On Sat, Aug 29, 2020 at 01:08:52AM -0700, John Hubbard wrote: > The new routines are: > iov_iter_pin_user_pages() > iov_iter_pin_user_pages_alloc() > > and those correspond to these pre-existing routines: > iov_iter_get_pages() > iov_iter_get_pages_alloc() > > Also, pipe_get_pages() and related are changed so as to pass > down a "use_pup" (use pin_user_page() instead of get_page()) bool > argument. > > Unlike the iov_iter_get_pages*() routines, the > iov_iter_pin_user_pages*() routines assert that only ITER_IOVEC or > ITER_PIPE items are passed in. They then call pin_user_page*(), instead > of get_user_pages_fast() or get_page(). > > Why: In order to incrementally change Direct IO callers from calling > get_user_pages_fast() and put_page(), over to calling > pin_user_pages_fast() and unpin_user_page(), there need to be mid-level > routines that specifically call one or the other systems, for both page > acquisition and page release. Hmm... Do you plan to kill iov_iter_get_pages* off, eventually getting rid of that use_pup argument?
