LVM: Activate source LV before cloning from it

LVM may be configured to not automatically activate
thin-provisioned LVs.

Ensure they are activated when performing a clone, otherwise
dd will fail as the device does not exist in /dev/mapper/.

Closes-Bug: #1252423

Change-Id: Ibcb946ffe7804b1976bf1b1863c48340c8cc7fd5

cinder/brick/local_dev/lvm.py

@@ -64,6 +64,7 @@ class LVM(executor.Executor):
         self.vg_uuid = None
         self.vg_thin_pool = None
         self.vg_thin_pool_size = 0
+        self._supports_lvchange_ignoreskipactivation = None
 
         if create_vg and physical_volumes is not None:
             self.pv_list = physical_volumes
@@ -146,6 +147,29 @@ class LVM(executor.Executor):
                     return True
         return False
 
+    @property
+    def supports_lvchange_ignoreskipactivation(self):
+        """Property indicating whether lvchange can ignore skip activation.
+
+        Tests whether lvchange -K/--ignoreactivationskip exists.
+        """
+
+        if self._supports_lvchange_ignoreskipactivation is not None:
+            return self._supports_lvchange_ignoreskipactivation
+
+        cmd = ['lvchange', '--help']
+        (out, err) = self._execute(*cmd)
+
+        self._supports_lvchange_ignoreskipactivation = False
+
+        lines = out.split('\n')
+        for line in lines:
+            if '-K' in line and '--ignoreactivationskip' in line:
+                self._supports_lvchange_ignoreskipactivation = True
+                break
+
+        return self._supports_lvchange_ignoreskipactivation
+
     @staticmethod
     def get_all_volumes(root_helper, vg_name=None, no_suffix=True):
         """Static method to get all LV's on a system.
@@ -404,6 +428,38 @@ class LVM(executor.Executor):
             LOG.error(_('StdErr  :%s') % err.stderr)
             raise
 
+    def _mangle_lv_name(self, name):
+        # Linux LVM reserves name that starts with snapshot, so that
+        # such volume name can't be created. Mangle it.
+        if not name.startswith('snapshot'):
+            return name
+        return '_' + name
+
+    def activate_lv(self, name):
+        """Ensure that logical volume/snapshot logical volume is activated.
+
+        :param name: Name of LV to activate
+        """
+        lv_path = self.vg_name + '/' + self._mangle_lv_name(name)
+
+        cmd = ['lvchange', '-a', 'y']
+
+        if self.supports_lvchange_ignoreskipactivation:
+            cmd.append('-K')
+
+        cmd.append(lv_path)
+
+        try:
+            self._execute(*cmd,
+                          root_helper=self._root_helper,
+                          run_as_root=True)
+        except putils.ProcessExecutionError as err:
+            LOG.exception(_('Error activating LV'))
+            LOG.error(_('Cmd     :%s') % err.cmd)
+            LOG.error(_('StdOut  :%s') % err.stdout)
+            LOG.error(_('StdErr  :%s') % err.stderr)
+            raise
+
     def delete(self, name):
         """Delete logical volume or snapshot.
 

cinder/tests/brick/test_brick_lvm.py

@@ -153,6 +153,48 @@ class BrickLvmTestCase(test.TestCase):
                        self.fake_customised_lvm_version)
         self.assertTrue(self.vg.supports_thin_provisioning('sudo'))
 
+    def test_lvchange_ignskipact_support_yes(self):
+        """Tests the ability to test support for lvchange -K
+
+        Stubs provide output for "lvchange --help".
+        """
+
+        def lvchange_ign_yes(obj, *args, **kwargs):
+            return ("""
+              WARNING: Running as a non-root user. Functionality may be
+              unavailable.
+              lvchange: Change the attributes of logical volume(s)
+
+            lvchange
+                [-A|--autobackup y|n]
+                [-k|--setactivationskip {y|n}]
+                [-K|--ignoreactivationskip]
+                [-y|--yes]
+                [-Z|--zero {y|n}]
+                LogicalVolume[Path] [LogicalVolume[Path]...]
+            """, "")
+
+        self.stubs.Set(self.vg, '_execute', lvchange_ign_yes)
+        self.assertTrue(self.vg.supports_lvchange_ignoreskipactivation)
+
+    def test_lvchange_ignskipact_support_no(self):
+        def lvchange_ign_no(obj, *args, **kwargs):
+            return ("""
+              WARNING: Running as a non-root user. Functionality may be
+              unavailable.
+              lvchange: Change the attributes of logical volume(s)
+
+            lvchange
+                [-A|--autobackup y|n]
+                [-k|--setactivationskip {y|n}]
+                [-y|--yes]
+                [-Z|--zero {y|n}]
+                LogicalVolume[Path] [LogicalVolume[Path]...]
+            """, "")
+
+        self.stubs.Set(self.vg, '_execute', lvchange_ign_no)
+        self.assertFalse(self.vg.supports_lvchange_ignoreskipactivation)
+
     def test_volume_create_after_thin_creation(self):
         """Test self.vg.vg_thin_pool is set to pool_name
 
@@ -175,3 +217,16 @@ class BrickLvmTestCase(test.TestCase):
     def test_lv_has_snapshot(self):
         self.assertTrue(self.vg.lv_has_snapshot('fake-volumes'))
         self.assertFalse(self.vg.lv_has_snapshot('test-volumes'))
+
+    def test_activate_lv(self):
+        self._mox.StubOutWithMock(self.vg, '_execute')
+        self.vg._supports_lvchange_ignoreskipactivation = True
+
+        self.vg._execute('lvchange', '-a', 'y', '-K', 'fake-volumes/my-lv',
+                         root_helper='sudo', run_as_root=True)
+
+        self._mox.ReplayAll()
+
+        self.vg.activate_lv('my-lv')
+
+        self._mox.VerifyAll()

cinder/volume/drivers/lvm.py

@@ -166,6 +166,10 @@ class LVMVolumeDriver(driver.VolumeDriver):
                             self.configuration.lvm_type,
                             self.configuration.lvm_mirrors)
 
+        # Some configurations of LVM do not automatically activate
+        # ThinLVM snapshot LVs.
+        self.vg.activate_lv(snapshot['name'])
+
         volutils.copy_volume(self.local_path(snapshot),
                              self.local_path(volume),
                              snapshot['volume_size'] * 1024,

etc/cinder/rootwrap.d/volume.filters

@@ -30,6 +30,9 @@ lvrename: CommandFilter, lvrename, root
 # cinder/volume/driver.py: 'lvextend', '-L' '%(new_size)s', '%(lv_name)s' ...
 lvextend: CommandFilter, lvextend, root
 
+# cinder/brick/local_dev/lvm.py: 'lvchange -a y -K <lv>'
+lvchange: CommandFilter, lvchange, root
+
 # cinder/volume/driver.py: 'iscsiadm', '-m', 'discovery', '-t',...
 # cinder/volume/driver.py: 'iscsiadm', '-m', 'node', '-T', ...
 iscsiadm: CommandFilter, iscsiadm, root