Add thin provisioning support checks.

Add a simple check to verify thin provisioning is supported
in the systems current LVM2 version.

Also add a helper to create thin pools.

Change-Id: I1ae3c168b148029a3085be827209f59bc68ca145

cinder/brick/local_dev/lvm.py

@@ -120,6 +120,28 @@ class LVM(object):
         else:
             return []
 
+    @staticmethod
+    def supports_thin_provisioning():
+        """Static method to check for thin LVM support on a system.
+
+        :returns: True if supported, False otherwise
+
+        """
+        cmd = ['vgs', '--version']
+        (out, err) = putils.execute(*cmd, root_helper='sudo', run_as_root=True)
+        lines = out.split('\n')
+
+        for line in lines:
+            if 'LVM version' in line:
+                version_list = line.split()
+                version = version_list[2]
+                if '(2)' in version:
+                    version = version.replace('(2)', '')
+                version_tuple = tuple(map(int, version.split('.')))
+                if version_tuple >= (2, 2, 95):
+                    return True
+        return False
+
     @staticmethod
     def get_all_volumes(vg_name=None):
         """Static method to get all LV's on a system.
@@ -250,6 +272,29 @@ class LVM(object):
 
         return vg_list[0]
 
+    def create_thin_pool(self, name=None, size_str=0):
+        """Creates a thin provisioning pool for this VG.
+
+        :param name: Name to use for pool, default is "<vg-name>-pool"
+        :param size_str: Size to allocate for pool, default is entire VG
+
+        """
+
+        if not self.supports_thin_provisioning():
+            LOG.error(_('Requested to setup thin provisioning, '
+                        'however current LVM version does not '
+                        'support it.'))
+            return None
+
+        if name is None:
+            name = '%s-pool' % self.vg_name
+
+        if size_str == 0:
+            self.update_volume_group_info()
+            size_str = self.vg_size
+
+        self.create_volume(name, size_str, 'thin')
+
     def create_volume(self, name, size_str, lv_type='default', mirror_count=0):
         """Creates a logical volume on the object's VG.
 

cinder/tests/brick/test_brick_lvm.py

@@ -46,12 +46,20 @@ class BrickLvmTestCase(test.TestCase):
     def failed_fake_execute(obj, *cmd, **kwargs):
         return ("\n", "fake-error")
 
+    def fake_pretend_lvm_version(obj, *cmd, **kwargs):
+        return ("  LVM version:     2.03.00 (2012-03-06)\n", "")
+
+    def fake_old_lvm_version(obj, *cmd, **kwargs):
+        return ("  LVM version:     2.02.65(2) (2012-03-06)\n", "")
+
     def fake_execute(obj, *cmd, **kwargs):
         cmd_string = ', '.join(cmd)
         data = "\n"
 
         if 'vgs, --noheadings, -o, name' == cmd_string:
             data = "  fake-volumes\n"
+        if 'vgs, --version' in cmd_string:
+            data = "  LVM version:     2.02.95(2) (2012-03-06)\n"
         elif 'vgs, --noheadings, -o uuid, fake-volumes' in cmd_string:
             data = "  kVxztV-dKpG-Rz7E-xtKY-jeju-QsYU-SLG6Z1\n"
         elif 'vgs, --noheadings, -o, name,size,free,lv_count,uuid' in\
@@ -124,3 +132,13 @@ class BrickLvmTestCase(test.TestCase):
         self.stubs.Set(processutils, 'execute', self.fake_execute)
         self.assertEqual(self.vg.update_volume_group_info()['name'],
                          'fake-volumes')
+
+    def test_thin_support(self):
+        self.stubs.Set(processutils, 'execute', self.fake_execute)
+        self.assertTrue(self.vg.supports_thin_provisioning())
+
+        self.stubs.Set(processutils, 'execute', self.fake_pretend_lvm_version)
+        self.assertTrue(self.vg.supports_thin_provisioning())
+
+        self.stubs.Set(processutils, 'execute', self.fake_old_lvm_version)
+        self.assertFalse(self.vg.supports_thin_provisioning())