Re: [PATCH v7 7/8] xfs: Implement ->notify_failure() for XFS

[Christoph Hellwig]

On Fri, Sep 24, 2021 at 09:09:58PM +0800, Shiyang Ruan wrote:
> +void fs_dax_register_holder(struct dax_device *dax_dev, void *holder,
> +		const struct dax_holder_operations *ops)
> +{
> +	dax_set_holder(dax_dev, holder, ops);
> +}
> +EXPORT_SYMBOL_GPL(fs_dax_register_holder);
> +
> +void fs_dax_unregister_holder(struct dax_device *dax_dev)
> +{
> +	dax_set_holder(dax_dev, NULL, NULL);
> +}
> +EXPORT_SYMBOL_GPL(fs_dax_unregister_holder);
> +
> +void *fs_dax_get_holder(struct dax_device *dax_dev)
> +{
> +	return dax_get_holder(dax_dev);
> +}
> +EXPORT_SYMBOL_GPL(fs_dax_get_holder);

These should not be in a XFS patch.  But why do we even need this
wrappers?

> @@ -377,6 +385,8 @@ xfs_close_devices(
>  
>  		xfs_free_buftarg(mp->m_logdev_targp);
>  		xfs_blkdev_put(logdev);
> +		if (dax_logdev)
> +			fs_dax_unregister_holder(dax_logdev);
>  		fs_put_dax(dax_logdev);

I'd prefer to include the fs_dax_unregister_holder in the fs_put_dax
call to avoid callers failing to unregister it.

> @@ -411,6 +425,9 @@ xfs_open_devices(
>  	struct block_device	*logdev = NULL, *rtdev = NULL;
>  	int			error;
>  
> +	if (dax_ddev)
> +		fs_dax_register_holder(dax_ddev, mp,
> +				&xfs_dax_holder_operations);

I'd include the holder registration with fs_dax_get_by_bdev as well.