resize2fs: Bad magic number in super-block while trying to open /dev/.../root

아래의 글에서 설명한 방법을,

Hyper-V에 설치한 리눅스 VM의 VHD 크기 늘리는 방법
; https://www.sysnet.pe.kr/2/0/1742

# vgextend centos /dev/sda5
Volume group "centos" successfully extended

# lvresize -l +100%FREE /dev/centos/root
Size of logical volume centos/root changed from <30.50 GiB (7807 extents) to 51.49 GiB (13182 extents).
Logical volume centos/root successfully resized.

# resize2fs /dev/centos/root
resize2fs 1.42.9 (28-Dec-2013)
resize2fs: Bad magic number in super-block while trying to open /dev/centos/root
Couldn't find valid filesystem superblock.

OS/CentOS 파티션 SIZE 늘리기
; https://pooh0928.tistory.com/63

# df -Th
Filesystem              Type      Size  Used Avail Use% Mounted on
devtmpfs                devtmpfs  2.0G     0  2.0G   0% /dev
tmpfs                   tmpfs     2.0G     0  2.0G   0% /dev/shm
tmpfs                   tmpfs     2.0G  8.6M  2.0G   1% /run
tmpfs                   tmpfs     2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/mapper/centos-root xfs        52G  5.9G   46G  12% /
/dev/sda1               xfs      1014M  207M  808M  21% /boot
tmpfs                   tmpfs     393M     0  393M   0% /run/user/1000

# xfs_growfs /dev/centos/root
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=1998592 blks
         =                       sectsz=4096  attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=7994368, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=3903, version=2
         =                       sectsz=4096  sunit=1 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 7994368 to 13498368