target/loop: Enable VARLEN CDB support

Field shost->max_cmd_len is used to inform Linux / the SCSI midlayer of
the maximum CDB size an LLD is capable of handling. Set this field to
SCSI_MAX_VARLEN_CDB_SIZE for target, to enable support for
variable-sized CDBs (0x7E).

Also remove the definition of TL_SCSI_MAX_CMD_LEN since it is now
redundant.
Signed-off-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Vangelis Koukis <vkoukis@arrikto.com>
Reviewed-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/loopback/tcm_loop.c

@@ -409,7 +409,7 @@ static int tcm_loop_driver_probe(struct device *dev)
 	sh->max_id = 2;
 	sh->max_lun = 0;
 	sh->max_channel = 0;
-	sh->max_cmd_len = TL_SCSI_MAX_CMD_LEN;
+	sh->max_cmd_len = SCSI_MAX_VARLEN_CDB_SIZE;
 
 	host_prot = SHOST_DIF_TYPE1_PROTECTION | SHOST_DIF_TYPE2_PROTECTION |
 		    SHOST_DIF_TYPE3_PROTECTION | SHOST_DIX_TYPE1_PROTECTION |

drivers/target/loopback/tcm_loop.h

@@ -2,11 +2,6 @@
 #define TL_WWN_ADDR_LEN			256
 #define TL_TPGS_PER_HBA			32
 
-/*
- * Used in tcm_loop_driver_probe() for struct Scsi_Host->max_cmd_len
- */
-#define TL_SCSI_MAX_CMD_LEN		32
-
 struct tcm_loop_cmd {
 	/* State of Linux/SCSI CDB+Data descriptor */
 	u32 sc_cmd_state;