fix(linstor): surface ambiguous template fallbacks and legacy orphan cleanup (#13078)

Co-authored-by: jmsperu <jmsperu@users.noreply.github.com>

Author: jmsperu

plugins/storage/volume/linstor/src/main/java/com/cloud/hypervisor/kvm/storage/LinstorStorageAdaptor.java

@@ -508,9 +508,19 @@ private boolean deRefOrDeleteResource(DevelopersApi api, String rscName, String
             // if there is only one template-for property left for templates, the template isn't needed anymore
             // or if it isn't a template anyway, it will not have this Aux property
             // _cs-template-for- properties work like a ref-count.
-            if (rd.getProps().keySet().stream()
+            long remainingTemplateRefs = rd.getProps().keySet().stream()
                     .filter(key -> key.startsWith("Aux/" + LinstorUtil.CS_TEMPLATE_FOR_PREFIX))
-                    .count() == expectedProps) {
+                    .count();
+            if (remainingTemplateRefs == expectedProps) {
+                // Surface the legacy case where a resource has zero `_cs-template-for-` aux
+                // properties even though we never decremented one — that's a template predating
+                // the ref-count convention, or a stale orphan. Logging before deletion lets
+                // operators audit how many such orphans existed at upgrade time.
+                if (expectedProps == 0) {
+                    logger.info("Linstor: deleting resource {} which has no _cs-template-for- aux properties " +
+                                    "(legacy template predating the ref-count convention, or a stale orphan). " +
+                                    "Resource group context: {}", rd.getName(), rscGrpName);
+                }
                 ApiCallRcList answers = api.resourceDefinitionDelete(rd.getName());
                 checkLinstorAnswersThrow(answers);
                 deleted = true;

plugins/storage/volume/linstor/src/main/java/org/apache/cloudstack/storage/datastore/util/LinstorUtil.java

@@ -543,7 +543,26 @@ public static ResourceDefinition findResourceDefinition(DevelopersApi api, Strin
                 .filter(rscDfn -> rscDfn.getProps().containsKey(LinstorUtil.getTemplateForAuxPropKey(rscGrpName)))
                 .findFirst();
 
-        return rd.orElseGet(() -> rdsStartingWith.get(0));
+        if (rd.isPresent()) {
+            return rd.get();
+        }
+        // Fallback: no resource has the exact "_cs-template-for-<rscGrpName>" property.
+        // This happens when (a) the matched resource is a legacy template created before that
+        // convention was introduced, or (b) the template was cached by a different resource
+        // group and the operator hopes to share it. Log so the ambiguity is visible — silent
+        // first-match fallback has previously routed clones to the wrong template when
+        // multiple resource groups coexisted on the same controller.
+        ResourceDefinition fallback = rdsStartingWith.get(0);
+        LOGGER.warn("LINSTOR findResourceDefinition: no resource for '{}' has the expected " +
+                        "Aux property '{}' for resource group '{}'; falling back to first match '{}' " +
+                        "(present aux properties: {}). If this is wrong, set the property explicitly " +
+                        "or remove the unrelated resource definition.",
+                rscName, getTemplateForAuxPropKey(rscGrpName), rscGrpName,
+                fallback.getName(),
+                fallback.getProps().keySet().stream()
+                        .filter(k -> k.startsWith("Aux/" + CS_TEMPLATE_FOR_PREFIX))
+                        .collect(Collectors.toList()));
+        return fallback;
     }
 
     public static boolean isRscDiskless(ResourceWithVolumes rsc) {