ubi: fastmap: erase_block: Get erase counter from wl_entry rather than flash

Just like sync_erase() does, getting erase counter from wl_entry is
faster than reading from flash.
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/fastmap.c

@@ -1399,36 +1399,27 @@ static int ubi_write_fastmap(struct ubi_device *ubi,
  */
 static int erase_block(struct ubi_device *ubi, struct ubi_wl_entry *e)
 {
-	int ret;
+	int err;
 	struct ubi_ec_hdr *ec_hdr;
-	long long ec;
+	long long ec = e->ec;
 
 	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
 	if (!ec_hdr)
 		return -ENOMEM;
 
-	ret = ubi_io_read_ec_hdr(ubi, e->pnum, ec_hdr, 0);
-	if (ret < 0)
-		goto out;
-	else if (ret && ret != UBI_IO_BITFLIPS) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	ret = ubi_io_sync_erase(ubi, e->pnum, 0);
-	if (ret < 0)
+	err = ubi_io_sync_erase(ubi, e->pnum, 0);
+	if (err < 0)
 		goto out;
 
-	ec = be64_to_cpu(ec_hdr->ec);
-	ec += ret;
+	ec += err;
 	if (ec > UBI_MAX_ERASECOUNTER) {
-		ret = -EINVAL;
+		err = -EINVAL;
 		goto out;
 	}
 
 	ec_hdr->ec = cpu_to_be64(ec);
-	ret = ubi_io_write_ec_hdr(ubi, e->pnum, ec_hdr);
-	if (ret < 0)
+	err = ubi_io_write_ec_hdr(ubi, e->pnum, ec_hdr);
+	if (err < 0)
 		goto out;
 
 	e->ec = ec;
@@ -1439,7 +1430,7 @@ static int erase_block(struct ubi_device *ubi, struct ubi_wl_entry *e)
 
 out:
 	kfree(ec_hdr);
-	return ret;
+	return err;
 }
 
 /**