Re: [PATCH 27/30] scm_blk: use blk_mq_alloc_disk and blk_cleanup_disk

[Niklas Schnelle <schnelle@linux.ibm.com>]

On Wed, 2021-06-02 at 09:53 +0300, Christoph Hellwig wrote:
> Use blk_mq_alloc_disk and blk_cleanup_disk to simplify the gendisk and
> request_queue allocation.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/s390/block/scm_blk.c | 21 ++++++---------------
>  1 file changed, 6 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
> index a4f6f2e62b1d..88cba6212ee2 100644
> --- a/drivers/s390/block/scm_blk.c
> +++ b/drivers/s390/block/scm_blk.c
> @@ -462,12 +462,12 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
>  	if (ret)
>  		goto out;
>  
> -	rq = blk_mq_init_queue(&bdev->tag_set);
> -	if (IS_ERR(rq)) {
> -		ret = PTR_ERR(rq);
> +	bdev->gendisk = blk_mq_alloc_disk(&bdev->tag_set, scmdev);
> +	if (IS_ERR(bdev->gendisk)) {
> +		ret = PTR_ERR(bdev->gendisk);
>  		goto out_tag;
>  	}
> -	bdev->rq = rq;
> +	rq = bdev->rq = bdev->gendisk->queue;
>  	nr_max_blk = min(scmdev->nr_max_block,
>  			 (unsigned int) (PAGE_SIZE / sizeof(struct aidaw)));
>  
> @@ -477,17 +477,11 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
>  	blk_queue_flag_set(QUEUE_FLAG_NONROT, rq);
>  	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, rq);
>  
> -	bdev->gendisk = alloc_disk(SCM_NR_PARTS);
> -	if (!bdev->gendisk) {
> -		ret = -ENOMEM;
> -		goto out_queue;
> -	}
> -	rq->queuedata = scmdev;
>  	bdev->gendisk->private_data = scmdev;
>  	bdev->gendisk->fops = &scm_blk_devops;
> -	bdev->gendisk->queue = rq;
>  	bdev->gendisk->major = scm_major;
>  	bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
> +	bdev->gendisk->minors = SCM_NR_PARTS;
>  
>  	len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
>  	if (devindex > 25) {
> @@ -504,8 +498,6 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
>  	device_add_disk(&scmdev->dev, bdev->gendisk, NULL);
>  	return 0;
>  
> -out_queue:
> -	blk_cleanup_queue(rq);
>  out_tag:
>  	blk_mq_free_tag_set(&bdev->tag_set);
>  out:
> @@ -516,9 +508,8 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
>  void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
>  {
>  	del_gendisk(bdev->gendisk);
> -	blk_cleanup_queue(bdev->gendisk->queue);
> +	blk_cleanup_disk(bdev->gendisk);
>  	blk_mq_free_tag_set(&bdev->tag_set);
> -	put_disk(bdev->gendisk);
>  }
>  
>  void scm_blk_set_available(struct scm_blk_dev *bdev)

Not an expert on SCM or this code but I gave this a quick test and it
seems to work fine.

Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>