"ipdata.meta.pfs_type & HAMMER2_PFSTYPE_SUPROOT" happened to have
the same result (except HAMMER2_PFSTYPE_DUMMY could also match).
Obtained from: Dragonfly (git 29e6489bbd4f8e237c9c17b300ac8b711f36770)
This is based on DragonFly's implementation from about 2019-09-13. It
only contains the basic code and header information to identify the
disks.
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D13369