pg_upgrade link mode

Hello, I have a 9.1 cluster with 50 databases, only one table per db with
2000 rows only, but a lot of schema around each one (postgis databases)

The old cluster size is 1GB

du -chs /var/lib/postgresql/9.1/main/
1.1G

now I run a pg_upgrade to 9.2 with hard link mode,

pg_upgrade --link \
--old-datadir=/var/lib/postgresql/9.1/main \
--new-datadir=/var/lib/postgresql/9.2/main \
--old-bindir=/usr/lib/postgresql/9.1/bin \
--new-bindir=/usr/lib/postgresql/9.2/bin

du -chs /var/lib/postgresql/9.2/main/
880M

Is the expected behaviour? I can't double the space in production.

Thanks.