Avoiding bad sectors?

Hi all,

I have a disk which has just developed a bad sector in the middle of 
swap space.  I'm seeing occasional:

  swap_pager: I/O error - pagein failed; blkno 38626,size 32768, error 5

errors in the logs, and whichever application happens to have a page 
there is killed.  The 'blkno' value is always the same.

I realise that I need to replace the disk.  However, while I'm waiting 
until I can schedule the downtime, is there a short term solution I can 
use to stop FreeBSD (I'm running current from a couple of months ago) 
from trying to use this block?

N