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

[Chao Yu]

On 2024/4/5 3:52, Jaegeuk Kim 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) {
> +		f2fs_warn(sbi, "Stopped filesystem due to readon: %d", reason);
>   		return;

Do we need to set RO after bdev_thaw() in f2fs_do_shutdown()?

Thanks,

> +	}
>   
>   	f2fs_warn(sbi, "Remounting filesystem read-only");
>   	/*