openstack
/
nova
Code Issues Proposed changes

Hyper-V: fix image handling when shared storage is being used 

The image cache operation uses thread locks, for which reason it is
prone to race conditions when using shared storage. This is avoided
by using file locks, placed on the shared path.

Change-Id: I2b002993b7ab0973960794bfdd81d4fe57bf7399
Closes-Bug: #1565895
This commit is contained in:
Lucian Petrut 2016-06-16 11:41:20 +03:00
parent b88677c2d1
commit 8c40c4268b
2 changed files with 27 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
nova/tests/unit/virt/hyperv/test_imagecache.py
View File

@ -242,6 +242,13 @@ class ImageCacheTestCase(test_base.HyperVBaseTestCase):
self.imagecache._pathutils.get_age_of_file.assert_has_calls(calls)
mock_get_backing_files.assert_called_once_with(mock.sentinel.image)
def test_remove_old_image(self):
fake_img_path = os.path.join(self.FAKE_BASE_DIR,
self.FAKE_IMAGE_REF)
self.imagecache._remove_old_image(fake_img_path)
self.imagecache._pathutils.remove.assert_called_once_with(
fake_img_path)
@mock.patch.object(imagecache.ImageCache, '_age_and_verify_cached_images')
@mock.patch.object(imagecache.ImageCache, '_list_base_images')
@mock.patch.object(imagecache.ImageCache, '_list_running_instances')

37
nova/virt/hyperv/imagecache.py
View File

@ -37,17 +37,6 @@ LOG = logging.getLogger(__name__)
CONF = nova.conf.CONF
def synchronize_with_path(f):
def wrapper(self, image_path):
@utils.synchronized(image_path)
def inner():
return f(self, image_path)
return inner()
return wrapper
class ImageCache(imagecache.ImageCacheManager):
def __init__(self):
super(ImageCache, self).__init__()
@ -79,7 +68,11 @@ class ImageCache(imagecache.ImageCacheManager):
root_vhd_size_gb,
path_parts[1])
@utils.synchronized(resized_vhd_path)
lock_path = os.path.dirname(resized_vhd_path)
lock_name = "%s-cache.lock" % os.path.basename(resized_vhd_path)
@utils.synchronized(name=lock_name, external=True,
lock_path=lock_path)
def copy_and_resize_vhd():
if not self._pathutils.exists(resized_vhd_path):
try:
@ -109,7 +102,10 @@ class ImageCache(imagecache.ImageCacheManager):
base_vhd_dir = self._pathutils.get_base_vhd_dir()
base_vhd_path = os.path.join(base_vhd_dir, image_id)
@utils.synchronized(base_vhd_path)
lock_name = "%s-cache.lock" % image_id
@utils.synchronized(name=lock_name, external=True,
lock_path=base_vhd_dir)
def fetch_image_if_not_existing():
vhd_path = None
for format_ext in ['vhd', 'vhdx']:
@ -206,11 +202,18 @@ class ImageCache(imagecache.ImageCacheManager):
age_seconds = self._pathutils.get_age_of_file(img)
if age_seconds > max_age_seconds:
LOG.info(_LI("Removing old, unused image: %s"), img)
self.remove_old_image(img)
self._remove_old_image(img)
@synchronize_with_path
def remove_old_image(self, img):
self._pathutils.remove(img)
def _remove_old_image(self, image_path):
lock_path = os.path.dirname(image_path)
lock_name = "%s-cache.lock" % os.path.basename(image_path)
@utils.synchronized(name=lock_name, external=True,
lock_path=lock_path)
def _image_synchronized_remove():
self._pathutils.remove(image_path)
_image_synchronized_remove()
def update(self, context, all_instances):
base_vhd_dir = self._pathutils.get_base_vhd_dir()