[PATCH v2 09/20] nvme: Add helper to execute Reservation Report

[Chaitanya Kulkarni]

On 8/8/22 17:04, Mike Christie wrote:
> This adds a helper to execute the Reservation Report. The next patches
> will then convert call it and convert that info to read_keys and
> read_reservation.
> 
> Signed-off-by: Mike Christie <michael.christie at oracle.com>
> ---
>   drivers/nvme/host/core.c | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 0dc768ae0c16..6b22a5dec122 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -2196,6 +2196,33 @@ 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)
> +{
> +	struct nvme_command c = { };
> +	int ret;
> +
> +	c.common.opcode = nvme_cmd_resv_report;
> +	c.common.cdw10 = cpu_to_le32(nvme_bytes_to_numd(data_len));
> +	c.common.cdw11 = 1;
> +	*eds = true;
> +
> +retry:
> +	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);
> +	if (ret == NVME_SC_HOST_ID_INCONSIST && c.common.cdw11) {
> +		c.common.cdw11 = 0;
> +		*eds = false;
> +		goto retry;

Unconditional retries without any limit can create problems,
perhaps consider adding some soft limits.

-ck