Add util for disk type retrieval

blueprint snapshots-for-everyone

Add libvirt.utils.get_disk_type that retrieves format
for given file. Format can be raw, qcow2, or lvm.

Change-Id: I33898983cfa15db6b2654648ce32f72b6dd920cb

4 files changed, 18 insertions, 12 deletions

diff --git a/nova/tests/fake_libvirt_utils.py b/nova/tests/fake_libvirt_utils.py
index 378515ac0..1862521c1 100644
--- a/nova/tests/fake_libvirt_utils.py
+++ b/nova/tests/fake_libvirt_utils.py
@@ -21,6 +21,7 @@ import StringIO
 files = {}
 disk_sizes = {}
 disk_backing_files = {}
+disk_type = "qcow2"
 
 
 def get_iscsi_initiator():
@@ -39,6 +40,10 @@ def get_disk_backing_file(path):
     return disk_backing_files.get(path, None)
 
 
+def get_disk_type(path):
+    return disk_type
+
+
 def copy_image(src, dest):
     pass
 
diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index 91cf8df7c..523761454 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -1162,6 +1162,7 @@ class LibvirtConnTestCase(test.TestCase):
         libvirt_driver.LibvirtDriver._conn.lookupByName = self.fake_lookup
         self.mox.StubOutWithMock(libvirt_driver.utils, 'execute')
         libvirt_driver.utils.execute = self.fake_execute
+        self.stubs.Set(libvirt_driver.libvirt_utils, 'disk_type', 'raw')
 
         self.mox.ReplayAll()
 
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 78b02633f..50227ae6d 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -808,16 +808,11 @@ class LibvirtDriver(driver.ComputeDriver):
             arch = base['properties']['architecture']
             metadata['properties']['architecture'] = arch
 
-        source_format = base.get('disk_format') or 'raw'
-        if source_format == 'ami':
-            # NOTE(vish): assume amis are raw
-            source_format = 'raw'
+        disk_path = libvirt_utils.find_disk(virt_dom)
+        source_format = libvirt_utils.get_disk_type(disk_path)
+
         image_format = FLAGS.snapshot_image_format or source_format
-        use_qcow2 = ((FLAGS.libvirt_images_type == 'default' and
-                FLAGS.use_cow_images) or
-                FLAGS.libvirt_images_type == 'qcow2')
-        if use_qcow2:
-            source_format = 'qcow2'
+
         # NOTE(vish): glance forces ami disk format to be ami
         if base.get('disk_format') == 'ami':
             metadata['disk_format'] = 'ami'
@@ -826,9 +821,6 @@ class LibvirtDriver(driver.ComputeDriver):
 
         metadata['container_format'] = base.get('container_format', 'bare')
 
-        # Find the disk
-        disk_path = libvirt_utils.find_disk(virt_dom)
-
         snapshot_name = uuid.uuid4().hex
 
         (state, _max_mem, _mem, _cpus, _t) = virt_dom.info()
diff --git a/nova/virt/libvirt/utils.py b/nova/virt/libvirt/utils.py
index 73e0201df..2d1b5558c 100644
--- a/nova/virt/libvirt/utils.py
+++ b/nova/virt/libvirt/utils.py
@@ -411,6 +411,14 @@ def find_disk(virt_dom):
     return disk_path
 
 
+def get_disk_type(path):
+    """Retrieve disk type (raw, qcow2, lvm) for given file"""
+    if path.startswith('/dev'):
+        return 'lvm'
+
+    return images.qemu_img_info(path)['file format']
+
+
 def get_fs_info(path):
     """Get free/used/total space info for a filesystem