From: "J. Bruce Fields" <bfields@fieldses.org>
To: Guo Chao <yan@linux.vnet.ibm.com>
Cc: "J. Bruce Fields" <bfields@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH 05/13] vfs: take i_mutex on renamed file
Date: Mon, 10 Sep 2012 10:35:41 -0400 [thread overview]
Message-ID: <20120910143541.GC30136@fieldses.org> (raw)
In-Reply-To: <20120910024051.GA10405@yanx>
On Mon, Sep 10, 2012 at 10:40:51AM +0800, Guo Chao wrote:
> On Fri, Sep 07, 2012 at 05:39:01PM -0400, J. Bruce Fields wrote:
> > On Fri, Sep 07, 2012 at 10:27:05AM +0800, Guo Chao wrote:
> > > One script ...
> > >
> > > #!/bin/bash
> > > while true
> > > do
> > > mount -t sysfs nodev mnt && umount mnt
> > > done
> > >
> > >
> > >
> > > The other ...
> > >
> > > #!/bin/bash
> > > while true
> > > do
> > > mv mnt mnt2 && mv mnt2 mnt
> > > done
> > >
> > >
> > >
> > > Run them simultaneously in two consoles. When mount keeps reporting
> > > 'mount point mnt does not exist', stop them, then you will see the
> > > familiar sysfs under mnt2.
> >
> > Oh, thanks, for some reason I assumed it would be more difficult to
> > reproduce.
> >
> > I think we can do this--I don't think it even requires any care to the
> > locking order of the renamed vs the victim directory, though I can't
> > completely convince myself of that.
> >
> > Is it necessary to fix this, though? Does it cause any problems other
> > than unexpected behavior?
> >
> > --b.
> > --
>
> Hard to say whether it's a bug or what's problems of being able to rename
> mountpoint.
>
> Anyway, this patch closes this race when mountpoint is a file. Thus we get
> different behaviour when deal with files and directories. It's apparently
> not well-defined, but again, is it a problem? Not sure ... ...
OK. I'm not seeing a strong argument to change the current behavior, so
inclined to leave it alone for now.
--b.
next prev parent reply other threads:[~2012-09-10 14:35 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-05 20:55 [RFC PATCH 00/13] Implement NFSv4 delegations, take 4 J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 03/13] vfs: don't use PARENT/CHILD lock classes for non-directories J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 04/13] vfs: rename I_MUTEX_QUOTA now that it's not used for quotas J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 07/13] locks: implement delegations J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 09/13] locks: break delegations on unlink J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 10/13] locks: helper functions for delegation breaking J. Bruce Fields
[not found] ` <1346878524-10585-1-git-send-email-bfields-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-09-05 20:55 ` [RFC PATCH 01/13] gfs2: Get rid of I_MUTEX_QUOTA usage J. Bruce Fields
[not found] ` <1346878524-10585-2-git-send-email-bfields-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-09-05 20:59 ` J. Bruce Fields
[not found] ` <20120905205920.GA10724-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>
2012-09-06 14:27 ` Steven Whitehouse
2012-09-06 17:08 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 02/13] vfs: pull ext4's double-i_mutex-locking into common code J. Bruce Fields
2012-09-06 2:53 ` Guo Chao
2012-09-06 13:49 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 05/13] vfs: take i_mutex on renamed file J. Bruce Fields
[not found] ` <1346878524-10585-6-git-send-email-bfields-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-09-06 3:05 ` Guo Chao
2012-09-06 17:51 ` J. Bruce Fields
[not found] ` <20120906175118.GC21736-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>
2012-09-07 2:27 ` Guo Chao
2012-09-07 21:39 ` J. Bruce Fields
[not found] ` <20120907213901.GA5927-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>
2012-09-10 2:40 ` Guo Chao
2012-09-10 5:10 ` Ram Pai
2012-09-10 6:37 ` Guo Chao
2012-09-10 7:27 ` Ram Pai
2013-02-14 2:01 ` Al Viro
2012-09-10 14:35 ` J. Bruce Fields [this message]
2012-09-05 20:55 ` [RFC PATCH 06/13] locks: introduce new FL_DELEG lock flag J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 08/13] namei: minor vfs_unlink cleanup J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 11/13] locks: break delegations on rename J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 12/13] locks: break delegations on link J. Bruce Fields
2012-09-05 21:02 ` J. Bruce Fields
2012-09-06 11:01 ` Jeff Layton
[not found] ` <20120906070122.58c21013-4QP7MXygkU+dMjc06nkz3ljfA9RmPOcC@public.gmane.org>
2012-09-06 13:33 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 13/13] locks: break delegations on any attribute modification J. Bruce Fields
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