lpfc: Add support for using block multi-queue

With blk-mq support in the mid-layer, lpfc can do IO steering based
on the information in the request tag.  This patch allows lpfc to use
blk-mq if enabled. If not enabled, we fall back into the emulex-internal
affinity mappings.

This feature can be turned on via CONFIG_SCSI_MQ_DEFAULT or passing
scsi_mod.use_blk_mq=Y as a parameter to the kernel.

Signed-off-by: Dick Kennedy <dick.kennedy@avagotech.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index 116df9c57870..4a2a81875cfe 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -3846,6 +3846,49 @@ lpfc_handle_fcp_err(struct lpfc_vport *vport, struct lpfc_scsi_buf *lpfc_cmd,
 }
 
 /**
+ * lpfc_sli4_scmd_to_wqidx_distr - scsi command to SLI4 WQ index distribution
+ * @phba: Pointer to HBA context object.
+ *
+ * This routine performs a roundrobin SCSI command to SLI4 FCP WQ index
+ * distribution.  This is called by __lpfc_sli_issue_iocb_s4() with the hbalock
+ * held.
+ * If scsi-mq is enabled, get the default block layer mapping of software queues
+ * to hardware queues. This information is saved in request tag.
+ *
+ * Return: index into SLI4 fast-path FCP queue index.
+ **/
+int lpfc_sli4_scmd_to_wqidx_distr(struct lpfc_hba *phba,
+				  struct lpfc_scsi_buf *lpfc_cmd)
+{
+	struct scsi_cmnd *cmnd = lpfc_cmd->pCmd;
+	struct lpfc_vector_map_info *cpup;
+	int chann, cpu;
+	uint32_t tag;
+	uint16_t hwq;
+
+	if (shost_use_blk_mq(cmnd->device->host)) {
+		tag = blk_mq_unique_tag(cmnd->request);
+		hwq = blk_mq_unique_tag_to_hwq(tag);
+
+		return hwq;
+	}
+
+	if (phba->cfg_fcp_io_sched == LPFC_FCP_SCHED_BY_CPU
+	    && phba->cfg_fcp_io_channel > 1) {
+		cpu = smp_processor_id();
+		if (cpu < phba->sli4_hba.num_present_cpu) {
+			cpup = phba->sli4_hba.cpu_map;
+			cpup += cpu;
+			return cpup->channel_id;
+		}
+	}
+	chann = atomic_add_return(1, &phba->fcp_qidx);
+	chann = (chann % phba->cfg_fcp_io_channel);
+	return chann;
+}
+
+
+/**
  * lpfc_scsi_cmd_iocb_cmpl - Scsi cmnd IOCB completion routine
  * @phba: The Hba for which this call is being executed.
  * @pIocbIn: The command IOCBQ for the scsi cmnd.