Apache 403 after /var/www backup

I’m running a WordPress site on a RHEL server and I do backup every week for the WP MySQL database and the /var/www folder:

mysqldump -uroot -p******** blog -l -F > /bak/blog.sql
tar -jcpv -f /bak/www.tar.bz2 /var/www

The latest backup was done at 6 a.m. (UTC +8) this morning and I upgraded WP to 3.9 at 7. Some features were not compatible with 3.9, so I decided to roll back. I restored the database and the folder:

mysql -uroot -p blog < /bak/blog.sql
tar -jxv -f /bak/www.tar.bz2 -C /

and then the site gave me a 403. I restarted Apache and rebooted the server but it didn’t help. The site was running before I upgraded WP, so I think the conf.s are the same before and after the backup/restore, therefore the problem might not be there. My homepage is redirect to my.si.te/blog/, and I can’t visit a pure index.html at my.si.te/test/ (/var/www/html/test/) either. It’s the same message: You don’t have permission to access /(blog/test) on this server.

[Mon Apr 21 08:42:48 2014] [crit] [client 144.*.*.*] (13)Permission denied: /var/www/html/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable
[Mon Apr 21 08:42:56 2014] [crit] [client 157.*.*.*] (13)Permission denied: /var/www/html/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable
[Mon Apr 21 08:42:58 2014] [crit] [client 178.*.*.*] (13)Permission denied: /var/www/html/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable, referer: http://my.si.te

What would be the problem and how can I fix it? Thanks!