Re: [RFC] persistent store (version 2) (part 1 of 2)

From: Andrew Morton
Date: Thu Dec 02 2010 - 05:14:24 EST


On Wed, 1 Dec 2010 22:00:12 -0800 "Luck, Tony" <tony.luck@xxxxxxxxx> wrote:

> > filenames refer to files! And lo, that's what we have here. A
> > filesystem! The files are created by the kernel and are read and
> > unlinked by userspace.
> >
> > So why not implement this whole thing as a proper filesystem?
> ...
> > Wait. It *is* a filesystem.
> ...
> > So why can't I remove these "records" with rm?
>
> Because I tried to use /sys for this and couldn't find a
> way to get notified about "unlink". Alan Cox called this
> bit "daft" in v1 (and I agreed with him). Peter Anvin gave
> me some pointers on how easy this would be to do as a real
> filesystem ... so v3 will be out in a little while with
> this insanity removed.

OK. Yes, the correct answer is usually "create a new filesystem
driver" ;)

<greps>

gad, there are over 200 register_filesystem() callsites.

One thing which does leap out of the v2 implementation is the hardwired
assumption that there is one store kernel-wide. I suppose that's OK as
a version-1 implementation detail thing, but we should avoid hardwiring
that assumption into the presentation of v1's userspace interfaces.

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