[nbd] switch sock_xmit() to sock_{send,recv}msg()

Step 1 - don't reinintialize ->msg_iter on each iteration.

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

1 files changed, 7 insertions, 9 deletions

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 38c576f76d36..8e63caecdd00 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -215,7 +215,7 @@ static int sock_xmit(struct nbd_device *nbd, int index, int send, void *buf,
         struct socket *sock = nbd->socks[index]->sock;
         int result;
         struct msghdr msg;
-        struct kvec iov;
+        struct kvec iov = {.iov_base = buf, .iov_len = size};
         unsigned long pflags = current->flags;
 
         if (unlikely(!sock)) {
@@ -225,11 +225,12 @@ static int sock_xmit(struct nbd_device *nbd, int index, int send, void *buf,
                 return -EINVAL;
         }
 
+        iov_iter_kvec(&msg.msg_iter, (send ? WRITE : READ) | ITER_KVEC,
+                      &iov, 1, size);
+
         current->flags |= PF_MEMALLOC;
         do {
                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
-                iov.iov_base = buf;
-                iov.iov_len = size;
                 msg.msg_name = NULL;
                 msg.msg_namelen = 0;
                 msg.msg_control = NULL;
@@ -237,19 +238,16 @@ static int sock_xmit(struct nbd_device *nbd, int index, int send, void *buf,
                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 
                 if (send)
-                        result = kernel_sendmsg(sock, &msg, &iov, 1, size);
+                        result = sock_sendmsg(sock, &msg);
                 else
-                        result = kernel_recvmsg(sock, &msg, &iov, 1, size,
-                                                msg.msg_flags);
+                        result = sock_recvmsg(sock, &msg, msg.msg_flags);
 
                 if (result <= 0) {
                         if (result == 0)
                                 result = -EPIPE; /* short read */
                         break;
                 }
-                size -= result;
-                buf += result;
-        } while (size > 0);
+        } while (msg_data_left(&msg));
 
         tsk_restore_flags(current, pflags, PF_MEMALLOC);