qa: remove get_lone_mds_id

This helps remove a dependence on the list of mds_daemons from
teuthology/cephadm.

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

qa/tasks/cephfs/filesystem.py

@@ -1050,21 +1050,6 @@ class Filesystem(MDSCluster):
 
             status = self.status()
 
-    def get_lone_mds_id(self):
-        """
-        Get a single MDS ID: the only one if there is only one
-        configured, else the only one currently holding a rank,
-        else raise an error.
-        """
-        if len(self.mds_ids) != 1:
-            alive = self.get_rank_names()
-            if len(alive) == 1:
-                return alive[0]
-            else:
-                raise ValueError("Explicit MDS argument required when multiple MDSs in use")
-        else:
-            return self.mds_ids[0]
-
     def put_metadata_object_raw(self, object_id, infile):
         """
         Save an object to the metadata pool
@@ -1127,13 +1112,13 @@ class Filesystem(MDSCluster):
 
     def mds_asok(self, command, mds_id=None, timeout=None):
         if mds_id is None:
-            mds_id = self.get_lone_mds_id()
+            return self.rank_asok(command, timeout=timeout)
 
         return self.json_asok(command, 'mds', mds_id, timeout=timeout)
 
     def mds_tell(self, command, mds_id=None):
         if mds_id is None:
-            mds_id = self.get_lone_mds_id()
+            return self.rank_tell(command)
 
         return json.loads(self.mon_manager.raw_cluster_cmd("tell", f"mds.{mds_id}", *command))
 

qa/tasks/cephfs/test_admin.py

@@ -313,12 +313,10 @@ class TestConfigCommands(CephFSTestCase):
         test_key = "mds_max_purge_ops"
         test_val = "123"
 
-        mds_id = self.fs.get_lone_mds_id()
-        self.fs.mon_manager.raw_cluster_cmd("tell", "mds.{0}".format(mds_id), "injectargs",
-                                            "--{0}={1}".format(test_key, test_val))
+        self.fs.rank_tell(['injectargs', "--{0}={1}".format(test_key, test_val)])
 
         # Read it back with asok because there is no `tell` equivalent
-        out = self.fs.mds_asok(['config', 'get', test_key])
+        out = self.fs.rank_tell(['config', 'get', test_key])
         self.assertEqual(out[test_key], test_val)
 
 

qa/tasks/cephfs/test_misc.py

@@ -205,14 +205,11 @@ class TestCacheDrop(CephFSTestCase):
 
     def _run_drop_cache_cmd(self, timeout=None):
         result = None
-        mds_id = self.fs.get_lone_mds_id()
+        args = ["cache", "drop"]
         if timeout is not None:
-            result = self.fs.mon_manager.raw_cluster_cmd("tell", "mds.{0}".format(mds_id),
-                                                    "cache", "drop", str(timeout))
-        else:
-            result = self.fs.mon_manager.raw_cluster_cmd("tell", "mds.{0}".format(mds_id),
-                                                    "cache", "drop")
-        return json.loads(result)
+            args.append(str(timeout))
+        result = self.fs.rank_tell(args)
+        return result
 
     def _setup(self, max_caps=20, threshold=400):
         # create some files