[RFC] Remove NTFS kernel support

[Robert Watson]

On Tue, 12 Feb 2008, Dag-Erling Smørgrav wrote:

> Csaba Henk <csaba-ml at creo.hu> writes:
>> Dag-Erling Smørgrav <des at 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. [...] 
>> So I think: fuse4bsd (ie, the kld + the mount util) + libfolly + sysctl fs 
>> could go to base under BSD license. It also might make sense to rebase 
>> 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 
> have a complete BSD-licensed FUSE implementation in the base system, with 
> minimal effort required to port FUSE-based file systems.

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

Robert N M Watson
Computer Laboratory
University of Cambridge