[GSoC] HAMMER compression and new unionfs

Naohiro Aota naota at elisp.net
Mon Mar 28 17:52:46 PDT 2011

"Samuel J. Greear" <sjg at evilcode.net> writes:

> 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."

Yeah, it should be. GSoC has "writing documents" phase, so I'll do the
work for it. (last year, I wrote Gentoo/DragonFly installation guide
http://elisp.net/gentoo-dragonfly/ )


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