[PATCH v2] target/stat: implement scsiPortBusyStatuses counter

[kensanya@163.com]

From: TanZheng <tanzheng@kylinos.cn>

Implement RFC 4455 scsiPortBusyStatuses (ConfigFS busy_count) by adding a
per-CPU busy_statuses counter to scsi_port_stats, incrementing it when
the target sends SAM_STAT_BUSY, and summing all CPUs in the show handler.

Signed-off-by: TanZheng <tanzheng@kylinos.cn>
---
v2: 
1.By taking snapshots of lun, scsi_status and flags before queue_status(),
  the dereferencing of cmd after the callback is avoided.

---
 drivers/target/target_core_internal.h  |  2 ++
 drivers/target/target_core_stat.c      | 31 ++++++++++++++++++++++++--
 drivers/target/target_core_transport.c | 26 ++++++++++++++++-----
 include/target/target_core_base.h      |  1 +
 4 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index 763e6d26e187..c3aa8c514db7 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -161,6 +161,8 @@ void	target_queued_submit_work(struct work_struct *work);
 void	target_stat_setup_dev_default_groups(struct se_device *);
 void	target_stat_setup_port_default_groups(struct se_lun *);
 void	target_stat_setup_mappedlun_default_groups(struct se_lun_acl *);
+void	target_stat_count_sent_status(struct se_lun *lun, u8 scsi_status,
+				      u32 flags);
 
 /* target_core_xcopy.c */
 extern struct se_portal_group xcopy_pt_tpg;
diff --git a/drivers/target/target_core_stat.c b/drivers/target/target_core_stat.c
index 083205052be2..8ae238287065 100644
--- a/drivers/target/target_core_stat.c
+++ b/drivers/target/target_core_stat.c
@@ -21,12 +21,30 @@
 #include <linux/seq_file.h>
 #include <linux/configfs.h>
 
+#include <scsi/scsi_proto.h>
+
 #include <target/target_core_base.h>
 #include <target/target_core_backend.h>
 #include <target/target_core_fabric.h>
 
 #include "target_core_internal.h"
 
+void target_stat_count_sent_status(struct se_lun *lun, u8 scsi_status,
+				 u32 flags)
+{
+	if (flags & SCF_SCSI_TMR_CDB)
+		return;
+
+	switch (scsi_status) {
+	case SAM_STAT_BUSY:
+		if (lun && lun->lun_stats)
+			this_cpu_inc(lun->lun_stats->busy_statuses);
+		break;
+	default:
+		break;
+	}
+}
+
 #ifndef INITIAL_JIFFIES
 #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))
 #endif
@@ -483,13 +501,22 @@ static ssize_t target_stat_port_busy_count_show(struct config_item *item,
 {
 	struct se_lun *lun = to_stat_port(item);
 	struct se_device *dev;
+	struct scsi_port_stats *stats;
+	unsigned int cpu;
+	u64 sum = 0;
 	ssize_t ret = -ENODEV;
 
 	rcu_read_lock();
 	dev = rcu_dereference(lun->lun_se_dev);
 	if (dev) {
-		/* FIXME: scsiPortBusyStatuses  */
-		ret = snprintf(page, PAGE_SIZE, "%u\n", 0);
+		/* scsiPortBusyStatuses */
+		if (lun->lun_stats) {
+			for_each_possible_cpu(cpu) {
+				stats = per_cpu_ptr(lun->lun_stats, cpu);
+				sum += stats->busy_statuses;
+			}
+		}
+		ret = snprintf(page, PAGE_SIZE, "%llu\n", sum);
 	}
 	rcu_read_unlock();
 	return ret;
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index fad03a15c969..bab5ee81817b 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -829,6 +829,20 @@ void transport_copy_sense_to_cmd(struct se_cmd *cmd, unsigned char *sense)
 }
 EXPORT_SYMBOL(transport_copy_sense_to_cmd);
 
+static int target_queue_status(struct se_cmd *cmd)
+{
+	int ret;
+	struct se_lun *lun = cmd->se_lun;
+	u8 scsi_status = cmd->scsi_status;
+	u32 flags = cmd->se_cmd_flags;
+
+	ret = cmd->se_tfo->queue_status(cmd);
+	if (!ret)
+		target_stat_count_sent_status(lun, scsi_status, flags);
+
+	return ret;
+}
+
 static void target_handle_abort(struct se_cmd *cmd)
 {
 	bool tas = cmd->transport_state & CMD_T_TAS;
@@ -843,7 +857,7 @@ static void target_handle_abort(struct se_cmd *cmd)
 			pr_debug("Setting SAM_STAT_TASK_ABORTED status for CDB: 0x%02x, ITT: 0x%08llx\n",
 				 cmd->t_task_cdb[0], cmd->tag);
 			trace_target_cmd_complete(cmd);
-			ret = cmd->se_tfo->queue_status(cmd);
+			ret = target_queue_status(cmd);
 			if (ret) {
 				transport_handle_queue_full(cmd, cmd->se_dev,
 							    ret, false);
@@ -2170,7 +2184,7 @@ void transport_generic_request_failure(struct se_cmd *cmd,
 
 queue_status:
 	trace_target_cmd_complete(cmd);
-	ret = cmd->se_tfo->queue_status(cmd);
+	ret = target_queue_status(cmd);
 	if (!ret)
 		goto check_stop;
 queue_full:
@@ -2487,7 +2501,7 @@ static void transport_complete_qf(struct se_cmd *cmd)
 	case DMA_NONE:
 queue_status:
 		trace_target_cmd_complete(cmd);
-		ret = cmd->se_tfo->queue_status(cmd);
+		ret = target_queue_status(cmd);
 		break;
 	default:
 		break;
@@ -2685,7 +2699,7 @@ static void target_complete_ok_work(struct work_struct *work)
 	case DMA_NONE:
 queue_status:
 		trace_target_cmd_complete(cmd);
-		ret = cmd->se_tfo->queue_status(cmd);
+		ret = target_queue_status(cmd);
 		if (ret)
 			goto queue_full;
 		break;
@@ -3599,7 +3613,7 @@ transport_send_check_condition_and_sense(struct se_cmd *cmd,
 		translate_sense_reason(cmd, reason);
 
 	trace_target_cmd_complete(cmd);
-	return cmd->se_tfo->queue_status(cmd);
+	return target_queue_status(cmd);
 }
 EXPORT_SYMBOL(transport_send_check_condition_and_sense);
 
@@ -3615,7 +3629,7 @@ int target_send_busy(struct se_cmd *cmd)
 
 	cmd->scsi_status = SAM_STAT_BUSY;
 	trace_target_cmd_complete(cmd);
-	return cmd->se_tfo->queue_status(cmd);
+	return target_queue_status(cmd);
 }
 EXPORT_SYMBOL(target_send_busy);
 
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 002b0fc57587..61a230331124 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -764,6 +764,7 @@ struct scsi_port_stats {
 	u64			cmd_pdus;
 	u64			tx_data_octets;
 	u64			rx_data_octets;
+	u64			busy_statuses;
 };
 
 struct se_lun {
-- 
2.25.1