[PATCH pve-network v4 05/20] sdn: ipam: write the lookup's cache entry under the cluster lock

[Hannes Laimer <h.laimer@proxmox.com>]

The lookup that stores the IPAM's answer wrote the whole cache back
without the cluster lock the other writers take. A change made
between its read and its write was lost. The lookup now takes the
lock and reads the cache again before it stores its answer.

Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>
---

Notes:
    v4:
     * new, split out of the MAC cache patch

 src/PVE/Network/SDN/Ipams.pm | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/PVE/Network/SDN/Ipams.pm b/src/PVE/Network/SDN/Ipams.pm
index 79591ea0..3d849d79 100644
--- a/src/PVE/Network/SDN/Ipams.pm
+++ b/src/PVE/Network/SDN/Ipams.pm
@@ -142,8 +142,8 @@ sub complete_sdn_vnet {
 sub get_ips_from_mac {
     my ($mac, $zoneid, $zone) = @_;
 
-    my $macdb = read_macdb();
-    return ($macdb->{macs}->{$mac}->{ip4}, $macdb->{macs}->{$mac}->{ip6}) if $macdb->{macs}->{$mac};
+    my $cached = read_macdb()->{macs}->{$mac};
+    return ($cached->{ip4}, $cached->{ip6}) if $cached;
 
     my $plugin_config = get_plugin_config($zone);
     my $plugin = PVE::Network::SDN::Ipams::Plugin->lookup($plugin_config->{type});
@@ -152,9 +152,17 @@ sub get_ips_from_mac {
     # an empty answer is not cached, since the record may simply not exist yet
     return if !defined($ip4) && !defined($ip6);
 
-    $macdb->{macs}->{$mac}->{ip4} = $ip4 if defined($ip4);
-    $macdb->{macs}->{$mac}->{ip6} = $ip6 if defined($ip6);
-    write_macdb($macdb);
+    cfs_lock_file(
+        $macdb_filename,
+        undef,
+        sub {
+            my $db = read_macdb();
+            $db->{macs}->{$mac}->{ip4} = $ip4 if defined($ip4);
+            $db->{macs}->{$mac}->{ip6} = $ip6 if defined($ip6);
+            write_macdb($db);
+        },
+    );
+    warn "$@" if $@;
 
     return ($ip4, $ip6);
 }
-- 
2.47.3