refactor(zfs): inline dataset ownership, add absent cleanup

Drop separate dataset-ownership.yml task file. Use
extra_zfs_properties.mountpoint directly instead of zfs get.
Add rmdir cleanup for absent dataset mountpoints.

roles/zfs/tasks/dataset-ownership.yml

@@ -1,24 +0,0 @@
----
-# due to Ansible limitations, we cannot loop over a block, so we loop over distinct task files
-# @see https://stackoverflow.com/a/58911694
-- name: Set ownership on dataset mountpoint
-  block:
-    - name: Get the mountpoint
-      ansible.builtin.command: "zfs get -H -o value mountpoint {{ dataset.name }}"
-      register: mountpoint
-      changed_when: false
-
-    - name: Fail if mountpoint is system directory
-      ansible.builtin.fail:
-        msg: "Mountpoint resolved to a system directory ({{ mountpoint.stdout }}), aborting to avoid changing ownership."
-      when:
-        - mountpoint.stdout | trim == ''
-        - mountpoint.stdout | trim is not match('^/$|^(/usr|/bin|/sbin|/etc|/var|/lib|/lib64)$')
-
-    - name: Set mountpoint ownership
-      ansible.builtin.file:
-        path: "{{ mountpoint.stdout }}"
-        owner: "{{ dataset.user | default(ansible_user) }}"
-        group: "{{ dataset.group | default(ansible_user) }}"
-        state: directory
-        recurse: false

roles/zfs/tasks/datasets.yml

@@ -8,8 +8,28 @@
     origin: "{{ item.origin | default(omit) }}"
   with_items: "{{ zfs_datasets }}"
 
-- name: Set dataset ownership
-  ansible.builtin.include_tasks: "./dataset-ownership.yml"
+- name: Set dataset mountpoint ownership
+  ansible.builtin.file:
+    path: "{{ item.extra_zfs_properties.mountpoint }}"
+    owner: "{{ item.user | default(ansible_user) }}"
+    group: "{{ item.group | default(ansible_user) }}"
+    state: directory
+    recurse: false
   loop: "{{ zfs_datasets }}"
-  loop_control:
-    loop_var: dataset
+  when:
+    - item.state | default('present') == 'present'
+    - item.extra_zfs_properties.mountpoint is defined
+    - item.extra_zfs_properties.mountpoint not in ['none', 'legacy']
+
+- name: Remove leftover empty mountpoint for absent datasets
+  ansible.builtin.command: "rmdir {{ item.extra_zfs_properties.mountpoint }}"
+  register: rmdir_result
+  failed_when:
+    - rmdir_result.rc != 0
+    - "'No such file or directory' not in rmdir_result.stderr"
+    - "'Directory not empty' not in rmdir_result.stderr"
+  changed_when: rmdir_result.rc == 0
+  loop: "{{ zfs_datasets }}"
+  when:
+    - item.state | default('present') == 'absent'
+    - item.extra_zfs_properties.mountpoint is defined