[PATCH 13/26] dm: convert to blk_alloc_disk/blk_cleanup_disk

[Hannes Reinecke]

On 5/21/21 7:51 AM, Christoph Hellwig wrote:
> Convert the dm driver to use the blk_alloc_disk and blk_cleanup_disk
> helpers to simplify gendisk and request_queue allocation.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>   drivers/md/dm.c | 16 +++++++---------
>   1 file changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index ca2aedd8ee7d..3c7c2d257018 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1801,13 +1801,13 @@ static void cleanup_mapped_device(struct mapped_device *md)
>   		md->disk->private_data = NULL;
>   		spin_unlock(&_minor_lock);
>   		del_gendisk(md->disk);
> -		put_disk(md->disk);
>   	}
>   
> -	if (md->queue) {
> +	if (md->queue)
>   		dm_queue_destroy_keyslot_manager(md->queue);
> -		blk_cleanup_queue(md->queue);
> -	}
> +
> +	if (md->disk)
> +		blk_cleanup_disk(md->disk);
>   
>   	cleanup_srcu_struct(&md->io_barrier);
>   

Can't these conditionals be merged into a single 'if (md->disk)'?
Eg like:

	if (md->disk) {
		spin_lock(&_minor_lock);
		md->disk->private_data = NULL;
		spin_unlock(&_minor_lock);
		del_gendisk(md->disk);
		dm_queue_destroy_keyslot_manager(md->queue);
		blk_cleanup_disk(md->queue);
	}

We're now always allocating 'md->disk' and 'md->queue' together,
so how can we end up in a situation where one is set without the other?

> @@ -1869,13 +1869,10 @@ static struct mapped_device *alloc_dev(int minor)
>   	 * established. If request-based table is loaded: blk-mq will
>   	 * override accordingly.
>   	 */
> -	md->queue = blk_alloc_queue(numa_node_id);
> -	if (!md->queue)
> -		goto bad;
> -
> -	md->disk = alloc_disk_node(1, md->numa_node_id);
> +	md->disk = blk_alloc_disk(md->numa_node_id);
>   	if (!md->disk)
>   		goto bad;
> +	md->queue = md->disk->queue;
>   
>   	init_waitqueue_head(&md->wait);
>   	INIT_WORK(&md->work, dm_wq_work);
> @@ -1888,6 +1885,7 @@ static struct mapped_device *alloc_dev(int minor)
>   
>   	md->disk->major = _major;
>   	md->disk->first_minor = minor;
> +	md->disk->minors = 1;
>   	md->disk->fops = &dm_blk_dops;
>   	md->disk->queue = md->queue;
>   	md->disk->private_data = md;
> 
Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare at suse.de                              +49 911 74053 688
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