[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>

3 files changed, 37 insertions, 13 deletions

diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 1f74bcd603fe..32742c4563de 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -30,13 +30,6 @@
 #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
@@ -136,6 +130,38 @@ extern const unsigned char scsi_command_size[8];
 #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.
  */
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 7ed883c8e48a..3e46dfae8194 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/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 */
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index d967d6dc7a28..1834fdfe82a7 100644
--- a/include/scsi/scsi_host.h
+++ b/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;