The issue leads that the IOC mediator's fd is turned off
incorrectly, causing the IOC mediator to fail.
The root cause is because after closing fd is not set
to an invalid fd.
The issue can be reproduced by the S3 stress test.
Tracked-On: #2301
Signed-off-by: Yuan Liu <yuan1.liu@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>