From mboxrd@z Thu Jan  1 00:00:00 1970
From: kenneth.heitke@intel.com (Heitke, Kenneth)
Date: Fri, 29 Mar 2019 11:27:26 -0600
Subject: [PATCH 1/2] nvmet: make MDTS value configurable
In-Reply-To: <20190329120404.55637-2-hare@suse.de>
References: <20190329120404.55637-1-hare@suse.de>
 <20190329120404.55637-2-hare@suse.de>
Message-ID: <bb74b5ef-40cb-f2cb-6d39-018b1e8a0a97@intel.com>



On 3/29/2019 6:04 AM, Hannes Reinecke wrote:
> For testing the bio splitting algorithm it's useful to be able to
> modify the mdts value.
> 
> Signed-off-by: Hannes Reinecke <hare at suse.com>
> ---
>   drivers/nvme/target/admin-cmd.c |  3 +--
>   drivers/nvme/target/configfs.c  | 27 +++++++++++++++++++++++++++
>   drivers/nvme/target/nvmet.h     |  2 ++
>   3 files changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
> index 76250181fee0..1c4cb371fac8 100644
> --- a/drivers/nvme/target/admin-cmd.c
> +++ b/drivers/nvme/target/admin-cmd.c
> @@ -311,8 +311,7 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
>   	/* we support multiple ports, multiples hosts and ANA: */
>   	id->cmic = (1 << 0) | (1 << 1) | (1 << 3);
>   
> -	/* no limit on data transfer sizes for now */
> -	id->mdts = 0;
> +	id->mdts = ctrl->subsys->mdts;
>   	id->cntlid = cpu_to_le16(ctrl->cntlid);
>   	id->ver = cpu_to_le32(ctrl->subsys->ver);
>   
> diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
> index adb79545cdd7..63b9991de79e 100644
> --- a/drivers/nvme/target/configfs.c
> +++ b/drivers/nvme/target/configfs.c
> @@ -859,10 +859,37 @@ static ssize_t nvmet_subsys_attr_serial_store(struct config_item *item,
>   }
>   CONFIGFS_ATTR(nvmet_subsys_, attr_serial);
>   
> +static ssize_t nvmet_subsys_attr_mdts_show(struct config_item *item,
> +					   char *page)
> +{
> +	struct nvmet_subsys *subsys = to_subsys(item);
> +
> +	return snprintf(page, PAGE_SIZE, "%u\n", subsys->mdts);
> +}
> +
> +static ssize_t nvmet_subsys_attr_mdts_store(struct config_item *item,
> +					    const char *page, size_t count)
> +{
> +	struct nvmet_subsys *subsys = to_subsys(item);
> +	unsigned int mdts;
> +	int ret;
> +
> +	ret = kstrtou32(page, 0, &mdts);
> +	if (ret)
> +		return ret;
> +	down_write(&nvmet_config_sem);
> +	subsys->mdts = mdts;

What is the convention, if any, for taking a possible 32-bit value and
putting it into an 8-bit variable? Should there be a warning if the
value is greater than the max allowed?

> +	up_write(&nvmet_config_sem);
> +
> +	return count;
> +}
> +CONFIGFS_ATTR(nvmet_subsys_, attr_mdts);
> +
>   static struct configfs_attribute *nvmet_subsys_attrs[] = {
>   	&nvmet_subsys_attr_attr_allow_any_host,
>   	&nvmet_subsys_attr_attr_version,
>   	&nvmet_subsys_attr_attr_serial,
> +	&nvmet_subsys_attr_attr_mdts,
>   	NULL,
>   };
>   
> diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
> index 51e49efd7849..f05f069f83ea 100644
> --- a/drivers/nvme/target/nvmet.h
> +++ b/drivers/nvme/target/nvmet.h
> @@ -217,6 +217,8 @@ struct nvmet_subsys {
>   	bool			allow_any_host;
>   
>   	u16			max_qid;
> +	u8			mdts;
> +	u8			mpsmin;
>   
>   	u64			ver;
>   	u64			serial;
>