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Date: Thu, 21 Mar 2024 17:30:13 -0700
From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Light Hsieh =?utf-8?B?KOisneaYjueHiCk=?= <Light.Hsieh@mediatek.com>
Cc: Ed Tsai =?utf-8?B?KOiUoeWul+i7kik=?= <Ed.Tsai@mediatek.com>,
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	"linux-f2fs-devel@lists.sourceforge.net" <linux-f2fs-devel@lists.sourceforge.net>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Chun-Hung Wu =?utf-8?B?KOW3q+mnv+Wujyk=?= <Chun-hung.Wu@mediatek.com>
Subject: Re: =?utf-8?B?5Zue6KaGOiDlm57opoY=?= =?utf-8?Q?=3A?= f2fs
 F2FS_IOC_SHUTDOWN hang issue
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On 03/21, Light Hsieh (謝明燈) wrote:
> Do you mean:
> 
> +           /* Avoid the deadlock from F2FS_GOING_DOWN_NOSYNC. */
> +           if (!sb_start_intwrite_trylock(sbi->sb))
> +                 continue;
> 
> After failure of trylock,  the 'continue'  make code flow goto the line:
>       } while (!kthread_should_stop());
> Since  kthrad_should_stop() is true now, so the issue_discard_thread will end?

Yes, but now I'm confused who is taking write_sem. :(

> 
> Light
> ________________________________
> 寄件者: Jaegeuk Kim <jaegeuk@kernel.org>
> 寄件日期: 2024年3月21日 上午 08:39
> 收件者: Light Hsieh (謝明燈) <Light.Hsieh@mediatek.com>
> 副本: Ed Tsai (蔡宗軒) <Ed.Tsai@mediatek.com>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>; linux-f2fs-devel@lists.sourceforge.net <linux-f2fs-devel@lists.sourceforge.net>; linux-fsdevel@vger.kernel.org <linux-fsdevel@vger.kernel.org>; Chun-Hung Wu (巫駿宏) <Chun-hung.Wu@mediatek.com>
> 主旨: Re: 回覆: f2fs F2FS_IOC_SHUTDOWN hang issue
> 
> 
> External email : Please do not click links or open attachments until you have verified the sender or the content.
> 
> 
> On 03/20, Light Hsieh (謝明燈) wrote:
> > On 2024/3/20 8:14, Jaegeuk Kim wrote:
> > > f2fs_ioc_shutdown(F2FS_GOING_DOWN_NOSYNC)  issue_discard_thread
> > >   - mnt_want_write_file()
> > >     - sb_start_write(SB_FREEZE_WRITE)
> > >                                               - sb_start_intwrite(SB_FREEZE_FS);
> > >   - f2fs_stop_checkpoint(sbi, false,            : waiting
> > >      STOP_CP_REASON_SHUTDOWN);
> > >   - f2fs_stop_discard_thread(sbi);
> > >     - kthread_stop()
> > >       : waiting
> > >
> > >   - mnt_drop_write_file(filp);
> > >
> > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> >
> > The case I encounter is f2fs_ic_shutdown with arg  F2FS_GOING_DOWN_FULLSYNC, not  F2FS_GOING_DOWN_NOSYNC.
> >
> > Or you are meaning that: besides the kernel patch, I need to change the invoked F2FS_IOC_SHUTDOWN to use arg F2FS_GOING_DOWN_NOSYNC?
> 
> I think this patch also addresses your case by using trylock.
> 
> >
> >
> >
>