drbd: Fixed processing of disk-barrier, disk-flushes and disk-drain

Since drbd_bump_write_ordering() is called in the attaching
process while the disk state is D_ATTACHING, it was not
considering these three flags during attach.

A call to this function was missing form drbd_adm_disk_opts().

Fixed both issues.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_nl.c

@@ -1229,6 +1229,9 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	mutex_unlock(&mdev->tconn->conf_update);
+
+	drbd_bump_write_ordering(mdev->tconn, WO_bdev_flush);
+
 	drbd_md_sync(mdev);
 
 	if (mdev->state.conn >= C_CONNECTED)

drivers/block/drbd/drbd_receiver.c

@@ -1229,7 +1229,7 @@ void drbd_bump_write_ordering(struct drbd_tconn *tconn, enum write_ordering_e wo
 	wo = min(pwo, wo);
 	rcu_read_lock();
 	idr_for_each_entry(&tconn->volumes, mdev, vnr) {
-		if (!get_ldev(mdev))
+		if (!get_ldev_if_state(mdev, D_ATTACHING))
 			continue;
 		dc = rcu_dereference(mdev->ldev->disk_conf);