From 2e96d8ac2695a13edf71976bd099003dda52056d Mon Sep 17 00:00:00 2001
From: Mike Christie <michaelc@cs.wisc.edu>
Date: Wed, 29 Jul 2015 04:23:49 -0500
Subject: [PATCH] target: compare and write backend driver sense handling
References: fate#318836
Patch-mainline: Not yet, SES2 clustered LIO/RBD

Currently, backend drivers seem to only fail IO with
SAM_STAT_CHECK_CONDITION which gets us
TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE.
For compare and write support we will want to be able to fail with
TCM_MISCOMPARE_VERIFY. This patch adds a new helper that allows backend
drivers to fail with specific sense codes.

It also allows the backend driver to set the miscompare offset.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: David Disseldorp <ddiss@suse.de>
[ddiss@suse.de rebase against ab78fef4d5 and 9ec1e1ce3a]
---
 drivers/target/target_core_transport.c |   35 ++++++++++++++++++++++++++++++---
 include/target/target_core_backend.h   |    1 
 include/target/target_core_base.h      |    5 +++-
 3 files changed, 37 insertions(+), 4 deletions(-)

--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -677,8 +677,7 @@ static void target_complete_failure_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);
 }
 
 /*
@@ -722,13 +721,15 @@ void transport_copy_sense_to_cmd(struct
 }
 EXPORT_SYMBOL(transport_copy_sense_to_cmd);
 
-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_device *dev = cmd->se_dev;
 	int success;
 	unsigned long flags;
 
 	cmd->scsi_status = scsi_status;
+	cmd->sense_reason = sense_reason;
 
 	spin_lock_irqsave(&cmd->t_state_lock, flags);
 	switch (cmd->scsi_status) {
@@ -776,8 +777,22 @@ void target_complete_cmd(struct se_cmd *
 	else
 		queue_work(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_complete_cmd_with_length(struct se_cmd *cmd, u8 scsi_status, int length)
 {
 	if (scsi_status == SAM_STAT_GOOD && length < cmd->data_length) {
@@ -1770,6 +1785,7 @@ void transport_generic_request_failure(s
 	case TCM_UNSUPPORTED_TARGET_DESC_TYPE_CODE:
 	case TCM_TOO_MANY_SEGMENT_DESCS:
 	case TCM_UNSUPPORTED_SEGMENT_DESC_TYPE_CODE:
+	case TCM_MISCOMPARE_VERIFY:
 		break;
 	case TCM_OUT_OF_RESOURCES:
 		cmd->scsi_status = SAM_STAT_TASK_SET_FULL;
@@ -2975,11 +2991,13 @@ bool transport_wait_for_tasks(struct se_
 }
 EXPORT_SYMBOL(transport_wait_for_tasks);
 
+
 struct sense_info {
 	u8 key;
 	u8 asc;
 	u8 ascq;
 	bool add_sector_info;
+	bool add_sense_info;
 };
 
 static const struct sense_info sense_info_table[] = {
@@ -3077,6 +3095,7 @@ static const struct sense_info sense_inf
 		.key = MISCOMPARE,
 		.asc = 0x1d, /* MISCOMPARE DURING VERIFY OPERATION */
 		.ascq = 0x00,
+		.add_sense_info = true,
 	},
 	[TCM_LOGICAL_BLOCK_GUARD_CHECK_FAILED] = {
 		.key = ABORTED_COMMAND,
@@ -3114,6 +3133,13 @@ static const struct sense_info sense_inf
 	},
 };
 
+static void transport_err_sense_info(unsigned char *buffer, u32 info)
+{
+	buffer[SPC_INFO_VALIDITY_OFFSET] |= 0x80;
+	/* Sense Information */
+	put_unaligned_be32(info, &buffer[3]);
+}
+
 static int translate_sense_reason(struct se_cmd *cmd, sense_reason_t reason)
 {
 	const struct sense_info *si;
@@ -3146,6 +3172,9 @@ static int translate_sense_reason(struct
 						  cmd->scsi_sense_length,
 						  cmd->bad_sector);
 
+	if (si->add_sense_info)
+		transport_err_sense_info(buffer, cmd->sense_info);
+
 	return 0;
 }
 
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -69,6 +69,7 @@ int	transport_backend_register(const str
 void	target_backend_unregister(const struct target_backend_ops *);
 
 void	target_complete_cmd(struct se_cmd *, u8);
+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 *);
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -21,11 +21,12 @@
  */
 #define TRANSPORT_SENSE_BUFFER			96
 /* Used by transport_send_check_condition_and_sense() */
+#define SPC_INFO_VALIDITY_OFFSET		0
 #define SPC_SENSE_KEY_OFFSET			2
 #define SPC_ADD_SENSE_LEN_OFFSET		7
 #define SPC_DESC_TYPE_OFFSET			8
 #define SPC_ADDITIONAL_DESC_LEN_OFFSET		9
-#define SPC_VALIDITY_OFFSET			10
+#define SPC_CMD_INFO_VALIDITY_OFFSET		10
 #define SPC_ASC_KEY_OFFSET			12
 #define SPC_ASCQ_KEY_OFFSET			13
 #define TRANSPORT_IQN_LEN			224
@@ -437,6 +438,8 @@ enum target_core_dif_check {
 #define TCM_ACA_TAG	0x24
 
 struct se_cmd {
+	sense_reason_t		sense_reason;
+	u32			sense_info;
 	/* SAM response code being sent to initiator */
 	u8			scsi_status;
 	u8			scsi_asc;