Comment 10 for bug 1858802

Test :: disco

$ lsb_release -cs
disco

$ uname -rv
5.0.0-37-generic #40-Ubuntu SMP Thu Nov 14 00:14:01 UTC 2019

$ dpkg -s bcache-tools xfsprogs | grep -i version
Version: 1.0.8-3
Version: 4.15.1-1ubuntu1

$ 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 02 00 |................|

Before:

$ dpkg -s libblkid1 | grep -i version
Version: 2.33.1-0.1ubuntu3

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

After:

$ dpkg -s libblkid1 | grep -i version
Version: 2.33.1-0.1ubuntu4

$ sudo blkid -o udev -p $BACKING_DEV
ID_FS_UUID=c3c22fe2-cb68-4966-8cde-aba13a079201
ID_FS_UUID_ENC=c3c22fe2-cb68-4966-8cde-aba13a079201
ID_FS_TYPE=bcache
ID_FS_USAGE=other