On Wed, Jun 5, 2019 at 9:22 AM Goldwyn Rodrigues <rgoldwyn@xxxxxxx> wrote: > > Hi Dan/Jerome, > > On 12:20 14/02, Dan Williams wrote: > > On Thu, Feb 14, 2019 at 12:09 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> 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@xxxxxxxxxx> 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. > > Was there any outcome on this and its implementation? I am specifically > interested in this for DAX support on btrfs/CoW: The TODO comment on > top of dax_associate_entry() :) > > If there are patches/git tree I could use to base my patches on, it would > be nice. Half joking, but I was hoping that by the time I had circled back to finally reviewing the brtfs dax patches that a solution to this problem would be waiting. We spent more time on other DAX topics. I recall that Jerome and I were mutually skeptical of each others approaches at first glance, but we did not get into the details. So, I think it will be a matter of getting the idea coded up. I'm finally coming out from under a pile of mm work so I should have some time this cycle to push the page proxy idea forward.
