mds: avoid modification of const Messages
PR #22555 (https://github.com/ceph/ceph/pull/22555/) converted all Message handling to use const to avoid potential errors with re-processing messages that have been changed elsewhere or (in the future) by another thread.
There were a few instances which were not resolved in the interest of getting #22555 done:
~/ceph/src/messages$ git grep mutable MClientRequest.h: mutable struct ceph_mds_request_head head; /* XXX HACK! */ MClientRequest.h: mutable ceph_mds_request_release item; MClientRequest.h: mutable vector<Release> releases; /* XXX HACK! */ MClientRequest.h: mutable bool queued_for_replay = false; MDirUpdate.h: mutable int tried_discover = 0; // XXX HACK MMDSSlaveRequest.h: mutable __u16 flags; /* XXX HACK for mark_interrupted */ MMDSSlaveRequest.h: mutable bufferlist straybl; // stray dir + dentry
Mostly, these are state the MDS uses when reprocessing a Message (after acquiring locks for instance). The MDS should split this state off into a Context and keep the Message purely const.