LU-7903 hsm: leaked export refcount

Add missed class_export_put() in mdt_hsm_agent_send().

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: Ie9119c53f11901573161034a85bfa7bf83ca6ff8
Reviewed-on: http://review.whamcloud.com/21942


Tested-by: Jenkins
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

lustre/mdt/mdt_hsm_cdt_agent.c

@@ -574,6 +574,8 @@ int mdt_hsm_agent_send(struct mdt_thread_info *mti,
 	 */
 	exp = cfs_hash_lookup(mdt2obd_dev(mdt)->obd_uuid_hash, &uuid);
 	if (exp == NULL || exp->exp_disconnected) {
+		if (exp != NULL)
+			class_export_put(exp);
 		/* This should clean up agents on evicted exports */
 		rc = -ENOENT;
 		CERROR("%s: agent uuid (%s) not found, unregistering:"