iov_iter: Separate type from direction and use accessor functions

In the iov_iter struct, separate the iterator type from the iterator
direction and use accessor functions to access them in most places.

Convert a bunch of places to use switch-statements to access them rather
then chains of bitwise-AND statements.  This makes it easier to add further
iterator types.  Also, this can be more efficient as to implement a switch
of small contiguous integers, the compiler can use ~50% fewer compare
instructions than it has to use bitwise-and instructions.

Further, cease passing the iterator type into the iterator setup function.
The iterator function can set that itself.  Only the direction is required.

Signed-off-by: David Howells <dhowells@redhat.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index ef8212a4b73e..ded9735d44af 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -1856,7 +1856,7 @@ int drbd_send(struct drbd_connection *connection, struct socket *sock,
 
 	/* THINK  if (signal_pending) return ... ? */
 
-	iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, &iov, 1, size);
+	iov_iter_kvec(&msg.msg_iter, WRITE, &iov, 1, size);
 
 	if (sock == connection->data.socket) {
 		rcu_read_lock();
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 75f6b47169e6..fcc70642b004 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -516,7 +516,7 @@ static int drbd_recv_short(struct socket *sock, void *buf, size_t size, int flag
 	struct msghdr msg = {
 		.msg_flags = (flags ? flags : MSG_WAITALL | MSG_NOSIGNAL)
 	};
-	iov_iter_kvec(&msg.msg_iter, READ | ITER_KVEC, &iov, 1, size);
+	iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, size);
 	return sock_recvmsg(sock, &msg, msg.msg_flags);
 }