cron: add scrub and trim jobs for btrfs/zfs

No longer depend on `rootfs` variable.

TODO.md

@@ -7,7 +7,7 @@ Stuff that are planned to be added/changed.
 - [ ] /etc/security/access.conf
 - [ ] Filesystem snapshot:
   - [ ] sanoid / zrepl (rootfs=zfs)
-- [ ] How should we figure out the underlying fstype if rootfs=tmpfs??
+- [ ] Root on tmpfs
 - [ ] Filesystem backup (I don't have spare hard drives -_- so not supported for now):
   - [ ] Local incremental backups (to spare disk)
   - [ ] Remote backups

requirements/accepted_variables.yml

@@ -4,9 +4,11 @@ initramfs_generator:
   - dracut
   - booster
 
-snapshot_tool: '{{ ["sanoid", "zrepl"] if rootfs == "zfs"
-  else ["snapper", "btrbk"] if rootfs == "btrfs"
-  else ["none"] }}'
+snapshot_tool:
+  - btrbk
+  - sanoid
+  - snapper
+  - zrepl
 
 # NOTE: Keep this in sync with `shell_mappings` in roles/user/defaults/main.yml
 usershell:

roles/cron/files/btrfs-scrub

@@ -1,5 +0,0 @@
-#!/bin/sh
-
-# Use flock to ensure the cron job won't start a 2nd time
-# Ref: https://wiki.archlinux.org/title/Cron#Ensuring_exclusivity
-/usr/bin/flock -nx /tmp/btrfs_scrub.lock /sbin/btrfs scrub start /

roles/cron/files/fstrim

@@ -1,5 +1,8 @@
 #!/bin/sh
 
-# This needs fstrim
-# For busybox's fstrim, using multiple 'fstrim /mount_point' is more feasible
-/sbin/fstrim -a
+# NOTE: we only trim things inside /etc/fstab to avoid ZFS mount paths
+# (they will be handled by `zpool trim` cron job)
+
+# This needs fstrim from util-linux package.
+# For busybox's fstrim, use multiple 'fstrim /mount_point'.
+exec /sbin/fstrim -A

roles/cron/tasks/main.yml

@@ -1,12 +1,4 @@
 ---
-- name: cron | Create fstrim daily job
-  copy:
-    src: fstrim
-    dest: /etc/periodic/daily/fstrim
-    owner: root
-    group: root
-    mode: '755'
-
 # It is recomended to preserve /var/tmp across reboots
 - name: cron | Create empty /var/tmp/ weekly job
   copy:
@@ -16,14 +8,11 @@
     group: root
     mode: '755'
 
-- name: cron | Create btrfs-scrub monthly job
-  copy:
-    src: btrfs-scrub
-    dest: /etc/periodic/monthly/btrfs-scrub
-    owner: root
-    group: root
-    mode: '755'
-  when: rootfs == 'btrfs'
+- name: cron | Create trimming cron jobs
+  import_tasks: trim.yml
+
+- name: cron | Create scrubbing cron jobs for zfs/btrfs
+  import_tasks: scrub.yml
 
 - name: cron | Install logrotate and cpulimit
   community.general.apk:

roles/cron/tasks/scrub.yml

@@ -0,0 +1,23 @@
+---
+- name: cron | Create BTRFS scrub monthly job
+  copy:
+    content: |
+      #!/bin/sh
+      exec /sbin/btrfs scrub start -B {{ item }}
+    dest: /etc/periodic/monthly/scrub-btrfs-{{ item | regex_replace('/', '@') }}
+    owner: root
+    group: root
+    mode: '755'
+  # PERF: a shorter version but requires `py3-jmespath`: '{{ ansible_mounts | json_query("[?fstype == `btrfs`].mount") }}'
+  loop: '{{ ansible_mounts | selectattr("fstype", "equalto", "btrfs") | map(attribute="mount") | list }}'
+
+- name: cron | Create ZFS pool scrub monthly job
+  copy:
+    content: |
+      #!/bin/sh
+      exec /usr/sbin/zpool scrub -w {{ item }}
+    dest: /etc/periodic/monthly/scrub-zfs-{{ item }}
+    mode: '755'
+    owner: root
+    group: root
+  loop: '{{ ansible_zfs_pools | map(attribute="name") | list }}'

roles/cron/tasks/trim.yml

@@ -0,0 +1,25 @@
+---
+# NOTE: dmcrypt discourages using `discard` mount option (as in BTRFS on LUKS),
+# so running trim manually in a cron job
+- name: cron | Create fstrim weekly job
+  copy:
+    src: fstrim
+    dest: /etc/periodic/weekly/fstrim
+    owner: root
+    group: root
+    mode: '755'
+
+- name: cron | Create ZFS pool trim weekly job
+  copy:
+    content: |
+      #!/bin/sh
+      if /usr/sbin/zpool status {{ item }} | grep -qF "trimming"; then
+        exec /usr/sbin/zpool wait -t trim {{ item }}
+      else
+        exec /usr/sbin/zpool trim -w {{ item }}
+      fi
+    dest: /etc/periodic/weekly/trim-zfs-{{ item }}
+    mode: '755'
+    owner: root
+    group: root
+  loop: '{{ ansible_zfs_pools | map(attribute="name") | list }}'

setup.yml

@@ -2,20 +2,7 @@
 - name: Setup the system
   hosts: all
   gather_facts: true
-  # vars:
-  #   # Determine the fstype of root filesystem
-  #   # PERF: a shorter version but requires `py3-jmespath`: '{{ ansible_mounts | json_query("[?mount == `/`].fstype") | first }}'
-  #   rootfs: '{{ ansible_mounts | selectattr("mount", "equalto", "/") | map(attribute="fstype") | first }}'
   pre_tasks:
-    # FIXME: ansible_mounts doesn't recognise ZFS dataset (yet???)
-    # Ref: https://github.com/ansible/ansible/issues/24644
-    - name: Guess fstype of the root filesystem
-      shell:
-        cmd: /bin/findmnt -M / -o FSTYPE -f | tail -n 1
-      register: findmnt_result
-    - name: Set rootfs variable
-      set_fact:
-        rootfs: findmnt_result.stdout
     - name: Sanity checks
       tags: always
       block:
@@ -32,6 +19,9 @@
             msg: 'Variable `{{ item }}` needs to be 1 of {{ accepted_values[item] }}'
           when: not vars[item] in accepted_values[item]
           loop: '{{ accepted_values | flatten }}'
+    - name: Get ZFS pool facts
+      community.general.zpool_facts:
+      tags: always
   roles:
     - role: essential
       tags: essential
@@ -67,7 +57,6 @@
       tags: zram
     - role: snapshot
       tags: snapshot
-      when: snapshot_tool != 'none'
     - role: earlyoom
       tags: earlyoom
     - role: user