Incorrect handling of child datasets of delegated dataset of a zone

[YanChii]

Reported by @matthewdunlap

The Snapshots and Backups are both configured for Disk 2, the Delegated ZFS Dataset.

Here is an example from a fresh SunOS Zone (OS Type 5):

[root@test02 ~]# zfs create zones/4a4d6877-971d-470e-ac62-31f301a95e65/data/child

Then the following operations:

• Snapshot Disk 2
• Backup Disk 2
• Migrate Compute Node

[root@test02 ~]# zfs list -t all -o name
NAME
zones
zones/4a4d6877-971d-470e-ac62-31f301a95e65
zones/4a4d6877-971d-470e-ac62-31f301a95e65/data
zones/4a4d6877-971d-470e-ac62-31f301a95e65/data@is-239
zones/4a4d6877-971d-470e-ac62-31f301a95e65/data@as-3436
zones/4a4d6877-971d-470e-ac62-31f301a95e65/data/child
zones/4a4d6877-971d-470e-ac62-31f301a95e65/data/child@esmigrate-1-1608683509648742102
zones/4a4d6877-971d-470e-ac62-31f301a95e65/data/child@esmigrate-2-1608683510839673052
zones/4a4d6877-971d-470e-ac62-31f301a95e65/data/child@esmigrate-3-1608683530575536200

Notice that child has no snapshot from scheduled snapshot or backup, and that it has leftover snapshots from the Compute Node Migration that were removed from the parent datasets.

I've only used 4.2 and 4.4, and the before is the same with both.