network: always set IPv6 MTU when we detect the device MTU is changed

Then, we can keep the IPv6 MTU even if the device MTU is changed by an
external tool, e.g. 'ip link set' command.

diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index bac44a3858181e2221e20a3f6fe786a4a79b0d7e..a69402ee9fd3d2fd9889c8b3c04a28717a6064b8 100644 (file)
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -2434,6 +2434,13 @@ static int link_update_mtu(Link *link, sd_netlink_message *message) {
 
         link->mtu = mtu;
 
+        if (IN_SET(link->state, LINK_STATE_CONFIGURING, LINK_STATE_CONFIGURED)) {
+                /* The kernel resets IPv6 MTU after changing device MTU. So, we need to re-set IPv6 MTU again. */
+                r = link_set_ipv6_mtu(link);
+                if (r < 0)
+                        log_link_warning_errno(link, r, "Failed to set IPv6 MTU, ignoring: %m");
+        }
+
         if (link->dhcp_client) {
                 r = sd_dhcp_client_set_mtu(link->dhcp_client, link->mtu);
                 if (r < 0)

diff --git a/src/network/networkd-setlink.c b/src/network/networkd-setlink.c
index a7e04dde2e7882be6b2e074460dde621c6d733af..058bc00ba10b24f78a8d19d3db5beaa429ddc426 100644 (file)
--- a/src/network/networkd-setlink.c
+++ b/src/network/networkd-setlink.c
@@ -173,19 +173,7 @@ static int link_unset_master_handler(sd_netlink *rtnl, sd_netlink_message *m, Re
 }
 
 static int link_set_mtu_handler(sd_netlink *rtnl, sd_netlink_message *m, Request *req, Link *link, void *userdata) {
-        int r;
-
-        r = set_link_handler_internal(rtnl, m, req, link, /* ignore = */ true, get_link_default_handler);
-        if (r <= 0)
-                return r;
-
-        /* The kernel resets ipv6 mtu after changing device mtu;
-         * we must set this here, after we've set device mtu */
-        r = link_set_ipv6_mtu(link);
-        if (r < 0)
-                log_link_warning_errno(link, r, "Failed to set IPv6 MTU, ignoring: %m");
-
-        return 0;
+        return set_link_handler_internal(rtnl, m, req, link, /* ignore = */ true, get_link_default_handler);
 }
 
 static int link_configure_fill_message(