md/raid1: check before referencing mddev->bitmap_ops

JIRA: https://issues.redhat.com/browse/RHEL-123668

commit 8d31ed3
Author: Yu Kuai <yukuai3@huawei.com>
Date:   Mon Jul 7 09:27:06 2025 +0800

    md/raid1: check before referencing mddev->bitmap_ops

    Prepare to introduce CONFIG_MD_BITMAP.

    Link: https://lore.kernel.org/linux-raid/20250707012711.376844-11-yukuai1@huaweicloud.com
    Signed-off-by: Yu Kuai <yukuai3@huawei.com>
    Reviewed-by: Xiao Ni <xni@redhat.com>

Signed-off-by: Nigel Croxon <ncroxon@redhat.com>

Author: ncroxon

drivers/md/raid1.c

@@ -2820,7 +2820,8 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
 		else /* completed sync */
 			conf->fullsync = 0;
 
-		mddev->bitmap_ops->close_sync(mddev);
+		if (md_bitmap_enabled(mddev, false))
+			mddev->bitmap_ops->close_sync(mddev);
 		close_sync(conf);
 
 		if (mddev_is_clustered(mddev)) {
@@ -2857,10 +2858,11 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
 	/* we are incrementing sector_nr below. To be safe, we check against
 	 * sector_nr + two times RESYNC_SECTORS
 	 */
-
-	mddev->bitmap_ops->cond_end_sync(mddev, sector_nr,
-		mddev_is_clustered(mddev) &&
-		(sector_nr + 2 * RESYNC_SECTORS > conf->cluster_sync_high));
+	if (md_bitmap_enabled(mddev, false))
+		mddev->bitmap_ops->cond_end_sync(mddev, sector_nr,
+			mddev_is_clustered(mddev) &&
+			(sector_nr + 2 * RESYNC_SECTORS >
+			 conf->cluster_sync_high));
 
 	if (raise_barrier(conf, sector_nr))
 		return 0;
@@ -3335,15 +3337,17 @@ static int raid1_resize(struct mddev *mddev, sector_t sectors)
 	 * worth it.
 	 */
 	sector_t newsize = raid1_size(mddev, sectors, 0);
-	int ret;
 
 	if (mddev->external_size &&
 	    mddev->array_sectors > newsize)
 		return -EINVAL;
 
-	ret = mddev->bitmap_ops->resize(mddev, newsize, 0);
-	if (ret)
-		return ret;
+	if (md_bitmap_enabled(mddev, false)) {
+		int ret = mddev->bitmap_ops->resize(mddev, newsize, 0);
+
+		if (ret)
+			return ret;
+	}
 
 	md_set_array_sectors(mddev, newsize);
 	if (sectors > mddev->dev_sectors &&