iscsi-target: add void (*iscsit_get_r2t_ttt)()

Add void (*iscsit_get_r2t_ttt)() to
struct iscsit_transport, iscsi-target
uses this callback to get
r2t->targ_xfer_tag.

cxgbit.ko needs this callback
for Direct Data Placement of Data Out
pdus, adapter uses ttt in Data Out pdus
for placing data directly in to the host
buffers.
Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target.c

@@ -3039,7 +3039,10 @@ static int iscsit_send_r2t(
 	int_to_scsilun(cmd->se_cmd.orig_fe_lun,
 			(struct scsi_lun *)&hdr->lun);
 	hdr->itt		= cmd->init_task_tag;
-	r2t->targ_xfer_tag	= session_get_next_ttt(conn->sess);
+	if (conn->conn_transport->iscsit_get_r2t_ttt)
+		conn->conn_transport->iscsit_get_r2t_ttt(conn, cmd, r2t);
+	else
+		r2t->targ_xfer_tag = session_get_next_ttt(conn->sess);
 	hdr->ttt		= cpu_to_be32(r2t->targ_xfer_tag);
 	hdr->statsn		= cpu_to_be32(conn->stat_sn);
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);

include/target/iscsi/iscsi_transport.h

@@ -27,6 +27,8 @@ struct iscsit_transport {
 	void (*iscsit_release_cmd)(struct iscsi_conn *, struct iscsi_cmd *);
 	void (*iscsit_get_rx_pdu)(struct iscsi_conn *);
 	int (*iscsit_validate_params)(struct iscsi_conn *);
+	void (*iscsit_get_r2t_ttt)(struct iscsi_conn *, struct iscsi_cmd *,
+				   struct iscsi_r2t *);
 	enum target_prot_op (*iscsit_get_sup_prot_ops)(struct iscsi_conn *);
 };