[pve-devel] [PATCH v3 pve-common 5/5] Inotify : add mtu option

[Wolfgang Bumiller]

On Tue, Aug 28, 2018 at 12:02:27PM +0200, Dennis Busch wrote:
> Hello Alexandre,
> 
> this check is IMHO uneccessary as Debian inherites MTU from parent to child
> interfaces. That is AFAIK officially documente behavior, so this check makes
> it impossible to edit an interface that uses mtu definition only on parent
> devices.
> 
> Best regards
> 
> Dennis
> 
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> Am 05.07.2018 um 02:56 schrieb Alexandre Derumier:
> > also check if mtu value is lower than parent interface
> > 
> > fixme: vxlan interface should be 50bytes lower than outgoing interface
> >         we need to find which interface is used (unicast/multicast/frr)
> > ---
> >   src/PVE/INotify.pm                              | 22 ++++++++++++++++++++++
> >   test/etc_network_interfaces/t.create_network.pl | 10 ++++++++++
> >   2 files changed, 32 insertions(+)
> > 
> > diff --git a/src/PVE/INotify.pm b/src/PVE/INotify.pm
> > index f0f3144..5dd08c2 100644
> > --- a/src/PVE/INotify.pm
> > +++ b/src/PVE/INotify.pm
> > @@ -753,6 +753,20 @@ my $extract_ovs_option = sub {
> >       return $v;
> >   };
> > +my $check_mtu = sub {
> > +   my ($ifaces, $parent, $child) = @_;
> > +
> > +   die "check mtu : missing parent interface\n" if !$parent;
> > +   die "check mtu : missing child interface\n" if !$child;
> > +
> > +   my $pmtu = $ifaces->{$parent}->{mtu} ? $ifaces->{$parent}->{mtu} : 1500;
> > +   my $cmtu = $ifaces->{$child}->{mtu} ? $ifaces->{$child}->{mtu} : 1500;

Might be enough to just remove the ternary and skip the check if
$ifaces->{$child}->{mtu} is not defined.

> > +
> > +   die "interface '$parent' - mtu $pmtu is bigger than '$child' - mtu $cmtu\n"
> > +                    if $pmtu gt $cmtu;

Also, apparently I missed the 'gt' here, that should be '>', ouch.

> > +
> > +};