默认是xfs文件系统
如果是xfs，收缩会损坏文件系统，导致文件丢失，要先备份。
mount 会报错 can't read superblock xfs
这时只能格式化了 mkfs.xfs -f /dev/mapper/centos-home
1、提前备份重要数据，xfs减小会导致数据丢失
备份可以用xfsdump，数据不大也可以备份到机器之外（此处略）
2、卸载卷/dev/mapper/cl-home
umount /home
3、减少卷/dev/mapper/cl-home大小（该步骤会导致数据丢失，请看第1点）
[root@localhost ~]# lvreduce -L 10G /dev/mapper/cl-home
WARNING: Reducing active logical volume to 10.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce cl/home? [y/n]:y
Size of logical volume cl/home changed from 178.25 GiB (45633 extents) to 10.00 GiB (2560 extents).
Logical volume cl/home successfully resized.
4、增加卷/dev/mapper/cl-root大小
[root@localhost ~]# lvextend -l +100%FREE /dev/mapper/cl-root
Size of logical volume cl/root changed from 50.00 GiB (12800 extents) to 218.26 GiB (55874 extents).
Logical volume cl/root successfully resized.
5、调整xfs文件系统大小
[root@localhost ~]# xfs_growfs /dev/mapper/cl-root
6、重新挂载、恢复数据
如果直接挂载会报错：
[root@localhost ~]# mount /dev/mapper/cl-home /home/
mount: /dev/mapper/cl-home: can't read superblock
需要先格式化
[root@localhost ~]# mkfs.xfs -f /dev/mapper/cl-home
格式化后挂载：
mount /dev/mapper/cl-home /home/
挂载后恢复数据
此步骤可以用xfsrestore，或者手动拷贝（参照第1点）
7、查看结果
[root@localhost ~]# df -h
参考
centos7下xfs格式的LVM卷空间伸缩实战
http://www.viper.im/archives/centos7-xfs-lvm-resize.html
CentOS 7扩展根分区
https://segmentfault.com/a/1190000007645451
如果某个fstab 中的文件系统故障，mount不上，启动会报错，进入维护模式
Error getting authority: Error initializing authority: Could not connect: No such file or directory (g-io-error-quark, 1)
可以 查看报错内容 journalctl -x | grep mount
手动mount 看报啥错
然后修复
或者改fstab注释掉错误的文件系统
还有一种可能是新增了硬盘或者u盘，导致硬盘序号发生变化
可以把磁盘名称更改为UUID。
# blkid
/dev/sdc1: UUID="ab4c28b5-1708-483c-973a-40f91d320a9d" TYPE="ext4"
...
# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Tue Aug 8 13:10:48 2017
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/cl-root / xfs defaults 0 0
UUID=a51fd6f8-a756-4e8f-ba44-5589fb99861e /boot xfs defaults 0 0
UUID=7D74-6C54 /boot/efi vfat umask=0077,shortname=winnt 0 0
/dev/mapper/cl-swap swap swap defaults 0 0
UUID=ab4c28b5-1708-483c-973a-40f91d320a9d /data ext4 defaults 0 0
参考
系统启动报错：Error getting authority: Error initializing authority: Could not connect: No such file or directory (g-io-error-quark, 1)
https://www.jianshu.com/p/ea57fb7834f2
CentOS 7磁盘寻找不到，卡在sulogin，造成的开机失败问题--Error getting authority...
https://www.cnblogs.com/redheat/p/7477380.html
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