f2fs_put_page(sum_page, 0);
> >
> > + if (get_valid_blocks(sbi, segno, 1) == 0 ||
> > + !PageUptodate(sum_page) ||
>
> Why uptodate flag of summary page can be cleared? someone truncates it?

Well, it looks like no problem to remove this, since it will hit
f2fs_cp_error(). I just intended to handle the above f2fs_bug_on here.

I found you added the above bug_on, but it's not a big deal to remain tho. :)

718e53fa: f2fs: enhance foreground GC

Thanks,

>
> Thanks,
>
> > + unlikely(f2fs_cp_error(sbi)))
> > + goto next;
> > +
> > sum = page_address(sum_page);
> > f2fs_bug_on(sbi, type != GET_SUM_TYPE((&sum->footer)));
> >
> >