[PVE-User] Storage migration failed

[Lex Rivera]

Sometimes while migrating VM from one storage to another (typical
scenario is LVM on top of iSCSI -> LVM on top of iSCSI) i got this error
right after copying disk image:
---
  device-mapper: remove ioctl on  failed: Device or resource busy
 Logical volume "vm-146-disk-1" successfully removed
  device-mapper: remove ioctl on  failed: Device or resource busy
TASK ERROR: storage migration failed: mirroring error: VM 146 qmp
command 'block-job-complete' failed - The active block job for device
'drive-ide0' cannot be completed
---
Restart usually helps, but it's pretty annoying when you wait ~hr for
some big VM to migrate and then after copy it throws this error and
undo(?) all changes. Well at least it's not wiping original disk...
Any ideas how to fix / prevent this?