make installworld fails

[Caleb Stein]

I am trying to update my FreeBSD 8.0 to FreeBSD 8.1.  Here is the order I  
ran the commands in (all as root):

cd /usr/src
make buildworld
make buildkernel
shutdown now
make installkernel
shutdown -r now
adjkerntz -i
mount -a -t ufs
mergemaster -p
cd /usr/src
make installworld
mergemaster
reboot

But I didn't get to run the last two.  When I run make installworld, I get  
errors telling me that the filesystem is full.  Now, I can assure you it  
is not.  Well, basically, what I am asking is why is the filesystem full  
after installing the new kernel?