[SCSI] usb: protocol - convert to accessors and !use_sg code path removal

 - Use scsi data accessors and remove of !use_sg code path
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Acked-by: Matthew Dharm <mdharm-scsi@one-eyed-alien.net>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/usb/storage/protocol.c

@@ -149,11 +149,7 @@ void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb,
  ***********************************************************************/
 
 /* Copy a buffer of length buflen to/from the srb's transfer buffer.
- * (Note: for scatter-gather transfers (srb->use_sg > 0), srb->request_buffer
- * points to a list of s-g entries and we ignore srb->request_bufflen.
- * For non-scatter-gather transfers, srb->request_buffer points to the
- * transfer buffer itself and srb->request_bufflen is the buffer's length.)
- * Update the *index and *offset variables so that the next copy will
+ * Update the **sgptr and *offset variables so that the next copy will
  * pick up from where this one left off. */
 
 unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
@@ -162,37 +158,22 @@ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
 {
 	unsigned int cnt;
 
-	/* If not using scatter-gather, just transfer the data directly.
-	 * Make certain it will fit in the available buffer space. */
-	if (srb->use_sg == 0) {
-		if (*offset >= srb->request_bufflen)
-			return 0;
-		cnt = min(buflen, srb->request_bufflen - *offset);
-		if (dir == TO_XFER_BUF)
-			memcpy((unsigned char *) srb->request_buffer + *offset,
-					buffer, cnt);
-		else
-			memcpy(buffer, (unsigned char *) srb->request_buffer +
-					*offset, cnt);
-		*offset += cnt;
-
-	/* Using scatter-gather.  We have to go through the list one entry
+	/* We have to go through the list one entry
 	 * at a time.  Each s-g entry contains some number of pages, and
 	 * each page has to be kmap()'ed separately.  If the page is already
 	 * in kernel-addressable memory then kmap() will return its address.
 	 * If the page is not directly accessible -- such as a user buffer
 	 * located in high memory -- then kmap() will map it to a temporary
 	 * position in the kernel's virtual address space. */
-	} else {
 	struct scatterlist *sg = *sgptr;
 
 	if (!sg)
-			sg = (struct scatterlist *) srb->request_buffer;
+		sg = scsi_sglist(srb);
 
 	/* This loop handles a single s-g list entry, which may
 		* include multiple pages.  Find the initial page structure
 		* and the starting offset within the page, and update
-		 * the *offset and *index values for the next loop. */
+		* the *offset and **sgptr values for the next loop. */
 	cnt = 0;
 	while (cnt < buflen) {
 		struct page *page = sg_page(sg) +
@@ -235,7 +216,6 @@ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
 		}
 	}
 	*sgptr = sg;
-	}
 
 	/* Return the amount actually transferred */
 	return cnt;
@@ -251,6 +231,6 @@ void usb_stor_set_xfer_buf(unsigned char *buffer,
 
 	usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
 			TO_XFER_BUF);
-	if (buflen < srb->request_bufflen)
-		srb->resid = srb->request_bufflen - buflen;
+	if (buflen < scsi_bufflen(srb))
+		scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
 }