CA-324971: lock LVM commands to avoid concurrency clashes

Signed-off-by: Mark Syms <mark.syms@citrix.com>

Author: MarkSymsCtx

drivers/lvutil.py

@@ -24,6 +24,7 @@
 import errno
 import time
 
+import lock
 import util
 import xs_errors
 import xml.dom.minidom
@@ -69,8 +70,9 @@
 LV_COMMANDS = frozenset({CMD_LVS, CMD_LVDISPLAY, CMD_LVCREATE, CMD_LVREMOVE,
                          CMD_LVCHANGE, CMD_LVRENAME, CMD_LVRESIZE,
                          CMD_LVEXTEND})
+DM_COMMANDS = frozenset({CMD_DMSETUP})
 
-LVM_COMMANDS = VG_COMMANDS.union(PV_COMMANDS, LV_COMMANDS)
+LVM_COMMANDS = VG_COMMANDS.union(PV_COMMANDS, LV_COMMANDS, DM_COMMANDS)
 
 def extract_vgname(str_in):
     """Search for and return a VG name
@@ -108,6 +110,16 @@ def extract_vgname(str_in):
 
     return None
 
+
+def get_lvm_lock():
+    """
+    Open and acquire a system wide lock to wrap LVM calls
+    :return: the created lock
+    """
+    new_lock = lock.Lock('lvm')
+    new_lock.acquire()
+    return new_lock
+
 def cmd_lvm(cmd, pread_func=util.pread2, *args):
     """ Construct and run the appropriate lvm command.
 
@@ -150,9 +162,14 @@ def cmd_lvm(cmd, pread_func=util.pread2, *args):
             util.SMlog("CMD_LVM: Not all lvm arguments are of type 'str'")
             return None
 
-    start_time = time.time()
-    stdout = pread_func([os.path.join(LVM_BIN, lvm_cmd)] + lvm_args, *args)
-    end_time = time.time()
+    lvm_lock = get_lvm_lock()
+
+    try:
+        start_time = time.time()
+        stdout = pread_func([os.path.join(LVM_BIN, lvm_cmd)] + lvm_args, *args)
+        end_time = time.time()
+    finally:
+        lvm_lock.release()
 
     if (end_time - start_time > MAX_OPERATION_DURATION):
         util.SMlog("***** Long LVM call of '%s' took %s" % (lvm_cmd, (end_time - start_time)))
@@ -705,7 +722,7 @@ def removeDevMapperEntry(path, strict=True):
     try:
         # remove devmapper entry using dmsetup
         cmd = [CMD_DMSETUP, "remove", path]
-        util.pread2(cmd)
+        cmd_lvm(cmd)
         return True
     except Exception, e:
         if not strict:

tests/test_lvutil.py

@@ -21,6 +21,11 @@ def decorated(self, context, *args, **kwargs):
 
 
 class TestCreate(unittest.TestCase):
+    def setUp(self):
+        lock_patcher = mock.patch('lvutil.lock', autospec=True)
+        self.addCleanup(lock_patcher.stop)
+        self.mock_lock = lock_patcher.start()
+
     @with_lvm_subsystem
     def test_create_volume_size(self, lvsystem):
         lvsystem.add_volume_group('VG_XenStorage-b3b18d06-b2ba-5b67-f098-3cdd5087a2a7')
@@ -88,6 +93,11 @@ def test_create_percentage_has_precedence_over_size(self, mock_pread):
         self.assertIn("10%F", mock_pread.call_args[0][0])
 
 class TestRemove(unittest.TestCase):
+    def setUp(self):
+        lock_patcher = mock.patch('lvutil.lock', autospec=True)
+        self.addCleanup(lock_patcher.stop)
+        self.mock_lock = lock_patcher.start()
+
     @with_lvm_subsystem
     def test_remove_removes_volume(self, lvsystem):
         lvsystem.add_volume_group('VG_XenStorage-b3b18d06-b2ba-5b67-f098-3cdd5087a2a7')