fix(cbt): implement recursive CBT deactivation

- Recursive CBT disabling on VDI all child snapshots
- Delete CBT log files when present

This resolves issues where CBT deactivation was incomplete
when processing multi-level snapshot chains.

Fixes: incomplete CBT deactivation on snapshot chains
Signed-off-by: Goulven Riou <goulven.riou@vates.tech>

Author: Lankou66

drivers/VDI.py

@@ -576,6 +576,20 @@ def in_sync_with_xenapi_record(self, x):
             return False
         return True
 
+    def _list_vdi_snapshots(self, vdi_uuid):
+        """List UUIDs of all direct snapshots of a VDI"""
+        try:
+            vdi_ref = self.session.xenapi.VDI.get_by_uuid(vdi_uuid)
+            record = self.session.xenapi.VDI.get_record(vdi_ref)
+            return [
+                self.session.xenapi.VDI.get_uuid(ref)
+                for ref in record.get("snapshots", [])
+                if self.session.xenapi.VDI.get_uuid(ref)
+            ]
+        except Exception as error:
+            util.SMlog("Error listing snapshots for VDI %s : %s" % (vdi_ref, error))
+            return []
+
     def configure_blocktracking(self, sr_uuid, vdi_uuid, enable):
         """Function for configuring blocktracking"""
         import blktap2
@@ -616,29 +630,50 @@ def configure_blocktracking(self, sr_uuid, vdi_uuid, enable):
                     self._delete_cbt_log()
                     raise xs_errors.XenError('CBTActivateFailed',
                                              opterr=str(error))
+
             else:
-                from lock import Lock
-                lock = Lock("cbtlog", str(vdi_uuid))
-                lock.acquire()
-                try:
-                    # Find parent of leaf metadata file, if any,
-                    # and nullify its successor
-                    logpath = self._get_cbt_logpath(self.uuid)
-                    parent = self._cbt_op(self.uuid,
-                                          cbtutil.get_cbt_parent, logpath)
-                    self._delete_cbt_log()
-                    parent_path = self._get_cbt_logpath(parent)
-                    if self._cbt_log_exists(parent_path):
-                        self._cbt_op(parent, cbtutil.set_cbt_child,
-                                     parent_path, uuid.UUID(int=0))
-                except Exception as error:
-                    raise xs_errors.XenError('CBTDeactivateFailed', str(error))
-                finally:
-                    lock.release()
-                    lock.cleanup("cbtlog", str(vdi_uuid))
+                self._disable_cbt(vdi_uuid)
+
         finally:
             blktap2.VDI.tap_unpause(self.session, sr_uuid, vdi_uuid)
 
+    def _disable_cbt(self, vdi_uuid, visited=None):
+        # Prevent infite loop
+        if visited is None:
+            visited = set()
+        if vdi_uuid in visited:
+            return
+        visited.add(vdi_uuid)
+
+        from lock import Lock
+        lock = Lock("cbtlog", str(vdi_uuid))
+        lock.acquire()
+        try:
+            self.uuid = vdi_uuid
+            vdi_ref = self.session.xenapi.VDI.get_by_uuid(self.uuid)
+            vdi_record = self.session.xenapi.VDI.get_record(vdi_ref)
+            logpath = self._get_cbt_logpath(self.uuid)
+            if self._cbt_log_exists(logpath):
+                parent = self._cbt_op(self.uuid, cbtutil.get_cbt_parent, logpath)
+                self._delete_cbt_log()
+                # Find parent of leaf metadata file, if any,
+                # and nullify its successor
+                parent_path = self._get_cbt_logpath(parent)
+                if self._cbt_log_exists(parent_path):
+                    self._cbt_op(parent, cbtutil.set_cbt_child, parent_path, uuid.UUID(int=0))
+                self.session.xenapi.VDI.set_cbt_enabled(vdi_ref, False)
+            for snapshot_ref in self._list_vdi_snapshots(self.uuid):
+                snap_ref = self.session.xenapi.VDI.get_by_uuid(snapshot_ref)
+                snapshot_uuid = self.session.xenapi.VDI.get_uuid(snap_ref)
+                self._disable_cbt(snapshot_uuid, visited)
+
+        except Exception as error:
+            util.SMlog(f"Error disabling CBT for VDI {self.uuid}: {error}")
+            raise xs_errors.XenError('CBTDeactivateFailed', str(error))
+        finally:
+            lock.release()
+            lock.cleanup("cbtlog", str(vdi_uuid))
+
     def data_destroy(self, sr_uuid, vdi_uuid):
         """Delete the data associated with a CBT enabled snapshot