zfs: optimize packages, invoke pkg manager only when required

roles/zfs/defaults/main.yml

@@ -1,6 +1,10 @@
 ---
-ZFS_PKGS:
+EL_ZFS_PKGS:
   - kernel-devel
   - "@Development tools"
   - dkms
   - zfs
+
+UBUNTU_ZFS_PKGS:
+  - zfsutils-linux
+  - zfs-initramfs

roles/zfs/tasks/main.yml

@@ -18,32 +18,29 @@
   yum:
     name: "http://download.zfsonlinux.org/epel/zfs-release.el7_7.noarch.rpm"
     state: present
-  when: (ansible_distribution in ["CentOS" , "Red Hat Enterprise Linux" ]) and (ansible_distribution_major_version == "7")
+  when: ('zfs-release' not in ansible_facts.packages) and ((ansible_distribution in ["CentOS" , "Red Hat Enterprise Linux" ]) and (ansible_distribution_major_version == "7"))
 
 - name: install zfs-release package (EPEL 8)
   yum:
     name: "http://download.zfsonlinux.org/epel/zfs-release.el8_1.noarch.rpm"
     state: present
-  when: (ansible_distribution in ["CentOS" , "Red Hat Enterprise Linux" ]) and (ansible_distribution_major_version == "8")
+  when: ('zfs-release' not in ansible_facts.packages) and ((ansible_distribution in ["CentOS" , "Red Hat Enterprise Linux" ]) and (ansible_distribution_major_version == "8"))
 
 - name: install zfs-release package (Fedora)
   dnf:
     name: "http://download.zfsonlinux.org/fedora/zfs-release.fc31.noarch.rpm"
     state: present
-  when: ansible_distribution in ["Fedora"] and not is_atomic
+  when: ('zfs-release' not in ansible_facts.packages) and (ansible_distribution in ["Fedora"] and not is_atomic)
 
-- name: install zfs utils (Ubuntu)
+- name: install ZFS (Ubuntu)
   package:
-    name: "{{ item }}"
+    name: "{{ UBUNTU_ZFS_PKGS | difference(ansible_facts.packages) }}"
     state: present
-  with_items:
-    - zfsutils-linux
-    - zfs-initramfs
   when: ansible_distribution in ["Ubuntu"]
 
 - name: install zfs and dkms
   package:
-    name: "{{ ZFS_PKGS | difference(ansible_facts.packages) }}"
+    name: "{{ EL_ZFS_PKGS | difference(ansible_facts.packages) }}"
     state: present
   register: zfs_installed
   when: ansible_distribution in ["CentOS" , "Red Hat Enterprise Linux", "Fedora" ] and not is_atomic