- b=958: recovery per export/import, not per connection

- b=958: recovery per export/import, not per connection
  - no more recovd thread:
    - import failure and upcall-execution is done by the failing thread
    - export failure and client eviction is done by the thread that's going
      to be waiting for it to complete anyway
    - import reconnection runs synchronously in the context of the lctl
      invocation, which means that we can now return errors to the upcall
  - no more fancy recovery state machine
  - no more RPCDEV service

- b=954: zero-impact OBD_PING opcode for MDS and OST

- Grand Unified Theory of Client Recovery
  - mdc_recover/osc_recovery unified in ptlrpc_recover_import