vagrantのマウントエラーの対処法

vagrantのマウントエラーの対処法
 
==> vagrant: Mounting shared folders...
    vagrant: /vagrant => /Users/ohira/projects/aucfan-settlement/opsfiles/vagrant
    Failed to mount folders in Linux guest. This is usually because
the "vboxsf" file system is not available. Please verify that
the guest additions are properly installed in the guest and
can work properly. The command attempted was:
 
$ sudo yum update
$ sudo yum install kernel-devel gcc
$ echo export KERN_DIR=/usr/src/kernels/`uname -r` >> ~/.bashrc
$ sudo shutdown -r now