[SCSI] add support for variable length extended commands

Add support for variable-length, extended, and vendor specific
CDBs to scsi-ml. It is now possible for initiators and ULD's
to issue these types of commands. LLDs need not change much.
All they need is to raise the .max_cmd_len to the longest command
they support (see iscsi patch).

- clean-up some code paths that did not expect commands to be
  larger than 16, and change cmd_len members' type to short as
  char is not enough.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

block/scsi_ioctl.c

@@ -33,13 +33,12 @@
 #include <scsi/scsi_cmnd.h>
 
 /* Command group 3 is reserved and should never be used.  */
-const unsigned char scsi_command_size[8] =
+const unsigned char scsi_command_size_tbl[8] =
 {
 	6, 10, 10, 12,
 	16, 12, 10, 10
 };
-
-EXPORT_SYMBOL(scsi_command_size);
+EXPORT_SYMBOL(scsi_command_size_tbl);
 
 #include <scsi/sg.h>
 

drivers/scsi/constants.c

@@ -28,7 +28,6 @@
 #define SERVICE_ACTION_OUT_12 0xa9
 #define SERVICE_ACTION_IN_16 0x9e
 #define SERVICE_ACTION_OUT_16 0x9f
-#define VARIABLE_LENGTH_CMD 0x7f
 
 
 
@@ -210,7 +209,7 @@ static void print_opcode_name(unsigned char * cdbp, int cdb_len)
 	cdb0 = cdbp[0];
 	switch(cdb0) {
 	case VARIABLE_LENGTH_CMD:
-		len = cdbp[7] + 8;
+		len = scsi_varlen_cdb_length(cdbp);
 		if (len < 10) {
 			printk("short variable length command, "
 			       "len=%d ext_len=%d", len, cdb_len);
@@ -300,7 +299,7 @@ static void print_opcode_name(unsigned char * cdbp, int cdb_len)
 	cdb0 = cdbp[0];
 	switch(cdb0) {
 	case VARIABLE_LENGTH_CMD:
-		len = cdbp[7] + 8;
+		len = scsi_varlen_cdb_length(cdbp);
 		if (len < 10) {
 			printk("short opcode=0x%x command, len=%d "
 			       "ext_len=%d", cdb0, len, cdb_len);
@@ -335,10 +334,7 @@ void __scsi_print_command(unsigned char *cdb)
 	int k, len;
 
 	print_opcode_name(cdb, 0);
-	if (VARIABLE_LENGTH_CMD == cdb[0])
-		len = cdb[7] + 8;
-	else
-		len = COMMAND_SIZE(cdb[0]);
+	len = scsi_command_size(cdb);
 	/* print out all bytes in cdb */
 	for (k = 0; k < len; ++k) 
 		printk(" %02x", cdb[k]);

drivers/scsi/scsi.c

@@ -78,15 +78,6 @@ static void scsi_done(struct scsi_cmnd *cmd);
 /* Do not call reset on error if we just did a reset within 15 sec. */
 #define MIN_RESET_PERIOD (15*HZ)
 
-/*
- * Macro to determine the size of SCSI command. This macro takes vendor
- * unique commands into account. SCSI commands in groups 6 and 7 are
- * vendor unique and we will depend upon the command length being
- * supplied correctly in cmd_len.
- */
-#define CDB_SIZE(cmd)	(((((cmd)->cmnd[0] >> 5) & 7) < 6) ? \
-				COMMAND_SIZE((cmd)->cmnd[0]) : (cmd)->cmd_len)
-
 /*
  * Note - the initial logging level can be set here to log events at boot time.
  * After the system is up, you may enable logging via the /proc interface.
@@ -709,9 +700,11 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 	 * Before we queue this command, check if the command
 	 * length exceeds what the host adapter can handle.
 	 */
-	if (CDB_SIZE(cmd) > cmd->device->host->max_cmd_len) {
+	if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
 		SCSI_LOG_MLQUEUE(3,
-				printk("queuecommand : command too long.\n"));
+			printk("queuecommand : command too long. "
+			       "cdb_size=%d host->max_cmd_len=%d\n",
+			       cmd->cmd_len, cmd->device->host->max_cmd_len));
 		cmd->result = (DID_ABORT << 16);
 
 		scsi_done(cmd);

drivers/scsi/scsi_lib.c

@@ -445,7 +445,7 @@ static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
 	scsi_set_resid(cmd, 0);
 	memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 	if (cmd->cmd_len == 0)
-		cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
+		cmd->cmd_len = scsi_command_size(cmd->cmnd);
 }
 
 void scsi_device_unbusy(struct scsi_device *sdev)

include/scsi/scsi.h

@@ -29,13 +29,6 @@
 #define SCSI_MAX_SG_CHAIN_SEGMENTS	SCSI_MAX_SG_SEGMENTS
 #endif
 
-/*
- *	SCSI command lengths
- */
-
-extern const unsigned char scsi_command_size[8];
-#define COMMAND_SIZE(opcode) scsi_command_size[((opcode) >> 5) & 7]
-
 /*
  * Special value for scanning to specify scanning or rescanning of all
  * possible channels, (target) ids, or luns on a given shost.
@@ -109,6 +102,7 @@ extern const unsigned char scsi_command_size[8];
 #define MODE_SENSE_10         0x5a
 #define PERSISTENT_RESERVE_IN 0x5e
 #define PERSISTENT_RESERVE_OUT 0x5f
+#define VARIABLE_LENGTH_CMD   0x7f
 #define REPORT_LUNS           0xa0
 #define MAINTENANCE_IN        0xa3
 #define MOVE_MEDIUM           0xa5
@@ -135,6 +129,38 @@ extern const unsigned char scsi_command_size[8];
 #define	ATA_16		      0x85	/* 16-byte pass-thru */
 #define	ATA_12		      0xa1	/* 12-byte pass-thru */
 
+/*
+ *	SCSI command lengths
+ */
+
+#define SCSI_MAX_VARLEN_CDB_SIZE 260
+
+/* defined in T10 SCSI Primary Commands-2 (SPC2) */
+struct scsi_varlen_cdb_hdr {
+	u8 opcode;        /* opcode always == VARIABLE_LENGTH_CMD */
+	u8 control;
+	u8 misc[5];
+	u8 additional_cdb_length;         /* total cdb length - 8 */
+	__be16 service_action;
+	/* service specific data follows */
+};
+
+static inline unsigned
+scsi_varlen_cdb_length(const void *hdr)
+{
+	return ((struct scsi_varlen_cdb_hdr *)hdr)->additional_cdb_length + 8;
+}
+
+extern const unsigned char scsi_command_size_tbl[8];
+#define COMMAND_SIZE(opcode) scsi_command_size_tbl[((opcode) >> 5) & 7]
+
+static inline unsigned
+scsi_command_size(const unsigned char *cmnd)
+{
+	return (cmnd[0] == VARIABLE_LENGTH_CMD) ?
+		scsi_varlen_cdb_length(cmnd) : COMMAND_SIZE(cmnd[0]);
+}
+
 /*
  *  SCSI Architecture Model (SAM) Status codes. Taken from SAM-3 draft
  *  T10/1561-D Revision 4 Draft dated 7th November 2002.

include/scsi/scsi_cmnd.h

@@ -78,7 +78,7 @@ struct scsi_cmnd {
 	int allowed;
 	int timeout_per_command;
 
-	unsigned char cmd_len;
+	unsigned short cmd_len;
 	enum dma_data_direction sc_data_direction;
 
 	/* These elements define the operation we are about to perform */

include/scsi/scsi_host.h

@@ -573,13 +573,11 @@ struct Scsi_Host {
 	/*
 	 * The maximum length of SCSI commands that this host can accept.
 	 * Probably 12 for most host adapters, but could be 16 for others.
+	 * or 260 if the driver supports variable length cdbs.
 	 * For drivers that don't set this field, a value of 12 is
-	 * assumed.  I am leaving this as a number rather than a bit
-	 * because you never know what subsequent SCSI standards might do
-	 * (i.e. could there be a 20 byte or a 24-byte command a few years
-	 * down the road?).  
+	 * assumed.
 	 */
-	unsigned char max_cmd_len;
+	unsigned short max_cmd_len;
 
 	int this_id;
 	int can_queue;