md/raid10: check before referencing mddev->bitmap_ops

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

commit 969f996
Author: Yu Kuai <yukuai3@huawei.com>
Date:   Mon Jul 7 09:27:07 2025 +0800

    md/raid10: check before referencing mddev->bitmap_ops

    Prepare to introduce CONFIG_MD_BITMAP.

    Link: https://lore.kernel.org/linux-raid/20250707012711.376844-12-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/raid10.c

@@ -3247,7 +3247,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 			}
 			conf->fullsync = 0;
 		}
-		mddev->bitmap_ops->close_sync(mddev);
+		if (md_bitmap_enabled(mddev, false))
+			mddev->bitmap_ops->close_sync(mddev);
 		close_sync(conf);
 		*skipped = 1;
 		return sectors_skipped;
@@ -3566,7 +3567,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 		 * safety reason, which ensures curr_resync_completed is
 		 * updated in bitmap_cond_end_sync.
 		 */
-		mddev->bitmap_ops->cond_end_sync(mddev, sector_nr,
+		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));
 
@@ -4220,7 +4222,6 @@ static int raid10_resize(struct mddev *mddev, sector_t sectors)
 	 */
 	struct r10conf *conf = mddev->private;
 	sector_t oldsize, size;
-	int ret;
 
 	if (mddev->reshape_position != MaxSector)
 		return -EBUSY;
@@ -4234,9 +4235,12 @@ static int raid10_resize(struct mddev *mddev, sector_t sectors)
 	    mddev->array_sectors > size)
 		return -EINVAL;
 
-	ret = mddev->bitmap_ops->resize(mddev, size, 0);
-	if (ret)
-		return ret;
+	if (md_bitmap_enabled(mddev, false)) {
+		int ret = mddev->bitmap_ops->resize(mddev, size, 0);
+
+		if (ret)
+			return ret;
+	}
 
 	md_set_array_sectors(mddev, size);
 	if (sectors > mddev->dev_sectors &&
@@ -4502,7 +4506,8 @@ static int raid10_start_reshape(struct mddev *mddev)
 		oldsize = raid10_size(mddev, 0, 0);
 		newsize = raid10_size(mddev, 0, conf->geo.raid_disks);
 
-		if (!mddev_is_clustered(mddev)) {
+		if (!mddev_is_clustered(mddev) &&
+		    md_bitmap_enabled(mddev, false)) {
 			ret = mddev->bitmap_ops->resize(mddev, newsize, 0);
 			if (ret)
 				goto abort;
@@ -4525,6 +4530,7 @@ static int raid10_start_reshape(struct mddev *mddev)
 			    MD_FEATURE_RESHAPE_ACTIVE)) || (oldsize == newsize))
 			goto out;
 
+		/* cluster can't be setup without bitmap */
 		ret = mddev->bitmap_ops->resize(mddev, newsize, 0);
 		if (ret)
 			goto abort;