scsi: target: srpt: Convert to new submission API

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

srpt uses target_stop_session() to sync session shutdown with LIO core, so
we use target_init_cmd()/target_submit_prep()/target_submit(), because
target_init_cmd() will detect the target_stop_session() call and return an
error.

Link: https://lore.kernel.org/r/20210227170006.5077-6-michael.christie@oracle.com
Cc: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/infiniband/ulp/srpt/ib_srpt.c

@@ -1528,16 +1528,19 @@ static void srpt_handle_cmd(struct srpt_rdma_ch *ch,
 		goto busy;
 	}
 
-	rc = target_submit_cmd_map_sgls(cmd, ch->sess, srp_cmd->cdb,
-			       &send_ioctx->sense_data[0],
-			       scsilun_to_int(&srp_cmd->lun), data_len,
-			       TCM_SIMPLE_TAG, dir, TARGET_SCF_ACK_KREF,
-			       sg, sg_cnt, NULL, 0, NULL, 0);
+	rc = target_init_cmd(cmd, ch->sess, &send_ioctx->sense_data[0],
+			     scsilun_to_int(&srp_cmd->lun), data_len,
+			     TCM_SIMPLE_TAG, dir, TARGET_SCF_ACK_KREF);
 	if (rc != 0) {
 		pr_debug("target_submit_cmd() returned %d for tag %#llx\n", rc,
 			 srp_cmd->tag);
 		goto busy;
 	}
+
+	if (target_submit_prep(cmd, srp_cmd->cdb, sg, sg_cnt, NULL, 0, NULL, 0))
+		return;
+
+	target_submit(cmd);
 	return;
 
 busy: