mxraid: Add deadlock workaround to mdcheck.safe

Sometimes, when the check is paused by setting sync_action to "idle",
the array deadlocks. It can be continued by setting array_state to
active.

If it takes more 10 seconds to set the sync_action to idle and the array
state is write-pending, then try to continue the array by setting its
state to active.

mxraid/mdcheck.safe

@@ -160,7 +160,13 @@ do
 		rm -f $fl
 		continue;
 	fi
-	echo idle > $sys/md/sync_action
+	echo idle > $sys/md/sync_action &
+	pid=$!
+	sleep 10
+	if [ -d /proc/$pid -a "$(cat $sys/md/array_state)" = write-pending ]; then
+		logger -p daemon.info restart hanging $dev
+		echo active > $sys/md/array_state
+	fi
 	cat $sys/md/sync_min > $fl
 	logger -p daemon.info pause checking $dev at `cat $fl`
 done