User mode linux block devices start with ubd, e.g. ubda, ubdb, etc..
ACTION=="remove", GOTO="persistent_storage_end"
SUBSYSTEM!="block", GOTO="persistent_storage_end"
-KERNEL!="loop*|mmcblk*[0-9]|msblk*[0-9]|mspblk*[0-9]|nvme*|sd*|sr*|vd*|xvd*|bcache*|cciss*|dasd*", GOTO="persistent_storage_end"
+KERNEL!="loop*|mmcblk*[0-9]|msblk*[0-9]|mspblk*[0-9]|nvme*|sd*|sr*|vd*|xvd*|bcache*|cciss*|dasd*|ubd*", GOTO="persistent_storage_end"
# ignore partitions that span the entire disk
TEST=="whole_disk", GOTO="persistent_storage_end"