nvmeof: Call findmnt with -v

The -v arg suppresses printing of [/dir] with the
device for bind mounts and btrfs volumes, which is
what we want for this usage.

This fixes _get_host_uuid() failing when using
a btrfs rootfs.

Closes-Bug: #2026257
Change-Id: I2d8f24193ecf821843bf8f4ea14b445561d6225c
(cherry picked from commit edc1bc433b)

os_brick/initiator/connectors/nvmeof.py

@@ -783,7 +783,7 @@ class NVMeOFConnector(base.BaseLinuxConnector):
 
     def _get_host_uuid(self) -> Optional[str]:
         """Get the UUID of the first mounted filesystem."""
-        cmd = ('findmnt', '/', '-n', '-o', 'SOURCE')
+        cmd = ('findmnt', '-v', '/', '-n', '-o', 'SOURCE')
         try:
             lines, err = self._execute(
                 *cmd, run_as_root=True, root_helper=self._root_helper)

releasenotes/notes/nvmeof-findmnt-args-b2c966af83bd3bf3.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    NVMe-oF connector `bug #2026257
+    <https://bugs.launchpad.net/os-brick/+bug/2026257>`_: Fixes _get_host_uuid for nvmeof failing when using a btrfs root fs.