io_uring/zcrx: convert to use netmem_desc

Convert zcrx to struct netmem_desc, and use struct net_iov::desc to
access its fields instead of struct net_iov inner union alises.
zcrx only directly reads niov->pp, so with this patch it doesn't depend
on the union anymore.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Byungchul Park <byungchul@sk.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: isilence

io_uring/zcrx.c

@@ -696,12 +696,12 @@ static void io_zcrx_return_niov(struct net_iov *niov)
 {
 	netmem_ref netmem = net_iov_to_netmem(niov);
 
-	if (!niov->pp) {
+	if (!niov->desc.pp) {
 		/* copy fallback allocated niovs */
 		io_zcrx_return_niov_freelist(niov);
 		return;
 	}
-	page_pool_put_unrefed_netmem(niov->pp, netmem, -1, false);
+	page_pool_put_unrefed_netmem(niov->desc.pp, netmem, -1, false);
 }
 
 static void io_zcrx_scrub(struct io_zcrx_ifq *ifq)
@@ -815,7 +815,7 @@ static void io_zcrx_ring_refill(struct page_pool *pp,
 		if (!page_pool_unref_and_test(netmem))
 			continue;
 
-		if (unlikely(niov->pp != pp)) {
+		if (unlikely(niov->desc.pp != pp)) {
 			io_zcrx_return_niov(niov);
 			continue;
 		}
@@ -1082,13 +1082,15 @@ static int io_zcrx_recv_frag(struct io_kiocb *req, struct io_zcrx_ifq *ifq,
 			     const skb_frag_t *frag, int off, int len)
 {
 	struct net_iov *niov;
+	struct page_pool *pp;
 
 	if (unlikely(!skb_frag_is_net_iov(frag)))
 		return io_zcrx_copy_frag(req, ifq, frag, off, len);
 
 	niov = netmem_to_net_iov(frag->netmem);
-	if (!niov->pp || niov->pp->mp_ops != &io_uring_pp_zc_ops ||
-	    io_pp_to_ifq(niov->pp) != ifq)
+	pp = niov->desc.pp;
+
+	if (!pp || pp->mp_ops != &io_uring_pp_zc_ops || io_pp_to_ifq(pp) != ifq)
 		return -EFAULT;
 
 	if (!io_zcrx_queue_cqe(req, niov, ifq, off + skb_frag_off(frag), len))