ssc: REPORT POSITION - Add support for 'long' format

Reference: http://mhvtl-linux-virtual-tape-library-community-forums.966029.n3.nabble.com/2nd-version-of-SCSI-command-READ-POSITION-34h-td4025371.html#a4025383

Reported-by: 'denjolras' via forum
Signed-off-by: Mark Harvey <markh794@gmail.com>

usr/ssc.c

@@ -1156,10 +1156,24 @@ uint8_t ssc_read_position(struct scsi_cmd *cmd)
 
 	switch (lu_priv->tapeLoaded) {
 	case TAPE_LOADED:
-		if ((service_action == 0) || (service_action == 1))
+		switch (service_action) {
+		case 0:
+		case 1:
 			cmd->dbuf_p->sz = resp_read_position(c_pos->blk_number,
 							cmd->dbuf_p->data,
 							sam_stat);
+			break;
+		case 6:
+			cmd->dbuf_p->sz =
+				resp_read_position_long(c_pos->blk_number,
+							cmd->dbuf_p->data,
+							sam_stat);
+			break;
+		default:
+			mkSenseBuf(ILLEGAL_REQUEST, E_INVALID_FIELD_IN_CDB,
+							sam_stat);
+			return SAM_STAT_CHECK_CONDITION;
+		}
 		break;
 	case TAPE_UNLOADED:
 		mkSenseBuf(NOT_READY, E_MEDIUM_NOT_PRESENT, sam_stat);

usr/vtllib.c

@@ -256,17 +256,11 @@ int resp_read_position_long(loff_t pos, uint8_t *buf, uint8_t *sam_stat)
 		buf[0] = 0x80;	/* Begining of Partition */
 
 	/* partition should be zero, as we only support one */
-	buf[4] = (partition >> 24);
-	buf[5] = (partition >> 16);
-	buf[6] = (partition >> 8);
-	buf[7] = partition;
+	put_unaligned_be32(partition, &buf[4]);
 
-	/* we don't know logical field identifier */
-	/* FIXME: this code is wrong -- pos should be returned in [8 - 15] */
-	buf[8] = buf[9]  = (pos >> 16);
-	buf[6] = buf[10] = (pos >> 8);
-	buf[7] = buf[11] = pos;
+	put_unaligned_be64(pos, &buf[8]);
 
+	MHVTL_DBG(1, "Positioned at block %ld", (long)pos);
 	return READ_POSITION_LONG_LEN;
 }
 
@@ -279,10 +273,8 @@ int resp_read_position(loff_t pos, uint8_t *buf, uint8_t *sam_stat)
 	if ((pos == 0) || (pos == 1))
 		buf[0] = 0x80;	/* Begining of Partition */
 
-	buf[4] = buf[8] = (pos >> 24);
-	buf[5] = buf[9] = (pos >> 16);
-	buf[6] = buf[10] = (pos >> 8);
-	buf[7] = buf[11] = pos;
+	put_unaligned_be32(pos, &buf[4]);
+	put_unaligned_be32(pos, &buf[8]);
 	MHVTL_DBG(1, "Positioned at block %ld", (long)pos);
 
 	return READ_POSITION_LEN;