[PATCH] io_getevents leak fix

Spotted by Suparna: if the first range check fails, we leak a ref on the io
context.

fs/aio.c

@@ -1240,11 +1240,9 @@ asmlinkage long sys_io_getevents(aio_context_t ctx_id,
 	struct kioctx *ioctx = lookup_ioctx(ctx_id);
 	long ret = -EINVAL;
 
-	if (unlikely(min_nr > nr || min_nr < 0 || nr < 0))
-		return ret;
-
-	if (likely(NULL != ioctx)) {
-		ret = read_events(ioctx, min_nr, nr, events, timeout);
+	if (likely(ioctx)) {
+		if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0))
+			ret = read_events(ioctx, min_nr, nr, events, timeout);
 		put_ioctx(ioctx);
 	}