block: refactor __blkdev_put

Reorder the code to have one big section for the last close, and to use
bdev_is_partition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/block_dev.c

@@ -1742,22 +1742,22 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
 		WARN_ON_ONCE(bdev->bd_holders);
 		sync_blockdev(bdev);
 		kill_bdev(bdev);
-
 		bdev_write_inode(bdev);
-	}
-	if (bdev->bd_contains == bdev) {
-		if (disk->fops->release)
+
+		if (!bdev_is_partition(bdev) && disk->fops->release)
 			disk->fops->release(disk, mode);
-	}
-	if (!bdev->bd_openers) {
+
 		disk_put_part(bdev->bd_part);
 		bdev->bd_part = NULL;
 		bdev->bd_disk = NULL;
-		if (bdev != bdev->bd_contains)
+		if (bdev_is_partition(bdev))
 			victim = bdev->bd_contains;
 		bdev->bd_contains = NULL;
 
 		put_disk_and_module(disk);
+	} else {
+		if (!bdev_is_partition(bdev) && disk->fops->release)
+			disk->fops->release(disk, mode);
 	}
 	mutex_unlock(&bdev->bd_mutex);
 	bdput(bdev);