Date: Thu, 18 Feb 1999 09:40:50 +0000 (GMT) From: Doug Rabson <dfr@nlsystems.com> To: AARON MARKS <amarks@sarnoff.com> Cc: freebsd-hackers@freebsd.org, Matthew Dillon <dillon@apollo.backplane.com> Subject: Re: Memory-Based VFS Question Message-ID: <Pine.BSF.4.05.9902180939460.61913-100000@herring.nlsystems.com> In-Reply-To: <36CB1C9B.77725962@sarnoff.com>
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On Wed, 17 Feb 1999, AARON MARKS wrote:
> I appologize for the ignorance, but:
>
> Terry Lambert wrote:
> >
> > The generic code assumes a vnode as a backing store. If he does not
> > have a vnode as a backing store, he can not use the generic code.
>
> What do you mean using a vnode as a backing store? A file in my MFS has
> a vnode allocated to it.
>
> >
> > Basically, if he could use it, since that's the default that's
> > inherited from the default ops vector, it'd already be working,
> > and he wouldn't be asking the question.
> >
> > He's asking, so ipso facto, he's not using a vnode as backing store.
> >
> > This makes sense, since he said he's writing a new MFS; he's probably
> > managing the page allocation himself from the KVA space.
>
> I think so. I allocate blocks of 8k memory and grow as necessary.
>
> >
> > To answer the question: pattern your code after the code in the file
> > /sys/vm/device_pager.c's dev_pager_getpages()/dev_pager_putpages()
> > code, and you should be OK.
>
> Great. I'll take a look-see.
>
> I have another question, though: I mapped my _{get,put}pages functions
> (they're empty, just print to console and return 0) to the vop functions
> but when I do a system file copy (via cp), the OS never calls my
> {get,put}pages functions.
Strange. Are they in the table of vnode ops for your filesystem? Try
setting a breakpoint in the vm code where it is about to call VOP_GETPAGES
and single step to see where it goes.
--
Doug Rabson Mail: dfr@nlsystems.com
Nonlinear Systems Ltd. Phone: +44 181 442 9037
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