vsock: enable SOCK_SUPPORT_ZC bit

This bit is used by io_uring in case of zerocopy tx mode. io_uring code
checks, that socket has this feature. This patch sets it in two places:
1) For socket in 'connect()' call.
2) For new socket which is returned by 'accept()' call.
Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/vmw_vsock/af_vsock.c

@@ -1406,6 +1406,9 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr,
 			goto out;
 		}
 
+		if (vsock_msgzerocopy_allow(transport))
+			set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
+
 		err = vsock_auto_bind(vsk);
 		if (err)
 			goto out;
@@ -1560,6 +1563,9 @@ static int vsock_accept(struct socket *sock, struct socket *newsock, int flags,
 		} else {
 			newsock->state = SS_CONNECTED;
 			sock_graft(connected, newsock);
+			if (vsock_msgzerocopy_allow(vconnected->transport))
+				set_bit(SOCK_SUPPORT_ZC,
+					&connected->sk_socket->flags);
 		}
 
 		release_sock(connected);