[Drbd-dev] [PATCH 01/32] block: Provide blkdev_get_handle_* functions

[Keith Busch]

On Tue, Jul 04, 2023 at 02:21:28PM +0200, Jan Kara wrote:
> +struct bdev_handle *blkdev_get_handle_by_dev(dev_t dev, blk_mode_t mode,
> +		void *holder, const struct blk_holder_ops *hops)
> +{
> +	struct bdev_handle *handle = kmalloc(sizeof(struct bdev_handle),
> +					     GFP_KERNEL);

I believe 'sizeof(*handle)' is the preferred style.

> +	struct block_device *bdev;
> +
> +	if (!handle)
> +		return ERR_PTR(-ENOMEM);
> +	bdev = blkdev_get_by_dev(dev, mode, holder, hops);
> +	if (IS_ERR(bdev))
> +		return ERR_CAST(bdev);

Need a 'kfree(handle)' before the error return. Or would it be simpler
to get the bdev first so you can check the mode settings against a
read-only bdev prior to the kmalloc?

> +	handle->bdev = bdev;
> +	handle->holder = holder;
> +	return handle;
> +}
> +EXPORT_SYMBOL(blkdev_get_handle_by_dev);
> +
>  /**
>   * blkdev_get_by_path - open a block device by name
>   * @path: path to the block device to open
> @@ -884,6 +902,28 @@ struct block_device *blkdev_get_by_path(const char *path, blk_mode_t mode,
>  }
>  EXPORT_SYMBOL(blkdev_get_by_path);
>  
> +struct bdev_handle *blkdev_get_handle_by_path(const char *path, blk_mode_t mode,
> +		void *holder, const struct blk_holder_ops *hops)
> +{
> +	struct bdev_handle *handle;
> +	dev_t dev;
> +	int error;
> +
> +	error = lookup_bdev(path, &dev);
> +	if (error)
> +		return ERR_PTR(error);
> +
> +	handle = blkdev_get_handle_by_dev(dev, mode, holder, hops);
> +	if (!IS_ERR(handle) && (mode & BLK_OPEN_WRITE) &&
> +	    bdev_read_only(handle->bdev)) {
> +		blkdev_handle_put(handle);
> +		return ERR_PTR(-EACCES);
> +	}
> +
> +	return handle;
> +}
> +EXPORT_SYMBOL(blkdev_get_handle_by_path);