Add mount options for better machinectl performance

The machinectl default options, while functional, could be tuned for
better overall performance. This change adds several options which will
ensure container workloads are using the lest amount of storage with the
best possible performance.

For more information on the options being used see
 * https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs(5)#MOUNT_OPTIONS

All of the "machines" mount procedures have been moved into a unified
volume task file. This was done to ensure a consistent experience across
our supported distros. To ensure any new options are non-disruptive, the
mount handler has been changed to use "reload-or-restart" which will first
try to reload a mount instead of restarting it mounts.

Change-Id: Ia962fd4c5bb2a73ddd884d3bb3837c47b43d6903
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>

handlers/main.yml

@@ -37,12 +37,26 @@
     name: "systemd-machined.service"
     state: "restarted"
 
-- name: Start machines mount
+- name: Enable machines mount
   systemd:
     daemon_reload: yes
     name: "var-lib-machines.mount"
     enabled: "yes"
-    state: "started"
+  listen: Start machines mount
+
+# NOTE(cloudnull): The systemd module is not used to start the
+#                  mount because we dont want to "restart" the
+#                  mount unnecessarily. To ensure we're able to
+#                  load new options without requiring a mount
+#                  restart the systemctl command is used with
+#                  the "reload-or-restart" argument.
+- name: Start or reload the machines mount
+  command: "systemctl reload-or-restart var-lib-machines.mount"
+  args:
+    warn: no
+  listen: Start machines mount
+  tags:
+    - skip_ansible_lint
 
 - name: Restart irqbalance
   service:

tasks/lxc_cache_preparation.yml

@@ -46,6 +46,8 @@
   when:
     - (deployment_environment_variables | default({})).keys() | length > 0
 
+- include_tasks: lxc_volume.yml
+
 - include_tasks: "lxc_cache_preparation_systemd_{{ (systemd_version.stdout_lines[0].split()[-1] | int > 219) | ternary('new', 'old') }}.yml"
 
 - block:

tasks/lxc_cache_preparation_systemd_new.yml

@@ -15,21 +15,6 @@
 
 # NOTE(cloudnull): When modern SystemD is running everywhere this can be
 #  collapsed back into the base preparation task file.
-# NOTE(odyssey4me):
-# The size is forced to be set in Gigabytes to maintain compatibility
-#  with the initial implementation done in Pike-Rocky. Do not change
-#  this without implementing some way of converting any pre-existing
-#  value properly during a major upgrade.
-- name: Set volume size
-  shell: machinectl set-limit {{ lxc_host_machine_volume_size | regex_replace('\D*$', '') }}G
-  changed_when: false
-  args:
-    executable: /bin/bash
-
-- name: Disable the machinectl quota system
-  command: "btrfs quota {{ lxc_host_machine_quota_disabled | bool | ternary('disable', 'enable') }} /var/lib/machines"
-  changed_when: false
-
 - name: Remove old image cache
   command: "machinectl remove {{ lxc_container_base_name }}"
   register: cache_refresh

tasks/lxc_cache_preparation_systemd_old.yml

@@ -13,101 +13,33 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# NOTE(cloudnull): This is only used when running SystemD <= 219
-# ==============================================================
-#  In later versions of SystemD this is automatically done for us
-#  by the machinectl cli on first run. To ensure we're handling the
-#  case of a mount point being just offline, we first try and start
-#  the systemd mount unit and then check for the mount points existance.
-- name: Check machinectl mount point
-  shell: |
-    mount -a || true
-    systemctl start var-lib-machines.mount || true
-    sleep 1
-    grep -w '/var/lib/machines' /proc/mounts
-  args:
-    warn: no
-  failed_when: false
-  changed_when: false
-  register: machinectl_mount
-  tags:
-    - skip_ansible_lint
+# In later versions of systemd this is not needed. Referenced in
+#  the following ML post resolves the bug.
+#  * https://lists.freedesktop.org/archives/systemd-devel/2015-March/029151.html
+- name: Move machined service into place
+  template:
+    src: systemd-machined.service.j2
+    dest: /etc/systemd/system/systemd-machined.service
+  register: machined_unit
+  notify:
+    - Reload systemd units
+    - Restart machined
 
-# NOTE(odyssey4me):
-# The size is forced to be set in Gigabytes to maintain compatibility
-#  with the initial implementation done in Pike-Rocky. Do not change
-#  this without implementing some way of converting any pre-existing
-#  value properly during a major upgrade.
-- name: Create systemd sparse file
-  shell: |
-    truncate -s '>{{ lxc_host_machine_volume_size | regex_replace("\D*$", "") }}G' /var/lib/machines.raw
-
-- name: Old systemd machinectl mount
-  block:
-    # In later versions of SystemD this is automatically done for us
-    #  by the machinectl cli on first run.
-    - name: Format the machines sparse file
-      filesystem:
-        fstype: btrfs
-        dev: /var/lib/machines.raw
-
-    # In later versions of SystemD this is automatically done for us
-    #  by the machinectl cli on first run.
-    - name: Create machines mount point
-      file:
-        path: "/var/lib/machines"
-        state: "directory"
-
-    # In later versions of SystemD this unit file has been corrected
-    #  and is packaged with systemd proper.
-    - name: Move machines mount into place
-      copy:
-        src: var-lib-machines.mount
-        dest: /etc/systemd/system/var-lib-machines.mount
-      register: mount_unit
-      notify:
-        - Start machines mount
-
-    # In later versions of SystemD this is not needed. Referenced in
-    #  the following ML post resolves the bug.
-    #  * https://lists.freedesktop.org/archives/systemd-devel/2015-March/029151.html
-    - name: Move machined service into place
-      template:
-        src: systemd-machined.service.j2
-        dest: /etc/systemd/system/systemd-machined.service
-      register: machined_unit
-      notify:
-        - Reload systemd units
-        - Restart machined
-
-    # In later versions of SystemD this is not needed. Referenced in
-    #  the following commit resolves the bug.
-    #  * https://cgit.freedesktop.org/systemd/systemd/commit/src/machine/org.freedesktop.machine1.conf?id=72c3897f77a7352618ea76b880a6764f52d6327b
-    - name: Move machine1 dbus config into place
-      copy:
-        src: org.freedesktop.machine1.conf
-        dest: /etc/dbus-1/system.d/org.freedesktop.machine1.conf
-      register: machine1_conf
-      notify:
-        - Reload systemd units
-        - Restart dbus
-  when:
-    - machinectl_mount.rc != 0
+# In later versions of systemd this is not needed. Referenced in
+#  the following commit resolves the bug.
+#  * https://cgit.freedesktop.org/systemd/systemd/commit/src/machine/org.freedesktop.machine1.conf?id=72c3897f77a7352618ea76b880a6764f52d6327b
+- name: Move machine1 dbus config into place
+  copy:
+    src: org.freedesktop.machine1.conf
+    dest: /etc/dbus-1/system.d/org.freedesktop.machine1.conf
+  register: machine1_conf
+  notify:
+    - Reload systemd units
+    - Restart dbus
 
 # Ensure lxc networks are running as they're supposed to
 - meta: flush_handlers
 
-# NOTE(cloudnull): Because the machines mount may be a manually created sparse
-#                  file we run an online resize to ensure the machines mount is
-#                  the size we expect.
-- name: Ensure the machines fs is sized correctly
-  command: "btrfs filesystem resize max /var/lib/machines"
-  changed_when: false
-
-- name: Disable the machinectl quota system
-  command: "btrfs quota {{ lxc_host_machine_quota_disabled | bool | ternary('disable', 'enable') }} /var/lib/machines"
-  changed_when: false
-
 # Because of this post and it's related bug(s) this is adding the container
 #  volumes the old way. The new way would simply be calling `machinectl`.
 #  * https://www.mail-archive.com/systemd-devel@lists.freedesktop.org/msg28255.html

tasks/lxc_volume.yml

@@ -0,0 +1,88 @@
+---
+# Copyright 2017, Rackspace US, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+- name: Check machinectl mount point
+  command: mountpoint /var/lib/machines
+  failed_when: false
+  changed_when: false
+  register: machinectl_mount
+
+# NOTE(odyssey4me):
+# The size is forced to be set in Gigabytes to maintain compatibility
+#  with the initial implementation done in Pike-Rocky. Do not change
+#  this without implementing some way of converting any pre-existing
+#  value properly during a major upgrade.
+- name: Set volume size
+  shell: |
+    if ! machinectl set-limit {{ lxc_host_machine_volume_size | regex_replace("\D*$", "") }}G; then
+      truncate -s '>{{ lxc_host_machine_volume_size | regex_replace("\D*$", "") }}G' /var/lib/machines.raw
+    fi
+  changed_when: false
+  register: machines_create
+  args:
+    executable: /bin/bash
+  tags:
+    - skip_ansible_lint
+
+- name: Systemd machinectl mount
+  block:
+    - name: Format the machines sparse file
+      filesystem:
+        fstype: btrfs
+        dev: /var/lib/machines.raw
+
+    - name: Create machines mount point
+      file:
+        path: "/var/lib/machines"
+        state: "directory"
+
+    - name: Move machines mount into place
+      template:
+        src: var-lib-machines.mount
+        dest: /etc/systemd/system/var-lib-machines.mount
+      register: mount_unit
+      notify:
+        - Reload systemd units
+        - Start machines mount
+  when:
+    - machinectl_mount.rc != 0
+
+- meta: flush_handlers
+
+- name: Disable the machinectl quota system
+  command: "btrfs quota {{ lxc_host_machine_quota_disabled | bool | ternary('disable', 'enable') }} /var/lib/machines"
+  args:
+    executable: /bin/bash
+  failed_when: false
+  register: machines_create
+  tags:
+  - skip_ansible_lint
+
+- name: Notice quota system was not disabled
+  debug:
+    msg: >-
+      The machinectl quota system could not be disabled. This typically
+      means it is already off or not available on the system.
+  when:
+    - machines_create.rc != 0
+
+# NOTE(cloudnull): Because the machines mount may be a manually created sparse
+#                  file we run an online resize to ensure the machines mount is
+#                  the size we expect.
+- name: Ensure the machines fs is sized correctly
+  command: "btrfs filesystem resize max /var/lib/machines"
+  failed_when: false
+  when:
+    - machines_create is changed

templates/var-lib-machines.mount

@@ -13,4 +13,4 @@ ConditionPathExists=/var/lib/machines.raw
 What=/var/lib/machines.raw
 Where=/var/lib/machines
 Type=btrfs
-Options=loop
+Options=loop,defaults,noatime,nodiratime,compress=lzo,commit=120,{{ (ansible_kernel is version_compare('4.5', '>=')) | ternary('space_cache=v2', 'space_cache') }}