zfs/udev/rules.d/60-zvol.rules.in - backupdr - Git at Google

 # Persistent links for zvol
 #
 # persistent disk links: /dev/zvol/dataset_name
 # also creates compatibility symlink of /dev/dataset_name

 KERNEL=="zd*" SUBSYSTEM=="block" ACTION=="add|change" PROGRAM="@udevdir@/zvol_id $tempnode" SYMLINK+="zvol/%c %c"
	# Persistent links for zvol
	#
	# persistent disk links: /dev/zvol/dataset_name
	# also creates compatibility symlink of /dev/dataset_name

	KERNEL=="zd*" SUBSYSTEM=="block" ACTION=="add\|change" PROGRAM="@udevdir@/zvol_id $tempnode" SYMLINK+="zvol/%c %c"