UBI: Fastmap: Fix memory leaks while closing the WL sub-system

Add a ubi_fastmap_close() to free all resources used by fastmap
at WL shutdown.
Signed-off-by: Richard Weinberger <richard@nod.at>
Tested-by: Guido Martínez <guido@vanguardiasur.com.ar>
Reviewed-by: Guido Martínez <guido@vanguardiasur.com.ar>

drivers/mtd/ubi/wl.c

@@ -2064,6 +2064,23 @@ static void protection_queue_destroy(struct ubi_device *ubi)
 	}
 }
 
+static void ubi_fastmap_close(struct ubi_device *ubi)
+{
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	int i;
+
+	flush_work(&ubi->fm_work);
+	return_unused_pool_pebs(ubi, &ubi->fm_pool);
+	return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
+
+	if (ubi->fm) {
+		for (i = 0; i < ubi->fm->used_blocks; i++)
+			kfree(ubi->fm->e[i]);
+	}
+	kfree(ubi->fm);
+#endif
+}
+
 /**
  * ubi_wl_close - close the wear-leveling sub-system.
  * @ubi: UBI device description object
@@ -2071,6 +2088,7 @@ static void protection_queue_destroy(struct ubi_device *ubi)
 void ubi_wl_close(struct ubi_device *ubi)
 {
 	dbg_wl("close the WL sub-system");
+	ubi_fastmap_close(ubi);
 	shutdown_work(ubi);
 	protection_queue_destroy(ubi);
 	tree_destroy(&ubi->used);