Re: [PATCH 10/20] hpfs: replace BKL with a global mutex

From: Miklos Szeredi
Date: Thu Jan 27 2011 - 05:57:29 EST

On Thu, 27 Jan 2011, Nick Piggin wrote:
> On Thu, Jan 27, 2011 at 3:52 AM, Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:
> > On Wed, Jan 26, 2011 at 01:50:42PM +0100, Arnd Bergmann wrote:
> >> On Wednesday 26 January 2011, Andi Kleen wrote:
> >> > I don't think that's a very good idea, there's danger
> >> > of holding it over IO and that would be really bad (as in like MINIX[1])
> >> >
> >> > It would be better to do it the i810 way and check for the number of
> >> > CPUs at module init time and refuse to run if it's > 1
> >>
> >> I don't see much value of one evil over the other, but why not. The code
> >> is going away anyway unless someone cleans it up further.
> >
> > I think it's fine because systems running OS/2 likely only have
> > one CPU. This way these guys (if they exist) won't see any regression.
> It would be really neat if there was a project to destage a lot of
> these old filesystems and implement read-only support with fuse
> implementations (not that I'm volunteering :P).

I did that using UML + fuse. It's pretty neat, UML boots fast when it
doesn't need a big userspace, so the mount is done in a few hundred
milliseconds, and performance isn't horrible. And you get support for
*all* the filesystems in a single 3MB executable.

The big drawback is that UML is not portable to lots of architectures
(x86 and ppc are the only ones it works on, I think).

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