In case you’ve managed to overcome other issues with system unable to boot, disk size not updated then there might be still one problem left. Sometimes resizing with gpart works fine but file system resize does not. I’ve encountered such issue and frankly speaking I’m not quite sure what is root cause of it. Is says that file system is dirty and I should run fsck which can be executed from console selecting number 5 and then F letter. System reboots and makes file system check. It says that the file system is fine, so it’s quite confusing.
Solution for this one is to boot the system in single user mode, by selecting number 5 and S. This skips few additional things normally executed during multi user boot mode. Now you can run the following to expand file system:
service growfs onestart
This command normally should be able to do its job, but this time, system should be run in single user mode to overcome it.