NetApp ONTAP: Set new sub-lun clone limit for ONTAP driver

Until ONTAP v8.3, the driver used to perform sub-lun clone of up to 64GB
per operation, but as of v9.1, ONTAP handles only 128MB per operation.
This new limit is causing error on volume extending operations, which
triggers sub-lun cloning when resizing exceeds max-resize-geometry.
For instance, if a volume is extended from 1GB to 64GB, the operation
fails because it triggers a single sub-lun cloning of 1GB.

This fix sets the limit used by sub-lun cloning to 128MB, therefore
if a volume is extended from 1GB to 64GB, it no longer fails, and
instead it will trigger 8 sub-lun cloning operations of 128MB.

Change-Id: Ib294cbdbdfe19d34a7702dafec2c8d29136a2f25
Closes-Bug: #1762424

cinder/tests/unit/volume/drivers/netapp/dataontap/client/test_client_cmode.py

@@ -733,9 +733,9 @@ class NetAppCmodeClientTestCase(test.TestCase):
     def test_clone_lun_multiple_zapi_calls(self):
         """Test for when lun clone requires more than one zapi call."""
 
-        # Max block-ranges per call = 32, max blocks per range = 2^24
+        # Max clone size per call = 2^18 blocks * 512 bytes/block = 128 MB
         # Force 2 calls
-        bc = 2 ** 24 * 32 * 2
+        bc = 2 ** 18 * 2
         self.client.clone_lun('volume', 'fakeLUN', 'newFakeLUN',
                               block_count=bc)
         self.assertEqual(2, self.connection.invoke_successfully.call_count)

cinder/volume/drivers/netapp/dataontap/client/client_cmode.py

@@ -452,19 +452,16 @@ class Client(client_base.Client):
     def clone_lun(self, volume, name, new_name, space_reserved='true',
                   qos_policy_group_name=None, src_block=0, dest_block=0,
                   block_count=0, source_snapshot=None, is_snapshot=False):
-        # zAPI can only handle 2^24 blocks per range
-        bc_limit = 2 ** 24  # 8GB
-        # zAPI can only handle 32 block ranges per call
-        br_limit = 32
-        z_limit = br_limit * bc_limit  # 256 GB
-        z_calls = int(math.ceil(block_count / float(z_limit)))
+        # ONTAP handles only 128 MB per call as of v9.1
+        bc_limit = 2 ** 18  # 2^18 blocks * 512 bytes/block = 128 MB
+        z_calls = int(math.ceil(block_count / float(bc_limit)))
         zbc = block_count
         if z_calls == 0:
             z_calls = 1
         for _call in range(0, z_calls):
-            if zbc > z_limit:
-                block_count = z_limit
-                zbc -= z_limit
+            if zbc > bc_limit:
+                block_count = bc_limit
+                zbc -= bc_limit
             else:
                 block_count = zbc
 

releasenotes/notes/bug-1762424-f76af2f37fe408f1.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    NetApp ONTAP (bug 1762424): Fix ONTAP NetApp driver not being able to extend
+    a volume to a size greater than the corresponding LUN max geometry.