[PATCH] swapoff accounting cleanup

From Hugh.  Remove some strangeness in the swapoff path.

"it dates from the days when that block set *swap_map to 0, but in
 2.4.13 I changed it to set *swap_map to 1 and delete_from_swap_cache
 afterwards: it's been wrong ever since, hasn't it?  swap_list_locking
 can go, it was there to guard nr_swap_pages for si_swapinfo; the
 swap_device_locking has to stay because swap_map is an array of
 unsigned _shorts_."

mm/swapfile.c

@@ -670,12 +670,9 @@ static int try_to_unuse(unsigned int type)
 		 * report them; but do report if we reset SWAP_MAP_MAX.
 		 */
 		if (*swap_map == SWAP_MAP_MAX) {
-			swap_list_lock();
 			swap_device_lock(si);
-			nr_swap_pages++;
 			*swap_map = 1;
 			swap_device_unlock(si);
-			swap_list_unlock();
 			reset_overflow = 1;
 		}