feat(linstor): add counter to GC volume deletion prefix

When a snapshot operation has failed, a rollback operation takes place
which marks the new leaf volume (which took the UUID of the volume being
snapshotted) for deletion, and updates the UUID of the volume being
snapshotted back to its original UUID.

The reason for the snapshot having failed may last for quite some time,
and the GC may not be able to actually destroy the volumes that are
marked for deletion.

If such a scenario occurs, further snapshot attempts will also fail, but
the rollback operation will also fail because a volume with the UUID of
the volume to snapshot was already marked for deletion by the first
snapshot attempt.

This fixes the issue by introducing a counter to the prefix of volume
UUIDs that are marked for deletion, therefore allowing multiple of them
co-existing until the underlying storage issues are fixed.

Signed-off-by: Alexandre Sollier <alexandre.sollier@vates.tech>

Author: Kuruyia

drivers/linstorvolumemanager.py

@@ -244,7 +244,8 @@ class LinstorVolumeManagerError(Exception):
     ERR_VOLUME_NOT_EXISTS = 2,
     ERR_VOLUME_DESTROY = 3,
     ERR_GROUP_NOT_EXISTS = 4,
-    ERR_VOLUME_IN_USE = 5
+    ERR_VOLUME_IN_USE = 5,
+    ERR_VOLUME_PROPERTIES_NOT_EMPTY = 6
 
     def __init__(self, message, code=ERR_GENERIC):
         super(LinstorVolumeManagerError, self).__init__(message)
@@ -1072,7 +1073,8 @@ def update_volume_uuid(self, volume_uuid, new_volume_uuid, force=False):
             raise LinstorVolumeManagerError(
                 'Cannot update volume uuid {} to {}: '
                 .format(volume_uuid, new_volume_uuid) +
-                'this last one is not empty'
+                'this last one is not empty',
+                LinstorVolumeManagerError.ERR_VOLUME_PROPERTIES_NOT_EMPTY
             )
 
         try:
@@ -1156,9 +1158,23 @@ def mark_volume_for_deletion(self, volume_uuid, force=False):
         if volume_uuid.startswith(DELETED_PREFIX):
             return
 
-        self.update_volume_uuid(
-            volume_uuid, DELETED_PREFIX + volume_uuid, force=force
-        )
+        deleted_prefix_counter = 0
+        while True:
+            new_volume_uuid = '{}{}_{}'.format(
+                DELETED_PREFIX, deleted_prefix_counter, volume_uuid
+            )
+
+            try:
+                self.update_volume_uuid(
+                    volume_uuid, new_volume_uuid, force=force
+                )
+
+                break
+            except LinstorVolumeManagerError as e:
+                if e.code != LinstorVolumeManagerError.ERR_VOLUME_PROPERTIES_NOT_EMPTY:
+                    raise
+
+                deleted_prefix_counter += 1
 
     def update_volume_name(self, volume_uuid, volume_name):
         """