Date: Sun, 27 Aug 2006 22:10:57 -0400
From: Josef Sipek <jsipek@fsl.cs.sunysb.edu>
To: =?iso-8859-1?Q?J=F6rn?= Engel <joern@wohnheim.fh-wedel.de>
Cc: Al Boldi <a1426z@gawab.com>, Eric Van Hensbergen <ericvh@gmail.com>,
       linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC] VFS: FS CoW using redirection
Message-ID: <20060828021057.GA30334@filer.fsl.cs.sunysb.edu>
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On Sun, Aug 27, 2006 at 07:15:10PM +0200, J?rn Engel wrote:
> On Sat, 26 August 2006 22:05:21 +0300, Al Boldi wrote:
... 
> > > Or you can give Unionfs a try: http://www.unionfs.org
> > 
> > UnionFS is great, but it incurs additional overhead, as it lives below the 
> > real VFS.  What could be really great, is to move some basic functionality 
> > abstractions from UnionFS into VFS proper.
> 
> If you want to make this vision happen, one of the missing pieces is a
> method for copyup, an in-kernel copying routine.  Unionfs needs is
> just the same as Jan's patches do and in the past Linus didn't like my
> approach of using sendfile for it.  You could take a stab at the
> splice code and see how that can be used for copyup.

The thing with union mounts/unionfs is that some of the functionality makes
sense to have in a file system while other parts make sense to have in the
VFS - the way I see it, namespace related bits should be in VFS while
persistent state should be done on the file system level.

Josef "Jeff" Sipek.

-- 
If I have trouble installing Linux, something is wrong. Very wrong.
		- Linus Torvalds
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