Merge ~ack/maas:1947013-raid0-size into maas:master

[Alberto Donato]

LP:1947013 fix size for raid0 with unequal devices

Linux raid0 allows to use all space on each device, so the total size is
effectively the sum of device size (minus partition overhead)

[MAAS Lander (maas-lander)]

UNIT TESTS
-b 1947013-raid0-size lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED
LOG: http://maas-ci.internal:8080/job/maas/job/branch-tester/11313/console
COMMIT: 8626844fa97413c635c2597c195163435abc6198

review: Needs Fixing

[MAAS Lander (maas-lander)]

UNIT TESTS
-b 1947013-raid0-size lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: 8313041175be29f18f69e92e3a05d63fff0ced1b

review: Approve

[Björn Tillenius (bjornt)]

+1

review: Approve

diff --git a/src/maasserver/api/tests/test_raid.py b/src/maasserver/api/tests/test_raid.py
index 832d9f5..23629e9 100644
--- a/src/maasserver/api/tests/test_raid.py
+++ b/src/maasserver/api/tests/test_raid.py
@@ -1,9 +1,6 @@
 # Copyright 2015-2016 Canonical Ltd.  This software is licensed under the
 # GNU Affero General Public License version 3 (see the file LICENSE).
 
-"""Tests for raid API."""
-
-
 import http.client
 import json
 import uuid
@@ -15,7 +12,7 @@ from testtools.matchers import ContainsDict, Equals
 from maasserver.enum import FILESYSTEM_GROUP_TYPE, FILESYSTEM_TYPE, NODE_STATUS
 from maasserver.models.blockdevice import MIN_BLOCK_DEVICE_SIZE
 from maasserver.models.filesystem import Filesystem
-from maasserver.models.filesystemgroup import RAID_SUPERBLOCK_OVERHEAD
+from maasserver.models.filesystemgroup import RAID, RAID_SUPERBLOCK_OVERHEAD
 from maasserver.models.partition import MIN_PARTITION_SIZE
 from maasserver.models.partitiontable import PARTITION_TABLE_EXTRA_SPACE
 from maasserver.testing.api import APITestCase
@@ -227,9 +224,8 @@ class TestRaidsAPI(APITestCase.ForUser):
             parsed_block_device_spares,
             parsed_partition_spares,
         ) = get_devices_from_raid(parsed_device)
-        self.assertEqual(
-            (10 * PART_SIZE) - RAID_SUPERBLOCK_OVERHEAD, parsed_device["size"]
-        )
+        raid = RAID.objects.get(id=parsed_device["id"])
+        self.assertEqual(parsed_device["size"], raid.get_size())
         self.assertEqual(uuid4, parsed_device["uuid"])
         self.assertCountEqual(block_devices, parsed_block_devices)
         self.assertCountEqual(partitions, parsed_partitions)
diff --git a/src/maasserver/models/filesystemgroup.py b/src/maasserver/models/filesystemgroup.py
index ed40c01..42e8ada 100644
--- a/src/maasserver/models/filesystemgroup.py
+++ b/src/maasserver/models/filesystemgroup.py
@@ -458,10 +458,7 @@ class FilesystemGroup(CleanSave, TimestampedModel):
 
     def get_total_size(self):
         """Return the size of all filesystems combined."""
-        total = 0
-        for fs in self.filesystems.all():
-            total += fs.get_size()
-        return total
+        return sum(fs.get_size() for fs in self.filesystems.all())
 
     def get_raid_size(self):
         """Size of this RAID.
@@ -479,9 +476,9 @@ class FilesystemGroup(CleanSave, TimestampedModel):
             # Possible when no filesytems are attached to this group.
             return 0
         elif self.group_type == FILESYSTEM_GROUP_TYPE.RAID_0:
-            return (
-                min_size * self.filesystems.count()
-            ) - RAID_SUPERBLOCK_OVERHEAD
+            return self.get_total_size() - (
+                RAID_SUPERBLOCK_OVERHEAD * self.filesystems.count()
+            )
         elif self.group_type == FILESYSTEM_GROUP_TYPE.RAID_1:
             return min_size - RAID_SUPERBLOCK_OVERHEAD
         else:
diff --git a/src/maasserver/models/tests/test_filesystemgroup.py b/src/maasserver/models/tests/test_filesystemgroup.py
index e1742bd..78b0e98 100644
--- a/src/maasserver/models/tests/test_filesystemgroup.py
+++ b/src/maasserver/models/tests/test_filesystemgroup.py
@@ -1,8 +1,6 @@
 # Copyright 2015-2019 Canonical Ltd.  This software is licensed under the
 # GNU Affero General Public License version 3 (see the file LICENSE).
 
-"""Tests for `FilesystemGroup`."""
-
 
 import random
 import re
@@ -783,7 +781,7 @@ class TestFilesystemGroup(MAASServerTestCase):
         fsgroup = FilesystemGroup(group_type=FILESYSTEM_GROUP_TYPE.RAID_0)
         self.assertEqual(0, fsgroup.get_size())
 
-    def test_get_size_returns_smallest_disk_size_for_raid_0(self):
+    def test_get_size_returns_sum_of_disk_size_for_raid_0(self):
         node = factory.make_Node()
         small_size = random.randint(
             MIN_BLOCK_DEVICE_SIZE, MIN_BLOCK_DEVICE_SIZE ** 2
@@ -806,10 +804,9 @@ class TestFilesystemGroup(MAASServerTestCase):
         fsgroup = factory.make_FilesystemGroup(
             group_type=FILESYSTEM_GROUP_TYPE.RAID_0, filesystems=filesystems
         )
-        # Size should be twice the smallest device (the rest of the larger
-        # device remains unused.
         self.assertEqual(
-            (small_size * 2) - RAID_SUPERBLOCK_OVERHEAD, fsgroup.get_size()
+            fsgroup.get_size(),
+            (small_size + large_size) - RAID_SUPERBLOCK_OVERHEAD * 2,
         )
 
     def test_get_size_returns_smallest_disk_size_for_raid_1(self):
diff --git a/src/maasserver/models/tests/test_virtualblockdevice.py b/src/maasserver/models/tests/test_virtualblockdevice.py
index 6775581..ecbed05 100644
--- a/src/maasserver/models/tests/test_virtualblockdevice.py
+++ b/src/maasserver/models/tests/test_virtualblockdevice.py
@@ -90,9 +90,11 @@ class TestVirtualBlockDeviceManager(MAASServerTestCase):
         # The new size of the RAID-0 array should be the size of the smallest
         # filesystem (in this case, they are all the same) times the number of
         # filesystems in it.
-        array_size = new_size * filesystem_group.filesystems.count()
+        array_size = (
+            new_size - RAID_SUPERBLOCK_OVERHEAD
+        ) * filesystem_group.filesystems.count()
         self.assertEqual(
-            array_size - RAID_SUPERBLOCK_OVERHEAD,
+            array_size,
             reload_object(filesystem_group.virtual_device).size,
         )