Date: Wed, 27 Feb 2008 23:59:52 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Pavel Emelyanov <xemul@openvz.org>
Cc: Ian Kent <raven@themaw.net>,
       Kernel Mailing List <linux-kernel@vger.kernel.org>,
       autofs mailing list <autofs@linux.kernel.org>,
       linux-fsdevel <linux-fsdevel@vger.kernel.org>,
       "Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH 3/4] autofs4 - track uid and gid of last mount requestor
Message-Id: <20080227235952.70a31d9f.akpm@linux-foundation.org>
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On Thu, 28 Feb 2008 10:51:08 +0300 Pavel Emelyanov <xemul@openvz.org> wrote:

> > So, why do we need the uid and gid? When someone walks over an autofs
> > dentry that is meant to cause a mount we send a request packet to the
> > daemon via a pipe which includes the process uid and gid, and as part of
> > the lookup we set macros for several mount map substitution variables,
> > derived from the uid and gid of the process requesting the mount and
> > they can be used within autofs maps.
> 
> Why do we need the uid then? Is just pid not enough to uniquely 
> identify a task?

The problem is that the userspace daemon is restarted.  ie: it exits
and is re-run.  It then needs to pick up various state from its previous
run.
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