On Thu, Sep 22, 2022 at 03:22:48AM +0100, Al Viro wrote: > What I'd like to have is the understanding of the places where we drop > the references acquired by iov_iter_get_pages(). How do we decide > whether to unpin? Add a iov_iter_unpin_pages that does the right thing based on the type. (block will need a modified copy of it as it doesn't keep the pages array around, but logic will be the same). > E.g. pipe_buffer carries a reference to page and no > way to tell whether it's a pinned one; results of iov_iter_get_pages() > on ITER_IOVEC *can* end up there, but thankfully only from data-source > (== WRITE, aka. ITER_SOURCE) iov_iter. So for those we don't care. > Then there's nfs_request; AFAICS, we do need to pin the references in > those if they are coming from nfs_direct_read_schedule_iovec(), but > not if they come from readpage_async_filler(). How do we deal with > coalescence, etc.? It's been a long time since I really looked at > that code... Christoph, could you give any comments on that one? I think the above should work, but I'll need to look at the NFS code in more detail to be sure.
