tcm_fc: Convert ft_send_work to use target_submit_cmd

This patch converts the main ft_send_work() I/O path to use
target_submit_cmd() with a single se_cmd->cmd_kref reference
that is released via the existing ft_check_stop_free() response
path callback.

It also makes ft_send_tm() use transport_init_se_cmd() and
target_get_sess_cmd() to also use single se_cmd->cmd_kref
reference.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Kiran Patil <kiran.patil@intel.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/tcm_fc/tfc_cmd.c

@@ -363,6 +363,11 @@ static void ft_send_tm(struct ft_cmd *cmd)
 	struct ft_sess *sess;
 	u8 tm_func;
 
+	transport_init_se_cmd(&cmd->se_cmd, &ft_configfs->tf_ops,
+			cmd->sess->se_sess, 0, DMA_NONE, 0,
+			&cmd->ft_sense_buffer[0]);
+	target_get_sess_cmd(cmd->sess->se_sess, &cmd->se_cmd, false);
+
 	fcp = fc_frame_payload_get(cmd->req_frame, sizeof(*fcp));
 
 	switch (fcp->fc_tm_flags) {
@@ -416,7 +421,6 @@ static void ft_send_tm(struct ft_cmd *cmd)
 			sess = cmd->sess;
 			transport_send_check_condition_and_sense(&cmd->se_cmd,
 				cmd->se_cmd.scsi_sense_reason, 0);
-			transport_generic_free_cmd(&cmd->se_cmd, 0);
 			ft_sess_put(sess);
 			return;
 		}
@@ -532,7 +536,6 @@ static void ft_send_work(struct work_struct *work)
 {
 	struct ft_cmd *cmd = container_of(work, struct ft_cmd, work);
 	struct fc_frame_header *fh = fc_frame_header_get(cmd->req_frame);
-	struct se_cmd *se_cmd;
 	struct fcp_cmnd *fcp;
 	int data_dir = 0;
 	u32 data_len;
@@ -587,55 +590,27 @@ static void ft_send_work(struct work_struct *work)
 		data_len = ntohl(fcp->fc_dl);
 		cmd->cdb = fcp->fc_cdb;
 	}
-
-	se_cmd = &cmd->se_cmd;
-	/*
-	 * Initialize struct se_cmd descriptor from target_core_mod
-	 * infrastructure
-	 */
-	transport_init_se_cmd(se_cmd, &ft_configfs->tf_ops, cmd->sess->se_sess,
-			      data_len, data_dir, task_attr,
-			      &cmd->ft_sense_buffer[0]);
 	/*
 	 * Check for FCP task management flags
 	 */
 	if (fcp->fc_tm_flags) {
 		ft_send_tm(cmd);
 		return;
 	}
-
 	fc_seq_exch(cmd->seq)->lp->tt.seq_set_resp(cmd->seq, ft_recv_seq, cmd);
-
 	cmd->lun = scsilun_to_int((struct scsi_lun *)fcp->fc_lun);
-	ret = transport_lookup_cmd_lun(&cmd->se_cmd, cmd->lun);
+	/*
+	 * Use a single se_cmd->cmd_kref as we expect to release se_cmd
+	 * directly from ft_check_stop_free callback in response path.
+	 */
+	ret = target_submit_cmd(&cmd->se_cmd, cmd->sess->se_sess, cmd->cdb,
+				&cmd->ft_sense_buffer[0], cmd->lun, data_len,
+				task_attr, data_dir, 0);
+	pr_debug("r_ctl %x alloc target_submit_cmd %d\n", fh->fh_r_ctl, ret);
 	if (ret < 0) {
 		ft_dump_cmd(cmd, __func__);
-		transport_send_check_condition_and_sense(&cmd->se_cmd,
-			cmd->se_cmd.scsi_sense_reason, 0);
-		return;
-	}
-
-	ret = transport_generic_allocate_tasks(se_cmd, cmd->cdb);
-
-	pr_debug("r_ctl %x alloc task ret %d\n", fh->fh_r_ctl, ret);
-	ft_dump_cmd(cmd, __func__);
-
-	if (ret == -ENOMEM) {
-		transport_send_check_condition_and_sense(se_cmd,
-				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
-		transport_generic_free_cmd(se_cmd, 0);
-		return;
-	}
-	if (ret == -EINVAL) {
-		if (se_cmd->se_cmd_flags & SCF_SCSI_RESERVATION_CONFLICT)
-			ft_queue_status(se_cmd);
-		else
-			transport_send_check_condition_and_sense(se_cmd,
-					se_cmd->scsi_sense_reason, 0);
-		transport_generic_free_cmd(se_cmd, 0);
 		return;
 	}
-	transport_handle_cdb_direct(se_cmd);
 	return;
 
 err: