nbd: Respect max_part for all partition scans

The creation path of the NBD device respects max_part and only scans for
partitions if max_part is not 0. However, some other code paths ignore
max_part, and unconditionally scan for partitions. Add a check for
max_part on each partition scan.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/nbd.c

@@ -318,6 +318,7 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 	blk_queue_logical_block_size(nbd->disk->queue, blksize);
 	blk_queue_physical_block_size(nbd->disk->queue, blksize);
 
+	if (max_part)
 		set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
 	if (!set_capacity_and_notify(nbd->disk, bytesize >> 9))
 		kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
@@ -1476,8 +1477,10 @@ static int nbd_open(struct block_device *bdev, fmode_t mode)
 		refcount_set(&nbd->config_refs, 1);
 		refcount_inc(&nbd->refs);
 		mutex_unlock(&nbd->config_lock);
+		if (max_part)
 			set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
 	} else if (nbd_disconnected(nbd->config)) {
+		if (max_part)
 			set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
 	}
 out: