Merge "libvirt: add configuration option for volume AIO mode"

nova/conf/libvirt.py

@@ -1652,6 +1652,15 @@ Possible values are:
   accessed by anyone else. The Libvirt secret is public and persistent. It
   can be read by anyone with sufficient access on the host. The instance can
   be live-migrated and automatically resumed after host reboot.
+"""),
+    cfg.BoolOpt(
+        'use_default_aio_mode_for_volumes',
+        default=False,
+        help="""
+With the NFS, FC, and iSCSI Cinder volume backends, Nova explicitly sets AIO
+mode ``io=native`` in the Libvirt guest XML. Operators may set this option to
+True in order to defer AIO mode selection to QEMU if forcing ``io=native`` is
+not desired.
 """),
 ]
 

nova/tests/unit/virt/libvirt/volume/test_fibrechannel.py

@@ -65,6 +65,22 @@ class LibvirtFibreChannelVolumeDriverTestCase(
         self.assertEqual('raw', tree.find('./driver').get('type'))
         self.assertEqual('native', tree.find('./driver').get('io'))
 
+    def test_libvirt_fibrechan_driver_get_config_default_aio_mode(self):
+        self.flags(use_default_aio_mode_for_volumes=True, group='libvirt')
+
+        libvirt_driver = fibrechannel.LibvirtFibreChannelVolumeDriver(
+                                                                self.fake_host)
+        device_path = '/dev/fake-dev'
+        connection_info = {'data': {'device_path': device_path}}
+
+        conf = libvirt_driver.get_config(connection_info, self.disk_info)
+        tree = conf.format_dom()
+
+        self.assertEqual('block', tree.get('type'))
+        self.assertEqual(device_path, tree.find('./source').get('dev'))
+        self.assertEqual('raw', tree.find('./driver').get('type'))
+        self.assertIsNone(tree.find('./driver').get('io'))
+
     def test_extend_volume(self):
         device_path = '/dev/fake-dev'
         connection_info = {'data': {'device_path': device_path}}

nova/tests/unit/virt/libvirt/volume/test_iscsi.py

@@ -45,6 +45,22 @@ class LibvirtISCSIVolumeDriverTestCase(
         self.assertEqual('raw', tree.find('./driver').get('type'))
         self.assertEqual('native', tree.find('./driver').get('io'))
 
+    def test_libvirt_iscsi_driver_get_config_default_aio_mode(self):
+        self.flags(use_default_aio_mode_for_volumes=True, group='libvirt')
+
+        libvirt_driver = iscsi.LibvirtISCSIVolumeDriver(self.fake_host)
+
+        device_path = '/dev/fake-dev'
+        connection_info = {'data': {'device_path': device_path}}
+
+        conf = libvirt_driver.get_config(connection_info, self.disk_info)
+        tree = conf.format_dom()
+
+        self.assertEqual('block', tree.get('type'))
+        self.assertEqual(device_path, tree.find('./source').get('dev'))
+        self.assertEqual('raw', tree.find('./driver').get('type'))
+        self.assertIsNone(tree.find('./driver').get('io'))
+
     @mock.patch.object(iscsi.LOG, 'warning')
     def test_libvirt_iscsi_driver_disconnect_volume_with_devicenotfound(self,
             mock_LOG_warning):

nova/tests/unit/virt/libvirt/volume/test_nfs.py

@@ -77,6 +77,24 @@ class LibvirtNFSVolumeDriverTestCase(test_volume.LibvirtVolumeBaseTestCase):
         self.assertEqual('raw', tree.find('./driver').get('type'))
         self.assertEqual('native', tree.find('./driver').get('io'))
 
+    def test_libvirt_nfs_driver_get_config_default_aio_mode(self):
+        self.flags(use_default_aio_mode_for_volumes=True, group='libvirt')
+
+        libvirt_driver = nfs.LibvirtNFSVolumeDriver(self.fake_host)
+        export_string = '192.168.1.1:/nfs/share1'
+        export_mnt_base = os.path.join(self.mnt_base,
+                                       utils.get_hash_str(export_string))
+        file_path = os.path.join(export_mnt_base, self.name)
+
+        connection_info = {'data': {'export': export_string,
+                                    'name': self.name,
+                                    'device_path': file_path}}
+        conf = libvirt_driver.get_config(connection_info, self.disk_info)
+        tree = conf.format_dom()
+        self._assertFileTypeEquals(tree, file_path)
+        self.assertEqual('raw', tree.find('./driver').get('type'))
+        self.assertIsNone(tree.find('./driver').get('io'))
+
     def test_libvirt_nfs_driver_with_opts(self):
         libvirt_driver = nfs.LibvirtNFSVolumeDriver(self.fake_host)
         export_string = '192.168.1.1:/nfs/share1'

nova/virt/libvirt/volume/fibrechannel.py

@@ -45,7 +45,8 @@ class LibvirtFibreChannelVolumeDriver(libvirt_volume.LibvirtBaseVolumeDriver):
 
         conf.source_type = "block"
         conf.source_path = connection_info['data']['device_path']
-        conf.driver_io = "native"
+        if not CONF.libvirt.use_default_aio_mode_for_volumes:
+            conf.driver_io = "native"
         return conf
 
     def connect_volume(self, connection_info, instance):

nova/virt/libvirt/volume/iscsi.py

@@ -55,7 +55,8 @@ class LibvirtISCSIVolumeDriver(libvirt_volume.LibvirtBaseVolumeDriver):
                      self).get_config(connection_info, disk_info)
         conf.source_type = "block"
         conf.source_path = connection_info['data']['device_path']
-        conf.driver_io = "native"
+        if not CONF.libvirt.use_default_aio_mode_for_volumes:
+            conf.driver_io = "native"
         return conf
 
     def connect_volume(self, connection_info, instance):

nova/virt/libvirt/volume/nfs.py

@@ -34,7 +34,8 @@ class LibvirtNFSVolumeDriver(fs.LibvirtMountedFileSystemVolumeDriver):
         conf.source_type = 'file'
         conf.source_path = connection_info['data']['device_path']
         conf.driver_format = connection_info['data'].get('format', 'raw')
-        conf.driver_io = "native"
+        if not CONF.libvirt.use_default_aio_mode_for_volumes:
+            conf.driver_io = "native"
         return conf
 
     def _mount_options(self, connection_info):

releasenotes/notes/config-default-aio-mode-for-volumes-7c8bcf1ebf01fbd5.yaml

@@ -0,0 +1,10 @@
+features:
+  - |
+    A new configuration option ``[libvirt]use_default_aio_mode_for_volumes``
+    has been added to enable use of QEMU default AIO modes for NFS, FC, and
+    iSCSI Cinder volumes.
+    By default, Nova explicitly sets AIO mode ``io=native`` in the Libvirt
+    guest XML for NFS, FC, and iSCSI Cinder volumes. Operators may set this
+    option to ``True`` in order to defer AIO mode selection to QEMU if forcing
+    ``io=native`` is not desired.
+