ACK/cmnt: [SRU][Xenial][PATCH 0/6] Backport Ceph CRUSH_TUNABLES5 support

[Stefan Bader]

On 01.11.2017 21:37, Billy Olsen wrote:
> From: Billy Olsen <billy.olsen at gmail.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1728739
> 
> [Impact]
> Attempting to use the kernel rbd driver to mount images from a
> Jewel (Xenial) or Luminous (Artful & Pike Ubuntu Cloud Archive)
> server causes the mount to fail. This is due to Ceph's addition
> of new CRUSH_TUNABLES5 feature which is not understood by the
> 4.4 kernel client.
> 
> [Fix]
> Backport the 5 original patches (clean cherry-picks) that added
> CRUSH_TUNABLES5 support in the upstream 4.5 kernel. Also backport
> an additional patch that allows the client to understand the new
> v7 format of the MOSDOpReply message.
> 
> - https://www.spinics.net/lists/ceph-devel/msg28421.html
> - https://www.spinics.net/lists/ceph-devel/msg28458.html
> 
> [Test Case]
> 1. Deploy a Jewel/Luminous Ceph Cluster with crush tunables set
>    to optimal.
> 2. Create an RBD image suitable for kernel client:
>    $ rbd create --pool rbd --image-feature layering --size 1G test
> 3. Map rbd device to local server node:
>    $ rbd map --pool rbd test
> 
> [Regression Potential]
> Minimal. Code is limited to kernel rbd driver and new code should
> primarily affect clients connecting to clusters with the new
> tunables options.
> 
> [Notes]
> Only applicable to Xenial LTS kernel 4.4 since code was included
> in the 4.5 kernel.
> 
> Ilya Dryomov (6):
>   crush: ensure bucket id is valid before indexing buckets array
>   crush: ensure take bucket value is valid
>   crush: add chooseleaf_stable tunable
>   crush: decode and initialize chooseleaf_stable
>   libceph: advertise support for TUNABLES5
>   libceph: MOSDOpReply v7 encoding
> 
>  include/linux/ceph/ceph_features.h | 16 +++++++++++++++-
>  include/linux/crush/crush.h        |  8 +++++++-
>  net/ceph/crush/mapper.c            | 33 ++++++++++++++++++++++++++-------
>  net/ceph/osd_client.c              | 10 ++++++++++
>  net/ceph/osdmap.c                  | 19 ++++++++++++++-----
>  5 files changed, 72 insertions(+), 14 deletions(-)
> 
The changes appear to be rather isolated and limited by feature flags which
should lower the risk of pulling those in. For verification testing it would be
good if it could add results of mapping a rbd device from servers using a 4.4
kernel to show backwards compat as well as fixing the failure case.

Acked-by: Stefan Bader <stefan.bader at canonical.com>


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