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Message-ID: <ZhVrJh3rackEiIfL@google.com>
Date: Tue, 9 Apr 2024 16:21:58 +0000
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
Light Hsieh (謝明燈) <Light.Hsieh@...iatek.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs: don't set RO when shutting down f2fs
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@...iatek.com>
> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.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.
>
> Thanks,
>
> > + }
> > f2fs_warn(sbi, "Remounting filesystem read-only");
> > /*
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