From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [RFC PATCH 4/4] Directory listing support for union mounted directories.
Date: Wed, 20 Jun 2007 18:02:21 +0100
Message-ID: <20070620170221.GA13237@infradead.org>
References: <20070620055050.GB4267@in.ibm.com> <20070620055418.GF4267@in.ibm.com> <20070620120947.GA3973@infradead.org> <1182349348.6225.15.camel@heimdal.trondhjem.org>
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Cc: Christoph Hellwig <hch@infradead.org>,
	Bharata B Rao <bharata@linux.vnet.ibm.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Jan Blunck <j.blunck@tu-harburg.de>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
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On Wed, Jun 20, 2007 at 10:22:28AM -0400, Trond Myklebust wrote:
> No it shouldn't. The struct file contains other stateful information
> from the open() call (such as authentication info) that needs to be
> passed into readdir.

Which is exactly that problem this tries to solve.  Once you have
union mounts you'll have a single open file descriptor for multiple
actual directories.   Beause of that you can't simply attach to the
state to the struct file but have to keep it in a different way.