The dmclock is an EXTERNAL library is not wholly owned by the ceph
repo.  Instead, it is brought into ceph repo via a "git subtree".

If you are unfamiliar with this technique, PLEASE READ
../../README.git-subtree.

IT'S VERY LIKELY YOU DO *NOT* WANT TO DIRECTLY MODIFY FILES IN OR
BELOW src/dmclock, AND THAT IF YOU DO MODIFY SUCH FILES YOUR
MODIFICATIONS WILL LIKELY BE REJECTED.

You should only modify files below src/dmclock if:

    1) you intend to diverge the ceph version of the dmclock library
       from the external library, and

    2) you intend for ceph developers to maintain those divergences
       for the foreseeable future, even as the dmclock library evolves
       and those changes are pulled into ceph.

[Note: this file is an example of such a modification; this file is
such a divergence.]

If you would like to submit a PR to the dmclock library itself, then
you'll want to submit a PR to:

    https://github.com/ceph/dmclock

After that PR is merged, you would then submit a PR to ceph that does
a "git subtree pull" (see ../../README.git-subtree for details).