UBI: fastmap: scrub PEB when bitflips are detected in a free PEB EC header

scan_pool() does not mark the PEB for scrubing when bitflips are
detected in the EC header of a free PEB (VID header region left to
0xff).
Make sure we scrub the PEB in this case.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Fixes: dbb7d2a88d2a ("UBI: Add fastmap core")
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/fastmap.c

@@ -498,10 +498,11 @@ static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai,
 			unsigned long long ec = be64_to_cpu(ech->ec);
 			unmap_peb(ai, pnum);
 			dbg_bld("Adding PEB to free: %i", pnum);
+
 			if (err == UBI_IO_FF_BITFLIPS)
-				add_aeb(ai, free, pnum, ec, 1);
-			else
-				add_aeb(ai, free, pnum, ec, 0);
+				scrub = 1;
+
+			add_aeb(ai, free, pnum, ec, scrub);
 			continue;
 		} else if (err == 0 || err == UBI_IO_BITFLIPS) {
 			dbg_bld("Found non empty PEB:%i in pool", pnum);