Patchwork ata: implement MODE SELECT command

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Submitter Paolo Bonzini
Date July 4, 2012, 11:13 a.m.
Message ID <1341400436-2546-1-git-send-email-pbonzini@redhat.com>
Download mbox | patch
Permalink /patch/168952/
State Not Applicable
Delegated to: David Miller
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Comments

Paolo Bonzini - July 4, 2012, 11:13 a.m.
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.

Cc: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 drivers/ata/libata-scsi.c |  147 +++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 142 insertions(+), 5 deletions(-)
Sergei Shtylyov - July 4, 2012, 3:38 p.m.
Hello.

On 07/04/2012 03:13 PM, Paolo Bonzini wrote:

> 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.

> Cc: Jeff Garzik <jgarzik@pobox.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  drivers/ata/libata-scsi.c |  147 +++++++++++++++++++++++++++++++++++++++++++--
>  1 files changed, 142 insertions(+), 5 deletions(-)

> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 41cde45..e7702d3 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3081,6 +3081,144 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
>  }
>  
>  /**
> + *	ata_mselect_caching - Simulate MODE SELECT for caching info page
> + *	@tf: taskfile to be filled
> + *	@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 unsigned int ata_mselect_caching(struct ata_taskfile *tf, const u8 *buf,
> +					int len)
> +{
> +	u8 wce;

   Empty line after declaration block wouldn't hurt...

> +	if (len == 0)
> +		return 1;
> +
> +	/*
> +	 * The first two bytes are a header, so offsets here are 2 less
> +	 * than in ata_msense_caching.
> +	 */
> +	wce = buf[0] & (1 << 2);

   Perhaps it's worth denying the command if the other page fields dfifer from
'def_cache_mpage' (i.e. all zeros)?

> +/**
> + *	ata_scsi_mode_select_xlat - Translate 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;
> +	struct ata_taskfile *tf = &qc->tf;
> +	const u8 *cdb = scmd->cmnd;
> +	const u8 *p;
> +	u8 pg, spg;
> +	unsigned six_byte, pg_len;
> +	int len;
> +
> +	VPRINTK("ENTER\n");
> +
> +	/*
> +	 * Get the command buffer.
> +	 */
> +	if (!scsi_sg_count(scmd))
> +		goto invalid_fld;
> +
> +	p = page_address(sg_page(scsi_sglist(scmd)));
> +
> +	six_byte = (cdb[0] == MODE_SELECT);
> +	if (six_byte) {
> +		if (scmd->cmd_len < 5)

   Not 6?

> +			goto invalid_fld;
> +
> +		len = cdb[4];
> +	} else {
> +		if (scmd->cmd_len < 9)

   Not 10?
   And ata_scsiop_mode_sense() don't seem to check this...
   And I doubt "Invalid field in CDB" is a proper sense code in this situation.

> +			goto invalid_fld;
> +
> +		len = (cdb[7] << 8) | cdb[8];
> +	}

> +	/*
> +	 * No mode subpages supported (yet) but asking for _all_
> +	 * subpages may be valid
> +	 */
> +	if (spg && (spg != ALL_SUB_MPAGES))
> +		goto invalid_fld;
> +	if (pg_len > len)
> +		goto invalid_fld;

   It's valid to have buffer size less than data size.

> +	switch (pg) {
> +	case CACHE_MPAGE:
> +		if (ata_mselect_caching(tf, p, pg_len))
> +			goto invalid_fld;
> +		break;
> +
> +	default:		/* invalid page code */
> +		goto invalid_fld;

   Page code is not a part of CDB, hence the sense code you'll return doesn't
fit there.

> +	}
> +	return 0;
> +
> + invalid_fld:
> +	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x24, 0x0);
> +	/* "Invalid field in cbd" */
> +	return 1;

MBR, Sergei

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Paolo Bonzini - July 4, 2012, 4:03 p.m.
Il 04/07/2012 17:38, Sergei Shtylyov ha scritto:
> Hello.
> 
> On 07/04/2012 03:13 PM, Paolo Bonzini wrote:
> 
>> 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.
> 
>> Cc: Jeff Garzik <jgarzik@pobox.com>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>  drivers/ata/libata-scsi.c |  147 +++++++++++++++++++++++++++++++++++++++++++--
>>  1 files changed, 142 insertions(+), 5 deletions(-)
> 
>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>> index 41cde45..e7702d3 100644
>> --- a/drivers/ata/libata-scsi.c
>> +++ b/drivers/ata/libata-scsi.c
>> @@ -3081,6 +3081,144 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
>>  }
>>  
>>  /**
>> + *	ata_mselect_caching - Simulate MODE SELECT for caching info page
>> + *	@tf: taskfile to be filled
>> + *	@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 unsigned int ata_mselect_caching(struct ata_taskfile *tf, const u8 *buf,
>> +					int len)
>> +{
>> +	u8 wce;
> 
>    Empty line after declaration block wouldn't hurt...
> 
>> +	if (len == 0)
>> +		return 1;
>> +
>> +	/*
>> +	 * The first two bytes are a header, so offsets here are 2 less
>> +	 * than in ata_msense_caching.
>> +	 */
>> +	wce = buf[0] & (1 << 2);
> 
>    Perhaps it's worth denying the command if the other page fields dfifer from
> 'def_cache_mpage' (i.e. all zeros)?

I thought about it, but it seemed a useless complication.

>> +/**
>> + *	ata_scsi_mode_select_xlat - Translate 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;
>> +	struct ata_taskfile *tf = &qc->tf;
>> +	const u8 *cdb = scmd->cmnd;
>> +	const u8 *p;
>> +	u8 pg, spg;
>> +	unsigned six_byte, pg_len;
>> +	int len;
>> +
>> +	VPRINTK("ENTER\n");
>> +
>> +	/*
>> +	 * Get the command buffer.
>> +	 */
>> +	if (!scsi_sg_count(scmd))
>> +		goto invalid_fld;
>> +
>> +	p = page_address(sg_page(scsi_sglist(scmd)));
>> +
>> +	six_byte = (cdb[0] == MODE_SELECT);
>> +	if (six_byte) {
>> +		if (scmd->cmd_len < 5)
> 
>    Not 6?

This is just protecting the next access.  The last byte is unused.

>> +			goto invalid_fld;
>> +
>> +		len = cdb[4];
>> +	} else {
>> +		if (scmd->cmd_len < 9)
> 
>    Not 10?
>    And ata_scsiop_mode_sense() don't seem to check this...

Yeah, but other xlat functions do this, see ata_scsi_start_stop_xlat.  I
wasn't sure why, so I went for the safer option.

>    And I doubt "Invalid field in CDB" is a proper sense code in this situation.
> 
>> +			goto invalid_fld;
>> +
>> +		len = (cdb[7] << 8) | cdb[8];
>> +	}
> 
>> +	/*
>> +	 * No mode subpages supported (yet) but asking for _all_
>> +	 * subpages may be valid
>> +	 */
>> +	if (spg && (spg != ALL_SUB_MPAGES))
>> +		goto invalid_fld;
>> +	if (pg_len > len)
>> +		goto invalid_fld;
> 
>    It's valid to have buffer size less than data size.

Perhaps for MODE SENSE, but not for MODE SELECT.  Otherwise, where do
you get the mode data from?

Anyhow, checking buffer size vs. data size is done early, in

+	/* Test early for possible overrun.  */
+	if (scsi_sglist(scmd)->length < len)
+		goto invalid_fld;

not here.  What this check is doing, is ensuring that the page data does
not extend past the end of the buffer.

>> +	switch (pg) {
>> +	case CACHE_MPAGE:
>> +		if (ata_mselect_caching(tf, p, pg_len))
>> +			goto invalid_fld;
>> +		break;
>> +
>> +	default:		/* invalid page code */
>> +		goto invalid_fld;
> 
>    Page code is not a part of CDB, hence the sense code you'll return doesn't
> fit there.

Yes, invalid field in parameter list probably would be better.  Let me
know if I should respin.

Thanks for the review!

Paolo

>> +	}
>> +	return 0;
>> +
>> + invalid_fld:
>> +	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x24, 0x0);
>> +	/* "Invalid field in cbd" */
>> +	return 1;
> 
> MBR, Sergei
> 


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Sergei Shtylyov - July 4, 2012, 5:08 p.m.
Hello.

On 07/04/2012 03:13 PM, Paolo Bonzini wrote:

> 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.

> Cc: Jeff Garzik <jgarzik@pobox.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  drivers/ata/libata-scsi.c |  147 +++++++++++++++++++++++++++++++++++++++++++--
>  1 files changed, 142 insertions(+), 5 deletions(-)

> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 41cde45..e7702d3 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
[...]
> +	switch (pg) {
> +	case CACHE_MPAGE:
> +		if (ata_mselect_caching(tf, p, pg_len))
> +			goto invalid_fld;

   Error is in the data, not CDB, so returning "invalied field in CDB" doesn't
make sense...

> +		break;
> +
> +	default:		/* invalid page code */
> +		goto invalid_fld;
> +	}
> +	return 0;
> +
> + invalid_fld:
> +	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x24, 0x0);
> +	/* "Invalid field in cbd" */

   s/cbd/CDB/

MBR, Sergei
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Sergei Shtylyov - July 4, 2012, 5:20 p.m.
On 07/04/2012 08:03 PM, Paolo Bonzini wrote:

>>> 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.

>>> Cc: Jeff Garzik <jgarzik@pobox.com>
>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>> ---
>>>  drivers/ata/libata-scsi.c |  147 +++++++++++++++++++++++++++++++++++++++++++--
>>>  1 files changed, 142 insertions(+), 5 deletions(-)

>>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>>> index 41cde45..e7702d3 100644
>>> --- a/drivers/ata/libata-scsi.c
>>> +++ b/drivers/ata/libata-scsi.c
>>> @@ -3081,6 +3081,144 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
>>>  }
>>>  
>>>  /**
>>> + *	ata_mselect_caching - Simulate MODE SELECT for caching info page
>>> + *	@tf: taskfile to be filled
>>> + *	@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 unsigned int ata_mselect_caching(struct ata_taskfile *tf, const u8 *buf,
>>> +					int len)
>>> +{
>>> +	u8 wce;

>>    Empty line after declaration block wouldn't hurt...

>>> +	if (len == 0)
>>> +		return 1;
>>> +
>>> +	/*
>>> +	 * The first two bytes are a header, so offsets here are 2 less
>>> +	 * than in ata_msense_caching.
>>> +	 */
>>> +	wce = buf[0] & (1 << 2);

>>    Perhaps it's worth denying the command if the other page fields dfifer from
>> 'def_cache_mpage' (i.e. all zeros)?

> I thought about it, but it seemed a useless complication.

   If you bothered to implement that, go all the way. :-)

>>> +/**
>>> + *	ata_scsi_mode_select_xlat - Translate 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)
>>> +{
[...]
>>> +	/*
>>> +	 * No mode subpages supported (yet) but asking for _all_
>>> +	 * subpages may be valid
>>> +	 */
>>> +	if (spg && (spg != ALL_SUB_MPAGES))
>>> +		goto invalid_fld;
>>> +	if (pg_len > len)
>>> +		goto invalid_fld;

>>    It's valid to have buffer size less than data size.

> Perhaps for MODE SENSE, but not for MODE SELECT.  Otherwise, where do
> you get the mode data from?

   They simply don't change?

> Anyhow, checking buffer size vs. data size is done early, in

> +	/* Test early for possible overrun.  */
> +	if (scsi_sglist(scmd)->length < len)
> +		goto invalid_fld;

> not here.  What this check is doing, is ensuring that the page data does
> not extend past the end of the buffer.

   That's what I say is valid. You can get incomplete data, according to the
buffer size. Though maybe it was only my impression...

>>> +	switch (pg) {
>>> +	case CACHE_MPAGE:
>>> +		if (ata_mselect_caching(tf, p, pg_len))
>>> +			goto invalid_fld;
>>> +		break;
>>> +
>>> +	default:		/* invalid page code */
>>> +		goto invalid_fld;

>>    Page code is not a part of CDB, hence the sense code you'll return doesn't
>> fit there.

> Yes, invalid field in parameter list probably would be better.

   Or "parameter not supported" (0x26/0x01).

> Let me know if I should respin.

   I'd prefer if you respin.

> Thanks for the review!

> Paolo

MBR, Sergei
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Paolo Bonzini - July 4, 2012, 7:34 p.m.
Il 04/07/2012 19:20, Sergei Shtylyov ha scritto:
>> > Perhaps for MODE SENSE, but not for MODE SELECT.  Otherwise, where do
>> > you get the mode data from?
>    They simply don't change?

The standard says "If the parameter list length results in the
truncation of any mode parameter header, mode parameter block
descriptor(s), or mode page, then the command shall be terminated with
CHECK CONDITION status, with the sense key set to ILLEGAL REQUEST, and
the additional sense code set to PARAMETER LIST LENGTH ERROR".

Paolo
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Patch

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 41cde45..e7702d3 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3081,6 +3081,144 @@  static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
 }
 
 /**
+ *	ata_mselect_caching - Simulate MODE SELECT for caching info page
+ *	@tf: taskfile to be filled
+ *	@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 unsigned int ata_mselect_caching(struct ata_taskfile *tf, const u8 *buf,
+					int len)
+{
+	u8 wce;
+	if (len == 0)
+		return 1;
+
+	/*
+	 * The first two bytes are a header, so offsets here are 2 less
+	 * than in ata_msense_caching.
+	 */
+	wce = buf[0] & (1 << 2);
+
+	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_scsi_mode_select_xlat - Translate 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;
+	struct ata_taskfile *tf = &qc->tf;
+	const u8 *cdb = scmd->cmnd;
+	const u8 *p;
+	u8 pg, spg;
+	unsigned six_byte, pg_len;
+	int len;
+
+	VPRINTK("ENTER\n");
+
+	/*
+	 * Get the command buffer.
+	 */
+	if (!scsi_sg_count(scmd))
+		goto invalid_fld;
+
+	p = page_address(sg_page(scsi_sglist(scmd)));
+
+	six_byte = (cdb[0] == MODE_SELECT);
+	if (six_byte) {
+		if (scmd->cmd_len < 5)
+			goto invalid_fld;
+
+		len = cdb[4];
+	} else {
+		if (scmd->cmd_len < 9)
+			goto invalid_fld;
+
+		len = (cdb[7] << 8) | cdb[8];
+	}
+
+	/* Test early for possible overrun.  */
+	if (scsi_sglist(scmd)->length < len)
+		goto invalid_fld;
+
+	p += six_byte ? 4 : 8;
+	len -= six_byte ? 4 : 8;
+
+	/* We only support PF=1, SP=0.  */
+	if ((cdb[1] & 0x11) != 0x10)
+		goto invalid_fld;
+
+	if (len == 0)
+		goto skip;
+
+	/* Parse both possible formats for the mode page headers.  */
+	pg = p[0] & 0x3f;
+	if (p[0] & 0x40) {
+		spg = p[1];
+		pg_len = (p[2] << 8) | p[3];
+		p += 4;
+		len -= 4;
+	} else {
+		spg = 0;
+		pg_len = p[1];
+		p += 2;
+		len -= 2;
+	}
+
+	/* We only support setting one page at a time.  */
+	if (len != pg_len)
+		goto invalid_fld;
+
+	/*
+	 * No mode subpages supported (yet) but asking for _all_
+	 * subpages may be valid
+	 */
+	if (spg && (spg != ALL_SUB_MPAGES))
+		goto invalid_fld;
+	if (pg_len > len)
+		goto invalid_fld;
+
+	switch (pg) {
+	case CACHE_MPAGE:
+		if (ata_mselect_caching(tf, p, pg_len))
+			goto invalid_fld;
+		break;
+
+	default:		/* invalid page code */
+		goto invalid_fld;
+	}
+	return 0;
+
+ invalid_fld:
+	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x24, 0x0);
+	/* "Invalid field in cbd" */
+	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
  *	@cmd: SCSI command opcode to consider
@@ -3120,6 +3257,11 @@  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;
 	}
@@ -3312,11 +3454,6 @@  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;