OSMount: fix internal VG name referencing conflict.

The Coriolis OSMount code would internally keep a mapping between
names of VGs it should activate and their PVs, which could potentially
lead to VGs with multiple PVs to be referneced both by their original
name, as well as a new one Coriolis generates to avoid naming conflicts
in /dev/$VG_NAME/$LVM_NAME.

Signed-off-by: Nashwan Azhari <nazhari@cloudbasesolutions.com>

coriolis/osmorphing/osmount/base.py

@@ -133,33 +133,48 @@ def _get_pvs(self):
         return pvs
 
     def _get_vgs(self):
+        """ Returns a dict of the form: {
+            "VG UUID": {
+                "name": "<VG name>",
+                "pvs": ["list", "of", "PV", "names", "in", "VG"],
+            }
+        }
+        """
         vgs_cmd = (
             "sudo vgs -o vg_name,pv_name,vg_uuid, --noheadings --separator :")
         out = self._exec_cmd(vgs_cmd).decode().splitlines()
         LOG.debug("Output of %s command: %s", vgs_cmd, out)
-        vgs = {}
+        vgs_uuid_map = {}
         for line in out:
             if line == "":
                 continue
             line = line.strip().split(":")
             if len(line) >= 3:
                 vg_name, pv_name, vg_uuid = line[0], line[1], line[2]
-                if vgs.get(vg_name) is None:
-                    vgs[vg_name] = pv_name
+
+                if vg_uuid in vgs_uuid_map:
+                    vgs_uuid_map[vg_uuid]["pvs"].append(pv_name)
                 else:
-                    new_name = str(uuid.uuid4())
-                    LOG.debug(
-                        "VG with name '%s' already detected. Renaming VG with "
-                        "UUID '%s' to '%s' to avoid conflicts",
-                        vg_name, vg_uuid, new_name)
-                    self._exec_cmd("sudo vgrename %s %s" %
-                                   (vg_uuid, new_name))
-                    vgs[new_name] = pv_name
+                    new_name = vg_name
+                    # Ensure that there isn't an existing VG with a
+                    # coinciding name, and rename it if so.
+                    if vg_name in [vg['name'] for vg in vgs_uuid_map.values()]:
+                        new_name = str(uuid.uuid4())
+                        LOG.debug(
+                            "VG with name '%s' already detected. Renaming VG with "
+                            "UUID '%s' to '%s' to avoid conflicts",
+                            vg_name, vg_uuid, new_name)
+                        self._exec_cmd("sudo vgrename %s %s" %
+                                       (vg_uuid, new_name))
+                    vgs_uuid_map[vg_uuid] = {
+                        "name": new_name,
+                        "pvs": [pv_name]
+                    }
             else:
                 LOG.warning("Ignoring improper `vgs` output entry: %s", line)
-        LOG.debug("Volume groups: %s", vgs)
+        LOG.debug("Volume groups: %s", vgs_uuid_map)
 
-        return vgs
+        return vgs_uuid_map
 
     def _check_vgs(self):
         try:
@@ -532,13 +547,15 @@ def mount_os(self):
         lvm_dev_paths = []
         self._check_vgs()
         vgs = self._get_vgs()
-        for vg_name, pv_name in vgs.items():
-            if pv_name in dev_paths:
-                self._exec_cmd("sudo vgchange -ay %s" % vg_name)
-                self._exec_cmd("sudo vgchange --refresh")
-                dev_paths_for_group = self._exec_cmd(
-                    "sudo ls -1 /dev/%s/*" % vg_name).decode().splitlines()
-                lvm_dev_paths.extend(dev_paths_for_group)
+        for vg_uuid, vg_props in vgs.items():
+            if not any([pv in dev_paths for pv in vg_props['pvs']]):
+                continue
+
+            self._exec_cmd("sudo vgchange -ay -S vg_uuid=%s" % vg_uuid)
+            self._exec_cmd("sudo vgchange --refresh")
+            dev_paths_for_group = self._exec_cmd(
+                "sudo ls -1 /dev/%s/*" % vg_props['name']).decode().splitlines()
+            lvm_dev_paths.extend(dev_paths_for_group)
         LOG.debug("All LVM vols to scan: %s", lvm_dev_paths)
 
         valid_filesystems = ['ext2', 'ext3', 'ext4', 'xfs', 'btrfs']