Re: [PATCH v4 5/7] fs: prioritize and separate direct_io from dax_io

[hch@xxxxxxxxxxxxx]

On Thu, May 05, 2016 at 09:45:07PM +0000, Verma, Vishal L wrote:
> I'm not sure I completely understand how this will work? Can you explain
> a bit? Would we have to export rw_bytes up to layers above the pmem
> driver? Where does get_user_pages come in?

A DAX filesystem can directly use the nvdimm layer the same way btt
doe,s what's the problem?

Re get_user_pages my idea was to simply use that to lock down the user
pages so that we can call rw_bytes on it.  How else would you do it?  Do
a kmalloc, copy_from_user and then another memcpy?