From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH] vfs: introduce UMOUNT_WAIT which waits for umount completion
Date: Thu, 14 Sep 2017 00:44:37 +0100 [thread overview]
Message-ID: <20170913234437.GO5426@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170913233116.GA45354@jaegeuk-macbookpro.roam.corp.google.com>
On Wed, Sep 13, 2017 at 04:31:16PM -0700, Jaegeuk Kim wrote:
> Hi Al,
>
> On 09/14, Al Viro wrote:
> > On Wed, Sep 13, 2017 at 01:09:41PM -0700, Jaegeuk Kim wrote:
> > > + if (!retval && (flags & UMOUNT_WAIT)) {
> > > + if (likely(!(current->flags & PF_KTHREAD)))
> > > + task_work_run();
> >
> > This is complete crap. The same damn thing will be done by
> > caller of sys_umount() pretty much immediately afterwards.
> > I'm not sure what it is that you are trying to paper over,
> > but this is just plain wrong.
>
> Okay.
>
> > What _is_ the semantics of UMOUNT_WAIT? What does it guarantee,
> > and what would be supplying it to umount(2)?
>
> When android tries to reboot the system, it calls umount(2) without any flag.
> Then, mntput_no_expire() will add delayed_mntput_work() which finally does
> cleanup_mnt() later. In the mean time, android proceeded to shutdown all
> the UFS devices.
Why has task_work_add() failed? Or is that umount(2) issued by a kernel thread?
next prev parent reply other threads:[~2017-09-13 23:44 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-13 20:09 [PATCH] vfs: introduce UMOUNT_WAIT which waits for umount completion Jaegeuk Kim
2017-09-13 23:04 ` Al Viro
2017-09-13 23:31 ` Jaegeuk Kim
2017-09-13 23:44 ` Al Viro [this message]
2017-09-14 1:10 ` Jaegeuk Kim
2017-09-14 1:10 ` Jaegeuk Kim
2017-09-14 1:30 ` Al Viro
2017-09-14 18:37 ` Al Viro
2017-09-14 19:14 ` Jaegeuk Kim
2017-09-15 0:19 ` Jaegeuk Kim
2017-09-15 2:06 ` Al Viro
2017-09-15 2:06 ` Al Viro
2017-09-15 3:45 ` Jaegeuk Kim
2017-09-15 4:21 ` Al Viro
2017-09-15 18:44 ` Jaegeuk Kim
2017-09-15 22:12 ` Theodore Ts'o
2017-09-15 22:12 ` Theodore Ts'o
2017-09-15 23:29 ` Jaegeuk Kim
2017-09-15 23:43 ` Al Viro
2017-09-19 15:55 ` Jaegeuk Kim
2017-09-16 7:11 ` Amir Goldstein
2017-09-16 7:11 ` Amir Goldstein
2017-09-20 17:38 ` [PATCH v2] " Jaegeuk Kim
2017-09-20 18:38 ` Al Viro
2017-09-21 0:34 ` Jaegeuk Kim
2017-09-21 2:42 ` Al Viro
2017-09-21 5:02 ` Jaegeuk Kim
2017-09-21 14:48 ` Theodore Ts'o
2017-09-21 17:16 ` Jaegeuk Kim
2017-09-21 18:20 ` [PATCH v3] vfs: introduce UMOUNT_WAIT to wait for delayed_fput/mntput completion Jaegeuk Kim
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