libata: eliminate the home grown dma padding in favour of
that provided by the block layer
ATA requires that all DMA transfers begin and end on word boundaries.
Because of this, a large amount of machinery grew up in ide to adjust
scatterlists on this basis. However, as of 2.5, the block layer has a
dma_alignment variable which ensures both the beginning and length of a
DMA transfer are aligned on the dma_alignment boundary. Although the
block layer does adjust the beginning of the transfer to ensure this
happens, it doesn't actually adjust the length, it merely makes sure
that space is allocated for transfers beyond the declared length. The
upshot of this is that scatterlists may be padded to any size between
the actual length and the length adjusted to the dma_alignment safely
knowing that memory is allocated in this region.
Right at the moment, SCSI takes the default dma_aligment which is on a
512 byte boundary. Note that this aligment only applies to transfers
coming in from user space. However, since all kernel allocations are
automatically aligned on a minimum of 32 byte boundaries, it is safe to
adjust them in this manner as well.
tj: * Adjusting sg after padding is done in block layer. Make libata
set queue alignment correctly for ATAPI devices and drop broken
sg mangling from ata_sg_setup().
* Use request->raw_data_len for ATAPI transfer chunk size.
* Killed qc->raw_nbytes.
* Separated out killing qc->n_iter.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 29e71bd..3c06e45 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1975,16 +1975,11 @@
struct ahci_port_priv *pp;
void *mem;
dma_addr_t mem_dma;
- int rc;
pp = devm_kzalloc(dev, sizeof(*pp), GFP_KERNEL);
if (!pp)
return -ENOMEM;
- rc = ata_pad_alloc(ap, dev);
- if (rc)
- return rc;
-
mem = dmam_alloc_coherent(dev, AHCI_PORT_PRIV_DMA_SZ, &mem_dma,
GFP_KERNEL);
if (!mem)
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index a109ccb..3587ac3 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4493,30 +4493,13 @@
struct ata_port *ap = qc->ap;
struct scatterlist *sg = qc->sg;
int dir = qc->dma_dir;
- void *pad_buf = NULL;
WARN_ON(sg == NULL);
- VPRINTK("unmapping %u sg elements\n", qc->mapped_n_elem);
+ VPRINTK("unmapping %u sg elements\n", qc->n_elem);
- /* if we padded the buffer out to 32-bit bound, and data
- * xfer direction is from-device, we must copy from the
- * pad buffer back into the supplied buffer
- */
- if (qc->pad_len && !(qc->tf.flags & ATA_TFLAG_WRITE))
- pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
-
- if (qc->mapped_n_elem)
- dma_unmap_sg(ap->dev, sg, qc->mapped_n_elem, dir);
- /* restore last sg */
- if (qc->last_sg)
- *qc->last_sg = qc->saved_last_sg;
- if (pad_buf) {
- struct scatterlist *psg = &qc->extra_sg[1];
- void *addr = kmap_atomic(sg_page(psg), KM_IRQ0);
- memcpy(addr + psg->offset, pad_buf, qc->pad_len);
- kunmap_atomic(addr, KM_IRQ0);
- }
+ if (qc->n_elem)
+ dma_unmap_sg(ap->dev, sg, qc->n_elem, dir);
qc->flags &= ~ATA_QCFLAG_DMAMAP;
qc->sg = NULL;
@@ -4767,97 +4750,6 @@
qc->cursg = qc->sg;
}
-static unsigned int ata_sg_setup_extra(struct ata_queued_cmd *qc,
- 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;
-
- if (likely(!qc->pad_len))
- return n_elem;
-
- /* locate last sg and save it */
- lsg = sg_last(qc->sg, n_elem);
- qc->last_sg = lsg;
- qc->saved_last_sg = *lsg;
-
- sg_init_table(qc->extra_sg, ARRAY_SIZE(qc->extra_sg));
-
- if (qc->pad_len) {
- struct scatterlist *psg = &qc->extra_sg[1];
- void *pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
- unsigned int offset;
-
- WARN_ON(qc->dev->class != ATA_DEV_ATAPI);
-
- memset(pad_buf, 0, ATA_DMA_PAD_SZ);
-
- /* psg->page/offset are used to copy to-be-written
- * data in this function or read data in ata_sg_clean.
- */
- offset = lsg->offset + lsg->length - qc->pad_len;
- sg_set_page(psg, nth_page(sg_page(lsg), offset >> PAGE_SHIFT),
- qc->pad_len, offset_in_page(offset));
-
- if (qc->tf.flags & ATA_TFLAG_WRITE) {
- void *addr = kmap_atomic(sg_page(psg), KM_IRQ0);
- memcpy(pad_buf, addr + psg->offset, qc->pad_len);
- kunmap_atomic(addr, KM_IRQ0);
- }
-
- sg_dma_address(psg) = ap->pad_dma + (qc->tag * ATA_DMA_PAD_SZ);
- sg_dma_len(psg) = ATA_DMA_PAD_SZ;
-
- /* Trim the last sg entry and chain the original and
- * padding sg lists.
- *
- * Because chaining consumes one sg entry, one extra
- * sg entry is allocated and the last sg entry is
- * copied to it if the length isn't zero after padded
- * amount is removed.
- *
- * If the last sg entry is completely replaced by
- * padding sg entry, the first sg entry is skipped
- * while chaining.
- */
- lsg->length -= qc->pad_len;
- if (lsg->length) {
- copy_lsg = &qc->extra_sg[0];
- tsg = &qc->extra_sg[0];
- } else {
- n_elem--;
- tsg = &qc->extra_sg[1];
- }
-
- esg = &qc->extra_sg[1];
-
- (*n_elem_extra)++;
- (*nbytes_extra) += 4 - qc->pad_len;
- }
-
- if (copy_lsg)
- sg_set_page(copy_lsg, sg_page(lsg), lsg->length, lsg->offset);
-
- sg_chain(lsg, 1, tsg);
- sg_mark_end(esg);
-
- /* sglist can't start with chaining sg entry, fast forward */
- if (qc->sg == lsg) {
- qc->sg = tsg;
- qc->cursg = tsg;
- }
-
- return n_elem;
-}
-
/**
* ata_sg_setup - DMA-map the scatter-gather table associated with a command.
* @qc: Command with scatter-gather table to be mapped.
@@ -4874,26 +4766,17 @@
static int ata_sg_setup(struct ata_queued_cmd *qc)
{
struct ata_port *ap = qc->ap;
- unsigned int n_elem, n_elem_extra, nbytes_extra;
+ unsigned int n_elem;
VPRINTK("ENTER, ata%u\n", ap->print_id);
- n_elem = ata_sg_setup_extra(qc, &n_elem_extra, &nbytes_extra);
+ n_elem = dma_map_sg(ap->dev, qc->sg, qc->n_elem, qc->dma_dir);
+ if (n_elem < 1)
+ return -1;
- if (n_elem) {
- n_elem = dma_map_sg(ap->dev, qc->sg, n_elem, qc->dma_dir);
- if (n_elem < 1) {
- /* restore last sg */
- if (qc->last_sg)
- *qc->last_sg = qc->saved_last_sg;
- return -1;
- }
- DPRINTK("%d sg elements mapped\n", n_elem);
- }
+ DPRINTK("%d sg elements mapped\n", n_elem);
- qc->n_elem = qc->mapped_n_elem = n_elem;
- qc->n_elem += n_elem_extra;
- qc->nbytes += nbytes_extra;
+ qc->n_elem = n_elem;
qc->flags |= ATA_QCFLAG_DMAMAP;
return 0;
@@ -5962,9 +5845,6 @@
*/
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))
@@ -6573,19 +6453,12 @@
int ata_port_start(struct ata_port *ap)
{
struct device *dev = ap->dev;
- int rc;
ap->prd = dmam_alloc_coherent(dev, ATA_PRD_TBL_SZ, &ap->prd_dma,
GFP_KERNEL);
if (!ap->prd)
return -ENOMEM;
- rc = ata_pad_alloc(ap, dev);
- if (rc)
- return rc;
-
- DPRINTK("prd alloc, virt %p, dma %llx\n", ap->prd,
- (unsigned long long)ap->prd_dma);
return 0;
}
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 1cea18f..6e15c5d 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -832,24 +832,16 @@
/* configure max sectors */
blk_queue_max_sectors(sdev->request_queue, dev->max_sectors);
- /* SATA DMA transfers must be multiples of 4 byte, so
- * we need to pad ATAPI transfers using an extra sg.
- * Decrement max hw segments accordingly.
- */
- if (dev->class == ATA_DEV_ATAPI) {
- struct request_queue *q = sdev->request_queue;
- blk_queue_max_hw_segments(q, q->max_hw_segments - 1);
-
+ if (dev->class == ATA_DEV_ATAPI)
/* set the min alignment */
blk_queue_update_dma_alignment(sdev->request_queue,
ATA_DMA_PAD_SZ - 1);
- } else
+ else {
/* ATA devices must be sector aligned */
blk_queue_update_dma_alignment(sdev->request_queue,
ATA_SECT_SIZE - 1);
-
- if (dev->class == ATA_DEV_ATA)
sdev->manage_start_stop = 1;
+ }
if (dev->flags & ATA_DFLAG_AN)
set_bit(SDEV_EVT_MEDIA_CHANGE, sdev->supported_events);
@@ -2500,7 +2492,7 @@
* want to set it properly, and for DMA where it is
* effectively meaningless.
*/
- nbytes = min(qc->nbytes, (unsigned int)63 * 1024);
+ nbytes = min(scmd->request->raw_data_len, (unsigned int)63 * 1024);
/* Most ATAPI devices which honor transfer chunk size don't
* behave according to the spec when odd chunk size which
@@ -3555,7 +3547,7 @@
* @ap: Port to initialize
*
* Called just after data structures for each port are
- * initialized. Allocates DMA pad.
+ * initialized.
*
* May be used as the port_start() entry in ata_port_operations.
*
@@ -3564,7 +3556,7 @@
*/
int ata_sas_port_start(struct ata_port *ap)
{
- return ata_pad_alloc(ap, ap->dev);
+ return 0;
}
EXPORT_SYMBOL_GPL(ata_sas_port_start);
@@ -3572,8 +3564,6 @@
* ata_port_stop - Undo ata_sas_port_start()
* @ap: Port to shut down
*
- * Frees the DMA pad.
- *
* May be used as the port_stop() entry in ata_port_operations.
*
* LOCKING:
@@ -3582,7 +3572,6 @@
void ata_sas_port_stop(struct ata_port *ap)
{
- ata_pad_free(ap, ap->dev);
}
EXPORT_SYMBOL_GPL(ata_sas_port_stop);
diff --git a/drivers/ata/pata_icside.c b/drivers/ata/pata_icside.c
index 5b8586d..f97068b 100644
--- a/drivers/ata/pata_icside.c
+++ b/drivers/ata/pata_icside.c
@@ -304,12 +304,6 @@
}
-static int pata_icside_port_start(struct ata_port *ap)
-{
- /* No PRD to alloc */
- return ata_pad_alloc(ap, ap->dev);
-}
-
static struct scsi_host_template pata_icside_sht = {
.module = THIS_MODULE,
.name = DRV_NAME,
@@ -389,8 +383,6 @@
.irq_clear = ata_dummy_noret,
.irq_on = ata_irq_on,
- .port_start = pata_icside_port_start,
-
.bmdma_stop = pata_icside_bmdma_stop,
.bmdma_status = pata_icside_bmdma_status,
};
diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
index efcb66b6..9323dd0 100644
--- a/drivers/ata/sata_fsl.c
+++ b/drivers/ata/sata_fsl.c
@@ -601,21 +601,9 @@
if (!pp)
return -ENOMEM;
- /*
- * allocate per command dma alignment pad buffer, which is used
- * internally by libATA to ensure that all transfers ending on
- * unaligned boundaries are padded, to align on Dword boundaries
- */
- retval = ata_pad_alloc(ap, dev);
- if (retval) {
- kfree(pp);
- return retval;
- }
-
mem = dma_alloc_coherent(dev, SATA_FSL_PORT_PRIV_DMA_SZ, &mem_dma,
GFP_KERNEL);
if (!mem) {
- ata_pad_free(ap, dev);
kfree(pp);
return -ENOMEM;
}
@@ -694,7 +682,6 @@
dma_free_coherent(dev, SATA_FSL_PORT_PRIV_DMA_SZ,
pp->cmdslot, pp->cmdslot_paddr);
- ata_pad_free(ap, dev);
kfree(pp);
}
diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 2ecd44d..1c1fbf3 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -1158,17 +1158,13 @@
struct mv_port_priv *pp;
void __iomem *port_mmio = mv_ap_base(ap);
unsigned long flags;
- int tag, rc;
+ int tag;
pp = devm_kzalloc(dev, sizeof(*pp), GFP_KERNEL);
if (!pp)
return -ENOMEM;
ap->private_data = pp;
- rc = ata_pad_alloc(ap, dev);
- if (rc)
- return rc;
-
pp->crqb = dma_pool_alloc(hpriv->crqb_pool, GFP_KERNEL, &pp->crqb_dma);
if (!pp->crqb)
return -ENOMEM;
diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
index b4b1f91..df7988d 100644
--- a/drivers/ata/sata_sil24.c
+++ b/drivers/ata/sata_sil24.c
@@ -1234,7 +1234,6 @@
union sil24_cmd_block *cb;
size_t cb_size = sizeof(*cb) * SIL24_MAX_CMDS;
dma_addr_t cb_dma;
- int rc;
pp = devm_kzalloc(dev, sizeof(*pp), GFP_KERNEL);
if (!pp)
@@ -1247,10 +1246,6 @@
return -ENOMEM;
memset(cb, 0, cb_size);
- rc = ata_pad_alloc(ap, dev);
- if (rc)
- return rc;
-
pp->cmd_block = cb;
pp->cmd_block_dma = cb_dma;
diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index 2074701..c72014a 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -5140,7 +5140,7 @@
struct ipr_ioarcb *ioarcb = &ipr_cmd->ioarcb;
struct ipr_ioadl_desc *ioadl = ipr_cmd->ioadl;
struct ipr_ioadl_desc *last_ioadl = NULL;
- int len = qc->nbytes + qc->pad_len;
+ int len = qc->nbytes;
struct scatterlist *sg;
unsigned int si;
@@ -5206,7 +5206,7 @@
ioarcb->cmd_pkt.request_type = IPR_RQTYPE_ATA_PASSTHRU;
ioarcb->cmd_pkt.flags_hi |= IPR_FLAGS_HI_NO_LINK_DESC;
ioarcb->cmd_pkt.flags_hi |= IPR_FLAGS_HI_NO_ULEN_CHK;
- ipr_cmd->dma_use_sg = qc->pad_len ? qc->n_elem + 1 : qc->n_elem;
+ ipr_cmd->dma_use_sg = qc->n_elem;
ipr_build_ata_ioadl(ipr_cmd, qc);
regs->flags |= IPR_ATA_FLAG_STATUS_ON_GOOD_COMPLETION;
diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 0996f86..7cd05b5 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -178,8 +178,8 @@
task->uldd_task = qc;
if (ata_is_atapi(qc->tf.protocol)) {
memcpy(task->ata_task.atapi_packet, qc->cdb, qc->dev->cdb_len);
- task->total_xfer_len = qc->nbytes + qc->pad_len;
- task->num_scatter = qc->pad_len ? qc->n_elem + 1 : qc->n_elem;
+ task->total_xfer_len = qc->nbytes;
+ task->num_scatter = qc->n_elem;
} else {
for_each_sg(qc->sg, sg, qc->n_elem, si)
xfer += sg->length;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index bc5a8d0..2e098f9 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -278,7 +278,6 @@
/* size of buffer to pad xfers ending on unaligned boundaries */
ATA_DMA_PAD_SZ = 4,
- ATA_DMA_PAD_BUF_SZ = ATA_DMA_PAD_SZ * ATA_MAX_QUEUE,
/* ering size */
ATA_ERING_SIZE = 32,
@@ -457,24 +456,18 @@
unsigned long flags; /* ATA_QCFLAG_xxx */
unsigned int tag;
unsigned int n_elem;
- unsigned int mapped_n_elem;
int dma_dir;
- unsigned int pad_len;
unsigned int sect_size;
unsigned int nbytes;
- unsigned int raw_nbytes;
unsigned int curbytes;
struct scatterlist *cursg;
unsigned int cursg_ofs;
- struct scatterlist *last_sg;
- struct scatterlist saved_last_sg;
struct scatterlist sgent;
- struct scatterlist extra_sg[2];
struct scatterlist *sg;
@@ -619,9 +612,6 @@
struct ata_prd *prd; /* our SG list */
dma_addr_t prd_dma; /* and its DMA mapping */
- void *pad; /* array of DMA pad buffers */
- dma_addr_t pad_dma;
-
struct ata_ioports ioaddr; /* ATA cmd/ctl/dma register blocks */
u8 ctl; /* cache of ATA control register */
@@ -1363,12 +1353,9 @@
qc->flags = 0;
qc->cursg = NULL;
qc->cursg_ofs = 0;
- qc->nbytes = qc->raw_nbytes = qc->curbytes = 0;
+ qc->nbytes = qc->curbytes = 0;
qc->n_elem = 0;
- qc->mapped_n_elem = 0;
qc->err_mask = 0;
- qc->pad_len = 0;
- qc->last_sg = NULL;
qc->sect_size = ATA_SECT_SIZE;
ata_tf_init(qc->dev, &qc->tf);
@@ -1423,19 +1410,6 @@
return mask;
}
-static inline int ata_pad_alloc(struct ata_port *ap, struct device *dev)
-{
- ap->pad_dma = 0;
- ap->pad = dmam_alloc_coherent(dev, ATA_DMA_PAD_BUF_SZ,
- &ap->pad_dma, GFP_KERNEL);
- return (ap->pad == NULL) ? -ENOMEM : 0;
-}
-
-static inline void ata_pad_free(struct ata_port *ap, struct device *dev)
-{
- dmam_free_coherent(dev, ATA_DMA_PAD_BUF_SZ, ap->pad, ap->pad_dma);
-}
-
static inline struct ata_port *ata_shost_to_port(struct Scsi_Host *host)
{
return *(struct ata_port **)&host->hostdata[0];