main/lxc: fix jumboframes in containers

1 files changed, 66 insertions, 0 deletions

diff --git a/main/lxc/0001-Clone-bridge-interface-MTU-setting.patch b/main/lxc/0001-Clone-bridge-interface-MTU-setting.patch
new file mode 100644
index 0000000000..7f18e4f293
--- /dev/null
+++ b/main/lxc/0001-Clone-bridge-interface-MTU-setting.patch
@@ -0,0 +1,66 @@
+From e54864d3632e3959bed6dd6b7e6d2cbd7eb8eec0 Mon Sep 17 00:00:00 2001
+From: Natanael Copa <ncopa@alpinelinux.org>
+Date: Fri, 21 Aug 2015 11:48:10 +0200
+Subject: [PATCH] Clone bridge interface MTU setting
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Instead of require static mtu setting in config we simply clone the
+existing MTU setting of the bridge interface.
+
+This fixes issue when bridge interface has bigger MTU (like 9000 for
+jumbo frame support) than the default 1500. When veth interface is
+created it has by default MTU set to 1500 and when this is added to the
+bridge, the kernel wee reduce the MTU for the bridge to 1500. We solve
+this by cloning the MTU value from bridge interface.
+
+This simplifies managing containers with bridge interface who supports
+jumbo frames (mtu 9000) and makes it easier to move containers between
+hosts with different MTU settings.
+
+Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
+Acked-by: Stéphane Graber <stgraber@ubuntu.com>
+---
+ src/lxc/conf.c | 16 +++++++++++-----
+ 1 file changed, 11 insertions(+), 5 deletions(-)
+
+diff --git a/src/lxc/conf.c b/src/lxc/conf.c
+index 309ceea..a3d45ee 100644
+--- a/src/lxc/conf.c
++++ b/src/lxc/conf.c
+@@ -2609,7 +2609,7 @@ static int instantiate_veth(struct lxc_handler *handler, struct lxc_netdev *netd
+ {
+ 	char veth1buf[IFNAMSIZ], *veth1;
+ 	char veth2buf[IFNAMSIZ], *veth2;
+-	int err;
++	int err, mtu = 0;
+ 
+ 	if (netdev->priv.veth_attr.pair) {
+ 		veth1 = netdev->priv.veth_attr.pair;
+@@ -2655,12 +2655,18 @@ static int instantiate_veth(struct lxc_handler *handler, struct lxc_netdev *netd
+ 	}
+ 
+ 	if (netdev->mtu) {
+-		err = lxc_netdev_set_mtu(veth1, atoi(netdev->mtu));
++		mtu = atoi(netdev->mtu);
++	} else if (netdev->link) {
++		mtu = netdev_get_mtu(if_nametoindex(netdev->link));
++	}
++
++	if (mtu) {
++		err = lxc_netdev_set_mtu(veth1, mtu);
+ 		if (!err)
+-			err = lxc_netdev_set_mtu(veth2, atoi(netdev->mtu));
++			err = lxc_netdev_set_mtu(veth2, mtu);
+ 		if (err) {
+-			ERROR("failed to set mtu '%s' for veth pair (%s and %s): %s",
+-			      netdev->mtu, veth1, veth2, strerror(-err));
++			ERROR("failed to set mtu '%i' for veth pair (%s and %s): %s",
++			      mtu, veth1, veth2, strerror(-err));
+ 			goto out_delete;
+ 		}
+ 	}
+-- 
+2.5.0
+