tcm_fc: Offload WRITE I/O backend submission to tpg workqueue

Defer the write processing to the internal to be able to use
target_execute_cmd.  I'm not even entirely sure the calling code requires
this due to the convoluted structure in libfc, but let's be safe for now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Mark Rustad <mark.d.rustad@intel.com>
Cc: Kiran Patil <Kiran.patil@intel.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/tcm_fc/tfc_io.c

@@ -183,6 +183,13 @@ int ft_queue_data_in(struct se_cmd *se_cmd)
 	return ft_queue_status(se_cmd);
 }
 
+static void ft_execute_work(struct work_struct *work)
+{
+	struct ft_cmd *cmd = container_of(work, struct ft_cmd, work);
+
+	target_execute_cmd(&cmd->se_cmd);
+}
+
 /*
  * Receive write data frame.
  */
@@ -307,8 +314,10 @@ void ft_recv_write_data(struct ft_cmd *cmd, struct fc_frame *fp)
 		cmd->write_data_len += tlen;
 	}
 last_frame:
-	if (cmd->write_data_len == se_cmd->data_length)
-		transport_generic_handle_data(se_cmd);
+	if (cmd->write_data_len == se_cmd->data_length) {
+		INIT_WORK(&cmd->work, ft_execute_work);
+		queue_work(cmd->sess->tport->tpg->workqueue, &cmd->work);
+	}
 drop:
 	fc_frame_free(fp);
 }