[GSoC] HAMMER compression and new unionfs

Samuel J. Greear sjg at evilcode.net
Mon Mar 28 09:11:43 PDT 2011

On Mar 28, 2011 10:02 AM, "Alex Hornung" <ahornung at gmail.com> wrote:
> On 28/03/11 16:48, Naohiro Aota wrote:
> > about implementing a new unionfs:
> >
> >> The current unionfs is completely broken as it relies on the whiteout
> >> VFS technique which is not supported by HAMMER.
> >
> > - Then main work would be to implement whiteout feature on HAMMER?
> > - or rewrite unionfs code not to depend on whiteout technique?
> I've now changed the text on the projects page to reflect that we don't
> want a new unionfs using whiteout. So the aim of this project is to
> develop a unionfs from scratch avoiding techniques which require messing
> with other filesystems.
> > and also:
> >
> > - Are there some docs (or some source code file) to help me understand
> >   DragonFly VFS and HAMMER internal?
> > - Are there some detailed guides about these ideas?
> About the VFS you can refer to the book "Design & Implementation of
> FreeBSD". Things have changed, but it gives a good general perspective
> of how things work. The namecache, most interesting part for unionfs,
> has no real documentation, only inline with the code.
> Regards,
> Alex Hornung
A great bullet point for any project would be "fully document related and undocumented feature x with a new manpage."

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