[PATCH 1/4] scsi: megaraid_sas: use private counter for tracking inflight per-LUN commands

[Ming Lei <ming.lei@redhat.com>]

Prepare for bypassing sdev->device_busy for improving performance on
fast SCSI storage device, so sdev->device_busy can't be relied
any more.

megaraid_sas may need one such counter for balancing load among LUNs in
some specific setting, so add one private counter for this purpose.

Cc: Sathya Prakash <sathya.prakash@broadcom.com>
Cc: Chaitra P B <chaitra.basappa@broadcom.com>
Cc: Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumit Saxena <sumit.saxena@broadcom.com>
Cc: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
Cc: Hannes Reinecke <hare@suse.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/scsi/megaraid/megaraid_sas.h        |  1 +
 drivers/scsi/megaraid/megaraid_sas_base.c   | 15 +++++++++++++--
 drivers/scsi/megaraid/megaraid_sas_fusion.c | 13 +++++++++----
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas.h b/drivers/scsi/megaraid/megaraid_sas.h
index a6e788c02ff4..f9562c02705b 100644
--- a/drivers/scsi/megaraid/megaraid_sas.h
+++ b/drivers/scsi/megaraid/megaraid_sas.h
@@ -2025,6 +2025,7 @@ struct MR_PRIV_DEVICE {
 	u8 interface_type;
 	u8 task_abort_tmo;
 	u8 target_reset_tmo;
+	atomic_t active_cmds;
 };
 struct megasas_cmd;
 
diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 42cf38c1ea99..3afead3bc96e 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -1759,6 +1759,7 @@ megasas_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
 {
 	struct megasas_instance *instance;
 	struct MR_PRIV_DEVICE *mr_device_priv_data;
+	int ret;
 
 	instance = (struct megasas_instance *)
 	    scmd->device->host->hostdata;
@@ -1821,7 +1822,11 @@ megasas_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
 		goto out_done;
 	}
 
-	return instance->instancet->build_and_issue_cmd(instance, scmd);
+	atomic_inc(&mr_device_priv_data->active_cmds);
+	ret = instance->instancet->build_and_issue_cmd(instance, scmd);
+	if (ret)
+		atomic_dec(&mr_device_priv_data->active_cmds);
+	return ret;
 
  out_done:
 	scmd->scsi_done(scmd);
@@ -2100,6 +2105,7 @@ static int megasas_slave_alloc(struct scsi_device *sdev)
 
 	atomic_set(&mr_device_priv_data->r1_ldio_hint,
 		   instance->r1_ldio_hint_default);
+	atomic_set(&mr_device_priv_data->active_cmds, 0);
 	return 0;
 }
 
@@ -3475,12 +3481,15 @@ megasas_complete_cmd(struct megasas_instance *instance, struct megasas_cmd *cmd,
 	unsigned long flags;
 	struct fusion_context *fusion = instance->ctrl_context;
 	u32 opcode, status;
+	struct MR_PRIV_DEVICE *mr_device_priv_data = NULL;
 
 	/* flag for the retry reset */
 	cmd->retry_for_fw_reset = 0;
 
-	if (cmd->scmd)
+	if (cmd->scmd) {
 		cmd->scmd->SCp.ptr = NULL;
+		mr_device_priv_data = cmd->scmd->device->hostdata;
+	}
 
 	switch (hdr->cmd) {
 	case MFI_CMD_INVALID:
@@ -3519,6 +3528,7 @@ megasas_complete_cmd(struct megasas_instance *instance, struct megasas_cmd *cmd,
 		if (exception) {
 
 			atomic_dec(&instance->fw_outstanding);
+			atomic_dec(&mr_device_priv_data->active_cmds);
 
 			scsi_dma_unmap(cmd->scmd);
 			cmd->scmd->scsi_done(cmd->scmd);
@@ -3567,6 +3577,7 @@ megasas_complete_cmd(struct megasas_instance *instance, struct megasas_cmd *cmd,
 		}
 
 		atomic_dec(&instance->fw_outstanding);
+		atomic_dec(&mr_device_priv_data->active_cmds);
 
 		scsi_dma_unmap(cmd->scmd);
 		cmd->scmd->scsi_done(cmd->scmd);
diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index e301458bcbae..10ed3bc3b643 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -2728,7 +2728,7 @@ megasas_build_ldio_fusion(struct megasas_instance *instance,
 	u8 *raidLUN;
 	unsigned long spinlock_flags;
 	struct MR_LD_RAID *raid = NULL;
-	struct MR_PRIV_DEVICE *mrdev_priv;
+	struct MR_PRIV_DEVICE *mrdev_priv = scp->device->hostdata;
 	struct RAID_CONTEXT *rctx;
 	struct RAID_CONTEXT_G35 *rctx_g35;
 
@@ -2826,7 +2826,7 @@ megasas_build_ldio_fusion(struct megasas_instance *instance,
 	}
 
 	if ((instance->perf_mode == MR_BALANCED_PERF_MODE) &&
-		atomic_read(&scp->device->device_busy) >
+		atomic_read(&mrdev_priv->active_cmds) >
 		(io_info.data_arms * MR_DEVICE_HIGH_IOPS_DEPTH))
 		cmd->request_desc->SCSIIO.MSIxIndex =
 			mega_mod64((atomic64_add_return(1, &instance->high_iops_outstanding) /
@@ -2849,7 +2849,6 @@ megasas_build_ldio_fusion(struct megasas_instance *instance,
 		 * with the SLD bit asserted.
 		 */
 		if (io_info.r1_alt_dev_handle != MR_DEVHANDLE_INVALID) {
-			mrdev_priv = scp->device->hostdata;
 
 			if (atomic_inc_return(&instance->fw_outstanding) >
 				(instance->host->can_queue)) {
@@ -3159,7 +3158,7 @@ megasas_build_syspd_fusion(struct megasas_instance *instance,
 	cmd->request_desc->SCSIIO.DevHandle = io_request->DevHandle;
 
 	if ((instance->perf_mode == MR_BALANCED_PERF_MODE) &&
-		atomic_read(&scmd->device->device_busy) > MR_DEVICE_HIGH_IOPS_DEPTH)
+		atomic_read(&mr_device_priv_data->active_cmds) > MR_DEVICE_HIGH_IOPS_DEPTH)
 		cmd->request_desc->SCSIIO.MSIxIndex =
 			mega_mod64((atomic64_add_return(1, &instance->high_iops_outstanding) /
 				MR_HIGH_IOPS_BATCH_COUNT), instance->low_latency_index_start);
@@ -3550,6 +3549,7 @@ complete_cmd_fusion(struct megasas_instance *instance, u32 MSIxIndex,
 
 	while (d_val.u.low != cpu_to_le32(UINT_MAX) &&
 	       d_val.u.high != cpu_to_le32(UINT_MAX)) {
+		struct MR_PRIV_DEVICE *mr_device_priv_data = NULL;
 
 		smid = le16_to_cpu(reply_desc->SMID);
 		cmd_fusion = fusion->cmd_list[smid - 1];
@@ -3585,6 +3585,8 @@ complete_cmd_fusion(struct megasas_instance *instance, u32 MSIxIndex,
 			}
 			/* Fall through - and complete IO */
 		case MEGASAS_MPI2_FUNCTION_LD_IO_REQUEST: /* LD-IO Path */
+			mr_device_priv_data = scmd_local->device->hostdata;
+			atomic_dec(&mr_device_priv_data->active_cmds);
 			atomic_dec(&instance->fw_outstanding);
 			if (cmd_fusion->r1_alt_dev_handle == MR_DEVHANDLE_INVALID) {
 				map_cmd_status(fusion, scmd_local, status,
@@ -4865,6 +4867,7 @@ int megasas_reset_fusion(struct Scsi_Host *shost, int reason)
 
 		/* Now return commands back to the OS */
 		for (i = 0 ; i < instance->max_scsi_cmds; i++) {
+			struct MR_PRIV_DEVICE *mr_device_priv_data = NULL;
 			cmd_fusion = fusion->cmd_list[i];
 			/*check for extra commands issued by driver*/
 			if (instance->adapter_type >= VENTURA_SERIES) {
@@ -4893,6 +4896,8 @@ int megasas_reset_fusion(struct Scsi_Host *shost, int reason)
 				megasas_return_cmd_fusion(instance, cmd_fusion);
 				scsi_dma_unmap(scmd_local);
 				scmd_local->scsi_done(scmd_local);
+				mr_device_priv_data = scmd_local->device->hostdata;
+				atomic_dec(&mr_device_priv_data->active_cmds);
 			}
 		}
 
-- 
2.20.1