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SubjectRe: [f2fs-dev] [PATCH] f2fs: don't set RO when shutting down f2fs
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On 2024/4/10 0:21, Jaegeuk Kim wrote:
> On 04/09, Chao Yu wrote:
>> 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@mediatek.com>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>> ---
>>> 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()?
>
> IIRC, shutdown doesn't need to set RO as we stopped the checkpoint.
> I'm more concerned on any side effect caused by this RO change.

Okay, I just wonder whether we need to follow semantics of errors=remount-ro
semantics, but it looks fine since shutdown operation simulated by ioctl
could not be treated as an inner critical error,

errors=%s Specify f2fs behavior on critical errors. This supports modes:
"panic", "continue" and "remount-ro", respectively, trigger
panic immediately, continue without doing anything, and remount
the partition in read-only mode. By default it uses "continue"
mode.

Also, it keeps the behavior consistent w/ what we do for errors=panic case.

if (F2FS_OPTION(sbi).errors == MOUNT_ERRORS_PANIC &&
!shutdown && !system_going_down() &&
^^^^^^^^^
!is_sbi_flag_set(sbi, SBI_IS_SHUTDOWN))
panic("F2FS-fs (device %s): panic forced after error\n",
sb->s_id);

Thanks,

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

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