This is a tell command which allows the MDS to drop its cache without restarting, trim its journal (so failover does not cause the cache to become warm from reading the journal), and ask clients to drop all caps not in use.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.