Reserve space for the 'pmspare' LV in a VG

The 'pmspare' LV is created by LVM behind our back and it serves as a temporary
space for some metadata reorganizations/cleanup/... so its size is equal to the
size of the biggest metadata LV in the VG. If we ignore it, we lack free space
in the VG later when creating LVs.

blivet/devices/lvm.py

@@ -347,6 +347,9 @@ def reservedSpace(self):
         elif self.reserved_space > Size(0):
             reserved = self.reserved_space
 
+        # reserve space for the pmspare LV LVM creates behind our back
+        reserved += self.pmSpareSize
+
         return self.align(reserved, roundup=True)
 
     @property
@@ -421,6 +424,16 @@ def thinlvs(self):
     def cachedLVs(self):
         return [l for l in self._lvs if l.cached]
 
+    @property
+    def pmSpareSize(self):
+        """Size of the pmspare LV LVM creates in every VG that contains some metadata
+        (even internal) LV. The size of such LV is equal to the size of the
+        biggest metadata LV in the VG.
+
+        """
+        # TODO: report correctly/better for existing VGs
+        return max([lv.metaDataSize for lv in self.lvs] + [Size(0)])
+
     @property
     def complete(self):
         """Check if the vg has all its pvs in the system

tests/devices_test/device_properties_test.py

@@ -791,8 +791,9 @@ def testLVMLogicalVolumeDeviceInit(self):
 
     def testLVMLogicalVolumeDeviceInitCached(self):
         self.stateCheck(self.cached_lv,
-            # 2 * (1 GiB - one extent) - 512 MiB
-            maxSize=xform(lambda x, m: self.assertEqual(x, Size("1528 MiB"), m) and
+            # 2 * (1 GiB - one extent) - 512 MiB - 8 MiB
+            #       PVfree               cache     pmspare
+            maxSize=xform(lambda x, m: self.assertEqual(x, Size("1520 MiB"), m) and
                           self.assertIsInstance(x, Size, m)),
             snapshots=xform(lambda x, m: self.assertEqual(x, [], m)),
             segType=xform(lambda x, m: self.assertEqual(x, "linear", m)),

tests/partitioning_test.py

@@ -508,8 +508,10 @@ def testVGChunk(self):
     def testVGChunkWithCache(self):
         pv = StorageDevice("pv1", size=Size("40 GiB"),
                            fmt=getFormat("lvmpv"))
-        # 1025 MiB so that the PV provides 1024 MiB of free space (see LVMVolumeGroupDevice.extents)
-        pv2 = StorageDevice("pv2", size=Size("1025 MiB"),
+        # 1033 MiB so that the PV provides 1032 MiB of free space (see
+        # LVMVolumeGroupDevice.extents) -- 1024 MiB for caches, 8 MiB for the
+        # pmspare LV
+        pv2 = StorageDevice("pv2", size=Size("1033 MiB"),
                            fmt=getFormat("lvmpv"))
         vg = LVMVolumeGroupDevice("vg", parents=[pv, pv2])
 
@@ -550,10 +552,11 @@ def testVGChunkWithCache(self):
     def testVGChunkWithCachePVfree(self):
         pv = StorageDevice("pv1", size=Size("40 GiB"),
                            fmt=getFormat("lvmpv"))
-        # 1069 MiB so that the PV provides 1068 MiB of free space (see
+        # 1077 MiB so that the PV provides 1076 MiB of free space (see
         # LVMVolumeGroupDevice.extents) which is 44 MiB more than the caches
-        # need and which should thus be split into the LVs
-        pv2 = StorageDevice("pv2", size=Size("1069 MiB"),
+        # need (including the 8MiB pmspare LV) and which should thus be split
+        # into the LVs
+        pv2 = StorageDevice("pv2", size=Size("1077 MiB"),
                            fmt=getFormat("lvmpv"))
         vg = LVMVolumeGroupDevice("vg", parents=[pv, pv2])