diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 1f321826ef02..22bbd06ba6a2 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -680,6 +680,7 @@ static int choose_slow_rdev(struct r1conf *conf, struct r1bio *r1_bio,
 		len = r1_bio->sectors;
 		read_len = raid1_check_read_range(rdev, this_sector, &len);
 		if (read_len == r1_bio->sectors) {
+			*max_sectors = read_len;
 			update_read_sectors(conf, disk, this_sector, read_len);
 			return disk;
 		}