Comment 12 for bug 1858802

Test :: xenial

$ lsb_release -cs
xenial

$ uname -rv
4.4.0-171-generic #200-Ubuntu SMP Tue Dec 3 11:04:55 UTC 2019

$ dpkg -s bcache-tools xfsprogs | grep -i version
Version: 1.0.8-2
Version: 4.3.0+nmu1ubuntu1.1

$ sudo hexdump -C $BACKING_DEV | grep -m2 -e XFSB -e 'fe ed ba be'
00002000 58 46 53 42 00 00 10 00 00 00 00 00 00 03 f0 00 |XFSB............|
00007000 fe ed ba be 00 00 00 01 00 00 00 02 00 00 00 14 |................|

Before:

$ dpkg -s libblkid1 | grep -i version
Version: 2.27.1-6ubuntu3.9

$ sudo blkid -o udev -p $BACKING_DEV
ID_FS_AMBIVALENT=other:bcache other:xfs_external_log

After:

$ dpkg -s libblkid1 | grep -i version
Version: 2.27.1-6ubuntu3.10

$ sudo blkid -o udev -p $BACKING_DEV
ID_FS_UUID=9dd54115-df08-4e6d-99eb-fb322fcfc04e
ID_FS_UUID_ENC=9dd54115-df08-4e6d-99eb-fb322fcfc04e
ID_FS_TYPE=bcache
ID_FS_USAGE=other