linux-kernel - Re: [PATCH] fs: f2fs: remove WARN_ON in f2fs_is_valid

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Date:   Sat, 9 Apr 2022 09:34:02 +0800
From:   Dongliang Mu <mudongliangabcd@...il.com>
To:     Chao Yu <chao@...nel.org>
Cc:     Dongliang Mu <dzm91@...t.edu.cn>, Jaegeuk Kim <jaegeuk@...nel.org>,
        syzbot+763ae12a2ede1d99d4dc@...kaller.appspotmail.com,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs: f2fs: remove WARN_ON in f2fs_is_valid_blkaddr

On Sat, Apr 9, 2022 at 8:27 AM Chao Yu <chao@...nel.org> wrote:
>
> On 2022/4/8 13:22, Dongliang Mu wrote:
> > From: Dongliang Mu <mudongliangabcd@...il.com>
> >
> > In f2fs_is_valid_blkaddr, if type is DATA_GENERIC_ENHANCE or
> > DATA_GENERIC_ENHANCE_READ, it invokes WARN_ON(1) not matter
> > blkaddr is in the range or not.
>
> If we run into the path where we invoke WARN_ON(1) in f2fs_is_valid_blkaddr(),
> It means f2fs image may be broken, or there is a bug in f2fs.
>
> So, do you suffer any related issue in your environment?

related issue? Can you explain a little?

If you mean if this warning occurs, any other issues or crash
behaviors are generated? I tested on the syzbot. After removing the
WARN_ON, there is no abnormal issue or crash behaviors followed with
the corresponding reproducer.


>
> Thanks,
>
> >
> > Fix this by removing WARN_ON.
> >
> > Note that, syzbot patch testing does not incur any further issues
> >
> > Reported-by: syzbot+763ae12a2ede1d99d4dc@...kaller.appspotmail.com
> > Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
> > ---
> >   fs/f2fs/checkpoint.c | 2 --
> >   1 file changed, 2 deletions(-)
> >
> > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> > index f5366feea82d..521498b2dd8c 100644
> > --- a/fs/f2fs/checkpoint.c
> > +++ b/fs/f2fs/checkpoint.c
> > @@ -158,7 +158,6 @@ static bool __is_bitmap_valid(struct f2fs_sb_info *sbi, block_t blkaddr,
> >               f2fs_err(sbi, "Inconsistent error blkaddr:%u, sit bitmap:%d",
> >                        blkaddr, exist);
> >               set_sbi_flag(sbi, SBI_NEED_FSCK);
> > -             WARN_ON(1);
> >       }
> >       return exist;
> >   }
> > @@ -196,7 +195,6 @@ bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
> >                       f2fs_warn(sbi, "access invalid blkaddr:%u",
> >                                 blkaddr);
> >                       set_sbi_flag(sbi, SBI_NEED_FSCK);
> > -                     WARN_ON(1);
> >                       return false;
> >               } else {
> >                       return __is_bitmap_valid(sbi, blkaddr, type);