firewire: sbp2: add support for disks >2 TB (and 16 bytes long CDBs)

Increase the command ORB data structure to transport up to 16 bytes long
CDBs (instead of 12 bytes), and tell the SCSI mid layer about it.  This
is notably necessary for READ CAPACITY(16) and friends, i.e. support of
large disks.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/sbp2.c

@@ -200,6 +200,12 @@ static struct fw_device *target_device(struct sbp2_target *tgt)
 #define SBP2_RETRY_LIMIT		0xf		/* 15 retries */
 #define SBP2_CYCLE_LIMIT		(0xc8 << 12)	/* 200 125us cycles */
 
+/*
+ * There is no transport protocol limit to the CDB length,  but we implement
+ * a fixed length only.  16 bytes is enough for disks larger than 2 TB.
+ */
+#define SBP2_MAX_CDB_SIZE		16
+
 /*
  * The default maximum s/g segment size of a FireWire controller is
  * usually 0x10000, but SBP-2 only allows 0xffff. Since buffers have to
@@ -312,7 +318,7 @@ struct sbp2_command_orb {
 		struct sbp2_pointer next;
 		struct sbp2_pointer data_descriptor;
 		__be32 misc;
-		u8 command_block[12];
+		u8 command_block[SBP2_MAX_CDB_SIZE];
 	} request;
 	struct scsi_cmnd *cmd;
 	scsi_done_fn_t done;
@@ -1146,6 +1152,8 @@ static int sbp2_probe(struct device *dev)
 	if (fw_device_enable_phys_dma(device) < 0)
 		goto fail_shost_put;
 
+	shost->max_cmd_len = SBP2_MAX_CDB_SIZE;
+
 	if (scsi_add_host(shost, &unit->device) < 0)
 		goto fail_shost_put;