[PATCH 03/11] dax: simplify the dax_device <-> gendisk association

[Mike Snitzer]

On Mon, Oct 18 2021 at 12:40P -0400,
Christoph Hellwig <hch at lst.de> wrote:

> Replace the dax_host_hash with an xarray indexed by the pointer value
> of the gendisk, and require explicitl calls from the block drivers that
> want to associate their gendisk with a dax_device.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>

...

> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 79737aee516b1..a0a4703620650 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1683,6 +1683,7 @@ static void cleanup_mapped_device(struct mapped_device *md)
>  	bioset_exit(&md->io_bs);
>  
>  	if (md->dax_dev) {
> +		dax_remove_host(md->disk);
>  		kill_dax(md->dax_dev);
>  		put_dax(md->dax_dev);
>  		md->dax_dev = NULL;
> @@ -1784,10 +1785,11 @@ static struct mapped_device *alloc_dev(int minor)
>  	sprintf(md->disk->disk_name, "dm-%d", minor);
>  
>  	if (IS_ENABLED(CONFIG_FS_DAX)) {
> -		md->dax_dev = alloc_dax(md, md->disk->disk_name,
> -					&dm_dax_ops, 0);
> +		md->dax_dev = alloc_dax(md, &dm_dax_ops, 0);
>  		if (IS_ERR(md->dax_dev))
>  			goto bad;
> +		if (dax_add_host(md->dax_dev, md->disk))
> +			goto bad;
>  	}
>  
>  	format_dev_t(md->name, MKDEV(_major, minor));

Acked-by: Mike Snitzer <snitzer at redhat.com>