md/raid5: check before referencing mddev->bitmap_ops

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

commit bb9317b
Author: Yu Kuai <yukuai3@huawei.com>
Date:   Mon Jul 7 09:27:08 2025 +0800

    md/raid5: check before referencing mddev->bitmap_ops

    Prepare to introduce CONFIG_MD_BITMAP.

    Link: https://lore.kernel.org/linux-raid/20250707012711.376844-13-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/raid5.c

@@ -6496,7 +6496,8 @@ static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_n
 					   &sync_blocks);
 		else /* completed sync */
 			conf->fullsync = 0;
-		mddev->bitmap_ops->close_sync(mddev);
+		if (md_bitmap_enabled(mddev, false))
+			mddev->bitmap_ops->close_sync(mddev);
 
 		return 0;
 	}
@@ -6534,7 +6535,8 @@ static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_n
 		return sync_blocks * RAID5_STRIPE_SECTORS(conf);
 	}
 
-	mddev->bitmap_ops->cond_end_sync(mddev, sector_nr, false);
+	if (md_bitmap_enabled(mddev, false))
+		mddev->bitmap_ops->cond_end_sync(mddev, sector_nr, false);
 
 	sh = raid5_get_active_stripe(conf, NULL, sector_nr,
 				     R5_GAS_NOBLOCK);
@@ -6760,7 +6762,8 @@ static void raid5d(struct md_thread *thread)
 			/* Now is a good time to flush some bitmap updates */
 			conf->seq_flush++;
 			spin_unlock_irq(&conf->device_lock);
-			mddev->bitmap_ops->unplug(mddev, true);
+			if (md_bitmap_enabled(mddev, true))
+				mddev->bitmap_ops->unplug(mddev, true);
 			spin_lock_irq(&conf->device_lock);
 			conf->seq_write = conf->seq_flush;
 			activate_bit_delay(conf, conf->temp_inactive_list);
@@ -8309,7 +8312,6 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
 	 */
 	sector_t newsize;
 	struct r5conf *conf = mddev->private;
-	int ret;
 
 	if (raid5_has_log(conf) || raid5_has_ppl(conf))
 		return -EINVAL;
@@ -8319,9 +8321,12 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
 	    mddev->array_sectors > newsize)
 		return -EINVAL;
 
-	ret = mddev->bitmap_ops->resize(mddev, sectors, 0);
-	if (ret)
-		return ret;
+	if (md_bitmap_enabled(mddev, false)) {
+		int ret = mddev->bitmap_ops->resize(mddev, sectors, 0);
+
+		if (ret)
+			return ret;
+	}
 
 	md_set_array_sectors(mddev, newsize);
 	if (sectors > mddev->dev_sectors &&