[GSoC] HAMMER compression and new unionfs

[Naohiro Aota]

Hi,

I'm Naohiro Aota, undergraduate student at Osaka University, Japan.

Last year I've participated GSoC with Gentoo and worked on porting
Gentoo system to DragonFly. Since then I'm so interested in DragnFly
kernel, so I'd like to take part in GSoC with some DragnFly kernel work
this year. I've read the project page and get interested these two
ideas: HAMMER compression and new unionfs. (yes, I like filesystem ;))

I have some question about the ideas.

about HAMMER compression:

- "compression could be turned on a per-file" may support all files
  under "/foo" get compressed?
- file size measurement commands, such as "df", "du" and "ls", also need
  to change? (actual disk space size and file size may differ if compressed)

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?

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?

Thanks,
Naohiro