switch memcpy_to_msg() and skb_copy{,_and_csum}_datagram_msg() to primitives

... making both non-draining.  That means that tcp_recvmsg() becomes
non-draining.  And _that_ would break iscsit_do_rx_data() unless we
	a) make sure tcp_recvmsg() is uniformly non-draining (it is)
	b) make sure it copes with arbitrary (including shifted)
iov_iter (it does, all it uses is iov_iter primitives)
	c) make iscsit_do_rx_data() initialize ->msg_iter only once.

Fortunately, (c) is doable with minimal work and we are rid of one
the two places where kernel send/recvmsg users would be unhappy with
non-draining behaviour.

Actually, that makes all but one of ->recvmsg() instances iov_iter-clean.
The exception is skcipher_recvmsg() and it also isn't hard to convert
to primitives (iov_iter_get_pages() is needed there).  That'll wait
a bit - there's some interplay with ->sendmsg() path for that one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 5 insertions, 7 deletions

diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index ce87ce9bdb9c..7c6a95bcb35e 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -1326,21 +1326,19 @@ static int iscsit_do_rx_data(
 	struct iscsi_conn *conn,
 	struct iscsi_data_count *count)
 {
-	int data = count->data_length, rx_loop = 0, total_rx = 0, iov_len;
-	struct kvec *iov_p;
+	int data = count->data_length, rx_loop = 0, total_rx = 0;
 	struct msghdr msg;
 
 	if (!conn || !conn->sock || !conn->conn_ops)
 		return -1;
 
 	memset(&msg, 0, sizeof(struct msghdr));
-
-	iov_p = count->iov;
-	iov_len	= count->iov_count;
+	iov_iter_kvec(&msg.msg_iter, READ | ITER_KVEC,
+		      count->iov, count->iov_count, data);
 
 	while (total_rx < data) {
-		rx_loop = kernel_recvmsg(conn->sock, &msg, iov_p, iov_len,
-					(data - total_rx), MSG_WAITALL);
+		rx_loop = sock_recvmsg(conn->sock, &msg,
+				      (data - total_rx), MSG_WAITALL);
 		if (rx_loop <= 0) {
 			pr_debug("rx_loop: %d total_rx: %d\n",
 				rx_loop, total_rx);