md: remove lock_bdev / unlock_bdev

These wrappers for blkdev_get / blkdev_put just horribly confuse the
code with their odd naming.  Remove them and improve the error unwinding
in md_import_device with the now folded code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>

drivers/md/md.c

@@ -2493,34 +2493,6 @@ static void unbind_rdev_from_array(struct md_rdev *rdev)
 	queue_work(md_rdev_misc_wq, &rdev->del_work);
 }
 
-/*
- * prevent the device from being mounted, repartitioned or
- * otherwise reused by a RAID array (or any other kernel
- * subsystem), by bd_claiming the device.
- */
-static int lock_rdev(struct md_rdev *rdev, dev_t dev, int shared)
-{
-	int err = 0;
-	struct block_device *bdev;
-
-	bdev = blkdev_get_by_dev(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
-				 shared ? (struct md_rdev *)lock_rdev : rdev);
-	if (IS_ERR(bdev)) {
-		pr_warn("md: could not open device unknown-block(%u,%u).\n",
-			MAJOR(dev), MINOR(dev));
-		return PTR_ERR(bdev);
-	}
-	rdev->bdev = bdev;
-	return err;
-}
-
-static void unlock_rdev(struct md_rdev *rdev)
-{
-	struct block_device *bdev = rdev->bdev;
-	rdev->bdev = NULL;
-	blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
-}
-
 void md_autodetect_dev(dev_t dev);
 
 static void export_rdev(struct md_rdev *rdev)
@@ -2531,7 +2503,8 @@ static void export_rdev(struct md_rdev *rdev)
 	if (test_bit(AutoDetected, &rdev->flags))
 		md_autodetect_dev(rdev->bdev->bd_dev);
 #endif
-	unlock_rdev(rdev);
+	blkdev_put(rdev->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
+	rdev->bdev = NULL;
 	kobject_put(&rdev->kobj);
 }
 
@@ -3675,9 +3648,10 @@ EXPORT_SYMBOL_GPL(md_rdev_init);
  */
 static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor)
 {
-	int err;
+	static struct md_rdev *claim_rdev; /* just for claiming the bdev */
 	struct md_rdev *rdev;
 	sector_t size;
+	int err;
 
 	rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
 	if (!rdev)
@@ -3685,14 +3659,20 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 
 	err = md_rdev_init(rdev);
 	if (err)
-		goto abort_free;
+		goto out_free_rdev;
 	err = alloc_disk_sb(rdev);
 	if (err)
-		goto abort_free;
+		goto out_clear_rdev;
 
-	err = lock_rdev(rdev, newdev, super_format == -2);
-	if (err)
-		goto abort_free;
+	rdev->bdev = blkdev_get_by_dev(newdev,
+			FMODE_READ | FMODE_WRITE | FMODE_EXCL,
+			super_format == -2 ? claim_rdev : rdev);
+	if (IS_ERR(rdev->bdev)) {
+		pr_warn("md: could not open device unknown-block(%u,%u).\n",
+			MAJOR(newdev), MINOR(newdev));
+		err = PTR_ERR(rdev->bdev);
+		goto out_clear_rdev;
+	}
 
 	kobject_init(&rdev->kobj, &rdev_ktype);
 
@@ -3701,7 +3681,7 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 		pr_warn("md: %pg has zero or unknown size, marking faulty!\n",
 			rdev->bdev);
 		err = -EINVAL;
-		goto abort_free;
+		goto out_blkdev_put;
 	}
 
 	if (super_format >= 0) {
@@ -3711,21 +3691,22 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 			pr_warn("md: %pg does not have a valid v%d.%d superblock, not importing!\n",
 				rdev->bdev,
 				super_format, super_minor);
-			goto abort_free;
+			goto out_blkdev_put;
 		}
 		if (err < 0) {
 			pr_warn("md: could not read %pg's sb, not importing!\n",
 				rdev->bdev);
-			goto abort_free;
+			goto out_blkdev_put;
 		}
 	}
 
 	return rdev;
 
-abort_free:
-	if (rdev->bdev)
-		unlock_rdev(rdev);
+out_blkdev_put:
+	blkdev_put(rdev->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
+out_clear_rdev:
 	md_rdev_clear(rdev);
+out_free_rdev:
 	kfree(rdev);
 	return ERR_PTR(err);
 }