autovacuum with lots of open file references to deleted files

Hello.

On this box I drop a 80GB database each night followed by a restore of a similar sized database. It is a restore of our
productiondatabase to a development server. This box is running 9.2rc1 (sorry). 

du and df reported quite different numbers and lsof show that autovacuum is holding lots of deleted files. After
killingthe autovacuum daemon, some disk space was restored and the du and df numbers was more equal.  

autovacuum hold roughly 100GB of deleted files. This running PostgreSQL instance has dumped/restored the 80GB database
~20times. 

Is this something that has been fixed in PostgreSQL or that can be fixed? Or am I doing something wrong? - besides
runninga release candidate.. 

postmaste 28573   postgres  360u      REG                8,1  1073741824   18319099
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.10(deleted) 
postmaste 28573   postgres  361u      REG                8,1  1073741824   18319095
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.11(deleted) 
postmaste 28573   postgres  362u      REG                8,1  1073741824   18319101
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.12(deleted) 
postmaste 28573   postgres  363u      REG                8,1  1073741824   18319102
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.13(deleted) 
postmaste 28573   postgres  364u      REG                8,1  1073741824   18319103
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.14(deleted) 
postmaste 28573   postgres  365u      REG                8,1  1073741824   18319100
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.15(deleted) 
postmaste 28573   postgres  366u      REG                8,1  1073741824   18319105
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.16(deleted) 
postmaste 28573   postgres  367u      REG                8,1  1073741824   18319108
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.21(deleted) 
postmaste 28573   postgres  368u      REG                8,1  1073741824   18319111
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.22(deleted) 
postmaste 28573   postgres  369u      REG                8,1  1073741824   18319110
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.23(deleted) 
postmaste 28573   postgres  370u      REG                8,1  1073741824   18319112
/usr/local/postgresql-9.2rc1/data/base/3211526/11991.25(deleted) 

# ps auxww|grep 28573
root     22536  0.0  0.0   7372   880 pts/0    S+   23:36   0:00 grep 28573
postgres 28573  0.0  0.2  61372 38048 ?        Ss   Sep07  44:34 postgres: autovacuum launcher process
                           

Regards,
Tore Halset.