Comment 12 for bug 1728739

Successfully verified this with kernel 4.4.0-102-generic in the xenial-proposed repository.

I verified mapping rbd devices against Ceph versions:

0.94.10 Hammer release (from trusty-kilo cloud-archive)
10.2.7 Jewel release (from xenial-updates)
12.2.0 Luminous release (from xenial-pike cloud-archive)

All versions had optimal tunables set, which previously prevented rbd mapping from completing for Jewel and Luminous releases due to missing TUNABLES5 support. All tests successfully mapped, formatted, and mounted.

Relevant kernel log snippets:

Nov 29 18:59:29 juju-49feb5-ceph-6 kernel: [ 0.000000] Linux version 4.4.0-102-generic (buildd@lgw01-amd64-055) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.5) ) #125-Ubuntu SMP Tue Nov 21 15:15:11 UTC 2017 (Ubuntu 4.4.0-102.125-generic 4.4.98)

==== RBD Mapping to Ceph Hammer Cluster v0.94.10 (trusty-kilo cloud-archive) ====
Nov 29 19:01:45 juju-49feb5-ceph-6 kernel: [ 148.314991] Key type ceph registered
Nov 29 19:01:45 juju-49feb5-ceph-6 kernel: [ 148.317382] libceph: loaded (mon/osd proto 15/24)
Nov 29 19:01:45 juju-49feb5-ceph-6 kernel: [ 148.323276] rbd: loaded (major 251)
Nov 29 19:01:45 juju-49feb5-ceph-6 kernel: [ 148.343492] libceph: client44139 fsid 6547bd3e-1397-11e2-82e5-53567c8d32dc
Nov 29 19:01:45 juju-49feb5-ceph-6 kernel: [ 148.346357] libceph: mon2 10.5.0.3:6789 session established
Nov 29 19:01:45 juju-49feb5-ceph-6 kernel: [ 148.415717] rbd: rbd0: added with size 0x280000000
Nov 29 19:02:04 juju-49feb5-ceph-6 kernel: [ 167.519366] EXT4-fs (rbd0): mounted filesystem with ordered data mode. Opts: (null)

==== RBD Mapping to Ceph Jewel Cluster v10.2.7 (xenial/trusty-mitaka cloud-archive) ====
Nov 29 19:17:48 juju-49feb5-ceph-6 kernel: [ 1111.874853] libceph: client64310 fsid 6547bd3e-1397-11e2-82e5-53567c8d32dc
Nov 29 19:17:48 juju-49feb5-ceph-6 kernel: [ 1111.876730] libceph: mon1 10.5.0.14:6789 session established
Nov 29 19:17:48 juju-49feb5-ceph-6 kernel: [ 1111.924995] rbd: rbd0: added with size 0x280000000
Nov 29 19:17:54 juju-49feb5-ceph-6 kernel: [ 1117.704119] EXT4-fs (rbd0): mounted filesystem with ordered data mode. Opts: (null)

==== RBD Mapping to Ceph Luminous Cluster v12.2.0 (xenial-ocata cloud-archive) ====
Nov 29 19:41:42 juju-49feb5-ceph-6 kernel: [ 2545.672870] libceph: client4216 fsid 6547bd3e-1397-11e2-82e5-53567c8d32dc
Nov 29 19:41:42 juju-49feb5-ceph-6 kernel: [ 2545.679350] libceph: mon1 10.5.0.12:6789 session established
Nov 29 19:41:42 juju-49feb5-ceph-6 kernel: [ 2545.717272] rbd: rbd0: added with size 0x280000000
Nov 29 19:42:04 juju-49feb5-ceph-6 kernel: [ 2567.088206] EXT4-fs (rbd0): mounted filesystem with ordered data mode. Opts: (null)