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Date:      Wed, 13 Feb 2008 09:03:59 +0000 (GMT)
From:      Robert Watson <rwatson@FreeBSD.org>
To:        =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
Cc:        Csaba Henk <csaba-ml@creo.hu>, freebsd-fs@freebsd.org, freebsd-arch@freebsd.org
Subject:   Re: [RFC] Remove NTFS kernel support
Message-ID:  <20080213085903.U13849@fledge.watson.org>
In-Reply-To: <86d4r2540f.fsf@ds4.des.no>
References:  <3bbf2fe10802061700p253e68b8s704deb3e5e4ad086@mail.gmail.com> <70e8236f0802070321n9097d3fy1b39f637b3c2a06@mail.gmail.com> <slrnfqrp6g.i6j.csaba-ml@beastie.creo.hu> <867ihdc34c.fsf@ds4.des.no> <20080212190207.GB49155@beastie.creo.hu> <86d4r2540f.fsf@ds4.des.no>

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On Tue, 12 Feb 2008, Dag-Erling Sm=F8rgrav wrote:

> Csaba Henk <csaba-ml@creo.hu> writes:
>> Dag-Erling Sm=F8rgrav <des@des.no> writes:
>>> How much work would you guess it would take to reimplement the
>>> userland part under a BSD license?
>> Well, I just started to work on a from scratch FUSE daemon library. [...=
]=20
>> So I think: fuse4bsd (ie, the kld + the mount util) + libfolly + sysctl =
fs=20
>> could go to base under BSD license. It also might make sense to rebase=
=20
>> ntfs-3g atop of folly -- although it won't help ntfs-3g being GPL'd.
>
> That doesn't matter; ntfs-3g can still be a port.
>
> What does matter is that if libfolly exports the same API as libfuse, we =
can=20
> have a complete BSD-licensed FUSE implementation in the base system, with=
=20
> minimal effort required to port FUSE-based file systems.

Has there been any work to add more mature interfaces to fuse over the last=
=20
couple of years?  When I looked at it previously, and that was a year or tw=
o=20
ago, fuse didn't work well with our notion of "referenced" vs. "open" vnode=
s,=20
and required explicit data copies from cache files into the kernel to be=20
exposed via fuse.  These are both areas where nnpfs, the userspace file sys=
tem=20
framework for Arla, does much better, as they offer improved handling of=20
memory mapping (which persists after file descriptor close(), as in execve(=
)=20
and with shared libraries) and performance (no need to feed data for files =
to=20
the kernel, you can just point the kernel at a persistent cache file, possi=
bly=20
cached from a previous session, allowing normal faulting of cache data into=
=20
memory rather than requiring that pages pass through user space).  My=20
understanding is that the NetBSD user space fs work offers a more mature=20
back-end interface than fuse, but allows the less complex fuse API to be us=
ed,=20
but I've not done any detailed reading.  These are areas where I assumed th=
at=20
over time we'd see functional improvements in fuse, so I guess I'm wonderin=
g=20
if that has happened?

Robert N M Watson
Computer Laboratory
University of Cambridge
--621616949-1602308289-1202893439=:13849--



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