[SCSI] libiscsi: allow drivers to modify the itt sent to the target

bnx2i and cxgb3i need to encode LLD info in the itt so that
the firmware/hardware can process the pdu. This patch allows
the LLDs to encode info in the task->hdr->itt that they
setup in the alloc_pdu callout (any resources that are allocated
can be freed with the pdu in the cleanup_task callout). If
the LLD encodes info in the itt they should implement a
parse_pdu_itt callout. If parse_pdu_itt is not implemented
libiscsi will do the right thing for the LLD.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

include/scsi/libiscsi.h

@@ -30,6 +30,7 @@
 #include <linux/workqueue.h>
 #include <scsi/iscsi_proto.h>
 #include <scsi/iscsi_if.h>
+#include <scsi/scsi_transport_iscsi.h>
 
 struct scsi_transport_template;
 struct scsi_host_template;
@@ -70,12 +71,12 @@ enum {
 /* Connection suspend "bit" */
 #define ISCSI_SUSPEND_BIT		1
 
-#define ISCSI_ITT_MASK			(0x1fff)
+#define ISCSI_ITT_MASK			0x1fff
 #define ISCSI_TOTAL_CMDS_MAX		4096
 /* this must be a power of two greater than ISCSI_MGMT_CMDS_MAX */
 #define ISCSI_TOTAL_CMDS_MIN		16
 #define ISCSI_AGE_SHIFT			28
-#define ISCSI_AGE_MASK			(0xf << ISCSI_AGE_SHIFT)
+#define ISCSI_AGE_MASK			0xf
 
 #define ISCSI_ADDRESS_BUF_LEN		64
 

include/scsi/scsi_transport_iscsi.h

@@ -122,6 +122,9 @@ struct iscsi_transport {
 	int (*xmit_pdu) (struct iscsi_task *task);
 	int (*init_pdu) (struct iscsi_task *task, unsigned int offset,
 			 unsigned int count);
+	void (*parse_pdu_itt) (struct iscsi_conn *conn, itt_t itt,
+			       int *index, int *age);
+
 	void (*session_recovery_timedout) (struct iscsi_cls_session *session);
 	struct iscsi_endpoint *(*ep_connect) (struct sockaddr *dst_addr,
 					      int non_blocking);