Avoid using lvmohba/lvmoiscsi LUNs for other SR tests

Add a WWN field to BlockDeviceInfo (populated from lsblk for local disks,
and from the DM alias for mpath devices). In the disks fixture, use WWNs to:

- Mark a LUN unavailable on all hosts if it is already in use on any host
  (cross-host deduplication for shared FC/iSCSI LUNs).
- Sort LUNs listed in LVMOHBA_DEVICE_CONFIG or LVMOISCSI_DEVICE_CONFIG to
  the end of each host's disk list, so they are only selected by other tests
  when no other disk is available.

Signed-off-by: Gaëtan Lehmann <gaetan.lehmann@vates.tech>

Author: glehmann

conftest.py

@@ -3,6 +3,7 @@
 import pytest
 
 import argparse
+import dataclasses
 import itertools
 import logging
 import os
@@ -435,6 +436,42 @@ def _host_disks(host: Host, hosts_cli_disks: list[DiskDevName] | None) -> Iterab
     ret = {host: list(_host_disks(host, cli_disks.get(host.hostname_or_ip)))
            for host in pools_hosts_by_name_or_ip.values()
            }
+    # Cross-host deduplication: a LUN in use on any host (same WWN) is unavailable on all hosts.
+    # This matters for shared FC/iSCSI LUNs visible on multiple hosts simultaneously.
+    used_wwns = {
+        disk.wwn
+        for host_disks in ret.values()
+        for disk in host_disks
+        if disk.wwn and not disk.available
+    }
+    if used_wwns:
+        logging.debug("cross-host used WWNs: %s", used_wwns)
+        ret = {
+            host: [
+                dataclasses.replace(disk, available=False) if (disk.wwn and disk.wwn in used_wwns) else disk
+                for disk in host_disks
+            ]
+            for host, host_disks in ret.items()
+        }
+    # LUNs reserved for lvmohba/lvmoiscsi: sort them to the end so they are
+    # only picked if no other disk is available.
+    reserved_wwns: set[str] = set()
+    try:
+        import data
+        for key in ('LVMOHBA_DEVICE_CONFIG', 'LVMOISCSI_DEVICE_CONFIG'):
+            cfg = getattr(data, key, None)
+            if isinstance(cfg, dict):
+                scsiid = cfg.get('SCSIid', '').lower().lstrip('0x')
+                if scsiid:
+                    reserved_wwns.add(scsiid)
+    except ImportError:
+        pass
+    if reserved_wwns:
+        logging.debug("reserved WWNs (lvmohba/lvmoiscsi): %s", reserved_wwns)
+        ret = {
+            host: sorted(host_disks, key=lambda d: d.wwn in reserved_wwns)
+            for host, host_disks in ret.items()
+        }
     logging.debug("disks collected: %s", {host.hostname_or_ip: value for host, value in ret.items()})
     return ret
 

lib/host.py

@@ -63,6 +63,7 @@ class BlockDeviceInfo:
         log_sec: int    # logical sector size; 0 for md/mpath
         type: str       # "disk", "md", "mpath"
         available: bool # not mounted, not member of md/lvm/mpath/zfs
+        wwn: str = ''   # LUN WWN (hex, no 0x prefix); same LUN has same WWN across hosts
 
     block_devices_info: list[BlockDeviceInfo]
 
@@ -677,7 +678,7 @@ def rescan_block_devices_info(self) -> None:
         """
         # Majors: 8=SCSI/SATA, 65-71,128-135=SCSI extended, 259=NVMe/blkext
         LOCAL_MAJORS = '8,65,66,67,68,69,70,71,128,129,130,131,132,133,134,135,259'
-        LSBLK_FIELDS = 'NAME,KNAME,PKNAME,SIZE,LOG-SEC,TYPE'
+        LSBLK_FIELDS = 'NAME,KNAME,PKNAME,SIZE,LOG-SEC,TYPE,WWN'
 
         devices: list[Host.BlockDeviceInfo] = []
 
@@ -698,13 +699,16 @@ def rescan_block_devices_info(self) -> None:
             disk_name = r['name']
             dev = f'/dev/{disk_name}'
             available = self._disk_is_available_local(disk_name)
+            raw_wwn = r.get('wwn', '').strip()
+            wwn = raw_wwn[2:] if raw_wwn.startswith('0x') else raw_wwn
             devices.append(Host.BlockDeviceInfo(
                 name=disk_name,
                 path=dev,
                 size=int(r['size']),
                 log_sec=int(r['log-sec']),
                 type='disk',
                 available=available,
+                wwn=wwn,
             ))
 
         # --- mdadm arrays ---
@@ -742,16 +746,19 @@ def rescan_block_devices_info(self) -> None:
             if not r or r.get('type') != 'mpath':
                 continue
             dm_name = r['name']     # e.g. "dm-3"
-            dm_alias = r.get('dm-name', '').strip()  # e.g. "mpathb"
+            dm_alias = r.get('dm-name', '').strip()  # e.g. "mpathb" or "3600507681381022548000000000001ec"
             path = f'/dev/mapper/{dm_alias}' if dm_alias else f'/dev/{dm_name}'
             mountpoint = self.ssh(f'lsblk --noheadings -o MOUNTPOINT /dev/{dm_name}').strip()
+            # DM alias is the LUN WWN when multipath names the device after it (all-hex, ≥16 chars)
+            wwn = dm_alias if re.fullmatch(r'[0-9a-f]{16,}', dm_alias) else ''
             devices.append(Host.BlockDeviceInfo(
                 name=dm_name,
                 path=path,
                 size=int(r['size']),
                 log_sec=int(r.get('log-sec', '0')),
                 type='mpath',
                 available=len(mountpoint) == 0,
+                wwn=wwn,
             ))
 
         self.block_devices_info = sorted(devices, key=lambda d: d.name)