On Wed, Feb 05, 2020 at 04:40:44PM -0800, Dan Williams wrote: > On Wed, Feb 5, 2020 at 12:03 PM Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > > > > On Wed, Feb 05, 2020 at 10:30:50AM -0800, Christoph Hellwig wrote: > > > > + /* > > > > + * There are no users as of now. Once users are there, fix dm code > > > > + * to be able to split a long range across targets. > > > > + */ > > > > > > This comment confused me. I think this wants to say something like: > > > > > > /* > > > * There are now callers that want to zero across a page boundary as of > > > * now. Once there are users this check can be removed after the > > > * device mapper code has been updated to split ranges across targets. > > > */ > > > > Yes, that's what I wanted to say but I missed one line. Thanks. Will fix > > it. > > > > > > > > > +static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, > > > > + unsigned int offset, size_t len) > > > > +{ > > > > + int rc = 0; > > > > + phys_addr_t phys_pos = pgoff * PAGE_SIZE + offset; > > > > > > Any reason not to pass a phys_addr_t in the calling convention for the > > > method and maybe also for dax_zero_page_range itself? > > > > I don't have any reason not to pass phys_addr_t. If that sounds better, > > will make changes. > > The problem is device-mapper. That wants to use offset to route > through the map to the leaf device. If it weren't for the firmware > communication requirement you could do: > > dax_direct_access(...) > generic_dax_zero_page_range(...) > > ...but as long as the firmware error clearing path is required I think > we need to do pass the pgoff through the interface and do the pgoff to > virt / phys translation inside the ops handler. Hi Dan, Drivers can easily convert offset into dax device (say phys_addr_t) to pgoff and offset into page, isn't it? pgoff_t = phys_addr_t/PAGE_SIZE; offset = phys_addr_t & (PAGE_SIZE - 1); And pgoff can easily be converted into sectors which dm/md can use for mapping and come up with pgoff in target device. Anyway, I am fine with anything. Thanks Vivek