target: Add protection SGLs to target_submit_cmd_map_sgls

This patch adds support to target_submit_cmd_map_sgls() for
accepting 'sgl_prot' + 'sgl_prot_count' parameters for
DIF protection information.

Note the passed parameters are stored at se_cmd->t_prot_sg
and se_cmd->t_prot_nents respectively.

Also, update tcm_loop and vhost-scsi fabrics usage of
target_submit_cmd_map_sgls() to take into account the
new parameters.

Cc: Martin K. Petersen <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Hannes Reinecke <[e-mail]>
Cc: Sagi Grimberg <[e-mail]>
Cc: Or Gerlitz <[e-mail]>
Signed-off-by: Nicholas Bellinger <[e-mail]>

drivers/target/loopback/tcm_loop.c

···
 			scsi_bufflen(sc), tcm_loop_sam_attr(sc),
 			sc->sc_data_direction, 0,
 			scsi_sglist(sc), scsi_sg_count(sc),
-			sgl_bidi, sgl_bidi_count);
+			sgl_bidi, sgl_bidi_count, NULL, 0);
 	if (rc < 0) {
 		set_host_byte(sc, DID_NO_CONNECT);
 		goto out_done;

drivers/target/target_core_transport.c

···
  * @sgl_count: scatterlist count for unidirectional mapping
  * @sgl_bidi: struct scatterlist memory for bidirectional READ mapping
  * @sgl_bidi_count: scatterlist count for bidirectional READ mapping
+ * @sgl_prot: struct scatterlist memory protection information
+ * @sgl_prot_count: scatterlist count for protection information
  *
  * Returns non zero to signal active I/O shutdown failure.  All other
  * setup exceptions will be returned as a SCSI CHECK_CONDITION response,
···
 		unsigned char *cdb, unsigned char *sense, u32 unpacked_lun,
 		u32 data_length, int task_attr, int data_dir, int flags,
 		struct scatterlist *sgl, u32 sgl_count,
-		struct scatterlist *sgl_bidi, u32 sgl_bidi_count)
+		struct scatterlist *sgl_bidi, u32 sgl_bidi_count,
+		struct scatterlist *sgl_prot, u32 sgl_prot_count)
 {
 	struct se_portal_group *se_tpg;
 	sense_reason_t rc;
···
 		transport_send_check_condition_and_sense(se_cmd, rc, 0);
 		target_put_sess_cmd(se_sess, se_cmd);
 		return 0;
+	}
+	/*
+	 * Save pointers for SGLs containing protection information,
+	 * if present.
+	 */
+	if (sgl_prot_count) {
+		se_cmd->t_prot_sg = sgl_prot;
+		se_cmd->t_prot_nents = sgl_prot_count;
 	}
 
 	rc = target_setup_cmd_from_cdb(se_cmd, cdb);
···
 			return 0;
 		}
 	}
+
 	/*
 	 * Check if we need to delay processing because of ALUA
 	 * Active/NonOptimized primary access state..
···
 {
 	return target_submit_cmd_map_sgls(se_cmd, se_sess, cdb, sense,
 			unpacked_lun, data_length, task_attr, data_dir,
-			flags, NULL, 0, NULL, 0);
+			flags, NULL, 0, NULL, 0, NULL, 0);
 }
 EXPORT_SYMBOL(target_submit_cmd);
 

drivers/vhost/scsi.c

···
 			cmd->tvc_lun, cmd->tvc_exp_data_len,
 			cmd->tvc_task_attr, cmd->tvc_data_direction,
 			TARGET_SCF_ACK_KREF, sg_ptr, cmd->tvc_sgl_count,
-			sg_bidi_ptr, sg_no_bidi);
+			sg_bidi_ptr, sg_no_bidi, NULL, 0);
 	if (rc < 0) {
 		transport_send_check_condition_and_sense(se_cmd,
 				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);

include/target/target_core_fabric.h

···
 sense_reason_t target_setup_cmd_from_cdb(struct se_cmd *, unsigned char *);
 int	target_submit_cmd_map_sgls(struct se_cmd *, struct se_session *,
 		unsigned char *, unsigned char *, u32, u32, int, int, int,
-		struct scatterlist *, u32, struct scatterlist *, u32);
+		struct scatterlist *, u32, struct scatterlist *, u32,
+		struct scatterlist *, u32);
 int	target_submit_cmd(struct se_cmd *, struct se_session *, unsigned char *,
 		unsigned char *, u32, u32, int, int, int);
 int	target_submit_tmr(struct se_cmd *se_cmd, struct se_session *se_sess,