[PATCH v4 6/7] scsi_debug: Support configuring the maximum segment size

[Bart Van Assche <bvanassche@acm.org>]

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>
---
 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 8553277effb3..603c9faac56f 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 atomic_t retired_max_queue;	/* if > 0 then was prior max_queue */
@@ -5841,6 +5842,7 @@ 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,
@@ -5917,6 +5919,7 @@ 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)");
@@ -7816,6 +7819,7 @@ 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;