s3: reduce ObjectVersion memory by not retaining full Entry (#7786)

s3: fix fallback owner lookup to use specific version

Address review feedback: the fallback logic was incorrectly using
getLatestObjectVersion which returns the wrong owner when different
versions have different owners.

Fix by using getSpecificObjectVersion with the version.VersionId to
fetch the correct entry for the specific version being processed.
This also simplifies the code by removing the separate null version
handling since getSpecificObjectVersion already handles that case.

weed/s3api/s3api_object_versioning.go

@@ -1064,26 +1064,13 @@ func (s3a *S3ApiServer) getObjectOwnerFromVersion(version *ObjectVersion, bucket
 		return CanonicalUser{ID: version.OwnerID, DisplayName: ownerDisplayName}
 	}
 
-	// Fallback: try to get owner from the current version of the object
-	// This handles cases where older versions might not have owner metadata
-	if version.VersionId == "null" {
-		// For null version, check the regular object file
-		bucketDir := s3a.option.BucketsPath + "/" + bucket
-		if entry, err := s3a.getEntry(bucketDir, objectKey); err == nil && entry.Extended != nil {
-			if ownerBytes, exists := entry.Extended[s3_constants.ExtAmzOwnerKey]; exists {
-				ownerId := string(ownerBytes)
-				ownerDisplayName := s3a.iam.GetAccountNameById(ownerId)
-				return CanonicalUser{ID: ownerId, DisplayName: ownerDisplayName}
-			}
-		}
-	} else {
-		// For versioned objects, try to get from latest version metadata
-		if latestVersion, err := s3a.getLatestObjectVersion(bucket, objectKey); err == nil && latestVersion.Extended != nil {
-			if ownerBytes, exists := latestVersion.Extended[s3_constants.ExtAmzOwnerKey]; exists {
-				ownerId := string(ownerBytes)
-				ownerDisplayName := s3a.iam.GetAccountNameById(ownerId)
-				return CanonicalUser{ID: ownerId, DisplayName: ownerDisplayName}
-			}
+	// Fallback: fetch the specific version entry to get the owner
+	// This handles cases where OwnerID wasn't populated during listing
+	if specificVersionEntry, err := s3a.getSpecificObjectVersion(bucket, objectKey, version.VersionId); err == nil && specificVersionEntry.Extended != nil {
+		if ownerBytes, exists := specificVersionEntry.Extended[s3_constants.ExtAmzOwnerKey]; exists {
+			ownerId := string(ownerBytes)
+			ownerDisplayName := s3a.iam.GetAccountNameById(ownerId)
+			return CanonicalUser{ID: ownerId, DisplayName: ownerDisplayName}
 		}
 	}