RDMA/srp: Add parse function for maximum initiator to target IU size

index b5960351bec0..b829dab0df77 100644
@@ -3411,6 +3411,7 @@ enum {
 	SRP_OPT_IP_SRC		= 1 << 15,
 	SRP_OPT_IP_DEST		= 1 << 16,
 	SRP_OPT_TARGET_CAN_QUEUE= 1 << 17,
+	SRP_OPT_MAX_IT_IU_SIZE  = 1 << 18,
 };
 
 static unsigned int srp_opt_mandatory[] = {

@@ -3443,6 +3444,7 @@ static const match_table_t srp_opt_tokens = {
 	{ SRP_OPT_QUEUE_SIZE,		"queue_size=%d"		},
 	{ SRP_OPT_IP_SRC,		"src=%s"		},
 	{ SRP_OPT_IP_DEST,		"dest=%s"		},
+	{ SRP_OPT_MAX_IT_IU_SIZE,	"max_it_iu_size=%d"	},
 	{ SRP_OPT_ERR,			NULL 			}
 };
 

@@ -3736,6 +3738,14 @@ static int srp_parse_options(struct net *net, const char *buf,
 			target->tl_retry_count = token;
 			break;
 
+		case SRP_OPT_MAX_IT_IU_SIZE:
+			if (match_int(args, &token) || token < 0) {
+				pr_warn("bad maximum initiator to target IU size '%s'\n", p);
+				goto out;
+			}
+			target->max_it_iu_size = token;
+			break;
+
 		default:
 			pr_warn("unknown parameter or missing value '%s' in target creation request\n",
 				p);

index b2861cd2087a..105b2bc6aa2f 100644
@@ -209,6 +209,7 @@ struct srp_target_port {
 	u32			ch_count;
 	u32			lkey;
 	enum srp_target_state	state;
+	uint32_t		max_it_iu_size;
 	unsigned int		cmd_sg_cnt;
 	unsigned int		indirect_size;
 	bool			allow_ext_sg;

index b829dab0df77..b3bf5d552de9 100644
@@ -139,7 +139,7 @@ MODULE_PARM_DESC(use_imm_data,
 
 static unsigned int srp_max_imm_data = 8 * 1024;
 module_param_named(max_imm_data, srp_max_imm_data, uint, 0644);
-MODULE_PARM_DESC(max_imm_data, "Maximum immediate data size.");
+MODULE_PARM_DESC(max_imm_data, "Maximum immediate data size if max_it_iu_size has not been specified.");
 
 static unsigned ch_count;
 module_param(ch_count, uint, 0444);

@@ -1362,15 +1362,23 @@ static void srp_terminate_io(struct srp_rport *rport)
 }
 
 /* Calculate maximum initiator to target information unit length. */
-static uint32_t srp_max_it_iu_len(int cmd_sg_cnt, bool use_imm_data)
+static uint32_t srp_max_it_iu_len(int cmd_sg_cnt, bool use_imm_data,
+				  uint32_t max_it_iu_size)
 {
 	uint32_t max_iu_len = sizeof(struct srp_cmd) + SRP_MAX_ADD_CDB_LEN +
 		sizeof(struct srp_indirect_buf) +
 		cmd_sg_cnt * sizeof(struct srp_direct_buf);
 
-	if (use_imm_data)
-		max_iu_len = max(max_iu_len, SRP_IMM_DATA_OFFSET +
-				 srp_max_imm_data);
+	if (use_imm_data) {
+		if (max_it_iu_size == 0) {
+			max_iu_len = max(max_iu_len,
+			   SRP_IMM_DATA_OFFSET + srp_max_imm_data);
+		} else {
+			max_iu_len = max_it_iu_size;
+		}
+	}
+
+	pr_debug("max_iu_len = %d\n", max_iu_len);
 
 	return max_iu_len;
 }

@@ -1389,7 +1397,8 @@ static int srp_rport_reconnect(struct srp_rport *rport)
 	struct srp_target_port *target = rport->lld_data;
 	struct srp_rdma_ch *ch;
 	uint32_t max_iu_len = srp_max_it_iu_len(target->cmd_sg_cnt,
-						srp_use_imm_data);
+						srp_use_imm_data,
+						target->max_it_iu_size);
 	int i, j, ret = 0;
 	bool multich = false;
 

@@ -2538,7 +2547,8 @@ static void srp_cm_rep_handler(struct ib_cm_id *cm_id,
 		ch->req_lim       = be32_to_cpu(lrsp->req_lim_delta);
 		ch->use_imm_data  = lrsp->rsp_flags & SRP_LOGIN_RSP_IMMED_SUPP;
 		ch->max_it_iu_len = srp_max_it_iu_len(target->cmd_sg_cnt,
-						      ch->use_imm_data);
+						      ch->use_imm_data,
+						      target->max_it_iu_size);
 		WARN_ON_ONCE(ch->max_it_iu_len >
 			     be32_to_cpu(lrsp->max_it_iu_len));
 

@@ -3897,7 +3907,9 @@ static ssize_t srp_create_target(struct device *dev,
 	target->mr_per_cmd = mr_per_cmd;
 	target->indirect_size = target->sg_tablesize *
 				sizeof (struct srp_direct_buf);
-	max_iu_len = srp_max_it_iu_len(target->cmd_sg_cnt, srp_use_imm_data);
+	max_iu_len = srp_max_it_iu_len(target->cmd_sg_cnt,
+				       srp_use_imm_data,
+				       target->max_it_iu_size);
 
 	INIT_WORK(&target->tl_err_work, srp_tl_err_work);
 	INIT_WORK(&target->remove_work, srp_remove_work);