On Thu, Feb 02, 2017 at 09:51:25AM +0000, Al Viro wrote: > On Wed, Jan 25, 2017 at 08:32:03AM -0500, Jeff Layton wrote: > > Small respin of the patch that I sent yesterday for the same thing. > > > > This moves the maxsize handling into iov_iter_pvec_size, so that we don't > > end up iterating past the max size we'll use anyway when trying to > > determine the pagevec length. > > > > Also, a respun patch to make ceph use iov_iter_get_pages_alloc instead of > > trying to do it via its own routine. > > > > Al, if these look ok, do you want to pick these up or shall I ask > > Ilya to merge them via the ceph tree? > > I'd rather have that kind of work go through the vfs tree; said that, > I really wonder if this is the right approach. Most of the users of > iov_iter_get_pages()/iov_iter_get_pages_alloc() look like they want > something like > iov_iter_for_each_page(iter, size, f, data) > with int (*f)(struct page *page, size_t from, size_t size, void *data) > passed as callback. Not everything fits that model, but there's a whole > lot of things that do. I was planning to do that, mostly because of the iomap dio code that would not only get a lot cleaner with this, but also support multi-page bvecs that we hope to have in the block layer soon. The issue with it is that we need to touch all the arch get_user_pages_fast implementations, so it's going to be a relatively invasive change that I didn't want to fix with just introducing the new direct I/O code.
