incorrect super block w recent changes

[mlh%goathill.org@localhost (MLH)]

With the recent changes (yesterday and today) that allow current
to boot again, I can't mount some drives:

NetBSD 7.99.13 (GENERIC) #2: Mon Apr 27 14:11:26 EDT 2015

wd0 at atabus3 drive 0
wd0: <ST1000DM003-1ER162>
wd0: drive supports 16-sector PIO transfers, LBA48 addressing
wd0: 931 GB, 1938021 cyl, 16 head, 63 sec, 512 bytes/sect x 1953525168 sectors
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
wd0(ahcisata1:0:0): using PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133) (using DMA)
wd1 at atabus4 drive 0
wd1: <ST500DM002-1BC142>
wd1: drive supports 16-sector PIO transfers, LBA48 addressing
wd1: 465 GB, 969021 cyl, 16 head, 63 sec, 512 bytes/sect x 976773168 sectors
wd1: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
wd1(ahcisata1:1:0): using PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133) (using DMA)

mount_ffs: /dev/wd1f on /opt2: incorrect super block

fsck can't find anything wrong with the drive and it doesn't appear
there is. Earlier kernels have no trouble mounting this drive.

Also, shutdown hangs now and never completes.