Commit 1b26d29c authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Jeff Garzik
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[libata] scsi: implement MODE SELECT command 



The cache_type file in sysfs lets users configure the disk cache in
write-through or write-back modes.  However, ata disks do not support
writing to the file because they do not implement the MODE SELECT
command.

This patch adds a translation from MODE SELECT (for the caching page
only) to the ATA SET FEATURES command.  The set of changeable parameters
answered by MODE SENSE is also adjusted accordingly.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent 6ca8e794

drivers/ata/libata-scsi.c

+188 −6
Original line number Diff line number Diff line
@@ -2243,7 +2243,7 @@ static void modecpy(u8 *dest, const u8 *src, int n, bool changeable) 
static unsigned int ata_msense_caching(u16 *id, u8 *buf, bool changeable)

{

	modecpy(buf, def_cache_mpage, sizeof(def_cache_mpage), changeable);

	if (!changeable && ata_id_wcache_enabled(id))

	if (changeable || ata_id_wcache_enabled(id))

		buf[2] |= (1 << 2);	/* write cache enable */

	if (!changeable && !ata_id_rahead_enabled(id))

		buf[12] |= (1 << 5);	/* disable read ahead */
@@ -3106,6 +3106,188 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc) 
	return 1;

}



/**

 *	ata_mselect_caching - Simulate MODE SELECT for caching info page

 *	@qc: Storage for translated ATA taskfile

 *	@buf: input buffer

 *	@len: number of valid bytes in the input buffer

 *

 *	Prepare a taskfile to modify caching information for the device.

 *

 *	LOCKING:

 *	None.

 */

static int ata_mselect_caching(struct ata_queued_cmd *qc,

			       const u8 *buf, int len)

{

	struct ata_taskfile *tf = &qc->tf;

	struct ata_device *dev = qc->dev;

	char mpage[CACHE_MPAGE_LEN];

	u8 wce;



	/*

	 * The first two bytes of def_cache_mpage are a header, so offsets

	 * in mpage are off by 2 compared to buf.  Same for len.

	 */



	if (len != CACHE_MPAGE_LEN - 2)

		return -EINVAL;



	wce = buf[0] & (1 << 2);



	/*

	 * Check that read-only bits are not modified.

	 */

	ata_msense_caching(dev->id, mpage, false);

	mpage[2] &= ~(1 << 2);

	mpage[2] |= wce;

	if (memcmp(mpage + 2, buf, CACHE_MPAGE_LEN - 2) != 0)

		return -EINVAL;



	tf->flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;

	tf->protocol = ATA_PROT_NODATA;

	tf->nsect = 0;

	tf->command = ATA_CMD_SET_FEATURES;

	tf->feature = wce ? SETFEATURES_WC_ON : SETFEATURES_WC_OFF;

	return 0;

}



/**

 *	ata_scsiop_mode_select - Simulate MODE SELECT 6, 10 commands

 *	@qc: Storage for translated ATA taskfile

 *

 *	Converts a MODE SELECT command to an ATA SET FEATURES taskfile.

 *	Assume this is invoked for direct access devices (e.g. disks) only.

 *	There should be no block descriptor for other device types.

 *

 *	LOCKING:

 *	spin_lock_irqsave(host lock)

 */

static unsigned int ata_scsi_mode_select_xlat(struct ata_queued_cmd *qc)

{

	struct scsi_cmnd *scmd = qc->scsicmd;

	const u8 *cdb = scmd->cmnd;

	const u8 *p;

	u8 pg, spg;

	unsigned six_byte, pg_len, hdr_len, bd_len;

	int len;



	VPRINTK("ENTER\n");



	six_byte = (cdb[0] == MODE_SELECT);

	if (six_byte) {

		if (scmd->cmd_len < 5)

			goto invalid_fld;



		len = cdb[4];

		hdr_len = 4;

	} else {

		if (scmd->cmd_len < 9)

			goto invalid_fld;



		len = (cdb[7] << 8) + cdb[8];

		hdr_len = 8;

	}



	/* We only support PF=1, SP=0.  */

	if ((cdb[1] & 0x11) != 0x10)

		goto invalid_fld;



	/* Test early for possible overrun.  */

	if (!scsi_sg_count(scmd) || scsi_sglist(scmd)->length < len)

		goto invalid_param_len;



	p = page_address(sg_page(scsi_sglist(scmd)));



	/* Move past header and block descriptors.  */

	if (len < hdr_len)

		goto invalid_param_len;



	if (six_byte)

		bd_len = p[3];

	else

		bd_len = (p[6] << 8) + p[7];



	len -= hdr_len;

	p += hdr_len;

	if (len < bd_len)

		goto invalid_param_len;

	if (bd_len != 0 && bd_len != 8)

		goto invalid_param;



	len -= bd_len;

	p += bd_len;

	if (len == 0)

		goto skip;



	/* Parse both possible formats for the mode page headers.  */

	pg = p[0] & 0x3f;

	if (p[0] & 0x40) {

		if (len < 4)

			goto invalid_param_len;



		spg = p[1];

		pg_len = (p[2] << 8) | p[3];

		p += 4;

		len -= 4;

	} else {

		if (len < 2)

			goto invalid_param_len;



		spg = 0;

		pg_len = p[1];

		p += 2;

		len -= 2;

	}



	/*

	 * No mode subpages supported (yet) but asking for _all_

	 * subpages may be valid

	 */

	if (spg && (spg != ALL_SUB_MPAGES))

		goto invalid_param;

	if (pg_len > len)

		goto invalid_param_len;



	switch (pg) {

	case CACHE_MPAGE:

		if (ata_mselect_caching(qc, p, pg_len) < 0)

			goto invalid_param;

		break;



	default:		/* invalid page code */

		goto invalid_param;

	}



	/*

	 * Only one page has changeable data, so we only support setting one

	 * page at a time.

	 */

	if (len > pg_len)

		goto invalid_param;



	return 0;



 invalid_fld:

	/* "Invalid field in CDB" */

	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x24, 0x0);

	return 1;



 invalid_param:

	/* "Invalid field in parameter list" */

	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x26, 0x0);

	return 1;



 invalid_param_len:

	/* "Parameter list length error" */

	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x1a, 0x0);

	return 1;



 skip:

	scmd->result = SAM_STAT_GOOD;

	return 1;

}



/**

 *	ata_get_xlat_func - check if SCSI to ATA translation is possible

 *	@dev: ATA device
@@ -3146,6 +3328,11 @@ static inline ata_xlat_func_t ata_get_xlat_func(struct ata_device *dev, u8 cmd) 
	case ATA_16:

		return ata_scsi_pass_thru;



	case MODE_SELECT:

	case MODE_SELECT_10:

		return ata_scsi_mode_select_xlat;

		break;



	case START_STOP:

		return ata_scsi_start_stop_xlat;

	}
@@ -3338,11 +3525,6 @@ void ata_scsi_simulate(struct ata_device *dev, struct scsi_cmnd *cmd) 
		ata_scsi_rbuf_fill(&args, ata_scsiop_mode_sense);

		break;



	case MODE_SELECT:	/* unconditionally return */

	case MODE_SELECT_10:	/* bad-field-in-cdb */

		ata_scsi_invalid_field(cmd);

		break;



	case READ_CAPACITY:

		ata_scsi_rbuf_fill(&args, ata_scsiop_read_cap);

		break;

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