From owner-freebsd-current@FreeBSD.ORG  Fri Aug 20 17:03:30 2010
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Date: Fri, 20 Aug 2010 19:03:27 +0200
From: Ed Schouten <ed@80386.nl>
To: Daichi GOTO <daichi@freebsd.org>
Message-ID: <20100820170327.GL2978@hoeg.nl>
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Cc: freebsd-fs@freebsd.org, freebsd-current@freebsd.org, ozawa@ongs.co.jp
Subject: Whiteout support for tmpfs [Was: unionfs a little improvement]
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Hi all,

Even though the proposed fix for unionfs would still be nice to have in
SVN, I just wrote a patch for tmpfs to add support for whiteouts:

	http://80386.nl/pub/tmpfs-whiteout.txt

Basically I've implemented it by allowing directory entries to refer to
NULL inodes, to indicate the entry is a whiteout. I think the patch
should work pretty well, but what I dislike about it, is that when it
removes a file and replaces it by a whiteout, it deallocates the entire
directory entry, followed by the allocation of a new directory entry for
the whiteout. This could be done more efficiently, but the problem is
that it turns the code into a mess.

Any comments?

--=20
 Ed Schouten <ed@80386.nl>
 WWW: http://80386.nl/

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