ecryptfs mounted as read-only

I just mounted postgres home(/var/lib/postgresql) with ecryptfs. After rebooting the machine, it is mounted for me automatically, but if I try to do any writes it tells me that it's a read-only filesystem. It's very weird coz mount shows it mounted as read/write.

# output of mount:
/var/lib/.postgresql on /var/lib/postgresql type ecryptfs (rw)

# when trying to start the service
root@sandbox:/var/lib/postgresql# service postgresql start
 * Starting PostgreSQL 9.1 database server
 * The PostgreSQL server failed to start. Please check the log output:
2014-05-04 04:20:55 GMT FATAL:  could not create lock file "postmaster.pid": Read-only file system
   ...fail!


# as postgres
postgres@sandbox:~$ pwd
/var/lib/postgresql
postgres@sandbox:~$ touch a.txt
touch: cannot touch `a.txt': Read-only file system

# as root
root@sandbox:/var/lib/postgresql# touch a.txt
touch: cannot touch `a.txt': Read-only file system