From: Jaegeuk Kim <jaegeuk@kernel.org>
To: "Theodore Ts'o" <tytso@mit.edu>,
Al Viro <viro@ZenIV.linux.org.uk>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH v2] vfs: introduce UMOUNT_WAIT which waits for umount completion
Date: Thu, 21 Sep 2017 10:16:44 -0700 [thread overview]
Message-ID: <20170921171644.GA3813@jaegeuk-macbookpro.roam.corp.google.com> (raw)
In-Reply-To: <20170921144809.wv6546fqtentm7vv@thunk.org>
On 09/21, Theodore Ts'o wrote:
> On Wed, Sep 20, 2017 at 10:02:37PM -0700, Jaegeuk Kim wrote:
> >
> > Yes, and actually, android retries umount(2) for several seconds, if it gets
> > failure. So, first I thought it'd be better to make umount() more deterministic.
> >
> > I'm not sure how many times we can retry and wait for this. IMHO, it'd be better
> > to use this together with the new flag, since this can detect unclosed namespace
> > given successful umount(2).
>
> Even if you could make umount wait for the binder deferred workqueue
> to exit, if it takes time, it takes time. And that's not the core
> VFS's fault. It's binder's.
>
> So... why not fix this by adding a binder ioctl which forces its
> workqueue to be flushed, and use that *before* you try calling mount?
Yes, we can, but I'm not 100% sure this happens only by binder. This is caused
by delayed_fput/mntput called by any kernel thread which would be much generic.
> If that binder ioctl takes minutes or hours to complete, then that's a
> binder bug, and needs to be fixed in binder.
>
> - Ted
next prev parent reply other threads:[~2017-09-21 17:16 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
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 [this message]
2017-09-21 18:20 ` [PATCH v3] vfs: introduce UMOUNT_WAIT to wait for delayed_fput/mntput completion Jaegeuk Kim
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