[PATCH container v10 06/10] destroy template: add early check for linked clones of volumes

["Michael Köppl" <m.koeppl@proxmox.com>]

This check matches the behavior already implemented for VMs and prevents
partial storage deletion if a container template has a linked clone. In
such cases, the destruction of the container template will now fail,
informing the user that the base volume is still in use by the linked
clone. In case of a storage error (such as the underlying storage not
existing anymore), a warning will be printed and execution continues,
mimicking the handling of storage errors in later stages of
destroy_lxc_container().

Originally-by: Stefan Hrdlicka <s.hrdlicka@proxmox.com>
 [ MK: use classify_mountpoint instead of pattern matching
       display warning for storage errors during linked clone check
       resolve style nit ]
Signed-off-by: Michael Köppl <m.koeppl@proxmox.com>
---
 src/PVE/LXC.pm | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
index e76da29f..3d217f24 100644
--- a/src/PVE/LXC.pm
+++ b/src/PVE/LXC.pm
@@ -1024,6 +1024,28 @@ sub destroy_lxc_container {
     my ($storage_cfg, $vmid, $conf, $replacement_conf, $purge_unreferenced) = @_;
 
     my $volids = {};
+
+    if ($conf->{template}) {
+        PVE::LXC::Config->foreach_volume_full(
+            $conf,
+            { include_unused => 1 },
+            sub {
+                my ($ms, $mountpoint) = @_;
+                my $volid = $mountpoint->{volume};
+                return if !$volid || PVE::LXC::Config->classify_mountpoint($volid) ne 'volume';
+                my $result =
+                    eval { PVE::Storage::volume_is_base_and_used($storage_cfg, $volid) };
+                if ($@) {
+                    # early check, removal of volume will fail later anyway, so warning here is fine
+                    PVE::RESTEnvironment::log_warn(
+                        "failed to check if volume '$volid' is used by linked clones: $@");
+                }
+
+                die "base volume '$volid' is still in use by linked clone\n" if $result;
+            },
+        );
+    }
+
     my $remove_volume = sub {
         my ($ms, $mountpoint) = @_;
 
-- 
2.47.3