iscsi-target: Refactor TX queue logic + export response PDU creation

This patch refactors TX immediate + response queue handling to use
the new iscsit_transport API callers, and exports the necessary
traditional iscsi PDU response creation functions for iser-target
to utilize.

This includes:

- Add iscsit_build_datain_pdu() for DATAIN PDU init + convert
  iscsit_build_datain_pdu()
- Add iscsit_build_logout_rsp() for LOGOUT_RSP PDU init + convert
  iscsit_send_logout()
- Add iscsit_build_nopin_rsp() for NOPIN_RSP PDU init + convert
  iscsit_send_nopin()
- Add iscsit_build_rsp_pdu() for SCSI_RSP PDU init + convert
  iscsit_send_response()
- Add iscsit_build_task_mgt_rsp for TM_RSP PDU init + convert
  iscsit_send_task_mgt_rsp()
- Refactor immediate queue state switch into iscsit_immediate_queue()
- Convert handle_immediate_queue() to use iscsit_transport caller
- Refactor response queue state switch into iscsit_response_queue()
- Convert handle_response_queue to use iscsit_transport caller
- Export iscsit_logout_post_handler(), iscsit_increment_maxcmdsn()
  and iscsit_tmr_post_handler() for external transport module usage

v5 changes:

- Fix solicited NopIN handling with RDMAExtensions=No (nab)

v3 changes:
- Add iscsit_build_reject for REJECT PDU init + convert
  iscsit_send_reject()

v2 changes:

- Add iscsit_queue_rsp() for iscsit_transport->iscsit_queue_data_in()
  and iscsit_transport->iscsit_queue_status()
- Update lio_queue_data_in() to use ->iscsit_queue_data_in()
- Update lio_queue_status() to use ->iscsit_queue_status()
- Use mutex_trylock() in iscsit_increment_maxcmdsn()
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target_configfs.c

@@ -27,6 +27,7 @@
 #include <target/target_core_fabric_configfs.h>
 #include <target/target_core_configfs.h>
 #include <target/configfs_macros.h>
+#include <target/iscsi/iscsi_transport.h>
 
 #include "iscsi_target_core.h"
 #include "iscsi_target_parameters.h"
@@ -1536,7 +1537,8 @@ static int lio_queue_data_in(struct se_cmd *se_cmd)
 	struct iscsi_cmd *cmd = container_of(se_cmd, struct iscsi_cmd, se_cmd);
 
 	cmd->i_state = ISTATE_SEND_DATAIN;
-	iscsit_add_cmd_to_response_queue(cmd, cmd->conn, cmd->i_state);
+	cmd->conn->conn_transport->iscsit_queue_data_in(cmd->conn, cmd);
+
 	return 0;
 }
 
@@ -1568,7 +1570,8 @@ static int lio_queue_status(struct se_cmd *se_cmd)
 	struct iscsi_cmd *cmd = container_of(se_cmd, struct iscsi_cmd, se_cmd);
 
 	cmd->i_state = ISTATE_SEND_STATUS;
-	iscsit_add_cmd_to_response_queue(cmd, cmd->conn, cmd->i_state);
+	cmd->conn->conn_transport->iscsit_queue_status(cmd->conn, cmd);
+
 	return 0;
 }
 

drivers/target/iscsi/iscsi_target_device.c

@@ -60,8 +60,13 @@ void iscsit_increment_maxcmdsn(struct iscsi_cmd *cmd, struct iscsi_session *sess
 
 	cmd->maxcmdsn_inc = 1;
 
-	mutex_lock(&sess->cmdsn_mutex);
+	if (!mutex_trylock(&sess->cmdsn_mutex)) {
+		sess->max_cmd_sn += 1;
+		pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn);
+		return;
+	}
 	sess->max_cmd_sn += 1;
 	pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn);
 	mutex_unlock(&sess->cmdsn_mutex);
 }
+EXPORT_SYMBOL(iscsit_increment_maxcmdsn);

drivers/target/iscsi/iscsi_target_tmr.c

@@ -472,6 +472,7 @@ int iscsit_tmr_post_handler(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
 
 	return 0;
 }
+EXPORT_SYMBOL(iscsit_tmr_post_handler);
 
 /*
  *	Nothing to do here, but leave it for good measure. :-)