start_mdmon now waits for mdmon to complete initialisation and,
importantly, listen on the socket, before continuing.
Signed-off-by: Neil Brown <neilb@suse.de>
The returned value was never used, and we don't really want
this return path anyway as writing to a pipe could conceivably
block, and the monitor must not block.
From: Dan Williams <dan.j.williams@intel.com>
Each md_message encapsulates a single command. A command includes an 'action'
member which describes what if any data comes after the action. Communication
with the monitor involves updating the active_cmd pointer and then writing to
mgr_pipe. Pass/fail status is returned via mon_pipe.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>