Commit 0bcc65ad authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik
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libata: make qc->nbytes include extra buffers 



qc->nbytes didn't use to include extra buffers setup by libata core
layer and my be odd.  This patch makes qc->nbytes include any extra
buffers setup by libata core layer and guaranteed to be aligned on 4
byte boundary.

This value is to be used to program the host controller.  As this
represents the actual length of buffer available to the controller and
the controller must be able to deal with short transfers for ATAPI
commands which can transfer variable length, this shouldn't break any
controllers while making problems like rounding-down and controllers
choking up on odd transfer bytes much less likely.

The unmodified value is stored in new field qc->raw_nbytes.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent ff2aeb1e

drivers/ata/libata-core.c

+10 −4
Original line number Diff line number Diff line
@@ -4763,13 +4763,15 @@ void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg, 
}



static unsigned int ata_sg_setup_extra(struct ata_queued_cmd *qc,

				       unsigned int *n_elem_extra)

				       unsigned int *n_elem_extra,

				       unsigned int *nbytes_extra)

{

	struct ata_port *ap = qc->ap;

	unsigned int n_elem = qc->n_elem;

	struct scatterlist *lsg, *copy_lsg = NULL, *tsg = NULL, *esg = NULL;



	*n_elem_extra = 0;

	*nbytes_extra = 0;



	/* needs padding? */

	qc->pad_len = qc->nbytes & 3;
@@ -4833,6 +4835,7 @@ static unsigned int ata_sg_setup_extra(struct ata_queued_cmd *qc, 
		esg = &qc->extra_sg[1];



		(*n_elem_extra)++;

		(*nbytes_extra) += 4 - qc->pad_len;

	}



	if (copy_lsg)
@@ -4866,11 +4869,11 @@ static unsigned int ata_sg_setup_extra(struct ata_queued_cmd *qc, 
static int ata_sg_setup(struct ata_queued_cmd *qc)

{

	struct ata_port *ap = qc->ap;

	unsigned int n_elem, n_elem_extra;

	unsigned int n_elem, n_elem_extra, nbytes_extra;



	VPRINTK("ENTER, ata%u\n", ap->print_id);



	n_elem = ata_sg_setup_extra(qc, &n_elem_extra);

	n_elem = ata_sg_setup_extra(qc, &n_elem_extra, &nbytes_extra);



	if (n_elem) {

		n_elem = dma_map_sg(ap->dev, qc->sg, n_elem, qc->dma_dir);
@@ -4885,7 +4888,7 @@ static int ata_sg_setup(struct ata_queued_cmd *qc) 


	qc->n_elem = qc->mapped_n_elem = n_elem;

	qc->n_elem += n_elem_extra;



	qc->nbytes += nbytes_extra;

	qc->flags |= ATA_QCFLAG_DMAMAP;



	return 0;
@@ -5949,6 +5952,9 @@ void ata_qc_issue(struct ata_queued_cmd *qc) 
	 */

	BUG_ON(ata_is_data(prot) && (!qc->sg || !qc->n_elem || !qc->nbytes));



	/* ata_sg_setup() may update nbytes */

	qc->raw_nbytes = qc->nbytes;



	if (ata_is_dma(prot) || (ata_is_pio(prot) &&

				 (ap->flags & ATA_FLAG_PIO_DMA)))

		if (ata_sg_setup(qc))

include/linux/libata.h

+2 −1
Original line number Diff line number Diff line
@@ -466,6 +466,7 @@ struct ata_queued_cmd { 
	unsigned int		sect_size;



	unsigned int		nbytes;

	unsigned int		raw_nbytes;

	unsigned int		curbytes;



	struct scatterlist	*cursg;
@@ -1362,7 +1363,7 @@ static inline void ata_qc_reinit(struct ata_queued_cmd *qc) 
	qc->flags = 0;

	qc->cursg = NULL;

	qc->cursg_ofs = 0;

	qc->nbytes = qc->curbytes = 0;

	qc->nbytes = qc->raw_nbytes = qc->curbytes = 0;

	qc->n_elem = 0;

	qc->mapped_n_elem = 0;

	qc->n_iter = 0;

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