Re: [PATCH 6/6] scsi_debug: add ability to enable clustering

[Douglas Gilbert <dgilbert@interlog.com>]

On 14-01-05 06:33 PM, Akinobu Mita wrote:
> This adds a module parameter to enable clustering.
>
> Without enabling clustering support, the transfer length for read and
> write scsi commands is limited upto 8MB when page size is 4KB and
> sg_tablesize is 2048 (= SCSI_MAX_SG_CHAIN_SEGMENTS).  I would like to
> test commands with more than that transfer length.
>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
> Cc: Douglas Gilbert <dgilbert@interlog.com>
> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> Cc: linux-scsi@vger.kernel.org
> ---
>   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 aca70c1..9297688d 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -196,6 +196,7 @@ static unsigned int scsi_debug_unmap_max_blocks = DEF_UNMAP_MAX_BLOCKS;
>   static unsigned int scsi_debug_unmap_max_desc = DEF_UNMAP_MAX_DESC;
>   static unsigned int scsi_debug_write_same_length = DEF_WRITESAME_LENGTH;
>   static bool scsi_debug_removable = DEF_REMOVABLE;
> +static bool scsi_debug_clustering;
>
>   static int scsi_debug_cmnd_count = 0;
>
> @@ -2787,6 +2788,7 @@ module_param_named(opts, scsi_debug_opts, int, S_IRUGO | S_IWUSR);
>   module_param_named(physblk_exp, scsi_debug_physblk_exp, int, S_IRUGO);
>   module_param_named(ptype, scsi_debug_ptype, int, S_IRUGO | S_IWUSR);
>   module_param_named(removable, scsi_debug_removable, bool, S_IRUGO | S_IWUSR);
> +module_param_named(clustering, scsi_debug_clustering, bool, S_IRUGO);

Umm, clustering is writeable, so: S_IRUGO | S_IWUSR

>   module_param_named(scsi_level, scsi_debug_scsi_level, int, S_IRUGO);
>   module_param_named(sector_size, scsi_debug_sector_size, int, S_IRUGO);
>   module_param_named(unmap_alignment, scsi_debug_unmap_alignment, int, S_IRUGO);
> @@ -3953,6 +3955,8 @@ static int sdebug_driver_probe(struct device * dev)
>   	sdbg_host = to_sdebug_host(dev);
>
>   	sdebug_driver_template.can_queue = scsi_debug_max_queue;
> +	if (scsi_debug_clustering)
> +		sdebug_driver_template.use_clustering = ENABLE_CLUSTERING;
>   	hpnt = scsi_host_alloc(&sdebug_driver_template, sizeof(sdbg_host));
>   	if (NULL == hpnt) {
>   		printk(KERN_ERR "%s: scsi_register failed\n", __func__);
>

And please document this extra parameter for modinfo.
Something like:
   MODULE_PARM_DESC(clustering, "when set enables larger transfers (def=0)");

placed in alphabetical order.

Doug Gilbert