Начиная с Linux 3.15 по умолчанию используется XFS версии 5 (см. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c99d609a). Однако поставляемые в p8 утилиты не работают с этой версией XFS.

wget -N https://cloud.centos.org/centos/7/images/CentOS-7-x86_64-GenericCloud.qcow2.xz
xz -d -k CentOS-7-x86_64-GenericCloud.qcow2.xz
qemu-img convert -f qcow2 -O raw CentOS-7-x86_64-GenericCloud.qcow2 CentOS-7-x86_64-GenericCloud.raw
dd if=CentOS-7-x86_64-GenericCloud.raw of=CentOS-7-x86_64-GenericCloud.rootfs bs=1M skip=1

/sbin/xfs_repair -f ./CentOS-7-x86_64-GenericCloud.rootfs 
Phase 1 - find and verify superblock...
bad primary superblock - bad or unsupported version !!!

attempting to find secondary superblock.............
[зависает]

/usr/sbin/xfs_copy -d CentOS-7-x86_64-GenericCloud.rootfs CentOS-7-x86_64-GenericCloud.rootfs.clone
xfs_copy: WARNING - filesystem uses v1 dirs,limited functionality provided.
cache_node_purge: refcount was 1, not zero (node=0x660a30)
xfs_copy: cannot read root inode (117)
xfs_copy: CentOS-7-x86_64-GenericCloud.rootfs filesystem failed to initialize
xfs_copy: Aborting.

При этом файловая система не повреждена:

sudo mount -o ro,loop,nodev,nosuid CentOS-7-x86_64-GenericCloud.rootfs /mnt
/mnt/sbin/xfs_repair -f ./CentOS-7-x86_64-GenericCloud.rootfs 
Phase 1 - find and verify superblock...
Cannot get host filesystem geometry.
Repair may fail if there is a sector size mismatch between
the image and the host filesystem.
Phase 2 - using internal log
        - zero log...
        - scan filesystem freespace and inode maps...
        - found root inode chunk
Phase 3 - for each AG...
        - scan and clear agi unlinked lists...
        - process known inodes and perform inode discovery...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - process newly discovered inodes...
Phase 4 - check for duplicate blocks...
        - setting up duplicate extent list...
        - check for inodes claiming duplicate blocks...
        - agno = 0
        - agno = 3
        - agno = 1
        - agno = 2
Phase 5 - rebuild AG headers and trees...
        - reset superblock...
Phase 6 - check inode connectivity...
        - resetting contents of realtime bitmap and summary inodes
        - traversing filesystem ...
        - traversal finished ...
        - moving disconnected inodes to lost+found ...
Phase 7 - verify and correct link counts...
done

sudo chroot /mnt /bin/bash --login
cat /etc/redhat-release 
CentOS Linux release 7.5.1804 (Core)