dm: allow autoloading of dm mod

Add devname:mapper/control and MAPPER_CTRL_MINOR module alias
to support dm-mod module autoloading.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Peter Rajnoha <prajnoha@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 4d4ced8..3e39193 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1599,12 +1599,15 @@
 };
 
 static struct miscdevice _dm_misc = {
-	.minor 		= MISC_DYNAMIC_MINOR,
+	.minor		= MAPPER_CTRL_MINOR,
 	.name  		= DM_NAME,
-	.nodename	= "mapper/control",
+	.nodename	= DM_DIR "/" DM_CONTROL_NODE,
 	.fops  		= &_ctl_fops
 };
 
+MODULE_ALIAS_MISCDEV(MAPPER_CTRL_MINOR);
+MODULE_ALIAS("devname:" DM_DIR "/" DM_CONTROL_NODE);
+
 /*
  * Create misc character device and link to DM_DIR/control.
  */