[PATCH] libata: add support for READ/WRITE LONG

[Mark Lord <liml@rtr.ca>]

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.

This patch was generated against a 2.6.21-rc3-git7 base:

 drivers/ata/libata-core.c |   20 ++++++++++----------
 drivers/ata/libata-scsi.c |   12 ++++++++++++
 include/linux/ata.h       |    6 ++++++
 include/linux/libata.h    |    2 ++
 4 files changed, 30 insertions(+), 10 deletions(-)

Signed-off-by:  Mark Lord <mlord@pobox.com>
---
--- linux/include/linux/libata.h.orig	2007-03-07 09:20:04.000000000 -0500
+++ linux/include/linux/libata.h	2007-03-12 13:16:29.000000000 -0400
@@ -425,6 +425,7 @@
 	int			dma_dir;
 
 	unsigned int		pad_len;
+	unsigned int		sect_size;
 
 	unsigned int		nbytes;
 	unsigned int		curbytes;
@@ -1171,6 +1172,7 @@
 	qc->n_elem = 0;
 	qc->err_mask = 0;
 	qc->pad_len = 0;
+	qc->sect_size = ATA_SECT_SIZE;
 
 	ata_tf_init(qc->dev, &qc->tf);
 
--- linux/include/linux/ata.h.orig	2007-03-07 09:21:25.000000000 -0500
+++ linux/include/linux/ata.h	2007-03-12 13:15:45.000000000 -0400
@@ -163,6 +163,12 @@
 	/* READ_LOG_EXT pages */
 	ATA_LOG_SATA_NCQ	= 0x10,
 
+	/* READ/WRITE LONG (obsolete) */
+	ATA_CMD_READ_LONG	= 0x22,
+	ATA_CMD_READ_LONG_ONCE	= 0x23,
+	ATA_CMD_WRITE_LONG	= 0x32,
+	ATA_CMD_WRITE_LONG_ONCE	= 0x33,
+
 	/* SETFEATURES stuff */
 	SETFEATURES_XFER	= 0x03,
 	XFER_UDMA_7		= 0x47,
--- linux/drivers/ata/libata-scsi.c.orig	2007-03-07 09:21:13.000000000 -0500
+++ linux/drivers/ata/libata-scsi.c	2007-03-12 13:14:46.000000000 -0400
@@ -2678,6 +2678,18 @@
 		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
--- linux/drivers/ata/libata-core.c.orig	2007-03-12 11:22:43.000000000 -0400
+++ linux/drivers/ata/libata-core.c	2007-03-12 13:08:28.000000000 -0400
@@ -4032,10 +4032,10 @@
 
 
 /**
- *	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.
@@ -4050,7 +4050,7 @@
 	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;
@@ -4070,17 +4070,17 @@
 		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++;
@@ -4089,10 +4089,10 @@
 }
 
 /**
- *	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:
@@ -4107,7 +4107,7 @@
 
 		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);