zfs-release(8) manual page

zfs hold [-r] tag snapshotâ¦ Adds a single reference, named with the tag argument, to the specified snapshots. Each snapshot has its own tag namespace, and tags must be unique within that space. If a hold exists on a snapshot, attempts to destroy that snapshot by using the zfs command return EBUSY.
-r
	Specifies that a hold with the given tag is applied recursively to the snapshots of all descendent file systems.

zfs holds [-rH] snapshotâ¦ Lists all existing user references for the given snapshot or snapshots.
-r
	Lists the holds that are set on the named descendent snapshots, in addition to listing the holds on the named snapshot.
-H
	Do not print headers, use tab-delimited output.

zfs release [-r] tag snapshotâ¦ Removes a single reference, named with the tag argument, from the specified snapshot or snapshots. The tag must already exist for each snapshot. If a hold exists on a snapshot, attempts to destroy that snapshot by using the zfs command return EBUSY.
-r
	Recursively releases a hold with the given tag on the snapshots of all descendent file systems.

Manual Pages — ZFS-HOLD