1、查看分区

df -h

vgdisplay

2、备份/home分区

tar cvf /tmp/home.tar /home

3、卸载/home分区，如果无法卸载，先终止使用/home分区的进程

fuser -km /home/

lvremove /home
   报错  "/home": Invalid path for Logical Volume.

lvremove /dev/mapper/centos-home
    Logical volume centos/home contains a filesystem in use.

umount /dev/mapper/centos-home

lvremove /dev/mapper/centos-home

    Do you really want to remove active logical volume centos/home? [y/n]: y
    Logical volume "home" successfully removed

加40G到/dev/mapper/centos-root

lvextend -L +40G /dev/mapper/centos-root

    Size of logical volume centos/root changed from 50.00 GiB (12800 extents) to 90.00 GiB (23040 extents).
    Logical volume centos/root successfully resized.

xfs_growfs /dev/mapper/centos-root

    meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=3276800 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=13107200, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=6400, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 13107200 to 23592960

lvcreate -L 10G -n /dev/mapper/centos-home

    Volume group "centos" has insufficient free space (1311 extents): 2560 required.


lvcreate -L 5G -n /dev/mapper/centos-home

    Logical volume "home" created.

 mkfs.xfs /dev/mapper/centos-home

meta-data=/dev/mapper/centos-home isize=512    agcount=4, agsize=327680 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=1310720, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

mount /dev/mapper/centos-home