Glad to hear somebody is willing to dive in to XFS.
Right now I am one of three people working on the XFS to linux port, so I
have
pretty good view of what is currently happening.
When is it going to be ready?
Don't hold your breath. Officially SGI has said by the end of the year,
technically... whew
frankly I can't even guess. I would hope within a month or so we will
have the basics of a FS.
There are a lot of hurtles to overcome. XFS is a very very complex file
system that relies on
some of the more advanced features of IRIX. The buffer cache and chunk
cache (chunking
buffers together to do large IO) are two examples that come to mind. SGI
is rewriting
the buffer cache (calling it the page cache) such that is will be able to
support XFS.
chunk cache... ? not sure what we are going to do with that.
We have been having several discussions about the best way to
"interface".
IRIX uses VFS,VNODE,BEHAVIOR which is similar to the BSD's interface
but of course very IRIX specific. Linux's vfs/vnode is different from
either.
Realizing this, a lot of our discussions have been around how to go at
making a
new/modify existing interface layer that might be more "universal"
i.e. not irix not linux not bsd not etc.... specific.
In reading Terry's & Bill's comments seems there is a a lot of room for
improvement.
Initially we trying to make as few changes as possible to XFS to get an
initial implementation
running on linux. After we get things running we will start to analyze
where the problems exist,
and decide what direction in terms of interface to take at that time.
I would like any constructive input people have on this matter. I have a
pretty good
chance of setting design direction.
Be waned: SGI at the moment is committed to linux, development directions
will favor that platform.
They are not against other OS's being XFS'atized but SGI is in the
business of selling
hardware/solutions based on that hardware and linux one of the OS they
have decided to use for
their intel based boxes.
Also as far as the GPL issue goes, get over it! I understand the issues
and agree with many
of the points.
My suggestion lets find a way to work with the GPL (i.e. loadable kernel
module /
softupdates model)
If somebody has a very very good argument/solution to the licensing
debate let me
know, I can present it to the people dealing with the lawyers.
The license issue has slowed the release of the actual code more than
anything else,
and will not be revisited again without great pain.
> I am currently conducting a thorough study of the VFS subsystem
> in preparation for an all-out effort to port SGI's XFS filesystem to
> FreeBSD 4.x at such time as SGI gives up the code. Matt Dillon
> has written in hackers- that the VFS subsystem is presently not
> well understood by any of the active kernel code contributers and
> that it will be rewritten later this year. This is obviously of great
> concern to me in this port. I greatly appreciate all assistance in
> answering the following questions:
>
> 1) What are the perceived problems with the current VFS?
> 2) What options are available to us as remedies?
> 3) To what extent will existing FS code require revision in order
> to be useful after the rewrite?
> 4) Will Chapters 6,7,8 & 9 of "The Design and Implementation of
> the 4.4BSD Operating System" still pertain after the rewrite?
> 5) How important are questions 3 & 4 in the design of the new
> VFS?
>
> I believe that the VFS is conceptually sound and that the existing
> semantics should be strictly retained in the new code. Any new
> functionality should be added in the form of entirely new kernel
> routines and system calls, or possibly by such means as
> converting the existing routines to the vararg format &etc.
>
> Does anyone know when SGI will release XFS?
>
>
--
Russell Cattelan
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