qa/suites/rbd: place cache file on tmpfs for xfstests

The RWL mode needs DAX and is dog slow otherwise -- qemu_xfstests.yaml
job always hits the 6 hour max_job_time limit.

As our tmpfs instance is limited and qemu_xfstests.yaml opens three
images at the same time, reduce the "big cache" size to 5G.  This facet
was added to iron out 32-bit head/tail pointer issues and 5G still does
the job there.

Going through the loop device is needed because tmpfs doesn't support
O_DIRECT.

Fixes: https://tracker.ceph.com/issues/55400
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

qa/suites/rbd/pwl-cache/tmpfs/.qa

@@ -0,0 +1 @@
+../.qa/

qa/suites/rbd/pwl-cache/tmpfs/1-base

@@ -0,0 +1 @@
+../../basic/base/

qa/suites/rbd/pwl-cache/tmpfs/2-cluster/.qa

@@ -0,0 +1 @@
+../.qa/

qa/suites/rbd/pwl-cache/tmpfs/2-cluster/fix-2.yaml

@@ -0,0 +1,3 @@
+roles:
+- [mon.a, mgr.x, osd.0, osd.1]
+- [mon.b, mgr.y, osd.2, osd.3, client.0]

qa/suites/rbd/pwl-cache/tmpfs/2-cluster/openstack.yaml

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+openstack:
+    - volumes: # attached to each instance
+        count: 4
+        size: 10 # GB

qa/suites/rbd/pwl-cache/tmpfs/3-supported-random-distro$

@@ -0,0 +1 @@
+.qa/distros/supported-random-distro$

qa/suites/rbd/pwl-cache/tmpfs/4-cache-path.yaml

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+overrides:
+  ceph:
+    conf:
+      client:
+        rbd_persistent_cache_path: /home/ubuntu/cephtest/rbd-pwl-cache
+        rbd_plugins: pwl_cache
+tasks:
+- exec:
+    client.0:
+      - "mkdir /home/ubuntu/cephtest/tmpfs"
+      - "mkdir /home/ubuntu/cephtest/rbd-pwl-cache"
+      - "sudo mount -t tmpfs -o size=20G tmpfs /home/ubuntu/cephtest/tmpfs"
+      - "truncate -s 20G /home/ubuntu/cephtest/tmpfs/loopfile"
+      - "mkfs.ext4 /home/ubuntu/cephtest/tmpfs/loopfile"
+      - "sudo mount -o loop /home/ubuntu/cephtest/tmpfs/loopfile /home/ubuntu/cephtest/rbd-pwl-cache"
+      - "sudo chmod 777 /home/ubuntu/cephtest/rbd-pwl-cache"
+- exec_on_cleanup:
+    client.0:
+      - "sudo umount /home/ubuntu/cephtest/rbd-pwl-cache"
+      - "sudo umount /home/ubuntu/cephtest/tmpfs"
+      - "rm -rf /home/ubuntu/cephtest/rbd-pwl-cache"
+      - "rm -rf /home/ubuntu/cephtest/tmpfs"

qa/suites/rbd/pwl-cache/tmpfs/5-cache-mode/.qa

@@ -0,0 +1 @@
+../.qa/

qa/suites/rbd/pwl-cache/tmpfs/5-cache-mode/rwl.yaml

@@ -0,0 +1,5 @@
+overrides:
+  ceph:
+    conf:
+      client:
+        rbd_persistent_cache_mode: rwl

qa/suites/rbd/pwl-cache/tmpfs/5-cache-mode/ssd.yaml

@@ -0,0 +1,5 @@
+overrides:
+  ceph:
+    conf:
+      client:
+        rbd_persistent_cache_mode: ssd

qa/suites/rbd/pwl-cache/tmpfs/6-cache-size/.qa

@@ -0,0 +1 @@
+../.qa/

qa/suites/rbd/pwl-cache/tmpfs/6-cache-size/1G.yaml

@@ -0,0 +1,5 @@
+overrides:
+  ceph:
+    conf:
+      client:
+        rbd_persistent_cache_size: 1073741824

qa/suites/rbd/pwl-cache/tmpfs/6-cache-size/5G.yaml

@@ -0,0 +1,5 @@
+overrides:
+  ceph:
+    conf:
+      client:
+        rbd_persistent_cache_size: 5368709120

qa/suites/rbd/pwl-cache/tmpfs/7-workloads/.qa

@@ -0,0 +1 @@
+../.qa/