scsi: target: tcm_loop: Convert to new submission API

target_submit_cmd_map_sgls() is being removed, so convert loop to
the new submission API.

Even though loop does its own shutdown sync, this has loop use
target_init_cmd()/target_submit_prep()/target_submit() since it needed to
map sgls and in the next patches it will use the API to use LIO's
workqueue.

Link: https://lore.kernel.org/r/20210227170006.5077-9-michael.christie@oracle.com
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/loopback/tcm_loop.c

@@ -113,7 +113,6 @@ static void tcm_loop_submission_work(struct work_struct *work)
 	struct tcm_loop_tpg *tl_tpg;
 	struct scatterlist *sgl_bidi = NULL;
 	u32 sgl_bidi_count = 0, transfer_length;
-	int rc;
 
 	tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
 	tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
@@ -151,17 +150,16 @@ static void tcm_loop_submission_work(struct work_struct *work)
 	}
 
 	se_cmd->tag = tl_cmd->sc_cmd_tag;
-	rc = target_submit_cmd_map_sgls(se_cmd, tl_nexus->se_sess, sc->cmnd,
-			&tl_cmd->tl_sense_buf[0], tl_cmd->sc->device->lun,
-			transfer_length, TCM_SIMPLE_TAG,
-			sc->sc_data_direction, 0,
-			scsi_sglist(sc), scsi_sg_count(sc),
-			sgl_bidi, sgl_bidi_count,
-			scsi_prot_sglist(sc), scsi_prot_sg_count(sc));
-	if (rc < 0) {
-		set_host_byte(sc, DID_NO_CONNECT);
-		goto out_done;
-	}
+	target_init_cmd(se_cmd, tl_nexus->se_sess, &tl_cmd->tl_sense_buf[0],
+			tl_cmd->sc->device->lun, transfer_length,
+			TCM_SIMPLE_TAG, sc->sc_data_direction, 0);
+
+	if (target_submit_prep(se_cmd, sc->cmnd, scsi_sglist(sc),
+			       scsi_sg_count(sc), sgl_bidi, sgl_bidi_count,
+			       scsi_prot_sglist(sc), scsi_prot_sg_count(sc)))
+		return;
+
+	target_submit(se_cmd);
 	return;
 
 out_done: