block: implement and use {disk|part}_to_dev()

Implement {disk|part}_to_dev() and use them to access generic device
instead of directly dereferencing {disk|part}->dev.  To make sure no
user is left behind, rename generic devices fields to __dev.

This is in preparation of unifying partition 0 handling with other
partitions.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 0c39782..3edb6cb 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -109,12 +109,12 @@
 static int
 aoedisk_add_sysfs(struct aoedev *d)
 {
-	return sysfs_create_group(&d->gd->dev.kobj, &attr_group);
+	return sysfs_create_group(&disk_to_dev(d->gd)->kobj, &attr_group);
 }
 void
 aoedisk_rm_sysfs(struct aoedev *d)
 {
-	sysfs_remove_group(&d->gd->dev.kobj, &attr_group);
+	sysfs_remove_group(&disk_to_dev(d->gd)->kobj, &attr_group);
 }
 
 static int
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 1778e4a..7b33512 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -403,7 +403,7 @@
 	BUG_ON(lo->magic != LO_MAGIC);
 
 	lo->pid = current->pid;
-	ret = sysfs_create_file(&lo->disk->dev.kobj, &pid_attr.attr);
+	ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 	if (ret) {
 		printk(KERN_ERR "nbd: sysfs_create_file failed!");
 		return ret;
@@ -412,7 +412,7 @@
 	while ((req = nbd_read_stat(lo)) != NULL)
 		nbd_end_request(req);
 
-	sysfs_remove_file(&lo->disk->dev.kobj, &pid_attr.attr);
+	sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 	return 0;
 }
 
diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index a51a30e..70aa86c 100644
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -1188,7 +1188,7 @@
 {
 	struct gendisk *p = data;
 	*part &= (1 << PARTN_BITS) - 1;
-	return &p->dev.kobj;
+	return &disk_to_dev(p)->kobj;
 }
 
 static int exact_lock(dev_t dev, void *data)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 6536247..6378066 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1186,7 +1186,7 @@
 	list_splice_init(&md->uevent_list, &uevents);
 	spin_unlock_irqrestore(&md->uevent_lock, flags);
 
-	dm_send_uevents(&uevents, &md->disk->dev.kobj);
+	dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
 
 	atomic_inc(&md->event_nr);
 	wake_up(&md->eventq);
@@ -1643,7 +1643,7 @@
  *---------------------------------------------------------------*/
 void dm_kobject_uevent(struct mapped_device *md)
 {
-	kobject_uevent(&md->disk->dev.kobj, KOBJ_CHANGE);
+	kobject_uevent(&disk_to_dev(md->disk)->kobj, KOBJ_CHANGE);
 }
 
 uint32_t dm_next_uevent_seq(struct mapped_device *md)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index deeac4b..96e9fcc 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1465,9 +1465,9 @@
 		goto fail;
 
 	if (rdev->bdev->bd_part)
-		ko = &rdev->bdev->bd_part->dev.kobj;
+		ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
 	else
-		ko = &rdev->bdev->bd_disk->dev.kobj;
+		ko = &disk_to_dev(rdev->bdev->bd_disk)->kobj;
 	if ((err = sysfs_create_link(&rdev->kobj, ko, "block"))) {
 		kobject_del(&rdev->kobj);
 		goto fail;
@@ -3470,8 +3470,8 @@
 	disk->queue = mddev->queue;
 	add_disk(disk);
 	mddev->gendisk = disk;
-	error = kobject_init_and_add(&mddev->kobj, &md_ktype, &disk->dev.kobj,
-				     "%s", "md");
+	error = kobject_init_and_add(&mddev->kobj, &md_ktype,
+				     &disk_to_dev(disk)->kobj, "%s", "md");
 	mutex_unlock(&disks_mutex);
 	if (error)
 		printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
@@ -3761,7 +3761,7 @@
 	sysfs_notify(&mddev->kobj, NULL, "array_state");
 	sysfs_notify(&mddev->kobj, NULL, "sync_action");
 	sysfs_notify(&mddev->kobj, NULL, "degraded");
-	kobject_uevent(&mddev->gendisk->dev.kobj, KOBJ_CHANGE);
+	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
 	return 0;
 }