fix: ensure libblockdev-loop package on EL7 for loop mounts

Cause: The blivet module on EL7 will try to use a function that is undefined when checking
for mounts if there is a loop mount (/dev/loopX) on the system.  The function is provided
by the libblockdev-loop package but that isn't always installed.

Consequence: The role will give an error like:
"The function 'bd_loop_get_backing_file' called, but not implemented"

Fix: Ensure that the libblockdev-loop package is installed if there are loop mounts
on the EL7 system.

Result: The role works on EL7 when there are loop mounts.

Added a test to create a loop mount.

Signed-off-by: Rich Megginson <[email protected]>

Author: richm

tasks/main-blivet.yml

@@ -39,6 +39,28 @@
   when: storage_skip_checks is not defined or
         not "packages_installed" in storage_skip_checks
 
+# There is a bug in blivet in EL7 where it will try to use a function defined
+# in libblockdev-loop that is not installed by default when there is a loop mount.
+# Ensure that the library is available in this case.
+- name: Ensure libblockdev-loop on EL7
+  when:
+    - ansible_facts['os_family'] == "RedHat"
+    - ansible_facts['distribution_major_version'] == "7"
+    - not "libblockdev-loop" in package_info.packages | d([])
+    - ansible_facts["packages"] | d([]) | selectattr("name", "match", "^libblockdev-loop$") | list | length == 0
+  block:
+    - name: Refresh mount facts
+      setup:
+        gather_subset: ["!all", "!min", "mounts"]
+
+    - name: Ensure libblockdev-loop is installed if there are loop mounts
+      package:
+        name: libblockdev-loop
+        state: present
+        use: "{{ (__storage_is_ostree | d(false)) |
+                 ternary('ansible.posix.rhel_rpm_ostree', omit) }}"
+      when: ansible_facts["mounts"] | selectattr("device", "match", "^/dev/loop") | list | length > 0
+
 - name: Make sure required packages are installed
   package:
     name: "{{ package_info.packages + extra_pkgs }}"

tests/tests_change_disk_mount.yml

@@ -8,6 +8,17 @@
     volume_size: '5g'
 
   tasks:
+    - name: Create blockdev and loop mount
+      shell: |
+        set -euxo pipefail
+        exec 1>&2
+        dd if=/dev/zero of=/tmp/loop.img bs=1024 count=64
+        mkfs.ext4 -v -F /tmp/loop.img
+        mkdir /mnt/loop_test
+        mount /tmp/loop.img /mnt/loop_test
+        cat /proc/mounts | grep loop
+      changed_when: false
+
     - name: Run the role
       include_role:
         name: linux-system-roles.storage
@@ -79,3 +90,11 @@
 
     - name: Verify role results - 4
       include_tasks: verify-role-results.yml
+
+    - name: Clean up loop mount
+      shell: |
+        set -euxo pipefail
+        exec 1>&2
+        umount /mnt/loop_test
+        rm -rf /tmp/loop.img /mnt/loop_test
+      changed_when: false