On Thu, Feb 14, 2019 at 11:10 AM Jerome Glisse <jglisse@xxxxxxxxxx> wrote: > > On Thu, Feb 14, 2019 at 10:25:07AM -0800, Dan Williams wrote: > > On Thu, Feb 14, 2019 at 5:46 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > > > On Wed 06-02-19 13:12:59, Dan Williams wrote: > > > [...] > > > > * Userfaultfd for file-backed mappings and DAX > > > > > > I assume that other topics are meant to be FS track but this one is MM, > > > right? > > > > Yes, but I think it is the lowest priority of all the noted sub-topics > > in this proposal. The DAX-reflink discussion, where a given > > physical-page may need to be mapped into multiple inodes at different > > offsets, might be more fruitful to have as a joint discussion with MM. > > Note that my generic page write protection work can be use for that ie > having a single page correspond to multiple different mapping with also > different offset within each mapping. While in my patchset i only solve > the mapping aliasing issue, the index can be solve in much the same way > because same thinking apply. Namely that when you work on a file you > know the mapping and file offset and thus the index and when you work on > the vma you know the mapping and offset within the vma which translate > to offset within the file. They are only few places that do not have the > informations available and those do not care about it. > > 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.
