---- [operating system] Linux system Linux / home disk space to remount / root

Below are centos7done on version testing  , use the following command to view disk usage 
ls -lh

文件系统                 容量  已用  可用 已用% 挂载点
devtmpfs                 3.9G     0  3.9G    0% /dev
tmpfs                    3.9G     0  3.9G    0% /dev/shm
tmpfs                    3.9G  2.9M  3.9G    1% /run
tmpfs                    3.9G     0  3.9G    0% /sys/fs/cgroup
/dev/mapper/fedora-root   60G   46G   12G   81% /
tmpfs                    3.9G  400K  3.9G    1% /tmp
/dev/sda1                477M  141M  307M   32% /boot
tmpfs                    787M     0  787M    0% /run/user/0
/dev/mapper/fedora-home  141G   60M  134G    1% /home

/dev/mapper/fedora-home Corresponding mount directory is / home 
/dev/mapper/fedora-root corresponding mount directory is / root 
seen from the above list of  /dev/mapper/fedora-home directory is very large, but we are now  /dev/mapper/fedora-root very small, how can it room to move past it? You can use the following operations

The following steps demonstrate the mobile / home 1G size of the space to the / root

Unmounted / home directory

umount -v /home

Check the disk to be transferred

e2fsck -ff  /dev/mapper/fedora-home
#此命令操作结果的5个步骤必需全部通过

Display is as follows

e2fsck 1.42.13 (17-May-2015)
第一步: 检查inode,块,和大小
第二步: 检查目录结构
第3步: 检查目录连接性
Pass 4: Checking reference counts
第5步: 检查簇概要信息
/dev/mapper/fedora-home: 130190/10838016 files (0.1% non-contiguous), 8077341/43338752 blocks

Change / dev / mapper / fedora-home disk size

Calculation step: 141G - Transfer 1g = 140G

resize2fs /dev/mapper/fedora-home  140G

Shear disk space

lvreduce -L -1G /dev/mapper/fedora-home

Remount / home

mount -v /home

Transfer to / root

lvextend -L+1G /dev/mapper/fedora-root

The / root space into effect

resize2fs /dev/mapper/fedora-root