Re: [PATCH v5 8/9] scsi_debug: Support configuring the maximum segment size

From: Douglas Gilbert <dgilbert@interlog.com>
To: Bart Van Assche <bvanassche@acm.org>, Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	jyescas@google.com, mcgrof@kernel.org,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>
Subject: Re: [PATCH v5 8/9] scsi_debug: Support configuring the maximum segment size
Date: Wed, 24 May 2023 16:50:36 -0400	[thread overview]
Message-ID: <d1c373e0-b27f-8e70-9c6b-2d131bf6b62e@interlog.com> (raw)
In-Reply-To: <20230522222554.525229-9-bvanassche@acm.org>

On 2023-05-22 18:25, Bart Van Assche wrote:
> Add a kernel module parameter for configuring the maximum segment size.
> This patch enables testing SCSI support for segments smaller than the
> page size.
> 
> Cc: Doug Gilbert <dgilbert@interlog.com>
> Cc: Martin K. Petersen <martin.petersen@oracle.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

Looks good.

Acked-by: Douglas Gilbert <dgilbert@interlog.com>

> ---
>   drivers/scsi/scsi_debug.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index 8c58128ad32a..e951c622bf64 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -752,6 +752,7 @@ static int sdebug_host_max_queue;	/* per host */
>   static int sdebug_lowest_aligned = DEF_LOWEST_ALIGNED;
>   static int sdebug_max_luns = DEF_MAX_LUNS;
>   static int sdebug_max_queue = SDEBUG_CANQUEUE;	/* per submit queue */
> +static unsigned int sdebug_max_segment_size = BLK_MAX_SEGMENT_SIZE;
>   static unsigned int sdebug_medium_error_start = OPT_MEDIUM_ERR_ADDR;
>   static int sdebug_medium_error_count = OPT_MEDIUM_ERR_NUM;
>   static int sdebug_ndelay = DEF_NDELAY;	/* if > 0 then unit is nanoseconds */
> @@ -5735,6 +5736,7 @@ module_param_named(lowest_aligned, sdebug_lowest_aligned, int, S_IRUGO);
>   module_param_named(lun_format, sdebug_lun_am_i, int, S_IRUGO | S_IWUSR);
>   module_param_named(max_luns, sdebug_max_luns, int, S_IRUGO | S_IWUSR);
>   module_param_named(max_queue, sdebug_max_queue, int, S_IRUGO | S_IWUSR);
> +module_param_named(max_segment_size, sdebug_max_segment_size, uint, S_IRUGO);
>   module_param_named(medium_error_count, sdebug_medium_error_count, int,
>   		   S_IRUGO | S_IWUSR);
>   module_param_named(medium_error_start, sdebug_medium_error_start, int,
> @@ -5811,6 +5813,7 @@ MODULE_PARM_DESC(lowest_aligned, "lowest aligned lba (def=0)");
>   MODULE_PARM_DESC(lun_format, "LUN format: 0->peripheral (def); 1 --> flat address method");
>   MODULE_PARM_DESC(max_luns, "number of LUNs per target to simulate(def=1)");
>   MODULE_PARM_DESC(max_queue, "max number of queued commands (1 to max(def))");
> +MODULE_PARM_DESC(max_segment_size, "max bytes in a single segment");
>   MODULE_PARM_DESC(medium_error_count, "count of sectors to return follow on MEDIUM error");
>   MODULE_PARM_DESC(medium_error_start, "starting sector number to return MEDIUM error");
>   MODULE_PARM_DESC(ndelay, "response delay in nanoseconds (def=0 -> ignore)");
> @@ -7723,6 +7726,7 @@ static int sdebug_driver_probe(struct device *dev)
>   
>   	sdebug_driver_template.can_queue = sdebug_max_queue;
>   	sdebug_driver_template.cmd_per_lun = sdebug_max_queue;
> +	sdebug_driver_template.max_segment_size = sdebug_max_segment_size;
>   	if (!sdebug_clustering)
>   		sdebug_driver_template.dma_boundary = PAGE_SIZE - 1;
>   