Php – session.save permission erorr

My Debain server created a session in private tmp folder /home/user/tmp
the temp folder owner:


drwxrwxrwx 2 user www-data 4096 2011-08-23 16:26 tmp


After the session created, the session detail:


-rw------- 1 user user 0 2011-08-23 16:30 sess_66nnga09kav0747k5ek95ghne2


I added the user to www-data group but still cannot use the session. I got following error message:

Warning: Unknown: write failed: Disk quota exceeded (122) in Unknown on line 0 Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/home/user/tmp) in Unknown on line 0

If I changed the owner of session to


-rw------- 1 user www-data 84 2011-08-23 16:35 sess_66nnga09kav0747k5ek95ghne2


I can pass the session. Can I force the session file with specified owner??