sock: Remove ->sendpage*() in favour of sendmsg(MSG_SPLICE_PAGES)

Remove ->sendpage() and ->sendpage_locked().  sendmsg() with
MSG_SPLICE_PAGES should be used instead.  This allows multiple pages and
multipage folios to be passed through.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de> # for net/can
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-afs@lists.infradead.org
cc: mptcp@lists.linux.dev
cc: rds-devel@oss.oracle.com
cc: tipc-discussion@lists.sourceforge.net
cc: virtualization@lists.linux-foundation.org
Link: https://lore.kernel.org/r/20230623225513.2732256-16-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

crypto/af_alg.c

@@ -482,7 +482,6 @@ static const struct proto_ops alg_proto_ops = {
 	.listen		=	sock_no_listen,
 	.shutdown	=	sock_no_shutdown,
 	.mmap		=	sock_no_mmap,
-	.sendpage	=	sock_no_sendpage,
 	.sendmsg	=	sock_no_sendmsg,
 	.recvmsg	=	sock_no_recvmsg,
 
@@ -1106,33 +1105,6 @@ unlock:
 }
 EXPORT_SYMBOL_GPL(af_alg_sendmsg);
 
-/**
- * af_alg_sendpage - sendpage system call handler
- * @sock: socket of connection to user space to write to
- * @page: data to send
- * @offset: offset into page to begin sending
- * @size: length of data
- * @flags: message send/receive flags
- *
- * This is a generic implementation of sendpage to fill ctx->tsgl_list.
- */
-ssize_t af_alg_sendpage(struct socket *sock, struct page *page,
-			int offset, size_t size, int flags)
-{
-	struct bio_vec bvec;
-	struct msghdr msg = {
-		.msg_flags = flags | MSG_SPLICE_PAGES,
-	};
-
-	if (flags & MSG_SENDPAGE_NOTLAST)
-		msg.msg_flags |= MSG_MORE;
-
-	bvec_set_page(&bvec, page, size, offset);
-	iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
-	return sock_sendmsg(sock, &msg);
-}
-EXPORT_SYMBOL_GPL(af_alg_sendpage);
-
 /**
  * af_alg_free_resources - release resources required for crypto request
  * @areq: Request holding the TX and RX SGL