scsifront: cleanup

- properly type the shadow field tracking the active command
- as a result, there's no need to also track the data direction
- in turn, re-arranging shadow fields reduces the size of the structure
  on 64-bit architectures
- there's no point in map_data_for_request() failing if there are no
  grant references available when none are needed anyway
- don't redundantly include linux/version.h

--- a/drivers/xen/scsifront/common.h
+++ b/drivers/xen/scsifront/common.h
@@ -80,21 +80,17 @@ struct vscsifrnt_shadow {
 	 * VSCSIIF_ACT_SCSI_CDB or VSCSIIF_ACT_SCSI_RESET */
 	unsigned char act;
 	
+	/* Number of pieces of scatter-gather */
+	unsigned int nr_segments;
+
 	/* do reset function */
 	wait_queue_head_t wq_reset;	/* reset work queue           */
 	int wait_reset;			/* reset work queue condition */
 	int32_t rslt_reset;		/* reset response status      */
 					/* (SUCESS or FAILED)         */
 
-	/* for DMA_TO_DEVICE(1), DMA_FROM_DEVICE(2), DMA_NONE(3) 
-	   requests */
-	unsigned int sc_data_direction;
-	
-	/* Number of pieces of scatter-gather */
-	unsigned int nr_segments;
-
 	/* requested struct scsi_cmnd is stored from kernel */
-	unsigned long req_scsi_cmnd;
+	struct scsi_cmnd *sc;
 	int gref[VSCSIIF_SG_TABLESIZE];
 };
 
--- a/drivers/xen/scsifront/scsifront.c
+++ b/drivers/xen/scsifront/scsifront.c
@@ -28,8 +28,6 @@
  * IN THE SOFTWARE.
  */
  
-
-#include <linux/version.h>
 #include "common.h"
 
 static int get_id_from_freelist(struct vscsifrnt_info *info)
@@ -57,8 +55,8 @@ static void add_id_to_freelist(struct vs
 
 	spin_lock_irqsave(&info->shadow_lock, flags);
 
-	info->shadow[id].next_free  = info->shadow_free;
-	info->shadow[id].req_scsi_cmnd = 0;
+	info->shadow[id].next_free = info->shadow_free;
+	info->shadow[id].sc = NULL;
 	info->shadow_free = id;
 
 	spin_unlock_irqrestore(&info->shadow_lock, flags);
@@ -111,7 +109,7 @@ static void scsifront_gnttab_done(struct
 {
 	int i;
 
-	if (s->sc_data_direction == DMA_NONE)
+	if (s->sc->sc_data_direction == DMA_NONE)
 		return;
 
 	if (s->nr_segments) {
@@ -138,7 +136,7 @@ static void scsifront_cdb_cmd_done(struc
 	uint8_t sense_len;
 
 	id = ring_res->rqid;
-	sc = (struct scsi_cmnd *)info->shadow[id].req_scsi_cmnd;
+	sc = info->shadow[id].sc;
 
 	if (sc == NULL)
 		BUG();
@@ -252,7 +250,7 @@ static int map_data_for_request(struct v
 	unsigned long buffer_pfn;
 	unsigned int data_len = 0;
 
-	if (sc->sc_data_direction == DMA_NONE)
+	if (sc->sc_data_direction == DMA_NONE || !sc->request_bufflen)
 		return 0;
 
 	err = gnttab_alloc_grant_references(VSCSIIF_SG_TABLESIZE, &gref_head);
@@ -300,7 +298,7 @@ static int map_data_for_request(struct v
 				ref_cnt++;
 			}
 		}
-	} else if (sc->request_bufflen) {
+	} else {
 		unsigned long end   = ((unsigned long)sc->request_buffer
 					+ sc->request_bufflen + PAGE_SIZE - 1) >> PAGE_SHIFT;
 		unsigned long start = (unsigned long)sc->request_buffer >> PAGE_SHIFT;
@@ -388,9 +386,8 @@ static int scsifront_queuecommand(struct
 	ring_req->sc_data_direction   = (uint8_t)sc->sc_data_direction;
 	ring_req->timeout_per_command = (sc->timeout_per_command / HZ);
 
-	info->shadow[rqid].req_scsi_cmnd     = (unsigned long)sc;
-	info->shadow[rqid].sc_data_direction = sc->sc_data_direction;
-	info->shadow[rqid].act               = ring_req->act;
+	info->shadow[rqid].sc  = sc;
+	info->shadow[rqid].act = VSCSIIF_ACT_SCSI_CDB;
 
 	ref_cnt = map_data_for_request(info, sc, ring_req, rqid);
 	if (ref_cnt < 0) {
--- a/drivers/xen/scsifront/xenbus.c
+++ b/drivers/xen/scsifront/xenbus.c
@@ -33,7 +33,6 @@
 * 2010, Samuel Kvasnica, IMS Nanofabrication AG
 */
 
-#include <linux/version.h>
 #include "common.h"
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,11)