libata: kill qc->nsect and cursect

libata used two separate sets of variables to record request size and
current offset for ATA and ATAPI.  This is confusing and fragile.
This patch replaces qc->nsect/cursect with qc->nbytes/curbytes and
kills them.  Also, ata_pio_sector() is updated to use bytes for
qc->cursg_ofs instead of sectors.  The field used to be used in bytes
for ATAPI and in sectors for ATA.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/libata-core.c

@@ -1249,7 +1249,6 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
 			buflen += sg[i].length;
 
 		ata_sg_init(qc, sg, n_elem);
-		qc->nsect = buflen / ATA_SECT_SIZE;
 		qc->nbytes = buflen;
 	}
 
@@ -4006,11 +4005,11 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
 	unsigned int offset;
 	unsigned char *buf;
 
-	if (qc->cursect == (qc->nsect - 1))
+	if (qc->curbytes == qc->nbytes - ATA_SECT_SIZE)
 		ap->hsm_task_state = HSM_ST_LAST;
 
 	page = sg[qc->cursg].page;
-	offset = sg[qc->cursg].offset + qc->cursg_ofs * ATA_SECT_SIZE;
+	offset = sg[qc->cursg].offset + qc->cursg_ofs;
 
 	/* get the current page and offset */
 	page = nth_page(page, (offset >> PAGE_SHIFT));
@@ -4035,10 +4034,10 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
 		ap->ops->data_xfer(qc->dev, buf + offset, ATA_SECT_SIZE, do_write);
 	}
 
-	qc->cursect++;
-	qc->cursg_ofs++;
+	qc->curbytes += ATA_SECT_SIZE;
+	qc->cursg_ofs += ATA_SECT_SIZE;
 
-	if ((qc->cursg_ofs * ATA_SECT_SIZE) == (&sg[qc->cursg])->length) {
+	if (qc->cursg_ofs == (&sg[qc->cursg])->length) {
 		qc->cursg++;
 		qc->cursg_ofs = 0;
 	}
@@ -4063,7 +4062,8 @@ static void ata_pio_sectors(struct ata_queued_cmd *qc)
 
 		WARN_ON(qc->dev->multi_count == 0);
 
-		nsect = min(qc->nsect - qc->cursect, qc->dev->multi_count);
+		nsect = min((qc->nbytes - qc->curbytes) / ATA_SECT_SIZE,
+			    qc->dev->multi_count);
 		while (nsect--)
 			ata_pio_sector(qc);
 	} else

drivers/ata/libata-eh.c

@@ -1443,15 +1443,10 @@ static void ata_eh_report(struct ata_port *ap)
 		};
 		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
 		struct ata_taskfile *cmd = &qc->tf, *res = &qc->result_tf;
-		unsigned int nbytes;
 
 		if (!(qc->flags & ATA_QCFLAG_FAILED) || !qc->err_mask)
 			continue;
 
-		nbytes = qc->nbytes;
-		if (!nbytes)
-			nbytes = qc->nsect << 9;
-
 		ata_dev_printk(qc->dev, KERN_ERR,
 			"cmd %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
 			"tag %d cdb 0x%x data %u %s\n         "
@@ -1461,7 +1456,7 @@ static void ata_eh_report(struct ata_port *ap)
 			cmd->lbal, cmd->lbam, cmd->lbah,
 			cmd->hob_feature, cmd->hob_nsect,
 			cmd->hob_lbal, cmd->hob_lbam, cmd->hob_lbah,
-			cmd->device, qc->tag, qc->cdb[0], nbytes,
+			cmd->device, qc->tag, qc->cdb[0], qc->nbytes,
 			dma_str[qc->dma_dir],
 			res->command, res->feature, res->nsect,
 			res->lbal, res->lbam, res->lbah,

drivers/ata/libata-scsi.c

@@ -1359,7 +1359,7 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc)
 		goto nothing_to_do;
 
 	qc->flags |= ATA_QCFLAG_IO;
-	qc->nsect = n_block;
+	qc->nbytes = n_block * ATA_SECT_SIZE;
 
 	rc = ata_build_rw_tf(&qc->tf, qc->dev, block, n_block, tf_flags,
 			     qc->tag);
@@ -2660,7 +2660,7 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
 	 * TODO: find out if we need to do more here to
 	 *       cover scatter/gather case.
 	 */
-	qc->nsect = scmd->request_bufflen / ATA_SECT_SIZE;
+	qc->nbytes = scmd->request_bufflen;
 
 	/* request result TF */
 	qc->flags |= ATA_QCFLAG_RESULT_TF;

drivers/ata/pata_pdc202xx_old.c

@@ -189,10 +189,7 @@ static void pdc2026x_bmdma_start(struct ata_queued_cmd *qc)
 	/* Cases the state machine will not complete correctly without help */
 	if ((tf->flags & ATA_TFLAG_LBA48) ||  tf->protocol == ATA_PROT_ATAPI_DMA)
 	{
-		if (tf->flags & ATA_TFLAG_LBA48)
-			len = qc->nsect * 512;
-		else
-			len = qc->nbytes;
+		len = qc->nbytes;
 
 		if (tf->flags & ATA_TFLAG_WRITE)
 			len |= 0x06000000;

drivers/ata/sata_qstor.c

@@ -325,7 +325,7 @@ static void qs_qc_prep(struct ata_queued_cmd *qc)
 	/* host control block (HCB) */
 	buf[ 0] = QS_HCB_HDR;
 	buf[ 1] = hflags;
-	*(__le32 *)(&buf[ 4]) = cpu_to_le32(qc->nsect * ATA_SECT_SIZE);
+	*(__le32 *)(&buf[ 4]) = cpu_to_le32(qc->nbytes);
 	*(__le32 *)(&buf[ 8]) = cpu_to_le32(nelem);
 	addr = ((u64)pp->pkt_dma) + QS_CPB_BYTES;
 	*(__le64 *)(&buf[16]) = cpu_to_le64(addr);

include/linux/libata.h

@@ -427,9 +427,6 @@ struct ata_queued_cmd {
 
 	unsigned int		pad_len;
 
-	unsigned int		nsect;
-	unsigned int		cursect;
-
 	unsigned int		nbytes;
 	unsigned int		curbytes;
 
@@ -1145,8 +1142,7 @@ static inline void ata_qc_reinit(struct ata_queued_cmd *qc)
 	qc->dma_dir = DMA_NONE;
 	qc->__sg = NULL;
 	qc->flags = 0;
-	qc->cursect = qc->cursg = qc->cursg_ofs = 0;
-	qc->nsect = 0;
+	qc->cursg = qc->cursg_ofs = 0;
 	qc->nbytes = qc->curbytes = 0;
 	qc->n_elem = 0;
 	qc->err_mask = 0;