Re: [Lsf-pc] [LSF/MM TOPIC] The end of the DAX experiment
On 14/02/2019 20:25, Dan Williams wrote:
On Thu, Feb 14, 2019 at 5:46 AM Michal Hocko
<mhocko(a)kernel.org> 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.
This topic is very interesting to me.
In current ZUFS implementation we support this option for a long time.
IE: Map same pte_t into different indexes of the same file-mappings as well as
in vma(s) of different files, at different indexes. Including invalidation
of mapping of a pwrite into such a shared page.
(A write to a shared block will allocate a new block for writing)
This effort off-course involves the participation of the FileSystem
to give a list of files and indexes for map_unmapping().
I can explain if you want how we did this.
Cheers
Boaz