[PATCH 2/3] vsock/virtio: Add SIOCINQ support for all virtio based transports

[Xuewei Niu <niuxuewei97@xxxxxxxxx>]

The virtio_vsock_sock has a new field called bytes_unread as the return
value of the SIOCINQ ioctl.

Though the rx_bytes exists, we introduce a bytes_unread field to the
virtio_vsock_sock struct. The reason is that it will not be updated
until the skbuff is fully consumed, which causes inconsistency.

The byte_unread is increased by the length of the skbuff when skbuff is
enqueued, and it is decreased when dequeued.

Signed-off-by: Xuewei Niu <niuxuewei.nxw@xxxxxxxxxxxx>
---
 drivers/vhost/vsock.c                   |  1 +
 include/linux/virtio_vsock.h            |  2 ++
 net/vmw_vsock/virtio_transport.c        |  1 +
 net/vmw_vsock/virtio_transport_common.c | 17 +++++++++++++++++
 net/vmw_vsock/vsock_loopback.c          |  1 +
 5 files changed, 22 insertions(+)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 802153e23073..0f20af6e5036 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -452,6 +452,7 @@ static struct virtio_transport vhost_transport = {
 		.notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
 
 		.unsent_bytes             = virtio_transport_unsent_bytes,
+		.unread_bytes             = virtio_transport_unread_bytes,
 
 		.read_skb = virtio_transport_read_skb,
 	},
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 0387d64e2c66..0a7bd240113a 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -142,6 +142,7 @@ struct virtio_vsock_sock {
 	u32 buf_alloc;
 	struct sk_buff_head rx_queue;
 	u32 msg_count;
+	size_t bytes_unread;
 };
 
 struct virtio_vsock_pkt_info {
@@ -195,6 +196,7 @@ s64 virtio_transport_stream_has_space(struct vsock_sock *vsk);
 u32 virtio_transport_seqpacket_has_data(struct vsock_sock *vsk);
 
 ssize_t virtio_transport_unsent_bytes(struct vsock_sock *vsk);
+ssize_t virtio_transport_unread_bytes(struct vsock_sock *vsk);
 
 void virtio_transport_consume_skb_sent(struct sk_buff *skb,
 				       bool consume);
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index f0e48e6911fc..917881537b63 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -585,6 +585,7 @@ static struct virtio_transport virtio_transport = {
 		.notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
 
 		.unsent_bytes             = virtio_transport_unsent_bytes,
+		.unread_bytes             = virtio_transport_unread_bytes,
 
 		.read_skb = virtio_transport_read_skb,
 	},
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 7f7de6d88096..11eae88c60fc 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -632,6 +632,7 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
 	free_space = vvs->buf_alloc - fwd_cnt_delta;
 	low_rx_bytes = (vvs->rx_bytes <
 			sock_rcvlowat(sk_vsock(vsk), 0, INT_MAX));
+	vvs->bytes_unread -= total;
 
 	spin_unlock_bh(&vvs->rx_lock);
 
@@ -782,6 +783,7 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
 		}
 
 		virtio_transport_dec_rx_pkt(vvs, pkt_len);
+		vvs->bytes_unread -= pkt_len;
 		kfree_skb(skb);
 	}
 
@@ -1132,6 +1134,19 @@ ssize_t virtio_transport_unsent_bytes(struct vsock_sock *vsk)
 }
 EXPORT_SYMBOL_GPL(virtio_transport_unsent_bytes);
 
+ssize_t virtio_transport_unread_bytes(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	size_t ret;
+
+	spin_lock_bh(&vvs->rx_lock);
+	ret = vvs->bytes_unread;
+	spin_unlock_bh(&vvs->rx_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_unread_bytes);
+
 static int virtio_transport_reset(struct vsock_sock *vsk,
 				  struct sk_buff *skb)
 {
@@ -1365,6 +1380,8 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
 		goto out;
 	}
 
+	vvs->bytes_unread += len;
+
 	if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM)
 		vvs->msg_count++;
 
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index 6e78927a598e..13a77db2a76f 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -99,6 +99,7 @@ static struct virtio_transport loopback_transport = {
 		.notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
 
 		.unsent_bytes             = virtio_transport_unsent_bytes,
+		.unread_bytes             = virtio_transport_unread_bytes,
 
 		.read_skb = virtio_transport_read_skb,
 	},
-- 
2.34.1