Simplify how ephemeral disks are created and named.

Resolves bug 1087028.

Change-Id: Ife7ec43cf76cf04a98f1db2135f9149a2eefb55d

3 files changed, 26 insertions, 30 deletions

diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index 5df7d920d..872c0498d 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -2295,6 +2295,9 @@ class LibvirtConnTestCase(test.TestCase):
         self.stubs.Set(imagebackend.Image,
                        'cache',
                        fake_none)
+        self.stubs.Set(libvirt_driver.LibvirtDriver,
+                       '_create_ephemeral',
+                       fake_none)
 
         conn.spawn(self.context, instance, None, [], 'herp',
                        network_info=network_info)
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 750ffb0a2..b2a90e862 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -251,6 +251,8 @@ MIN_LIBVIRT_VERSION = (0, 9, 6)
 # delete it & corresponding code using it
 MIN_LIBVIRT_HOST_CPU_VERSION = (0, 9, 10)
 
+ONE_GIGABYTE = 1024 * 1024 * 1024
+
 
 def _get_eph_disk(ephemeral):
     return 'disk.eph' + str(ephemeral['num'])
@@ -1269,9 +1271,15 @@ class LibvirtDriver(driver.ComputeDriver):
         if fs_format:
             utils.mkfs(fs_format, target, label)
 
-    def _create_ephemeral(self, target, ephemeral_size, fs_label, os_type):
-        self._create_local(target, ephemeral_size)
-        disk.mkfs(os_type, fs_label, target)
+    def _create_ephemeral(self, instance, disk_name, size_in_gb, number):
+        fname = os.path.join(CONF.instances_path, instance['name'],
+                             disk_name)
+
+        LOG.info(_('Creating ephemeral disk named %(disk_name)s of size '
+                   '%(size_in_gb)s gb at %(fname)s'), locals(),
+                 instance=instance)
+        self._create_local(fname, size_in_gb)
+        disk.mkfs(instance['os_type'], 'ephemeral%d' % number, fname)
 
     @staticmethod
     def _create_swap(target, swap_mb):
@@ -1349,7 +1357,7 @@ class LibvirtDriver(driver.ComputeDriver):
                                      project_id=instance['project_id'])
 
         root_fname = hashlib.sha1(str(disk_images['image_id'])).hexdigest()
-        size = instance['root_gb'] * 1024 * 1024 * 1024
+        size = instance['root_gb'] * ONE_GIGABYTE
 
         inst_type = instance['instance_type']
         if size == 0 or suffix == '.rescue':
@@ -1365,36 +1373,19 @@ class LibvirtDriver(driver.ComputeDriver):
                                 user_id=instance['user_id'],
                                 project_id=instance['project_id'])
 
+        # NOTE(mikal): we don't go through imagebackend here, as ephemeral
+        # disks aren't cached in _base, they're new images each time
         ephemeral_gb = instance['ephemeral_gb']
         if ephemeral_gb and not self._volume_in_mapping(
                 self.default_second_device, block_device_info):
             swap_device = self.default_third_device
-            fn = functools.partial(self._create_ephemeral,
-                                   fs_label='ephemeral0',
-                                   os_type=instance["os_type"])
-            fname = "ephemeral_%s_%s_%s" % ("0",
-                                            ephemeral_gb,
-                                            instance["os_type"])
-            size = ephemeral_gb * 1024 * 1024 * 1024
-            image('disk.local').cache(fetch_func=fn,
-                                      filename=fname,
-                                      size=size,
-                                      ephemeral_size=ephemeral_gb)
+            self._create_ephemeral(instance, 'disk.local', ephemeral_gb, 0)
         else:
             swap_device = self.default_second_device
 
         for eph in driver.block_device_info_get_ephemerals(block_device_info):
-            fn = functools.partial(self._create_ephemeral,
-                                   fs_label='ephemeral%d' % eph['num'],
-                                   os_type=instance["os_type"])
-            size = eph['size'] * 1024 * 1024 * 1024
-            fname = "ephemeral_%s_%s_%s" % (eph['num'],
-                                            eph['size'],
-                                            instance["os_type"])
-            image(_get_eph_disk(eph)).cache(fetch_func=fn,
-                                            filename=fname,
-                                            size=size,
-                                            ephemeral_size=eph['size'])
+            self._create_ephemeral(instance, _get_eph_disk(eph), eph['size'],
+                                   eph['num'])
 
         swap_mb = 0
 
@@ -2935,7 +2926,7 @@ class LibvirtDriver(driver.ComputeDriver):
                 size = instance['ephemeral_gb']
             else:
                 size = 0
-            size *= 1024 * 1024 * 1024
+            size *= ONE_GIGABYTE
 
             # If we have a non partitioned image that we can extend
             # then ensure we're in 'raw' format so we can extend file system.
diff --git a/nova/virt/libvirt/imagebackend.py b/nova/virt/libvirt/imagebackend.py
index a77e9e74f..86502ee9e 100644
--- a/nova/virt/libvirt/imagebackend.py
+++ b/nova/virt/libvirt/imagebackend.py
@@ -49,6 +49,8 @@ CONF = cfg.CONF
 CONF.register_opts(__imagebackend_opts)
 CONF.import_opt('base_dir_name', 'nova.virt.libvirt.imagecache')
 
+ONE_GIGABYTE = 1024 * 1024 * 1024
+
 
 class Image(object):
     __metaclass__ = abc.ABCMeta
@@ -103,9 +105,9 @@ class Image(object):
         return info
 
     def cache(self, fetch_func, filename, size=None, *args, **kwargs):
-        """Creates image from template.
+        """Creates an image from a template.
 
-        Ensures that template and image not already exists.
+        Ensures that template and image do not already exist.
         Ensures that base directory exists.
         Synchronizes on template fetching.
 
@@ -179,7 +181,7 @@ class Qcow2(Image):
         def copy_qcow2_image(base, target, size):
             qcow2_base = base
             if size:
-                size_gb = size / (1024 * 1024 * 1024)
+                size_gb = size / (ONE_GIGABYTE)
                 qcow2_base += '_%d' % size_gb
                 if not os.path.exists(qcow2_base):
                     with utils.remove_path_on_error(qcow2_base):