[RESEND PATCH 0/3] scsi: target: Set correct residual data

[RESEND PATCH 0/3] scsi: target: Set correct residual data

[Anastasia Kovaleva]

Hi Martin,
Please apply the changes to 5.11/scsi-queue at your earliest
convenience.

The series changes the behavior of the target in regard to processing
commands with overflow/underflow in accordance with the standarts.

The target driver used to process the DMA_TO_DEVICE commands with
residuals (in particular, WRITE command) incorrectly. The target
response contained neither a residual count, nor an OVERFLOW/UNDERFLOW
bit. Such behavior did not comply with the RFC 7143. Also the
returned ASC and ASCQ were incorrect according to FCP-4,
and residuals were not set for the 4Kn devices.

This patches fix the major inconsistances in processing these kind of
commands.

This patch series has been tested with a modified libiscsi testing
library.
The link to the pull request:
https://github.com/sahlberg/libiscsi/pull/345

Write10Residuals, Write12Residuals, Write16Residuals tests have passed.

Thanks,
Anastasia

Anastasia Kovaleva (2):
  scsi: target: core: Signal WRITE residuals
  scsi: target: core: Change ASCQ for residual write

Roman Bolshakov (1):
  scsi: target: core: Set residuals for 4Kn devices

 drivers/target/target_core_transport.c | 53 +++++++++++++-------------
 include/target/target_core_base.h      |  1 +
 2 files changed, 28 insertions(+), 26 deletions(-)

-- 
2.24.3 (Apple Git-128)

[RESEND PATCH 1/3] scsi: target: core: Set residuals for 4Kn devices

[Anastasia Kovaleva]

From: Roman Bolshakov <r.bolshakov@yadro.com>

TCM always fails SBC commands with residuals for 4Kn devices when the
command is processed by sbc_parse_cdb(). That prevents residual
signalling to the transport driver because residual kind and residual
amount aren't set. It also makes residual handling different from
512-byte formatted devices - if there are residuals 512-byte LUN would
proceed with command execution while 4K-byte LUN would fail.

Based-on: https://patchwork.kernel.org/project/target-devel/patch/20170523234854.21452-31-bart.vanassche@sandisk.com/
Based-on-patch-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Konstantin Vinogradov <k.vinogradov@yadro.com>
---
 drivers/target/target_core_transport.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index fca4bd079d02..f27a7d6cc1e0 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1332,17 +1332,6 @@ target_cmd_size_check(struct se_cmd *cmd, unsigned int size)
 				return TCM_INVALID_CDB_FIELD;
 			}
 		}
-		/*
-		 * Reject READ_* or WRITE_* with overflow/underflow for
-		 * type SCF_SCSI_DATA_CDB.
-		 */
-		if (dev->dev_attrib.block_size != 512)  {
-			pr_err("Failing OVERFLOW/UNDERFLOW for LBA op"
-				" CDB on non 512-byte sector setup subsystem"
-				" plugin: %s\n", dev->transport->name);
-			/* Returns CHECK_CONDITION + INVALID_CDB_FIELD */
-			return TCM_INVALID_CDB_FIELD;
-		}
 		/*
 		 * For the overflow case keep the existing fabric provided
 		 * ->data_length.  Otherwise for the underflow case, reset
-- 
2.24.3 (Apple Git-128)

[RESEND PATCH 2/3] scsi: target: core: Signal WRITE residuals

[Anastasia Kovaleva]

According to RFC 7143 11.4.5.2.:

  If SPDTL > EDTL for a task, iSCSI Overflow MUST be signaled in the
  SCSI Response PDU as specified in Section 11.4.5.1.  The Residual
  Count MUST be set to the numerical value of (SPDTL - EDTL).

  If SPDTL < EDTL for a task, iSCSI Underflow MUST be signaled in the
  SCSI Response PDU as specified in Section 11.4.5.1.  The Residual
  Count MUST be set to the numerical value of (EDTL - SPDTL).

libiscsi has residual write tests that check residual kind and residual
amount and all of them (Write10Residuals, Write12Residuals,
Write16Residuals) currently fail.

One of the reasons why they fail is because target completes write
commands with INVALID FIELD IN CDB before setting the Overflow/Underflow
bit and residual amount.

Set the Overflow/Underflow bit and the residual amount before failing a
write to comply with RFC 7143.

Signed-off-by: Anastasia Kovaleva <a.kovaleva@yadro.com>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
---
 drivers/target/target_core_transport.c | 34 +++++++++++++++-----------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index f27a7d6cc1e0..eb51298cab4f 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1313,6 +1313,26 @@ target_cmd_size_check(struct se_cmd *cmd, unsigned int size)
 			" %u does not match SCSI CDB Length: %u for SAM Opcode:"
 			" 0x%02x\n", cmd->se_tfo->fabric_name,
 				cmd->data_length, size, cmd->t_task_cdb[0]);
+		/*
+		 * For READ command for the overflow case keep the existing
+		 * fabric provided ->data_length. Otherwise for the underflow
+		 * case, reset ->data_length to the smaller SCSI expected data
+		 * transfer length.
+		 */
+		if (size > cmd->data_length) {
+			cmd->se_cmd_flags |= SCF_OVERFLOW_BIT;
+			cmd->residual_count = (size - cmd->data_length);
+		} else {
+			cmd->se_cmd_flags |= SCF_UNDERFLOW_BIT;
+			cmd->residual_count = (cmd->data_length - size);
+			/*
+			 * Do not truncate ->data_length for WRITE command to
+			 * dump all payload
+			 */
+			if (cmd->data_direction == DMA_FROM_DEVICE) {
+				cmd->data_length = size;
+			}
+		}
 
 		if (cmd->data_direction == DMA_TO_DEVICE) {
 			if (cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) {
@@ -1332,20 +1352,6 @@ target_cmd_size_check(struct se_cmd *cmd, unsigned int size)
 				return TCM_INVALID_CDB_FIELD;
 			}
 		}
-		/*
-		 * For the overflow case keep the existing fabric provided
-		 * ->data_length.  Otherwise for the underflow case, reset
-		 * ->data_length to the smaller SCSI expected data transfer
-		 * length.
-		 */
-		if (size > cmd->data_length) {
-			cmd->se_cmd_flags |= SCF_OVERFLOW_BIT;
-			cmd->residual_count = (size - cmd->data_length);
-		} else {
-			cmd->se_cmd_flags |= SCF_UNDERFLOW_BIT;
-			cmd->residual_count = (cmd->data_length - size);
-			cmd->data_length = size;
-		}
 	}
 
 	return target_check_max_data_sg_nents(cmd, dev, size);
-- 
2.24.3 (Apple Git-128)

[RESEND PATCH 3/3] scsi: target: core: Change ASCQ for residual write

[Anastasia Kovaleva]

According to FCP-4 (9.4.2):

  If the command requested that data beyond the length specified by the
  FCP_DL field be transferred, then the device server shall set the
  FCP_RESID_OVER bit (see 9.5.8) to one in the FCP_RSP IU and:

  a) process the command normally except that data beyond the FCP_DL
  count shall not be requested or transferred;

  b) transfer no data and return CHECK CONDITION status with the sense
  key set to ILLEGAL REQUEST and the additional sense code set to INVALID
  FIELD IN COMMAND INFORMATION UNIT; or

  c) may transfer data and return CHECK CONDITION status with the sense
  key set to ABORTED COMMAND and the additional sense code set to
  INVALID FIELD IN COMMAND INFORMATION UNIT.

TCM follows b) and transfers no data for residual writes but returns
INVALID FIELD IN CDB instead of INVALID FIELD IN COMMAND INFORMATION
UNIT.

Change the ASCQ to INVALID FIELD IN COMMAND INFORMATION UNIT to meet the
standart.

Signed-off-by: Anastasia Kovaleva <a.kovaleva@yadro.com>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
---
 drivers/target/target_core_transport.c | 8 +++++++-
 include/target/target_core_base.h      | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index eb51298cab4f..94cee131f5b7 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1338,7 +1338,7 @@ target_cmd_size_check(struct se_cmd *cmd, unsigned int size)
 			if (cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) {
 				pr_err_ratelimited("Rejecting underflow/overflow"
 						   " for WRITE data CDB\n");
-				return TCM_INVALID_CDB_FIELD;
+				return TCM_INVALID_FIELD_IN_COMMAND_IU;
 			}
 			/*
 			 * Some fabric drivers like iscsi-target still expect to
@@ -1879,6 +1879,7 @@ void transport_generic_request_failure(struct se_cmd *cmd,
 	case TCM_UNSUPPORTED_TARGET_DESC_TYPE_CODE:
 	case TCM_TOO_MANY_SEGMENT_DESCS:
 	case TCM_UNSUPPORTED_SEGMENT_DESC_TYPE_CODE:
+	case TCM_INVALID_FIELD_IN_COMMAND_IU:
 		break;
 	case TCM_OUT_OF_RESOURCES:
 		cmd->scsi_status = SAM_STAT_TASK_SET_FULL;
@@ -3205,6 +3206,11 @@ static const struct sense_detail sense_detail_table[] = {
 		.asc = 0x55,
 		.ascq = 0x04, /* INSUFFICIENT REGISTRATION RESOURCES */
 	},
+	[TCM_INVALID_FIELD_IN_COMMAND_IU] = {
+		.key = ILLEGAL_REQUEST,
+		.asc = 0x0e,
+		.ascq = 0x03, /* INVALID FIELD IN COMMAND INFORMATION UNIT */
+	},
 };
 
 /**
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 63dd12124139..54dcc0eb25fa 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -187,6 +187,7 @@ enum tcm_sense_reason_table {
 	TCM_UNSUPPORTED_SEGMENT_DESC_TYPE_CODE	= R(0x1c),
 	TCM_INSUFFICIENT_REGISTRATION_RESOURCES	= R(0x1d),
 	TCM_LUN_BUSY				= R(0x1e),
+	TCM_INVALID_FIELD_IN_COMMAND_IU         = R(0x1f),
 #undef R
 };
 
-- 
2.24.3 (Apple Git-128)

Re: [RESEND PATCH 0/3] scsi: target: Set correct residual data

[Anastasia Kovaleva]

Hi,

Could you please tell me if there are any objections to these changes?
These patches are applicable to 5.12/scsi-queue.

Thanks,
Anastasia

On 03.12.2020, 11:21, "Anastasia Kovaleva" <a.kovaleva@yadro.com> wrote:

    Hi Martin,
    Please apply the changes to 5.11/scsi-queue at your earliest
    convenience.

    The series changes the behavior of the target in regard to processing
    commands with overflow/underflow in accordance with the standarts.

    The target driver used to process the DMA_TO_DEVICE commands with
    residuals (in particular, WRITE command) incorrectly. The target
    response contained neither a residual count, nor an OVERFLOW/UNDERFLOW
    bit. Such behavior did not comply with the RFC 7143. Also the
    returned ASC and ASCQ were incorrect according to FCP-4,
    and residuals were not set for the 4Kn devices.

    This patches fix the major inconsistances in processing these kind of
    commands.

    This patch series has been tested with a modified libiscsi testing
    library.
    The link to the pull request:
    https://github.com/sahlberg/libiscsi/pull/345

    Write10Residuals, Write12Residuals, Write16Residuals tests have passed.

    Thanks,
    Anastasia

    Anastasia Kovaleva (2):
      scsi: target: core: Signal WRITE residuals
      scsi: target: core: Change ASCQ for residual write

    Roman Bolshakov (1):
      scsi: target: core: Set residuals for 4Kn devices

     drivers/target/target_core_transport.c | 53 +++++++++++++-------------
     include/target/target_core_base.h      |  1 +
     2 files changed, 28 insertions(+), 26 deletions(-)

    -- 
    2.24.3 (Apple Git-128)

Re: [RESEND PATCH 0/3] scsi: target: Set correct residual data

[Martin K. Petersen]

Anastasia,

> The series changes the behavior of the target in regard to processing
> commands with overflow/underflow in accordance with the standarts.

Applied to 5.12/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [RESEND PATCH 0/3] scsi: target: Set correct residual data

[Martin K. Petersen]

On Thu, 3 Dec 2020 11:20:32 +0300, Anastasia Kovaleva wrote:

> Please apply the changes to 5.11/scsi-queue at your earliest
> convenience.
> 
> The series changes the behavior of the target in regard to processing
> commands with overflow/underflow in accordance with the standarts.
> 
> The target driver used to process the DMA_TO_DEVICE commands with
> residuals (in particular, WRITE command) incorrectly. The target
> response contained neither a residual count, nor an OVERFLOW/UNDERFLOW
> bit. Such behavior did not comply with the RFC 7143. Also the
> returned ASC and ASCQ were incorrect according to FCP-4,
> and residuals were not set for the 4Kn devices.
> 
> [...]

Applied to 5.12/scsi-queue, thanks!

[1/3] scsi: target: core: Set residuals for 4Kn devices
      https://git.kernel.org/mkp/scsi/c/eb90e45542b5
[2/3] scsi: target: core: Signal WRITE residuals
      https://git.kernel.org/mkp/scsi/c/cc0b6ad72e18
[3/3] scsi: target: core: Change ASCQ for residual write
      https://git.kernel.org/mkp/scsi/c/ead0ffc95a89

-- 
Martin K. Petersen	Oracle Linux Engineering