swapoff /dev/mapper/dmgroup-lvswap
lvreduce -L -54.5G /dev/mapper/dmgroup-lvswap
mkswap /dev/mapper/dmgroup-lvswap
swapon /dev/mapper/dmgroup-lvswap
lvextend -L +54G /dev/mapper/dmgroup-lvroot
resize2fs -p /dev/mapper/dmgroup-lvroot
##### -54.5G是针对swap来做的和+54G是针对根目录来做的，操作系统版本centos6.7