From mboxrd@z Thu Jan  1 00:00:00 1970
From: Valerie Aurora <vaurora@redhat.com>
Subject: Re: [PATCH 17/38] union-mount: Union mounts documentation
Date: Thu, 17 Jun 2010 14:39:13 -0400
Message-ID: <20100617183912.GA14389@shell>
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Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Jan Blunck <jblunck@suse.de>,
	Christoph Hellwig <hch@infradead.org>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
To: Alex Riesen <raa.lkml@gmail.com>
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On Thu, Jun 17, 2010 at 10:01:30AM +0200, Alex Riesen wrote:
> On Tue, Jun 15, 2010 at 20:39, Valerie Aurora <vaurora@redhat.com> wrote:
> > +git://git.kernel.org/pub/scm/fs/ext2/val/e2fsprogs.git
> > +
> > +Currently, whiteout directory entries are not returned to userland.
> > +While the directory type for whiteouts, DT_WHT, has been defined for
> > +many years, very little userland code handles them. ??Userland will
> > +never see fallthru directory entries.
> 
> This may be a dumb question (I must admit I did only very little research),
> but how does one cleanup the topmost layer of whiteouts and fallthroughs,
> so that the entries of lower layer(s) can be made visible again?

I'm not sure how best to do this.  We don't want to add more system
calls.  One thought of mine has been to do this offline, when the file
system is unmounted.  For example, e2fsck could add a feature to
delete whiteouts and fallthrus.  Another option is to add a flag to an
existing system call.

Any ideas?

-VAL