Re: [PATCH 2/2] vfsmount_lock / mnt_parent

From: raven
Date: Tue Jan 27 2004 - 10:26:21 EST



Sorry I mised this thread but ...

On Tue, 27 Jan 2004, Maneesh Soni wrote:

> On Mon, Jan 26, 2004 at 11:11:31PM +0000, Mike Waychison wrote:
> > The attached patch ensures that we grab vfsmount_lock when grabbing a
> > reference to mnt_parent in follow_up and follow_dotdot.
> >
> > We also don't need to access ->mnt_parent in follow_mount and
> > __follow_down to mntput because we already the parent pointer on the stack.
> >
> >
>
> As pointed by Viro on IRC, there are other places where we access/use
> mnt_parent without any protection. IIUC this needs either vfsmount_lock or the
> namespace sem for protection. I did audit such places and hope not missed
> anything else.
>
> One such place is in autofs4's is_vfsmnt_tree_busy() routine. I hope Ian still
> has the expire patch which corrects it. Didn't know why this patch never hit
> lkml.

The patch has never been posted seperately. It is part of a patch set for
autofs4, to support the autofs 4.1.0+ daemon, that I sent to Andrew
Morton. I was hoping that Jeremy would review them and they would make
their way to Al but perhaps neither has had time to follow up.

I must add that Mike has pointed out that the vfsmount_lock, used by the
patch is not exported and the patch does not change that.

Ian

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