Re: [f2fs-dev] [PATCH] f2fs: don't set RO when shutting down f2fs

[Daeho Jeong]

On Thu, Apr 4, 2024 at 12:54 PM Jaegeuk Kim <jaegeuk@xxxxxxxxxx> wrote:
>
> 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 (謝明燈)" <Light.Hsieh@xxxxxxxxxxxx>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
>  fs/f2fs/super.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index df9765b41dac..ba6288e870c5 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -4135,9 +4135,16 @@ void f2fs_handle_critical_error(struct f2fs_sb_info *sbi, unsigned char reason,
>         if (shutdown)
>                 set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
>
> -       /* continue filesystem operators if errors=continue */
> -       if (continue_fs || f2fs_readonly(sb))
> +       /*
> +        * Continue filesystem operators if errors=continue. Should not set
> +        * RO by shutdown, since RO bypasses thaw_super which can hang the
> +        * system.
> +        */
> +       if (continue_fs || f2fs_readonly(sb) ||
> +                               reason == STOP_CP_REASON_SHUTDOWN) {

I think we can use "shutdown" variable instead of "reason ==
STOP_CP_REASON_SHUTDOWN" to be concise.

> +               f2fs_warn(sbi, "Stopped filesystem due to readon: %d", reason);

readon -> reason?

>                 return;
> +       }
>
>         f2fs_warn(sbi, "Remounting filesystem read-only");
>         /*
> --
> 2.44.0.478.gd926399ef9-goog
>
>
>
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