[RFC 7/8] sd.c and sr.c move to scsi_sgtable implementation

[Boaz Harrosh <bharrosh@panasas.com>]

  - sd and sr would adjust IO size to align on device's block
    size. So code needs to change once we move to scsi_sgtable
    implementation. (Not compatible with un-converted drivers)
  - Convert code to use scsi_for_each_sg
  - Use Data accessors wherever is appropriate.

 Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
---
 drivers/scsi/sd.c |   10 ++++------
 drivers/scsi/sr.c |   27 ++++++++++++---------------
 2 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 448d316..459fd23 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -338,7 +338,7 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
 	struct request *rq = SCpnt->request;
 	struct gendisk *disk = rq->rq_disk;
 	sector_t block = rq->sector;
-	unsigned int this_count = SCpnt->request_bufflen >> 9;
+	unsigned int this_count = scsi_bufflen(SCpnt) >> 9;
 	unsigned int timeout = sdp->timeout;
 
 	SCSI_LOG_HLQUEUE(1, scmd_printk(KERN_INFO, SCpnt,
@@ -418,9 +418,6 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
 	} else if (rq_data_dir(rq) == READ) {
 		SCpnt->cmnd[0] = READ_6;
 		SCpnt->sc_data_direction = DMA_FROM_DEVICE;
-	} else {
-		scmd_printk(KERN_ERR, SCpnt, "Unknown command %x\n", rq->cmd_flags);
-		return 0;
 	}
 
 	SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
@@ -480,7 +477,8 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
 		SCpnt->cmnd[4] = (unsigned char) this_count;
 		SCpnt->cmnd[5] = 0;
 	}
-	SCpnt->request_bufflen = this_count * sdp->sector_size;
+	BUG_ON(!SCpnt->sgtable);
+	SCpnt->sgtable->length = this_count * sdp->sector_size;
 
 	/*
 	 * We shouldn't disconnect in the middle of a sector, so with a dumb
@@ -892,7 +890,7 @@ static struct block_device_operations sd_fops = {
 static void sd_rw_intr(struct scsi_cmnd * SCpnt)
 {
 	int result = SCpnt->result;
- 	unsigned int xfer_size = SCpnt->request_bufflen;
+ 	unsigned int xfer_size = scsi_bufflen(SCpnt);
  	unsigned int good_bytes = result ? 0 : xfer_size;
  	u64 start_lba = SCpnt->request->sector;
  	u64 bad_lba;
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index f9a52af..ed61ca9 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -218,7 +218,7 @@ int sr_media_change(struct cdrom_device_info *cdi, int slot)
 static void rw_intr(struct scsi_cmnd * SCpnt)
 {
 	int result = SCpnt->result;
-	int this_count = SCpnt->request_bufflen;
+	int this_count = scsi_bufflen(SCpnt);
 	int good_bytes = (result == 0 ? this_count : 0);
 	int block_sectors = 0;
 	long error_sector;
@@ -345,23 +345,20 @@ static int sr_init_command(struct scsi_cmnd * SCpnt)
 	} else if (rq_data_dir(SCpnt->request) == READ) {
 		SCpnt->cmnd[0] = READ_10;
 		SCpnt->sc_data_direction = DMA_FROM_DEVICE;
-	} else {
-		blk_dump_rq_flags(SCpnt->request, "Unknown sr command");
-		return 0;
 	}
 
 	{
-		struct scatterlist *sg = SCpnt->request_buffer;
-		int i, size = 0;
-		for (i = 0; i < SCpnt->use_sg; i++)
-			size += sg[i].length;
+		struct scatterlist *sg;
+		int i, size = 0, sg_count = scsi_sg_count(SCpnt);
+		scsi_for_each_sg (SCpnt, sg, sg_count, i)
+			size += sg->length;
 
-		if (size != SCpnt->request_bufflen && SCpnt->use_sg) {
+		if (size != SCpnt->sgtable->length) {
 			scmd_printk(KERN_ERR, SCpnt,
 				"mismatch count %d, bytes %d\n",
-				size, SCpnt->request_bufflen);
-			if (SCpnt->request_bufflen > size)
-				SCpnt->request_bufflen = size;
+				size, SCpnt->sgtable->length);
+			if (SCpnt->sgtable->length > size)
+				SCpnt->sgtable->length = size;
 		}
 	}
 
@@ -369,12 +366,12 @@ static int sr_init_command(struct scsi_cmnd * SCpnt)
 	 * request doesn't start on hw block boundary, add scatter pads
 	 */
 	if (((unsigned int)SCpnt->request->sector % (s_size >> 9)) ||
-	    (SCpnt->request_bufflen % s_size)) {
+	    (SCpnt->sgtable->length % s_size)) {
 		scmd_printk(KERN_NOTICE, SCpnt, "unaligned transfer\n");
 		return 0;
 	}
 
-	this_count = (SCpnt->request_bufflen >> 9) / (s_size >> 9);
+	this_count = (SCpnt->sgtable->length >> 9) / (s_size >> 9);
 
 
 	SCSI_LOG_HLQUEUE(2, printk("%s : %s %d/%ld 512 byte blocks.\n",
@@ -388,7 +385,7 @@ static int sr_init_command(struct scsi_cmnd * SCpnt)
 
 	if (this_count > 0xffff) {
 		this_count = 0xffff;
-		SCpnt->request_bufflen = this_count * s_size;
+		SCpnt->sgtable->length = this_count * s_size;
 	}
 
 	SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;
-- 
1.5.2.2.249.g45fd