lvmdbusd: Bug fix for missing LV properties

When we are processing the LVs we need to build up dbus objects from least
dependent to most dependent, so that we have information available when
constructing.

daemons/lvmdbusd/lv.py

@@ -24,6 +24,39 @@ from . import background
 from .utils import round_size
 
 
+# Try and build a key for a LV, so that we sort the LVs with least dependencies
+# first.  This may be error prone because of the flexibility LVM
+# provides and what you can stack.
+def get_key(i):
+
+	name = i['lv_name']
+	parent = i['lv_parent']
+	pool = i['pool_lv']
+	a1 = ""
+	a2 = ""
+
+	if name[0] == '[':
+		a1 = '#'
+
+	# We have a parent
+	if parent:
+		# Check if parent is hidden
+		if parent[0] == '[':
+			a2 = '##'
+		else:
+			a2 = '#'
+
+	# If a LV has a pool, then it should be sorted/loaded after the pool
+	# lv, unless it's a hidden too, then after other hidden, but before visible
+	if pool:
+		if pool[0] != '[':
+			a2 += '~'
+		else:
+			a1 = '$' + a1
+
+	return "%s%s%s" % (a1, a2, name)
+
+
 # noinspection PyUnusedLocal
 def lvs_state_retrieve(selection, cache_refresh=True):
 	rc = []
@@ -31,7 +64,13 @@ def lvs_state_retrieve(selection, cache_refresh=True):
 	if cache_refresh:
 		cfg.db.refresh()
 
-	for l in cfg.db.fetch_lvs(selection):
+	# When building up the model, it's best to process LVs with the least
+	# dependencies to those that are dependant upon other LVs.  Otherwise, when
+	# we are trying to gather information we could be in a position where we
+	# don't have information available yet.
+	lvs = sorted(cfg.db.fetch_lvs(selection), key=get_key)
+
+	for l in lvs:
 		rc.append(LvState(
 			l['lv_uuid'], l['lv_name'],
 			l['lv_path'], n(l['lv_size']),