Re: [RFC] VFS: FS CoW using redirection

From: Josef Sipek
Date: Sun Aug 27 2006 - 22:08:20 EST


On Sun, Aug 27, 2006 at 07:15:10PM +0200, Jörn 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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