RE: Cleancache [PATCH 2/7] (was Transcendent Memory): core files

From: Dan Magenheimer
Date: Mon May 24 2010 - 22:17:21 EST


> > The third one is pgoff_t; again, use sane types, _if_ you actually
> want
> > the argument #3 at all - it can be derived from struct page you are
> > passing there as well.
>
> I thought it best to declare the _ops so that the struct page
> is opaque to the "backend" (driver). The kernel-side ("frontend")
> defines the handle and ensures coherency, so the backend shouldn't
> be allowed to derive or muck with the three-tuple passed by the
> kernel. In the existing (Xen tmem) driver, the only operation
> performed on the struct page parameter is page_to_pfn(). OTOH,
> I could go one step further and pass a pfn_t instead of a
> struct page, since it is really only the physical page frame that
> the backend needs to know about and (synchronously) read/write from/to.
>
> Thoughts?

Silly me. pfn_t is a Xen/KVM type not otherwise used in the
kernel AFAICT. Please ignore...

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