[SRU][F][G][PATCH 0/1] ceph -- Unable to mount ceph volume on s390x (LP: 1875863)

[frank.heimes at canonical.com]

Buglink: https://bugs.launchpad.net/bugs/1875863

SRU Justification:

[Impact]

* Unable to mount ceph volumes on big endian systems, like s390x.

* The mount operation always fails with an IO error.

* This is caused by an endiness issue in function handle_session where variable features is always little endian.

* But test_bit assumes the host order of bytes, hence causes a problem on big endian systems.

[Fix]

* 0fa8263367db9287aa0632f96c1a5f93cc478150 0fa8263367db "ceph: fix endianness bug when handling MDS session feature bits"

[Test Case]

* Setup ceph on s390x.

* Try to mount a ceph volume.

* If it mounts correctly the patch is applied and working.

* Without the patch a mount always fails on big endian / s390x.

[Regression Potential] 

* There is regression potential with having code changes in ceph's session handler, which is common code.

* However, the patch was accepted (slightly changed) by the ceph maintainers and with that got upstream accepted, too.

* The patch is fairly limited (5 lines removed, 3 added), hence the changes are quite traceable.

Jeff Layton (1):
  From: Jeff Layton <jlayton at kernel.org>

 fs/ceph/mds_client.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

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2.25.1