From 06f1a61a87182edc3a6c3a6f6420ab9f2012b2d3 Mon Sep 17 00:00:00 2001 From: David Wragg Date: Wed, 10 Feb 2016 00:05:58 +0000 Subject: [PATCH] datapath: Set a large MTU on tunnel devices. Upstream commit: Prior to 4.3, openvswitch tunnel vports (vxlan, gre and geneve) could transmit vxlan packets of any size, constrained only by the ability to send out the resulting packets. 4.3 introduced netdevs corresponding to tunnel vports. These netdevs have an MTU, which limits the size of a packet that can be successfully encapsulated. The default MTU values are low (1500 or less), which is awkwardly small in the context of physical networks supporting jumbo frames, and leads to a conspicuous change in behaviour for userspace. Instead, set the MTU on openvswitch-created netdevs to be the relevant maximum (i.e. the maximum IP packet size minus any relevant overhead), effectively restoring the behaviour prior to 4.3. Signed-off-by: David Wragg Signed-off-by: David S. Miller Upstream: 7e059158d57b ("vxlan, gre, geneve: Set a large MTU on ovs-created tunnel devices") Signed-off-by: Joe Stringer Acked-by: Jesse Gross --- acinclude.m4 | 1 + datapath/linux/compat/geneve.c | 18 ++++++++++++++---- .../linux/compat/include/net/ip_tunnels.h | 6 ++++++ datapath/linux/compat/ip_gre.c | 8 ++++++++ datapath/linux/compat/ip_tunnel.c | 19 ++++++++++++++++--- datapath/linux/compat/vxlan.c | 11 ++++++++--- datapath/vport-vxlan.c | 2 ++ 7 files changed, 55 insertions(+), 10 deletions(-) diff --git a/acinclude.m4 b/acinclude.m4 index dc06be632..11c77877d 100644 --- a/acinclude.m4 +++ b/acinclude.m4 @@ -354,6 +354,7 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [ OVS_GREP_IFELSE([$KSRC/include/net/ip.h], [IPSKB_FRAG_PMTU], [OVS_DEFINE([HAVE_CORRECT_MRU_HANDLING])]) + OVS_GREP_IFELSE([$KSRC/include/net/ip_tunnels.h], [__ip_tunnel_change_mtu]) OVS_GREP_IFELSE([$KSRC/include/net/inet_frag.h], [hashfn.*const], [OVS_DEFINE([HAVE_INET_FRAGS_CONST])]) OVS_GREP_IFELSE([$KSRC/include/net/inet_frag.h], [last_in], diff --git a/datapath/linux/compat/geneve.c b/datapath/linux/compat/geneve.c index 29a65a0a4..50ed3936d 100644 --- a/datapath/linux/compat/geneve.c +++ b/datapath/linux/compat/geneve.c @@ -1039,11 +1039,21 @@ struct net_device *rpl_geneve_dev_create_fb(struct net *net, const char *name, return dev; err = geneve_configure(net, dev, 0, 0, 0, 0, htons(dst_port), true); - if (err) { - free_netdev(dev); - return ERR_PTR(err); - } + if (err) + goto err; + + /* openvswitch users expect packet sizes to be unrestricted, + * so set the largest MTU we can. + */ + err = geneve_change_mtu(dev, IP_MAX_MTU); + if (err) + goto err; + return dev; + +err: + free_netdev(dev); + return ERR_PTR(err); } EXPORT_SYMBOL_GPL(rpl_geneve_dev_create_fb); diff --git a/datapath/linux/compat/include/net/ip_tunnels.h b/datapath/linux/compat/include/net/ip_tunnels.h index 3e1ceef21..5eda8a2e3 100644 --- a/datapath/linux/compat/include/net/ip_tunnels.h +++ b/datapath/linux/compat/include/net/ip_tunnels.h @@ -327,4 +327,10 @@ int rpl_ip_tunnel_get_iflink(const struct net_device *dev); #define ip_tunnel_get_link_net rpl_ip_tunnel_get_link_net struct net *rpl_ip_tunnel_get_link_net(const struct net_device *dev); #endif /* HAVE_METADATA_DST */ + +#ifndef HAVE___IP_TUNNEL_CHANGE_MTU +#define __ip_tunnel_change_mtu rpl___ip_tunnel_change_mtu +int rpl___ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict); +#endif + #endif /* __NET_IP_TUNNELS_H */ diff --git a/datapath/linux/compat/ip_gre.c b/datapath/linux/compat/ip_gre.c index c9197e965..f6a841fbc 100644 --- a/datapath/linux/compat/ip_gre.c +++ b/datapath/linux/compat/ip_gre.c @@ -613,6 +613,14 @@ struct net_device *rpl_gretap_fb_dev_create(struct net *net, const char *name, #endif if (err < 0) goto out; + + /* openvswitch users expect packet sizes to be unrestricted, + * so set the largest MTU we can. + */ + err = __ip_tunnel_change_mtu(dev, IP_MAX_MTU, false); + if (err) + goto out; + return dev; out: free_netdev(dev); diff --git a/datapath/linux/compat/ip_tunnel.c b/datapath/linux/compat/ip_tunnel.c index 2d4070ecc..819093702 100644 --- a/datapath/linux/compat/ip_tunnel.c +++ b/datapath/linux/compat/ip_tunnel.c @@ -137,18 +137,31 @@ static int ip_tunnel_bind_dev(struct net_device *dev) return mtu; } -int rpl_ip_tunnel_change_mtu(struct net_device *dev, int new_mtu) +int rpl___ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict) { struct ip_tunnel *tunnel = netdev_priv(dev); int t_hlen = tunnel->hlen + sizeof(struct iphdr); + int max_mtu = 0xFFF8 - dev->hard_header_len - t_hlen; - if (new_mtu < 68 || - new_mtu > 0xFFF8 - dev->hard_header_len - t_hlen) + 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; } +int rpl_ip_tunnel_change_mtu(struct net_device *dev, int new_mtu) +{ + return rpl___ip_tunnel_change_mtu(dev, new_mtu, true); +} + static void ip_tunnel_dev_free(struct net_device *dev) { #ifdef HAVE_DEV_TSTATS diff --git a/datapath/linux/compat/vxlan.c b/datapath/linux/compat/vxlan.c index f443a1b03..769b76f53 100644 --- a/datapath/linux/compat/vxlan.c +++ b/datapath/linux/compat/vxlan.c @@ -1905,6 +1905,7 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev, int err; bool use_ipv6 = false; __be16 default_port = vxlan->cfg.dst_port; + struct net_device *lowerdev = NULL; vxlan->net = src_net; @@ -1924,9 +1925,7 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev, } if (conf->remote_ifindex) { - struct net_device *lowerdev - = __dev_get_by_index(src_net, conf->remote_ifindex); - + lowerdev = __dev_get_by_index(src_net, conf->remote_ifindex); dst->remote_ifindex = conf->remote_ifindex; if (!lowerdev) { @@ -1957,6 +1956,12 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev, dev->needed_headroom = ETH_HLEN + VXLAN_HEADROOM; } + if (conf->mtu) { + err = __vxlan_change_mtu(dev, lowerdev, dst, conf->mtu, false); + if (err) + return err; + } + memcpy(&vxlan->cfg, conf, sizeof(*conf)); if (!vxlan->cfg.dst_port) vxlan->cfg.dst_port = default_port; diff --git a/datapath/vport-vxlan.c b/datapath/vport-vxlan.c index 66b79f4db..c05f5d447 100644 --- a/datapath/vport-vxlan.c +++ b/datapath/vport-vxlan.c @@ -91,6 +91,8 @@ static struct vport *vxlan_tnl_create(const struct vport_parms *parms) struct vxlan_config conf = { .no_share = true, .flags = VXLAN_F_COLLECT_METADATA, + /* Don't restrict the packets that can be sent by MTU */ + .mtu = IP_MAX_MTU, }; if (!options) { -- 2.20.1