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From: Daeho Jeong <daeho43@gmail.com>
Date: Tue, 9 Apr 2024 16:37:32 -0700
Message-ID: <CACOAw_xrXi_adcBHqBPURv=SP98S92qYyF1o5xtsOJ9yLfT56g@mail.gmail.com>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: don't set RO when shutting down f2fs
To: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, 
	=?UTF-8?B?TGlnaHQgSHNpZWggKOisneaYjueHiCk=?= <Light.Hsieh@mediatek.com>
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On Tue, Apr 9, 2024 at 9:21=E2=80=AFAM Jaegeuk Kim <jaegeuk@kernel.org> wro=
te:
>
> Shutdown does not check the error of thaw_super due to readonly, which
> causes a deadlock like below.
>
> f2fs_ioc_shutdown(F2FS_GOING_DOWN_FULLSYNC)        issue_discard_thread
>  - bdev_freeze
>   - freeze_super
>  - f2fs_stop_checkpoint()
>   - f2fs_handle_critical_error                     - sb_start_write
>     - set RO                                         - waiting
>  - bdev_thaw
>   - thaw_super_locked
>     - return -EINVAL, if sb_rdonly()
>  - f2fs_stop_discard_thread
>   -> wait for kthread_stop(discard_thread);
>
> Reported-by: "Light Hsieh (=E8=AC=9D=E6=98=8E=E7=87=88)" <Light.Hsieh@med=
iatek.com>
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>
>  Change log from v1:
>   - use better variable
>   - fix typo
>
>  fs/f2fs/super.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 8ac4734c2df6..df32573d1f62 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -4159,9 +4159,15 @@ void f2fs_handle_critical_error(struct f2fs_sb_inf=
o *sbi, unsigned char reason,
>         if (shutdown)
>                 set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
>
> -       /* continue filesystem operators if errors=3Dcontinue */
> -       if (continue_fs || f2fs_readonly(sb))
> +       /*
> +        * Continue filesystem operators if errors=3Dcontinue. Should not=
 set
> +        * RO by shutdown, since RO bypasses thaw_super which can hang th=
e
> +        * system.
> +        */
> +       if (continue_fs || f2fs_readonly(sb) || shutdown) {
> +               f2fs_warn(sbi, "Stopped filesystem due to reason: %d", re=
ason);
>                 return;
> +       }
>
>         f2fs_warn(sbi, "Remounting filesystem read-only");
>         /*
> --
> 2.44.0.478.gd926399ef9-goog
>
>

Reviewed-by: Daeho Jeong <daehojeong@google.com>


>
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