run xfstests on 3 parallel clients

suites/kernel/singleton/fs/btrfs.yaml

@@ -0,0 +1,3 @@
+overrides:
+  ceph:
+    fs: btrfs

suites/kernel/singleton/msgr-failures/few.yaml

@@ -0,0 +1,5 @@
+overrides:
+  ceph:
+    conf:
+      global:
+        ms inject socket failures: 5000

suites/kernel/singleton/msgr-failures/many.yaml

@@ -0,0 +1,5 @@
+overrides:
+  ceph:
+    conf:
+      global:
+        ms inject socket failures: 500

suites/kernel/singleton/tasks/rbd_xfstests.yaml

@@ -0,0 +1,21 @@
+roles:
+- [mon.a, mon.c, osd.0, osd.1, osd.2]
+- [mon.b, mds.a, osd.3, osd.4, osd.5]
+- [client.0]
+- [client.1]
+- [client.2]
+tasks:
+- ceph:
+- rbd.xfstests:
+    client.0:
+        tests: 1-9 11-15 17 19-21 26-29 31-34 41 46-48 50-54 56 61 63-67 69-70 74-76 78-79 84-89 91
+        test_image: 'test_image-0'
+        scratch_image: 'scratch_image-0'
+    client.1:
+        tests: 92 100 103 105 108 110 116-121 124 126 129-132
+        test_image: 'test_image-1'
+        scratch_image: 'scratch_image-1'
+    client.2:
+        tests: 133-135 137-141 164-167 179 182-184 186-190 192 194 196 199 201 203 214-216 220-227 234 236-238 241 243-249 253 257-259 261-262 269 273 275 277-278
+        test_image: 'test_image-2'
+        scratch_image: 'scratch_image-2'

suites/regression/kernel-singleton

@@ -0,0 +1 @@
+../kernel/singleton