check ephemeral disk format at libvirt before use

Add ephemeral disk format at libvirt. There is no check before
so it will be used directly. This patch adds valid check function
and validate it before eph disk was used in virt layer.

Change-Id: I1934573e79f126e725cef4848b15c11a595161c9
Closes-Bug: #1293880

nova/tests/virt/libvirt/test_driver.py

@@ -4904,6 +4904,34 @@ class LibvirtConnTestCase(test.TestCase):
             ]
         self.assertEqual(gotFiles, wantFiles)
 
+    def test_create_ephemeral_specified_fs_not_valid(self):
+        CONF.set_override('default_ephemeral_format', 'ext4')
+        ephemerals = [{'device_type': 'disk',
+                       'disk_bus': 'virtio',
+                       'device_name': '/dev/vdb',
+                       'guest_format': 'dummy',
+                       'size': 1}]
+        block_device_info = {
+                'ephemerals': ephemerals}
+        instance_ref = self.test_instance
+        instance_ref['image_ref'] = 1
+        instance = db.instance_create(self.context, instance_ref)
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        image_meta = {'id': instance['image_ref']}
+        disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
+                                            instance,
+                                            None,
+                                            image_meta)
+        disk_info['mapping'].pop('disk.local')
+
+        with contextlib.nested(
+            mock.patch.object(utils, 'execute'),
+            mock.patch.object(conn, 'get_info'),
+            mock.patch.object(conn, '_create_domain_and_network')):
+            self.assertRaises(exception.InvalidBDMFormat, conn._create_image,
+                              context, instance, disk_info['mapping'],
+                              block_device_info=block_device_info)
+
     def test_create_ephemeral_default(self):
         conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
         self.mox.StubOutWithMock(utils, 'execute')
@@ -6919,6 +6947,18 @@ class LibvirtConnTestCase(test.TestCase):
                                                ephemerals, swap,
                                                block_device_mapping)
 
+    def test_is_supported_fs_format(self):
+        supported_fs = [disk.FS_FORMAT_EXT2, disk.FS_FORMAT_EXT3,
+                        disk.FS_FORMAT_EXT4, disk.FS_FORMAT_XFS]
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        for fs in supported_fs:
+            self.assertTrue(conn.is_supported_fs_format(fs))
+
+        supported_fs = ['', 'dummy']
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        for fs in supported_fs:
+            self.assertFalse(conn.is_supported_fs_format(fs))
+
     def test_hypervisor_hostname_caching(self):
         # Make sure that the first hostname is always returned
         class FakeConn(object):

nova/virt/libvirt/driver.py

@@ -2662,6 +2662,12 @@ class LibvirtDriver(driver.ComputeDriver):
         for idx, eph in enumerate(driver.block_device_info_get_ephemerals(
                 block_device_info)):
             disk_image = image(blockinfo.get_eph_disk(idx))
+
+            specified_fs = eph.get('guest_format')
+            if specified_fs and not self.is_supported_fs_format(specified_fs):
+                msg = _("%s format is not supported") % specified_fs
+                raise exception.InvalidBDMFormat(details=msg)
+
             fn = functools.partial(self._create_ephemeral,
                                    fs_label='ephemeral%d' % idx,
                                    os_type=instance["os_type"],
@@ -5287,6 +5293,10 @@ class LibvirtDriver(driver.ComputeDriver):
                                        ephemerals, swap,
                                        block_device_mapping)
 
+    def is_supported_fs_format(self, fs_type):
+        return fs_type in [disk.FS_FORMAT_EXT2, disk.FS_FORMAT_EXT3,
+                           disk.FS_FORMAT_EXT4, disk.FS_FORMAT_XFS]
+
 
 class HostState(object):
     """Manages information about the compute node through libvirt."""