nbd: use set_capacity_and_notify

Use set_capacity_and_notify to update the disk and block device sizes and
send a RESIZE uevent to userspace.  Note that blktests relies on uevents
being sent also for updates that did not change the device size, so the
explicit kobject_uevent remains for that case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/nbd.c

@@ -299,8 +299,6 @@ static void nbd_size_clear(struct nbd_device *nbd)
 static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 		loff_t blksize)
 {
-	struct block_device *bdev;
-
 	if (!blksize)
 		blksize = NBD_DEF_BLKSIZE;
 	if (blksize < 512 || blksize > PAGE_SIZE || !is_power_of_2(blksize))
@@ -320,16 +318,9 @@ 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);
 
-	set_capacity(nbd->disk, bytesize >> 9);
-	bdev = bdget_disk(nbd->disk, 0);
-	if (bdev) {
-		if (bdev->bd_disk)
-			bd_set_nr_sectors(bdev, bytesize >> 9);
-		else
-			set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
-		bdput(bdev);
-	}
-	kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
+	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);
 	return 0;
 }