Re: [dm-devel] [PATCH v3 09/19] nvme: Add pr_ops read_keys support

From: Christoph Hellwig <hch@lst.de>
To: Mike Christie <michael.christie@oracle.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org,
	chaitanyak@nvidia.com, bvanassche@acm.org,
	linux-scsi@vger.kernel.org, snitzer@kernel.org,
	linux-nvme@lists.infradead.org,
	james.bottomley@hansenpartnership.com, dm-devel@redhat.com,
	target-devel@vger.kernel.org, martin.petersen@oracle.com,
	kbusch@kernel.org, hch@lst.de
Subject: Re: [dm-devel] [PATCH v3 09/19] nvme: Add pr_ops read_keys support
Date: Sun, 30 Oct 2022 09:17:08 +0100	[thread overview]
Message-ID: <20221030081708.GA4774@lst.de> (raw)
In-Reply-To: <20221026231945.6609-10-michael.christie@oracle.com>

On Wed, Oct 26, 2022 at 06:19:35PM -0500, Mike Christie wrote:
> This patch adds support for the pr_ops read_keys callout by calling the
> NVMe Reservation Report helper, then parsing that info to get the
> controller's registered keys. Because the callout is only used in the
> kernel where the callers do not know about controller/host IDs, the
> callout just returns the registered keys which is required by the SCSI PR
> in READ KEYS command.
> 
> Signed-off-by: Mike Christie <michael.christie@oracle.com>
> ---
>  drivers/nvme/host/pr.c | 73 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/nvme.h   |  4 +++
>  2 files changed, 77 insertions(+)
> 
> diff --git a/drivers/nvme/host/pr.c b/drivers/nvme/host/pr.c
> index aa88c55879b2..df7eb2440c67 100644
> --- a/drivers/nvme/host/pr.c
> +++ b/drivers/nvme/host/pr.c
> @@ -118,10 +118,83 @@ static int nvme_pr_release(struct block_device *bdev, u64 key, enum pr_type type
>  	return nvme_pr_command(bdev, cdw10, key, 0, nvme_cmd_resv_release);
>  }
>  
> +static int nvme_pr_resv_report(struct block_device *bdev, u8 *data,
> +		u32 data_len, bool *eds)

Is there any good reason this method seems to take a u8 instead of a void
pointer?  As that seems to make a few things a bit messy.

> +	if (IS_ENABLED(CONFIG_NVME_MULTIPATH) &&
> +	    bdev->bd_disk->fops == &nvme_ns_head_ops)
> +		ret = nvme_send_ns_head_pr_command(bdev, &c, data, data_len);
> +	else
> +		ret = nvme_send_ns_pr_command(bdev->bd_disk->private_data, &c,
> +					      data, data_len);

Can you please add a hlper for this logic?

> +	for (i = 0; i < num_ret_keys; i++) {
> +		if (eds) {
> +			keys_info->keys[i] =
> +					le64_to_cpu(status->regctl_eds[i].rkey);
> +		} else {
> +			keys_info->keys[i] =
> +					le64_to_cpu(status->regctl_ds[i].rkey);
> +		}

If you shorten the status variable name to something like rs this becomes
much easier to follow :)

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