tcm_qla2xxx: Offload WRITE I/O backend submission to tcm_qla2xxx wq

Defer the whole tcm_qla2xxx_handle_data call instead of just the error
path to the qla2xxx-internal workqueue.  Also remove the useless lock around
the CMD_T_ABORTED check.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@purestorage.com>
Cc: Giridhar Malavali <giridhar.malavali@qlogic.com>
Cc: tcm-qla2xxx@qlogic.com
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/scsi/qla2xxx/qla_target.h

@@ -639,7 +639,7 @@ struct qla_tgt_func_tmpl {
 
 	int (*handle_cmd)(struct scsi_qla_host *, struct qla_tgt_cmd *,
 			unsigned char *, uint32_t, int, int, int);
-	int (*handle_data)(struct qla_tgt_cmd *);
+	void (*handle_data)(struct qla_tgt_cmd *);
 	int (*handle_tmr)(struct qla_tgt_mgmt_cmd *, uint32_t, uint8_t,
 			uint32_t);
 	void (*free_cmd)(struct qla_tgt_cmd *);

drivers/scsi/qla2xxx/tcm_qla2xxx.c

@@ -604,22 +604,10 @@ static int tcm_qla2xxx_handle_cmd(scsi_qla_host_t *vha, struct qla_tgt_cmd *cmd,
 	return 0;
 }
 
-static void tcm_qla2xxx_do_rsp(struct work_struct *work)
+static void tcm_qla2xxx_handle_data_work(struct work_struct *work)
 {
 	struct qla_tgt_cmd *cmd = container_of(work, struct qla_tgt_cmd, work);
-	/*
-	 * Dispatch ->queue_status from workqueue process context
-	 */
-	transport_generic_request_failure(&cmd->se_cmd);
-}
 
-/*
- * Called from qla_target.c:qlt_do_ctio_completion()
- */
-static int tcm_qla2xxx_handle_data(struct qla_tgt_cmd *cmd)
-{
-	struct se_cmd *se_cmd = &cmd->se_cmd;
-	unsigned long flags;
 	/*
 	 * Ensure that the complete FCP WRITE payload has been received.
 	 * Otherwise return an exception via CHECK_CONDITION status.
@@ -629,24 +617,26 @@ static int tcm_qla2xxx_handle_data(struct qla_tgt_cmd *cmd)
 		 * Check if se_cmd has already been aborted via LUN_RESET, and
 		 * waiting upon completion in tcm_qla2xxx_write_pending_status()
 		 */
-		spin_lock_irqsave(&se_cmd->t_state_lock, flags);
-		if (se_cmd->transport_state & CMD_T_ABORTED) {
-			spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);
-			complete(&se_cmd->t_transport_stop_comp);
-			return 0;
+		if (cmd->se_cmd.transport_state & CMD_T_ABORTED) {
+			complete(&cmd->se_cmd.t_transport_stop_comp);
+			return;
 		}
-		spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);
 
-		se_cmd->scsi_sense_reason = TCM_CHECK_CONDITION_ABORT_CMD;
-		INIT_WORK(&cmd->work, tcm_qla2xxx_do_rsp);
-		queue_work(tcm_qla2xxx_free_wq, &cmd->work);
-		return 0;
+		cmd->se_cmd.scsi_sense_reason = TCM_CHECK_CONDITION_ABORT_CMD;
+		transport_generic_request_failure(&cmd->se_cmd);
+		return;
 	}
-	/*
-	 * We now tell TCM to queue this WRITE CDB with TRANSPORT_PROCESS_WRITE
-	 * status to the backstore processing thread.
+
+	return target_execute_cmd(&cmd->se_cmd);
+}
+
+/*
+ * Called from qla_target.c:qlt_do_ctio_completion()
  */
-	return transport_generic_handle_data(&cmd->se_cmd);
+static void tcm_qla2xxx_handle_data(struct qla_tgt_cmd *cmd)
+{
+	INIT_WORK(&cmd->work, tcm_qla2xxx_handle_data_work);
+	queue_work(tcm_qla2xxx_free_wq, &cmd->work);
 }
 
 /*