Verification done on xenial-proposed. Now libblkid1 detects only the bcache superblock and prints udev/uuid variables.
$ lsb_release -cs xenial $ DISK_IMG=disk.img $ rm -f $DISK_IMG $ dd if=/dev/zero of=$DISK_IMG bs=1G count=0 seek=1 $ BACKING_DEV=$(sudo losetup --find --show $DISK_IMG) $ sudo make-bcache -B $BACKING_DEV $ BCACHE_DEV="$(readlink -e /sys/block/$(basename $BACKING_DEV)/bcache/dev)" $ BCACHE_DEV="/dev/$(basename $BCACHE_DEV)" $ sudo mkfs.xfs -d agsize=16m -l agnum=0 -f $BCACHE_DEV $ echo 1 | sudo tee /sys/block/$(basename $BCACHE_DEV)/bcache/stop $ 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 |................| xenial-updates: --- $ 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 xenial-proposed: --- $ apt-cache madison libblkid1 | grep proposed libblkid1 | 2.27.1-6ubuntu3.10 | http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages $ sudo apt install libblkid1 -y $ dpkg -s libblkid1 | grep -i version Version: 2.27.1-6ubuntu3.10 $ sudo blkid -o udev -p $BACKING_DEV ID_FS_UUID=6cdf846c-52ea-4f24-8554-7302c41bca8f ID_FS_UUID_ENC=6cdf846c-52ea-4f24-8554-7302c41bca8f ID_FS_TYPE=bcache ID_FS_USAGE=other ** Tags added: verification-done-xenial -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1858802 Title: libblkid: no bcache UUID due to ambivalent detection of bcache and xfs_external_log for regular xfs in bcache backing device To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1858802/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs