[Devel] [PATCH RHEL8 COMMIT] net: openvswitch: add capability to specify ifindex of new links

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-193.6.3.vz8.4.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-193.6.3.vz8.4.6
------>
commit 5e825b7e975d0593a648f467c585bcaded7036b3
Author: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
Date:   Tue Sep 22 15:07:25 2020 +0300

    net: openvswitch: add capability to specify ifindex of new links
    
    CRIU is preserving ifindexes of net devices after restoration, but
    current Open vSwitch API are not capable to do that. So we need to
    modify it, because
    
    - Restoring net devices with random ifindex will lead to some excessive
      work to restore master relationship.
    
    - OVS device taking another link ifindex will likely cause some problems
      and may snowball previous point.
    
    - Although OVS daemon is not supported yet, it is holding some tables
      which have ifindex.
    
    Openvswitch creates several net devices, but unlike rtnetlink API there is
    no option to specify ifindex for link. This is crucial for criu during
    restore stage.
    Use ovs_header->dp_ifindex during OVS_DP_CMD_NEW as desired ifindex.
    Use OVS_VPORT_ATTR_IFINDEX during OVS_VPORT_CMD_NEW to specify new netdev
    ifindex. Both values were not relevant for corresponding requests, so
    existing software won't mess with it.
    
    https://jira.sw.ru/browse/PSBM-105844
    Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
---
 net/openvswitch/datapath.c           | 16 ++++++++++++++--
 net/openvswitch/vport-internal_dev.c |  1 +
 net/openvswitch/vport.h              |  2 ++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 900b16e668a1..a720430daaa3 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1600,6 +1600,7 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	struct vport *vport;
 	struct ovs_net *ovs_net;
 	int err, i;
+	struct ovs_header *ovs_header = info->userhdr;
 
 	err = -EINVAL;
 	if (!a[OVS_DP_ATTR_NAME] || !a[OVS_DP_ATTR_UPCALL_PID])
@@ -1649,6 +1650,7 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	parms.dp = dp;
 	parms.port_no = OVSP_LOCAL;
 	parms.upcall_portids = a[OVS_DP_ATTR_UPCALL_PID];
+	parms.desired_ifindex = ovs_header->dp_ifindex;
 
 	err = ovs_dp_change(dp, a);
 	if (err)
@@ -2044,7 +2046,10 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	if (!a[OVS_VPORT_ATTR_NAME] || !a[OVS_VPORT_ATTR_TYPE] ||
 	    !a[OVS_VPORT_ATTR_UPCALL_PID])
 		return -EINVAL;
-	if (a[OVS_VPORT_ATTR_IFINDEX])
+
+	parms.type = nla_get_u32(a[OVS_VPORT_ATTR_TYPE]);
+
+	if (a[OVS_VPORT_ATTR_IFINDEX] && parms.type != OVS_VPORT_TYPE_INTERNAL)
 		return -EOPNOTSUPP;
 
 	port_no = a[OVS_VPORT_ATTR_PORT_NO]
@@ -2081,12 +2086,19 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	parms.name = nla_data(a[OVS_VPORT_ATTR_NAME]);
-	parms.type = nla_get_u32(a[OVS_VPORT_ATTR_TYPE]);
 	parms.options = a[OVS_VPORT_ATTR_OPTIONS];
 	parms.dp = dp;
 	parms.port_no = port_no;
 	parms.upcall_portids = a[OVS_VPORT_ATTR_UPCALL_PID];
 
+	if (parms.type == OVS_VPORT_TYPE_INTERNAL) {
+		if (a[OVS_VPORT_ATTR_IFINDEX])
+			parms.desired_ifindex =
+				nla_get_u32(a[OVS_VPORT_ATTR_IFINDEX]);
+		else
+			parms.desired_ifindex = 0;
+	}
+
 	vport = new_vport(&parms);
 	err = PTR_ERR(vport);
 	if (IS_ERR(vport)) {
diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
index 3ebf8ba7c389..a9bb6e5e11ad 100644
--- a/net/openvswitch/vport-internal_dev.c
+++ b/net/openvswitch/vport-internal_dev.c
@@ -200,6 +200,7 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
 	if (vport->port_no == OVSP_LOCAL)
 		vport->dev->features |= NETIF_F_NETNS_LOCAL;
 
+	dev->ifindex = parms->desired_ifindex;
 	rtnl_lock();
 	err = register_netdevice(vport->dev);
 	if (err)
diff --git a/net/openvswitch/vport.h b/net/openvswitch/vport.h
index cda66c26ad08..c5281b52f489 100644
--- a/net/openvswitch/vport.h
+++ b/net/openvswitch/vport.h
@@ -109,6 +109,8 @@ struct vport_parms {
 	enum ovs_vport_type type;
 	struct nlattr *options;
 
+	int desired_ifindex;
+
 	/* For ovs_vport_alloc(). */
 	struct datapath *dp;
 	u16 port_no;