add multimds subtree thrashing test

collections/multimds/clusters/7-multimds.yaml

@@ -0,0 +1,8 @@
+roles:
+- [mon.a, mds.a, mds.a-s]
+- [mon.b, mds.b, mds.b-s]
+- [mon.c, mds.c, mds.c-s]
+- [osd.0]
+- [osd.1]
+- [osd.2]
+- [client.0]

collections/multimds/tasks/fsstress_thrash_subtrees.yaml

@@ -0,0 +1,13 @@
+tasks:
+- ceph:
+    conf:
+      mds:
+        mds thrash exports: 1
+        mds debug subtrees: 1
+        mds debug scatterstat: 1
+        mds verify scatter: 1
+- cfuse:
+- workunit:
+    client.0:
+      - suites/fsstress.sh
+