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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Thu, 14 Feb 2019 12:20:11 -0800
Message-ID: <CAPcyv4hsDqvrV5yiDq8oWPuWb3WpuCEk_HB4qBxfiDpUwo75QQ@mail.gmail.com>
Subject: Re: [Lsf-pc] [LSF/MM TOPIC] The end of the DAX experiment
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Jerome Glisse <jglisse@redhat.com>,
        Michal Hocko <mhocko@kernel.org>,
        lsf-pc@lists.linux-foundation.org,
        linux-xfs <linux-xfs@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-ext4 <linux-ext4@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-nvdimm <linux-nvdimm@lists.01.org>
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On Thu, Feb 14, 2019 at 12:09 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Feb 14, 2019 at 11:31:24AM -0800, Dan Williams wrote:
> > On Thu, Feb 14, 2019 at 11:10 AM Jerome Glisse <jglisse@redhat.com> wrote:
> > > I am just again working on my struct page mapping patchset as well as
> > > the generic page write protection that sits on top. I hope to be able
> > > to post the v2 in couple weeks. You can always look at my posting last
> > > year to see more details.
> >
> > Yes, I have that in mind as one of the contenders. However, it's not
> > clear to me that its a suitable fit for filesystem-reflink. Others
> > have floated the 'page proxy' idea, so it would be good to discuss the
> > merits of the general approaches.
>
> ... and my preferred option of putting pfn entries in the page cache.

Another option to include the discussion.

> Or is that what you meant by "page proxy"?

Page proxy would be an object that a filesystem could allocate to
point back to a single physical 'struct page *'. The proxy would
contain an override for page->index.