vxlan: Relax MTU constraints
Allow the MTU of vxlan devices without an underlying device to be set
to larger values (up to a maximum based on IP packet limits and vxlan
overhead).
Previously, their MTUs could not be set to higher than the
conventional ethernet value of 1500. This is a very arbitrary value
in the context of vxlan, and prevented vxlan devices from being able
to take advantage of jumbo frames etc.
The default MTU remains 1500, for compatibility.
Signed-off-by: David Wragg <david@weave.works>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 6543918..e992c6a 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2367,27 +2367,41 @@
{
}
+static int __vxlan_change_mtu(struct net_device *dev,
+ struct net_device *lowerdev,
+ struct vxlan_rdst *dst, int new_mtu, bool strict)
+{
+ int max_mtu = IP_MAX_MTU;
+
+ if (lowerdev)
+ max_mtu = lowerdev->mtu;
+
+ if (dst->remote_ip.sa.sa_family == AF_INET6)
+ max_mtu -= VXLAN6_HEADROOM;
+ else
+ max_mtu -= VXLAN_HEADROOM;
+
+ if (new_mtu < 68)
+ return -EINVAL;
+
+ if (new_mtu > max_mtu) {
+ if (strict)
+ return -EINVAL;
+
+ new_mtu = max_mtu;
+ }
+
+ dev->mtu = new_mtu;
+ return 0;
+}
+
static int vxlan_change_mtu(struct net_device *dev, int new_mtu)
{
struct vxlan_dev *vxlan = netdev_priv(dev);
struct vxlan_rdst *dst = &vxlan->default_dst;
- struct net_device *lowerdev;
- int max_mtu;
-
- lowerdev = __dev_get_by_index(vxlan->net, dst->remote_ifindex);
- if (lowerdev == NULL)
- return eth_change_mtu(dev, new_mtu);
-
- if (dst->remote_ip.sa.sa_family == AF_INET6)
- max_mtu = lowerdev->mtu - VXLAN6_HEADROOM;
- else
- max_mtu = lowerdev->mtu - VXLAN_HEADROOM;
-
- if (new_mtu < 68 || new_mtu > max_mtu)
- return -EINVAL;
-
- dev->mtu = new_mtu;
- return 0;
+ struct net_device *lowerdev = __dev_get_by_index(vxlan->net,
+ dst->remote_ifindex);
+ return __vxlan_change_mtu(dev, lowerdev, dst, new_mtu, true);
}
static int egress_ipv4_tun_info(struct net_device *dev, struct sk_buff *skb,