[ceph] Add thin-provisioned LV support for Ceph OSDs

When cifmw_ceph_thin_pool is defined, create thin LVs from an existing
VG thin pool instead of loop-backed files. This supports baremetal hosts
where the disk is fully consumed by a thin pool with no raw devices
available for cephadm.
The new play runs before the existing loop device play and sets
cifmw_ceph_spec_data_devices with explicit LV paths, which also
causes the loop device play to be skipped.

Signed-off-by: Bohdan Dobrelia <bdobreli@redhat.com>

Author: bogdando

hooks/playbooks/ceph.yml

@@ -124,6 +124,60 @@
         name: cifmw_cephadm
         tasks_from: install_cephadm
 
+- name: Create thin-provisioned LVs for Ceph OSDs
+  tags: block
+  hosts: "{{ cifmw_ceph_target | default('computes') }}"
+  gather_facts: true
+  become: true
+  pre_tasks:
+    - name: Skip when thin pool is not configured
+      when:
+        - cifmw_ceph_thin_pool is not defined or
+          not _deploy_ceph | default(true)
+      ansible.builtin.meta: end_play
+  tasks:
+    - name: Compute OSD count per host
+      ansible.builtin.set_fact:
+        cifmw_num_osds_perhost: >-
+          {% if groups[cifmw_ceph_target | default('computes')] | length == 1 %}3{% else %}1{% endif %}
+
+    - name: Install LVM prerequisite packages
+      ansible.builtin.dnf:
+        name:
+          - lvm2
+          - jq
+        state: present
+
+    - name: Create thin LVs from existing thin pool
+      ansible.builtin.command:
+        cmd: >-
+          lvcreate -V {{ cifmw_ceph_thin_lv_size | default('50G') }}
+          --thin -n ceph_osd_{{ item }}
+          {{ cifmw_ceph_thin_pool }}
+        creates: "/dev/{{ cifmw_ceph_thin_pool.split('/')[0] }}/ceph_osd_{{ item }}"
+      loop: "{{ range(0, cifmw_num_osds_perhost | int) | list }}"
+
+    - name: Build data_devices paths list
+      ansible.builtin.set_fact:
+        _ceph_thin_lv_paths: >-
+          {{ range(0, cifmw_num_osds_perhost | int) | map('regex_replace', '^(.*)$',
+             '/dev/' ~ cifmw_ceph_thin_pool.split('/')[0] ~ '/ceph_osd_\1') | list }}
+
+    - name: Set cifmw_ceph_spec_data_devices on compute hosts
+      ansible.builtin.set_fact:
+        cifmw_ceph_spec_data_devices: |
+          data_devices:
+            paths:
+          {% for p in _ceph_thin_lv_paths %}
+              - {{ p }}
+          {% endfor %}
+
+    - name: Propagate cifmw_ceph_spec_data_devices to localhost
+      ansible.builtin.set_fact:
+        cifmw_ceph_spec_data_devices: "{{ cifmw_ceph_spec_data_devices }}"
+      delegate_to: localhost
+      delegate_facts: true
+
 - name: Create Block Device on target nodes
   tags: block
   hosts: "{{ cifmw_ceph_target | default('computes')  }}"