This patch teaches virt/libvirt how to format filesystem on ephemeral device depending on os_type so that the behaviour matches with EC2's.

Such behaviour isn't explicitly described in the documentation, but it is confirmed by checking realy EC2 instances.  This patch introduces options virt_mkfs as multistring.
Its format is --virt_mkfs=<os_type>=<mkfs command> When creating ephemeral device, format it according to the option depending on os_type.  This addresses the bugs,
https://bugs.launchpad.net/nova/+bug/827598
https://bugs.launchpad.net/nova/+bug/828357

2 files changed, 60 insertions, 2 deletions

diff --git a/nova/virt/disk.py b/nova/virt/disk.py
index cd3422829..9fe164cfb 100644
--- a/nova/virt/disk.py
+++ b/nova/virt/disk.py
@@ -52,6 +52,47 @@ flags.DEFINE_integer('timeout_nbd', 10,
 flags.DEFINE_integer('max_nbd_devices', 16,
                      'maximum number of possible nbd devices')
 
+# NOTE(yamahata): DEFINE_list() doesn't work because the command may
+#                 include ','. For example,
+#                 mkfs.ext3 -O dir_index,extent -E stride=8,stripe-width=16
+#                 --label %(fs_label)s %(target)s
+#
+#                 DEFINE_list() parses its argument by
+#                 [s.strip() for s in argument.split(self._token)]
+#                 where self._token = ','
+#                 No escape nor exceptional handling for ','.
+#                 DEFINE_list() doesn't give us what we need.
+flags.DEFINE_multistring('virt_mkfs',
+                         ['windows=mkfs.ntfs --fast --label %(fs_label)s '
+                          '%(target)s',
+                          # NOTE(yamahata): vfat case
+                          #'windows=mkfs.vfat -n %(fs_label)s %(target)s',
+                          'linux=mkfs.ext3 -L %(fs_label)s -F %(target)s',
+                          'default=mkfs.ext3 -L %(fs_label)s -F %(target)s'],
+                         'mkfs commands for ephemeral device. The format is'
+                         '<os_type>=<mkfs command>')
+
+
+_MKFS_COMMAND = {}
+_DEFAULT_MKFS_COMMAND = None
+
+
+for s in FLAGS.virt_mkfs:
+    # NOTE(yamahata): mkfs command may includes '=' for its options.
+    #                 So item.partition('=') doesn't work here
+    os_type, mkfs_command = s.split('=', 1)
+    if os_type:
+        _MKFS_COMMAND[os_type] = mkfs_command
+    if os_type == 'default':
+        _DEFAULT_MKFS_COMMAND = mkfs_command
+
+
+def mkfs(os_type, fs_label, target):
+    mkfs_command = (_MKFS_COMMAND.get(os_type, _DEFAULT_MKFS_COMMAND) or
+                    '') % locals()
+    if mkfs_command:
+        utils.execute(*mkfs_command.split())
+
 
 def extend(image, size):
     """Increase image to size"""
diff --git a/nova/virt/libvirt/connection.py b/nova/virt/libvirt/connection.py
index f591ce02c..f192079f4 100644
--- a/nova/virt/libvirt/connection.py
+++ b/nova/virt/libvirt/connection.py
@@ -38,6 +38,7 @@ Supports KVM, LXC, QEMU, UML, and XEN.
 """
 
 import hashlib
+import functools
 import multiprocessing
 import netaddr
 import os
@@ -778,6 +779,10 @@ class LibvirtConnection(driver.ComputeDriver):
         if fs_format:
             utils.execute('mkfs', '-t', fs_format, target)
 
+    def _create_ephemeral(self, target, local_size, fs_label, os_type):
+        self._create_local(target, local_size)
+        disk.mkfs(os_type, fs_label, target)
+
     def _create_swap(self, target, swap_gb):
         """Create a swap file of specified size"""
         self._create_local(target, swap_gb)
@@ -866,9 +871,13 @@ class LibvirtConnection(driver.ComputeDriver):
                               local_size=local_gb)
 
         for eph in driver.block_device_info_get_ephemerals(block_device_info):
-            self._cache_image(fn=self._create_local,
+            fn = functools.partial(self._create_ephemeral,
+                                   fs_label='ephemeral%d' % eph['num'],
+                                   os_type=inst.os_type)
+            self._cache_image(fn=fn,
                               target=basepath(_get_eph_disk(eph)),
-                              fname="local_%s" % eph['size'],
+                              fname="ephemeral_%s_%s_%s" %
+                              (eph['num'], eph['size'], inst.os_type),
                               cow=FLAGS.use_cow_images,
                               local_size=eph['size'])
 
@@ -1102,6 +1111,11 @@ class LibvirtConnection(driver.ComputeDriver):
                 nova_context.get_admin_context(), instance['id'],
                 {'root_device_name': '/dev/' + self.default_root_device})
 
+        if local_device:
+            db.instance_update(
+                nova_context.get_admin_context(), instance['id'],
+                {'default_local_device': '/dev/' + self.default_local_device})
+
         swap = driver.block_device_info_get_swap(block_device_info)
         if driver.swap_is_usable(swap):
             xml_info['swap_device'] = block_device.strip_dev(
@@ -1110,6 +1124,9 @@ class LibvirtConnection(driver.ComputeDriver):
               not self._volume_in_mapping(self.default_swap_device,
                                           block_device_info)):
             xml_info['swap_device'] = self.default_swap_device
+            db.instance_update(
+                nova_context.get_admin_context(), instance['id'],
+                {'default_swap_device': '/dev/' + self.default_swap_device})
 
         config_drive = False
         if instance.get('config_drive') or instance.get('config_drive_id'):