ERROR: /packages/ufs-file-system: Last Trap: Division by Zero

I've seen this a few times now, where I have applied the latest Recommended Patchset and get the following error on reboot:

 Boot device: /pci@0/pci@0/pci@2/scsi@0/disk@0,0:a  File and args: -v -mverbose
 -
 ERROR: /packages/ufs-file-system: Last Trap: Division by Zero
 
 {0} ok

You'll probably also see this beforehand, when you reboot the server after the patching:

  [root@biggus]$ reboot
  Jun 11 11:09:18 biggus reboot: rebooted by root
  updating /platform/sun4v/boot_archive
  Jun 11 11:09:51 biggus unix: /kernel/sys/sparcv9/kaio: undefined symbol
  Jun 11 11:09:51 biggus unix:  'aio_copyout_result_common'
  Jun 11 11:09:51 biggus unix: WARNING: mod_load: cannot load module 'kaio'
  Jun 11 11:09:51 biggus unix: /kernel/sys/sparcv9/kaio: undefined symbol
  Jun 11 11:09:51 biggus unix:  'aio_copyout_result_common'
  Jun 11 11:09:51 biggus unix: WARNING: mod_load: cannot load module 'kaio'
  Jun 11 11:09:52 biggus ufs: NOTICE: mount: not a UFS magic number (0xffffffff)

Before panic sets in, you need to do the following:

1. Boot the server off a CDROM or network

2. Exit out of the installer so you get a basic command shell

3. Re-install the boot block on the boot disk

  installboot /usr/platform/`uname -i`/lib/fs/ufs/bootblk /dev/rdsk/c1t0d0s0

4. Update the boot archive.

  mount -F ufs /dev/dsk/c1t0d0s0 /a
  bootadm update-archive -R /a

5. Reboot.