[PATCH net-next v2 1/3] vsock: Add support for SIOCINQ ioctl

[Xuewei Niu <niuxuewei97@xxxxxxxxx>]

This patch adds support for SIOCINQ ioctl, which returns the number of
bytes unread in the socket.

Signed-off-by: Xuewei Niu <niuxuewei.nxw@xxxxxxxxxxxx>
---
 include/net/af_vsock.h   |  2 ++
 net/vmw_vsock/af_vsock.c | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index d56e6e135158..723a886253ba 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -171,6 +171,8 @@ struct vsock_transport {
 
 	/* SIOCOUTQ ioctl */
 	ssize_t (*unsent_bytes)(struct vsock_sock *vsk);
+	/* SIOCINQ ioctl */
+	ssize_t (*unread_bytes)(struct vsock_sock *vsk);
 
 	/* Shutdown. */
 	int (*shutdown)(struct vsock_sock *, int);
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 2e7a3034e965..466b1ebadbbc 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1389,6 +1389,28 @@ static int vsock_do_ioctl(struct socket *sock, unsigned int cmd,
 	vsk = vsock_sk(sk);
 
 	switch (cmd) {
+	case SIOCINQ: {
+		ssize_t n_bytes;
+
+		if (!vsk->transport || !vsk->transport->unread_bytes) {
+			ret = -EOPNOTSUPP;
+			break;
+		}
+
+		if (sock_type_connectible(sk->sk_type) &&
+		    sk->sk_state == TCP_LISTEN) {
+			ret = -EINVAL;
+			break;
+		}
+
+		n_bytes = vsk->transport->unread_bytes(vsk);
+		if (n_bytes < 0) {
+			ret = n_bytes;
+			break;
+		}
+		ret = put_user(n_bytes, arg);
+		break;
+	}
 	case SIOCOUTQ: {
 		ssize_t n_bytes;
 
-- 
2.34.1