[SCSI] gdth: Setup proper per-command private data

  - scsi_cmnd and specifically ->SCp of, where heavily abused
    with internal meaning members and flags. So introduce a new
    struct gdth_cmndinfo, put it on ->host_scribble and define a
    gdth_cmnd_priv() accessor to retrieve it from a scsi_cmnd.

  - The structure now holds two members:
    internal_command - replaces the IS_GDTH_INTERNAL_CMD() croft.
    sense_paddr - which was a 64-bit spanning on 2 32-bit members of SCp.
    More overloaded members from SCp and scsi_cmnd will be moved in a later
    patch (For easy review).

  - Split up gdth_queuecommand to an additional internal_function. The later
    is the one called by gdth_execute(). This will be more evident later in
    the scsi accessors patch, but it also facilitates in the differentiation
    between internal_command and external. And the setup of gdth_cmndinfo of
    each command.

Signed-off-by Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/gdth.h b/drivers/scsi/gdth.h
index e6178c4..be4ae5a 100644
--- a/drivers/scsi/gdth.h
+++ b/drivers/scsi/gdth.h
@@ -919,6 +919,11 @@
         Scsi_Cmnd       *cmnd;                  /* pending request */
         ushort          service;                /* service */
     } cmd_tab[GDTH_MAXCMDS];                    /* table of pend. requests */
+    struct gdth_cmndinfo {                      /* per-command private info */
+        int index;
+        int internal_command;                   /* don't call scsi_done */
+        dma_addr_t sense_paddr;                 /* sense dma-addr */
+    } cmndinfo[GDTH_MAXCMDS];                   /* index==0 is free */
     unchar              bus_cnt;                /* SCSI bus count */
     unchar              tid_cnt;                /* Target ID count */
     unchar              bus_id[MAXBUS];         /* IOP IDs */
@@ -941,6 +946,11 @@
     struct scsi_device         *sdev;
 } gdth_ha_str;
 
+static inline struct gdth_cmndinfo *gdth_cmnd_priv(struct scsi_cmnd* cmd)
+{
+	return (struct gdth_cmndinfo *)cmd->host_scribble;
+}
+
 /* INQUIRY data format */
 typedef struct {
     unchar      type_qual;