Comment 50 for bug 1729145

Xenial verified.

root@ubuntu:~# lsb_release -rd
Description: Ubuntu 16.04.4 LTS
Release: 16.04
root@ubuntu:~# uname -a
Linux ubuntu 4.4.0-117-generic #141-Ubuntu SMP Tue Mar 13 11:58:07 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
root@ubuntu:~# apt-cache policy linux-image-virtual
linux-image-virtual:
  Installed: 4.4.0.117.123
  Candidate: 4.4.0.117.123
  Version table:
 *** 4.4.0.117.123 500
        500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     4.4.0.116.122 500
        500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
     4.4.0.21.22 500
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
root@ubuntu:~# ls -al /dev/bcache/*
/dev/bcache/by-label:
total 0
drwxr-xr-x 2 root root 120 Mar 19 19:07 .
drwxr-xr-x 4 root root 80 Mar 19 19:07 ..
lrwxrwxrwx 1 root root 13 Mar 19 19:07 backing-sdb -> ../../bcache0
lrwxrwxrwx 1 root root 13 Mar 19 19:07 backing-sdd -> ../../bcache3
lrwxrwxrwx 1 root root 13 Mar 19 19:07 backing-sde -> ../../bcache2
lrwxrwxrwx 1 root root 13 Mar 19 19:07 backing-sdf -> ../../bcache1

/dev/bcache/by-uuid:
total 0
drwxr-xr-x 2 root root 120 Mar 19 19:07 .
drwxr-xr-x 4 root root 80 Mar 19 19:07 ..
lrwxrwxrwx 1 root root 13 Mar 19 19:07 1f531b44-437f-49cc-b7db-16db6d699c41 -> ../../bcache1
lrwxrwxrwx 1 root root 13 Mar 19 19:07 31474eb7-687d-4bb7-8c6b-b4efd472e860 -> ../../bcache0
lrwxrwxrwx 1 root root 13 Mar 19 19:07 3653ce1f-b6aa-43ad-9a91-506530db2d50 -> ../../bcache3
lrwxrwxrwx 1 root root 13 Mar 19 19:07 94041d44-4bb2-4e4d-8641-21d4ae410595 -> ../../bcache2
root@ubuntu:~# ls -al /dev/bcache/by-label/backing-sdb
lrwxrwxrwx 1 root root 13 Mar 19 19:07 /dev/bcache/by-label/backing-sdb -> ../../bcache0
root@ubuntu:~# ls -al /sys/class/block/bcache0/slaves
total 0
drwxr-xr-x 2 root root 0 Mar 19 19:08 .
drwxr-xr-x 8 root root 0 Mar 19 19:07 ..
lrwxrwxrwx 1 root root 0 Mar 19 19:08 sda -> ../../../../pci0000:00/0000:00:04.0/virtio1/host2/target2:0:0/2:0:0:0/block/sda
lrwxrwxrwx 1 root root 0 Mar 19 19:08 sdb -> ../../../../pci0000:00/0000:00:04.0/virtio1/host2/target2:0:1/2:0:1:0/block/sdb
root@ubuntu:~# ls -al /dev/bcache/by-label/backing-sdd
lrwxrwxrwx 1 root root 13 Mar 19 19:07 /dev/bcache/by-label/backing-sdd -> ../../bcache3
root@ubuntu:~# ls -al /sys/class/block/bcache3/slaves
total 0
drwxr-xr-x 2 root root 0 Mar 19 19:09 .
drwxr-xr-x 8 root root 0 Mar 19 19:07 ..
lrwxrwxrwx 1 root root 0 Mar 19 19:09 sda -> ../../../../pci0000:00/0000:00:04.0/virtio1/host2/target2:0:0/2:0:0:0/block/sda
lrwxrwxrwx 1 root root 0 Mar 19 19:09 sdd -> ../../../../pci0000:00/0000:00:04.0/virtio1/host2/target2:0:3/2:0:3:0/block/sdd
root@ubuntu:~# ls -al /dev/bcache/by-label/backing-sde
lrwxrwxrwx 1 root root 13 Mar 19 19:07 /dev/bcache/by-label/backing-sde -> ../../bcache2
root@ubuntu:~# ls -al /sys/class/block/bcache2/slaves
total 0
drwxr-xr-x 2 root root 0 Mar 19 19:09 .
drwxr-xr-x 8 root root 0 Mar 19 19:07 ..
lrwxrwxrwx 1 root root 0 Mar 19 19:09 sdc -> ../../../../pci0000:00/0000:00:04.0/virtio1/host2/target2:0:2/2:0:2:0/block/sdc
lrwxrwxrwx 1 root root 0 Mar 19 19:09 sde -> ../../../../pci0000:00/0000:00:04.0/virtio1/host2/target2:0:4/2:0:4:0/block/sde
root@ubuntu:~# ls -al /dev/bcache/by-label/backing-sdf
lrwxrwxrwx 1 root root 13 Mar 19 19:07 /dev/bcache/by-label/backing-sdf -> ../../bcache1
root@ubuntu:~# ls -al /sys/class/block/bcache1/slaves
total 0
drwxr-xr-x 2 root root 0 Mar 19 19:09 .
drwxr-xr-x 8 root root 0 Mar 19 19:07 ..
lrwxrwxrwx 1 root root 0 Mar 19 19:09 sdc -> ../../../../pci0000:00/0000:00:04.0/virtio1/host2/target2:0:2/2:0:2:0/block/sdc
lrwxrwxrwx 1 root root 0 Mar 19 19:09 sdf -> ../../../../pci0000:00/0000:00:04.0/virtio1/host2/target2:0:5/2:0:5:0/block/sdf
root@ubuntu:~# dmesg | grep bcache
[ 1.271827] bcache: register_bdev() registered backing device sdb
[ 1.276685] bcache: register_bdev() registered backing device sdf
[ 1.286218] bcache: bch_journal_replay() journal replay done, 0 keys in 2 entries, seq 13
[ 1.309504] bcache: bch_cached_dev_attach() Caching sdb as bcache0 on set 0dbdcc17-7af0-4318-bd57-bbdf5c7f1bfa
[ 1.313789] bcache: register_cache() registered cache device sda
[ 1.365415] bcache: bch_journal_replay() journal replay done, 0 keys in 2 entries, seq 13
[ 1.380090] bcache: bch_cached_dev_attach() Caching sdf as bcache1 on set d36b419d-a49d-42e2-95af-710138a20700
[ 1.382049] bcache: register_cache() registered cache device sdc
[ 1.383332] bcache: register_bdev() registered backing device sde
[ 1.391625] bcache: bch_cached_dev_attach() Caching sde as bcache2 on set d36b419d-a49d-42e2-95af-710138a20700
[ 1.395701] bcache: register_bdev() registered backing device sdd
[ 1.405870] bcache: bch_cached_dev_attach() Caching sdd as bcache3 on set 0dbdcc17-7af0-4318-bd57-bbdf5c7f1bfa
[ 4.533291] bcache: register_bcache() error opening /dev/sda: device already registered
[ 4.547519] bcache: register_bcache() error opening /dev/sdb: device already registered (emitting change event)
[ 4.547616] bcache: register_bcache() error opening /dev/sdc: device already registered
[ 4.562176] bcache: register_bcache() error opening /dev/sdd: device already registered (emitting change event)
[ 4.562930] bcache: register_bcache() error opening /dev/sdf: device already registered (emitting change event)
[ 4.563401] bcache: register_bcache() error opening /dev/sde: device already registered (emitting change event)