Centos7 出现Welcome to emergency mode!

做mount挂载时，修改了  /etc/fstab 文件，导致Centos7重启时出现如下图所示错误：

Welcome to emergency  mode! After logging in, type "journalctl -xb" to view

system logs,"systemctl  reboot" to reboot ,"systemctl default" or ^D

to try again to boot into default mode.

Give root password for maintenance

(or type Control-D to continue):

输如root权限密码， vi /etc/fstab 将自己多配置的一行内容删除，wq保存,之后reboot重启虚拟机，就恢复正常了。