admin api: return total buckets, objects and bytes in GetClusterStatistics

doc/api/garage-admin-v2.json

@@ -2607,6 +2607,12 @@
           "freeform"
         ],
         "properties": {
+          "bucketCount": {
+            "type": "integer",
+            "format": "int64",
+            "description": "number of buckets in the cluster",
+            "minimum": 0
+          },
           "dataAvail": {
             "type": "integer",
             "format": "int64",
@@ -2617,7 +2623,7 @@
             "type": "string",
             "description": "cluster statistics as a free-form string, kept for compatibility with nodes\nrunning older v2.x versions of garage"
           },
-          "incompleteInfo": {
+          "incompleteAvailInfo": {
             "type": "boolean",
             "description": "true if the available storage space statistics are imprecise due to missing\ninformation of disconnected nodes. When this is the case, the actual\nspace available in the cluster might be lower than the reported values."
           },
@@ -2626,6 +2632,18 @@
             "format": "int64",
             "description": "available storage space for object metadata in the entire cluster, in bytes",
             "minimum": 0
+          },
+          "totalObjectBytes": {
+            "type": "integer",
+            "format": "int64",
+            "description": "total size of objects stored in all buckets, before compression, deduplication and\nreplication (this is NOT equivalent to actual disk usage in the cluster)",
+            "minimum": 0
+          },
+          "totalObjectCount": {
+            "type": "integer",
+            "format": "int64",
+            "description": "total number of objects stored in all buckets",
+            "minimum": 0
           }
         }
       },