libata: add support for READ/WRITE LONG

The READ/WRITE LONG commands are theoretically obsolete,
but the majority of drives in existance still implement them.

The WRITE_LONG and WRITE_LONG_ONCE commands are of particular
interest for fault injection testing -- eg. creating "media errors"
at specific locations on a disk.

The fussy bit is that these commands require a non-standard
sector size, usually 520 bytes instead of 512.

This patch adds support to libata for READ/WRITE LONG commands
issued via SG_IO/ATA_16.

Signed-off-by:  Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

2 files changed, 22 insertions, 10 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 971a737a8734..96bf86f67388 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4106,10 +4106,10 @@ void ata_data_xfer_noirq(struct ata_device *adev, unsigned char *buf,
 
 
 /**
- *      ata_pio_sector - Transfer ATA_SECT_SIZE (512 bytes) of data.
+ *      ata_pio_sector - Transfer a sector of data.
  *      @qc: Command on going
  *
- *      Transfer ATA_SECT_SIZE of data from/to the ATA device.
+ *      Transfer qc->sect_size bytes of data from/to the ATA device.
  *
  *      LOCKING:
  *      Inherited from caller.
@@ -4124,7 +4124,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
         unsigned int offset;
         unsigned char *buf;
 
-        if (qc->curbytes == qc->nbytes - ATA_SECT_SIZE)
+        if (qc->curbytes == qc->nbytes - qc->sect_size)
                 ap->hsm_task_state = HSM_ST_LAST;
 
         page = sg[qc->cursg].page;
@@ -4144,17 +4144,17 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
                 buf = kmap_atomic(page, KM_IRQ0);
 
                 /* do the actual data transfer */
-                ap->ops->data_xfer(qc->dev, buf + offset, ATA_SECT_SIZE, do_write);
+                ap->ops->data_xfer(qc->dev, buf + offset, qc->sect_size, do_write);
 
                 kunmap_atomic(buf, KM_IRQ0);
                 local_irq_restore(flags);
         } else {
                 buf = page_address(page);
-                ap->ops->data_xfer(qc->dev, buf + offset, ATA_SECT_SIZE, do_write);
+                ap->ops->data_xfer(qc->dev, buf + offset, qc->sect_size, do_write);
         }
 
-        qc->curbytes += ATA_SECT_SIZE;
-        qc->cursg_ofs += ATA_SECT_SIZE;
+        qc->curbytes += qc->sect_size;
+        qc->cursg_ofs += qc->sect_size;
 
         if (qc->cursg_ofs == (&sg[qc->cursg])->length) {
                 qc->cursg++;
@@ -4163,10 +4163,10 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
 }
 
 /**
- *      ata_pio_sectors - Transfer one or many 512-byte sectors.
+ *      ata_pio_sectors - Transfer one or many sectors.
  *      @qc: Command on going
  *
- *      Transfer one or many ATA_SECT_SIZE of data from/to the
+ *      Transfer one or many sectors of data from/to the
  *      ATA device for the DRQ request.
  *
  *      LOCKING:
@@ -4181,7 +4181,7 @@ static void ata_pio_sectors(struct ata_queued_cmd *qc)
 
                 WARN_ON(qc->dev->multi_count == 0);
 
-                nsect = min((qc->nbytes - qc->curbytes) / ATA_SECT_SIZE,
+                nsect = min((qc->nbytes - qc->curbytes) / qc->sect_size,
                             qc->dev->multi_count);
                 while (nsect--)
                         ata_pio_sector(qc);
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 7d41afe8ccbc..563ef0bfb038 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2678,6 +2678,18 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
                 tf->device = qc->dev->devno ?
                         tf->device | ATA_DEV1 : tf->device & ~ATA_DEV1;
 
+        /* READ/WRITE LONG use a non-standard sect_size */
+        qc->sect_size = ATA_SECT_SIZE;
+        switch (tf->command) {
+        case ATA_CMD_READ_LONG:
+        case ATA_CMD_READ_LONG_ONCE:
+        case ATA_CMD_WRITE_LONG:
+        case ATA_CMD_WRITE_LONG_ONCE:
+                if (tf->protocol != ATA_PROT_PIO || tf->nsect != 1)
+                        goto invalid_fld;
+                qc->sect_size = scmd->request_bufflen;
+        }
+
         /*
          * Filter SET_FEATURES - XFER MODE command -- otherwise,
          * SET_FEATURES - XFER MODE must be preceded/succeeded