rbd: set initial capacity in rbd_init_disk()

Move the setting of the initial capacity for an rbd image mapping
into rb_init_disk().

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index fa99b94..3274943 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1901,6 +1901,8 @@
 
 	rbd_dev->disk = disk;
 
+	set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
+
 	return 0;
 out_disk:
 	put_disk(disk);
@@ -2646,7 +2648,6 @@
 
 	/* Everything's ready.  Announce the disk to the world. */
 
-	set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
 	add_disk(rbd_dev->disk);
 	pr_info("%s: added with size 0x%llx\n", rbd_dev->disk->disk_name,
 		(unsigned long long) rbd_dev->mapping.size);