[v2 0/2] target: core: Fix sense key for invalid XCOPY request

[v2 0/2] target: core: Fix sense key for invalid XCOPY request

[Sergey Samoylenko]

EXTENDED COPY tests in libiscsi [1] show that TCM doesn't
follow SPC4 when detects invalid parameters in a XCOPY
command or IO errors. The replies from TCM contain wrong sense
key or ASCQ for incorrect request.

The series fixes the following tests from libiscsi:

  SCSI.ExtendedCopy.DescrType
  SCSI.ExtendedCopy.DescrLimits
  SCSI.ExtendedCopy.ParamHdr
  SCSI.ExtendedCopy.ValidSegDescr
  SCSI.ExtendedCopy.ValidTgtDescr

1. https://github.com/sahlberg/libiscsi

Sergey Samoylenko (2):
  target: allows backend drivers to fail with specific sense codes
  target: core: Fix sense key for invalid XCOPY request

 drivers/target/target_core_transport.c | 21 ++++++++++++++++++---
 drivers/target/target_core_xcopy.c     | 26 +++++++++++++++-----------
 include/target/target_core_backend.h   |  1 +
 include/target/target_core_base.h      |  2 ++
 4 files changed, 36 insertions(+), 14 deletions(-)

-- 
2.25.1

[v2 1/2] target: allows backend drivers to fail with specific sense codes

[Sergey Samoylenko]

Currently, backend drivers can fail IO with
SAM_STAT_CHECK_CONDITION which gets us
TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE. The patch adds
a new helper that allows backend drivers to fail with
specific sense codes.

This is based on a patch from Mike Christie <michael.christie@oracle.com>.

Cc: Mike Christie <michael.christie@oracle.com>
Cc: David Disseldorp <ddiss@suse.de>
[ Moved target_complete_cmd_with_sense() helper to mainline ]
Signed-off-by: Sergey Samoylenko <s.samoylenko@yadro.com>
---
 drivers/target/target_core_transport.c | 21 ++++++++++++++++++---
 include/target/target_core_backend.h   |  1 +
 include/target/target_core_base.h      |  2 ++
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 26ceabe34de5..d2a2892bda9c 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -736,8 +736,7 @@ static void target_complete_failure_work(struct work_struct *work)
 {
 	struct se_cmd *cmd = container_of(work, struct se_cmd, work);
 
-	transport_generic_request_failure(cmd,
-			TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+	transport_generic_request_failure(cmd, cmd->sense_reason);
 }
 
 /*
@@ -855,7 +854,8 @@ static bool target_cmd_interrupted(struct se_cmd *cmd)
 }
 
 /* May be called from interrupt context so must not sleep. */
-void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
+static void __target_complete_cmd(struct se_cmd *cmd, u8 scsi_status,
+				  sense_reason_t sense_reason)
 {
 	struct se_wwn *wwn = cmd->se_sess->se_tpg->se_tpg_wwn;
 	int success, cpu;
@@ -865,6 +865,7 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
 		return;
 
 	cmd->scsi_status = scsi_status;
+	cmd->sense_reason = sense_reason;
 
 	spin_lock_irqsave(&cmd->t_state_lock, flags);
 	switch (cmd->scsi_status) {
@@ -893,8 +894,22 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
 
 	queue_work_on(cpu, target_completion_wq, &cmd->work);
 }
+
+void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
+{
+	__target_complete_cmd(cmd, scsi_status, scsi_status ?
+			      TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE :
+			      TCM_NO_SENSE);
+}
 EXPORT_SYMBOL(target_complete_cmd);
 
+void target_complete_cmd_with_sense(struct se_cmd *cmd,
+				    sense_reason_t sense_reason)
+{
+	__target_complete_cmd(cmd, SAM_STAT_CHECK_CONDITION, sense_reason);
+}
+EXPORT_SYMBOL(target_complete_cmd_with_sense);
+
 void target_set_cmd_data_length(struct se_cmd *cmd, int length)
 {
 	if (length < cmd->data_length) {
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 1f78b09bba55..3cc50d30231a 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -75,6 +75,7 @@ void	target_backend_unregister(const struct target_backend_ops *);
 
 void	target_complete_cmd(struct se_cmd *, u8);
 void	target_set_cmd_data_length(struct se_cmd *, int);
+void	target_complete_cmd_with_sense(struct se_cmd *, sense_reason_t);
 void	target_complete_cmd_with_length(struct se_cmd *, u8, int);
 
 void	transport_copy_sense_to_cmd(struct se_cmd *, unsigned char *);
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 85c16c266eac..8c85d3b83a70 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -453,6 +453,8 @@ enum target_core_dif_check {
 #define TCM_ACA_TAG	0x24
 
 struct se_cmd {
+	/* Used for fail with specific sense codes */
+	sense_reason_t		sense_reason;
 	/* SAM response code being sent to initiator */
 	u8			scsi_status;
 	u8			scsi_asc;
-- 
2.25.1

[v2 2/2] target: core: Fix sense key for invalid XCOPY request

[Sergey Samoylenko]

TCM fails to pass the following tests in libiscsi:

  SCSI.ExtendedCopy.DescrType
  SCSI.ExtendedCopy.DescrLimits
  SCSI.ExtendedCopy.ParamHdr
  SCSI.ExtendedCopy.ValidSegDescr
  SCSI.ExtendedCopy.ValidTgtDescr

XCOPY always returns the same NOT READY sense key for all
detected errors. It changes a sense key for invalid requests
to ILLEGAL REQUEST sense key, for aborted transferring data
(IO error and etc.) to COPY ABORTED.

Fixes: d877d7275be34ad ("target: Fix a deadlock between the XCOPY code and iSCSI session shutdown")
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Konstantin Shelekhin <k.shelekhin@yadro.com>
Signed-off-by: Sergey Samoylenko <s.samoylenko@yadro.com>
---
 drivers/target/target_core_xcopy.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c
index 0f1319336f3e..64baf3e8c079 100644
--- a/drivers/target/target_core_xcopy.c
+++ b/drivers/target/target_core_xcopy.c
@@ -674,12 +674,16 @@ static void target_xcopy_do_work(struct work_struct *work)
 	unsigned int max_sectors;
 	int rc = 0;
 	unsigned short nolb, max_nolb, copied_nolb = 0;
+	sense_reason_t sense_rc;
 
-	if (target_parse_xcopy_cmd(xop) != TCM_NO_SENSE)
+	sense_rc = target_parse_xcopy_cmd(xop);
+	if (sense_rc != TCM_NO_SENSE)
 		goto err_free;
 
-	if (WARN_ON_ONCE(!xop->src_dev) || WARN_ON_ONCE(!xop->dst_dev))
+	if (WARN_ON_ONCE(!xop->src_dev) || WARN_ON_ONCE(!xop->dst_dev)) {
+		sense_rc = TCM_INVALID_PARAMETER_LIST;
 		goto err_free;
+	}
 
 	src_dev = xop->src_dev;
 	dst_dev = xop->dst_dev;
@@ -762,20 +766,20 @@ static void target_xcopy_do_work(struct work_struct *work)
 	return;
 
 out:
+	/*
+	 * The XCOPY command was aborted after some data was transferred.
+	 * Terminate command with CHECK CONDITION status, with the sense key
+	 * set to COPY ABORTED.
+	 */
+	sense_rc = TCM_COPY_TARGET_DEVICE_NOT_REACHABLE;
 	xcopy_pt_undepend_remotedev(xop);
 	target_free_sgl(xop->xop_data_sg, xop->xop_data_nents);
 
 err_free:
 	kfree(xop);
-	/*
-	 * Don't override an error scsi status if it has already been set
-	 */
-	if (ec_cmd->scsi_status == SAM_STAT_GOOD) {
-		pr_warn_ratelimited("target_xcopy_do_work: rc: %d, Setting X-COPY"
-			" CHECK_CONDITION -> sending response\n", rc);
-		ec_cmd->scsi_status = SAM_STAT_CHECK_CONDITION;
-	}
-	target_complete_cmd(ec_cmd, ec_cmd->scsi_status);
+	pr_warn_ratelimited("target_xcopy_do_work: rc: %d, sense: %u,"
+		" XCOPY operation failed\n", rc, sense_rc);
+	target_complete_cmd_with_sense(ec_cmd, sense_rc);
 }
 
 /*
-- 
2.25.1

Re: [v2 1/2] target: allows backend drivers to fail with specific sense codes

[David Disseldorp]

Hi Sergey,

On Mon, 26 Jul 2021 18:16:45 +0300, Sergey Samoylenko wrote:

> Currently, backend drivers can fail IO with
> SAM_STAT_CHECK_CONDITION which gets us
> TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE. The patch adds
> a new helper that allows backend drivers to fail with
> specific sense codes.
> 
> This is based on a patch from Mike Christie <michael.christie@oracle.com>.

This looks good and works for me, but I have one comment...

> Cc: Mike Christie <michael.christie@oracle.com>
> Cc: David Disseldorp <ddiss@suse.de>
> [ Moved target_complete_cmd_with_sense() helper to mainline ]
> Signed-off-by: Sergey Samoylenko <s.samoylenko@yadro.com>
> ---
>  drivers/target/target_core_transport.c | 21 ++++++++++++++++++---
>  include/target/target_core_backend.h   |  1 +
>  include/target/target_core_base.h      |  2 ++
>  3 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> index 26ceabe34de5..d2a2892bda9c 100644
> --- a/drivers/target/target_core_transport.c
> +++ b/drivers/target/target_core_transport.c
> @@ -736,8 +736,7 @@ static void target_complete_failure_work(struct work_struct *work)
>  {
>  	struct se_cmd *cmd = container_of(work, struct se_cmd, work);
>  
> -	transport_generic_request_failure(cmd,
> -			TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE);
> +	transport_generic_request_failure(cmd, cmd->sense_reason);
>  }
>  
>  /*
> @@ -855,7 +854,8 @@ static bool target_cmd_interrupted(struct se_cmd *cmd)
>  }
>  
>  /* May be called from interrupt context so must not sleep. */
> -void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
> +static void __target_complete_cmd(struct se_cmd *cmd, u8 scsi_status,
> +				  sense_reason_t sense_reason)
>  {
>  	struct se_wwn *wwn = cmd->se_sess->se_tpg->se_tpg_wwn;
>  	int success, cpu;
> @@ -865,6 +865,7 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
>  		return;
>  
>  	cmd->scsi_status = scsi_status;
> +	cmd->sense_reason = sense_reason;
>  
>  	spin_lock_irqsave(&cmd->t_state_lock, flags);
>  	switch (cmd->scsi_status) {
> @@ -893,8 +894,22 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
>  
>  	queue_work_on(cpu, target_completion_wq, &cmd->work);
>  }
> +
> +void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
> +{
> +	__target_complete_cmd(cmd, scsi_status, scsi_status ?
> +			      TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE :
> +			      TCM_NO_SENSE);
> +}
>  EXPORT_SYMBOL(target_complete_cmd);
>  
> +void target_complete_cmd_with_sense(struct se_cmd *cmd,
> +				    sense_reason_t sense_reason)
> +{
> +	__target_complete_cmd(cmd, SAM_STAT_CHECK_CONDITION, sense_reason);
> +}
> +EXPORT_SYMBOL(target_complete_cmd_with_sense);
> +

It's a little unclear from the function prototype that this actually
fails the command with SAM_STAT_CHECK_CONDITION. I could imagine people
erroneously calling target_complete_cmd_with_sense(cmd, TCM_NO_SENSE)
and expecting success.
I think it might be a bit clearer if you just export
__target_complete_cmd() as target_complete_cmd_with_sense() with all
three parameters and leave it up to the caller to flag
CHECK_CONDITION.

Cheers, David

RE: [v2 1/2] target: allows backend drivers to fail with specific sense codes

[Sergey Samoylenko]

Hi David,
Sorry for the long answer.

> Hi Sergey,
>
> On Mon, 26 Jul 2021 18:16:45 +0300, Sergey Samoylenko wrote:
>
>> Currently, backend drivers can fail IO with
>> SAM_STAT_CHECK_CONDITION which gets us
>> TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE. The patch adds
>> a new helper that allows backend drivers to fail with
>> specific sense codes.
>> 
>> This is based on a patch from Mike Christie <michael.christie@oracle.com>.
>
> This looks good and works for me, but I have one comment...
>
> It's a little unclear from the function prototype that this actually
> fails the command with SAM_STAT_CHECK_CONDITION. I could imagine people
> erroneously calling target_complete_cmd_with_sense(cmd, TCM_NO_SENSE)
> and expecting success.
> I think it might be a bit clearer if you just export
> __target_complete_cmd() as target_complete_cmd_with_sense() with all
> three parameters and leave it up to the caller to flag
> CHECK_CONDITION.
>
> Cheers, David

David, am I getting the idea right?

We want to get something like this:
-----------------------------------------------------------------------------------
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 7e35eddd9eb7..6dbfba7f16a6 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -736,8 +736,7 @@ static void target_complete_failure_work(struct work_struct *work)
 {
        struct se_cmd *cmd = container_of(work, struct se_cmd, work);

-       transport_generic_request_failure(cmd,
-                       TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+       transport_generic_request_failure(cmd, cmd->sense_reason);
 }

 /*
@@ -855,7 +854,8 @@ static bool target_cmd_interrupted(struct se_cmd *cmd)
 }

 /* May be called from interrupt context so must not sleep. */
-void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
+void target_complete_cmd_with_sense(struct se_cmd *cmd, u8 scsi_status,
+                                   sense_reason_t sense_reason)
 {
        struct se_wwn *wwn = cmd->se_sess->se_tpg->se_tpg_wwn;
        int success, cpu;
@@ -865,6 +865,7 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
                return;

        cmd->scsi_status = scsi_status;
+       cmd->sense_reason = sense_reason;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        switch (cmd->scsi_status) {
@@ -893,6 +894,14 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)

        queue_work_on(cpu, target_completion_wq, &cmd->work);
 }
+EXPORT_SYMBOL(target_complete_cmd_with_sense);
+
+void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
+{
+       target_complete_cmd_with_sense(cmd, scsi_status, scsi_status ?
+                             TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE :
+                             TCM_NO_SENSE);
+}
 EXPORT_SYMBOL(target_complete_cmd);

 void target_set_cmd_data_length(struct se_cmd *cmd, int length)
-----------------------------------------------------------------------------------

Then we use it as follows:
-----------------------------------------------------------------------------------
diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c
index 0f1319336f3e..1b4faafedb1a 100644
--- a/drivers/target/target_core_xcopy.c
+++ b/drivers/target/target_core_xcopy.c
@@ -674,12 +674,16 @@ static void target_xcopy_do_work(struct work_struct *work)
...
err_free:
        kfree(xop);
-       /*
-        * Don't override an error scsi status if it has already been set
-        */
-       if (ec_cmd->scsi_status == SAM_STAT_GOOD) {
-               pr_warn_ratelimited("target_xcopy_do_work: rc: %d, Setting X-COPY"
-                       " CHECK_CONDITION -> sending response\n", rc);
-               ec_cmd->scsi_status = SAM_STAT_CHECK_CONDITION;
-       }
-       target_complete_cmd(ec_cmd, ec_cmd->scsi_status);
+       pr_warn_ratelimited("target_xcopy_do_work: rc: %d, sense: %u,"
+               " XCOPY operation failed\n", rc, sense_rc);
+       target_complete_cmd_with_sense(ec_cmd, SAM_STAT_CHECK_CONDITION, sense_rc);
 }
-----------------------------------------------------------------------------------

Best regards,
Sergey

Re: [v2 1/2] target: allows backend drivers to fail with specific sense codes

[David Disseldorp]

Hi Sergey,

On Mon, 2 Aug 2021 18:31:06 +0000, Sergey Samoylenko wrote:

> David, am I getting the idea right?
> 
> We want to get something like this:
[trimmed]

Yes, this is my preference (with the corresponding .h changes).
Please send it as a git-send-email patchset and feel free to add my
reviewed-by tag.

Cheers, David