superblock is invalid, fsck looks at the label to help guess where
the next superblock should be. If the partition type is 4.2BSD,
fsck assumed that the block size was valid and divided by it, so
it dumped core if the size was 0.
Initialization of the label was broken almost 3 years ago in rev.1.9
of newfs/newfs.c. Newfs does not change the label at all, so there
is no problem (except the breakage of the automatic search for
backup superblocks) unless something else sets the partition type
to 4.2BSD. However, it is too easy to set partition types to
4.2.BSD by copying an old label or by using a disktab entry to
create the label.
PR: 2537
something closer to how we used to do it. The Lite2 way is to check the
"fsclean" flag in the superblock and stop there if so (during preen).
We now do the various superblock sanity checks that we used to do before
since it's cheap. We now get the filesystem state summary again instead
of "FILESYSTEM CLEAN; CHECKING SKIPPED" (or whatever).
