nbd: Shutdown socket before closing.

This forces finishing data sending to client before closing the socket like in
exports listing or replying with NBD_REP_ERR_UNSUP cases.

Signed-off-by: Hani Benhabiles <kroosec@gmail.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 18dc528..b3a2474 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -28,6 +28,7 @@
 
     int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
     if (fd >= 0 && !nbd_client_new(NULL, fd, nbd_client_put)) {
+        shutdown(fd, 2);
         close(fd);
     }
 }
diff --git a/qemu-nbd.c b/qemu-nbd.c
index ba60436..626e584 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -372,6 +372,7 @@
     if (nbd_client_new(exp, fd, nbd_client_closed)) {
         nb_fds++;
     } else {
+        shutdown(fd, 2);
         close(fd);
     }
 }