core-admin/misc/qubes_block.rules

# Expose all (except xen-frontend) block devices via xenstore

# Only block devices are interesting
SUBSYSTEM!="block", GOTO="qubes_block_end"

# Skip xen-blkfront devices
ENV{MAJOR}=="202", GOTO="qubes_block_end"

# Skip device-mapper devices
ENV{MAJOR}=="253", GOTO="qubes_block_end"

ACTION=="add", IMPORT{program}="/usr/lib/qubes/block_add_change"
ACTION=="change", IMPORT{program}="/usr/lib/qubes/block_add_change"
ACTION=="remove", RUN+="/usr/lib/qubes/block_remove"

LABEL="qubes_block_end"

# Cleanup disconnected frontend from xenstore
ACTION=="remove", SUBSYSTEM=="block", ENV{MAJOR}=="202", RUN+="/usr/lib/qubes/block_cleanup"