On Wed, Jul 26, 2017 at 09:08:00AM -0700, Dan Williams wrote:
Another question, does ->rw_page() really buy us that much with
pmem driver? If applications want to enjoy the lowest latency access
they can just use DAX. There's now only 4 drivers that use rw_page
since nvme dropped its usage and I'd be inclined to just rip it out.
nvme never supported rw_page (there was a page for it, but it
fortunately never got merged).
rw_page are massive pain the ass and the method should go away.
For make_request drivers that actually operate synchronous (e.g.
the ramdisk) it's not much of a benefit, and even for normally
asynchronous drivers like nvme the block layer polling interface
is much more suitable.