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

[Sergey Samoylenko <s.samoylenko@xxxxxxxxx>]

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@xxxxxxxxxx>.

Cc: Mike Christie <michael.christie@xxxxxxxxxx>
Cc: David Disseldorp <ddiss@xxxxxxx>
[ Moved target_complete_cmd_with_sense() helper to mainline ]
Signed-off-by: Sergey Samoylenko <s.samoylenko@xxxxxxxxx>
---
 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