[PATCH] scsi_debug: Add OPTIMAL TRANSFER LENGTH GRANULARITY option.

[Lukas Herbolt <lherbolt@redhat.com>]

Signed-off-by: Lukas Herbolt <lherbolt@redhat.com>
---
 drivers/scsi/scsi_debug.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index cf04a36..6910ea1 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -125,6 +125,7 @@ static const char *sdebug_version_date = "20160430";
 #define DEF_OPTS   0
 #define DEF_OPT_BLKS 1024
 #define DEF_PHYSBLK_EXP 0
+#define DEF_OPT_XFERLEN_EXP 0
 #define DEF_PTYPE   TYPE_DISK
 #define DEF_REMOVABLE false
 #define DEF_SCSI_LEVEL   7    /* INQUIRY, byte2 [6->SPC-4; 7->SPC-5] */
@@ -590,6 +591,7 @@ static int sdebug_num_tgts = DEF_NUM_TGTS; /* targets per host */
 static int sdebug_opt_blks = DEF_OPT_BLKS;
 static int sdebug_opts = DEF_OPTS;
 static int sdebug_physblk_exp = DEF_PHYSBLK_EXP;
+static int sdebug_opt_xferlen_exp = DEF_OPT_XFERLEN_EXP;
 static int sdebug_ptype = DEF_PTYPE; /* SCSI peripheral device type */
 static int sdebug_scsi_level = DEF_SCSI_LEVEL;
 static int sdebug_sector_size = DEF_SECTOR_SIZE;
@@ -1205,7 +1207,10 @@ static int inquiry_vpd_b0(unsigned char *arr)
 	memcpy(arr, vpdb0_data, sizeof(vpdb0_data));
 
 	/* Optimal transfer length granularity */
-	gran = 1 << sdebug_physblk_exp;
+	if (sdebug_opt_xferlen_exp != 0 && sdebug_physblk_exp < sdebug_opt_xferlen_exp)
+		gran = 1 <<  sdebug_opt_xferlen_exp;
+	else
+		gran = 1 << sdebug_physblk_exp;
 	put_unaligned_be16(gran, arr + 2);
 
 	/* Maximum Transfer Length */
@@ -4161,6 +4166,7 @@ module_param_named(num_tgts, sdebug_num_tgts, int, S_IRUGO | S_IWUSR);
 module_param_named(opt_blks, sdebug_opt_blks, int, S_IRUGO);
 module_param_named(opts, sdebug_opts, int, S_IRUGO | S_IWUSR);
 module_param_named(physblk_exp, sdebug_physblk_exp, int, S_IRUGO);
+module_param_named(opt_xferlen_exp, sdebug_opt_xferlen_exp, int, S_IRUGO);
 module_param_named(ptype, sdebug_ptype, int, S_IRUGO | S_IWUSR);
 module_param_named(removable, sdebug_removable, bool, S_IRUGO | S_IWUSR);
 module_param_named(scsi_level, sdebug_scsi_level, int, S_IRUGO);
@@ -4212,6 +4218,7 @@ MODULE_PARM_DESC(num_tgts, "number of targets per host to simulate(def=1)");
 MODULE_PARM_DESC(opt_blks, "optimal transfer length in blocks (def=1024)");
 MODULE_PARM_DESC(opts, "1->noise, 2->medium_err, 4->timeout, 8->recovered_err... (def=0)");
 MODULE_PARM_DESC(physblk_exp, "physical block exponent (def=0)");
+MODULE_PARM_DESC(opt_xferlen_exp, "optimal transfer length granularity exponent (def=physblk_exp)");
 MODULE_PARM_DESC(ptype, "SCSI peripheral type(def=0[disk])");
 MODULE_PARM_DESC(removable, "claim to have removable media (def=0)");
 MODULE_PARM_DESC(scsi_level, "SCSI level to simulate(def=7[SPC-5])");
-- 
2.7.4