v0.78
~~~~~

* CephFS recently added support for a new 'backtrace' attribute on
  file data objects that is used for lookup by inode number (i.e., NFS
  reexport and hard links), and will later be used by fsck repair.
  This replaces the existing anchor table mechanism that is used for
  hard link resolution.  In order to completely phase that out, any
  inode that has an outdated backtrace attribute will get updated when
  the inode itself is modified.  This will result in some extra workload
  after a legacy CephFS file system is upgraded.