How to get ACL working in CentOS?

I have this line in fstab:

/dev/sda3  /  ext3  defaults  1  2

I supposed I should change it to:

/dev/sda3  /  ext3  defaults,acl  1  2

I also suppose I should run:

mount -t ext3 -o acl /dev/sda3 /

Oh, but I get an error that it’s already mounted or “/” is busy. How do I do this without crashing the system?

My answer:

You can pass the remount option to the mount command, for instance:

mount -o remount /

This will cause it to re-read /etc/fstab and apply your new options.