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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>
This commit is contained in:
David Wragg 2016-02-10 00:05:55 +00:00 committed by David S. Miller
parent 461547f315
commit 72564b59ff
1 changed files with 31 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
drivers/net/vxlan.c
View File

@ -2367,27 +2367,41 @@ static void vxlan_set_multicast_list(struct net_device *dev)
{
}
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,