Re: The argument for fs assistance in handling archives (was: silent semantic changes with reiser4)

Charles P. Wright
2004-09-02T19:04:49Z

On Thu, 2004-09-02 at 14:03, Linus Torvalds wrote:
> On Thu, 2 Sep 2004, Christoph Hellwig wrote:
> >
> > http://oss.oracle.com/projects/userfs/ has code that clues gnomevfs onto
> > a kernel filesystem. The code is horrible, but it shows that it can
> > be done.
>
> I do like the setup where the extended features are done as a "view" on
> top of some other filesystem, so that you can choose to _either_ access
> the raw (and supposedly stable, simply by virtue of simplicity) or the
> "fancy" interface. Without having to reformat the disk to a filesystem you
> don't trust, or you have other reasons you can't use (disk sharing with
> other systems, whatever).
>
> It doesn't have to be "user", btw, in the sense that a lot of the normal
> code could be in kernel mode. Same way as Tux handling all the regular
> static requests entirely in kernel mode, but having the ability for
> calling down to apache..
Stackable file systems are a good fit for doing things like this. They
layer on top of an existing directory and intercept all of the vfs_*
calls. You can do lots of neat things like encryption versioning,
compression, and more.

At Stony Brook's Filesystems and Storage Laboratory
(http://www.fsl.cs.sunysb.edu), we maintain a toolkit (FiST) that makes
developing these file systems easier by providing stackable file system
templates for Linux and FreeBSD.

There are papers and the FiST toolkit available at
http://www.filesystems.org/

Charles