[PATCH 1/2] nvme-fc: Add support for map_queues.

[Nilesh Javali <njavali@xxxxxxxxxxx>]

From: Saurav Kashyap <skashyap@xxxxxxxxxxx>

NVMe FC don't have support for map queues as compared
to pci, rdma and tcp. It doesn't provide a provision to
LLDs to change the queue mapping like scsi layer. This
patch adds an option for LLDs to change the queue mapping.

Signed-off-by: Saurav Kashyap <skashyap@xxxxxxxxxxx>
Signed-off-by: Nilesh Javali <njavali@xxxxxxxxxxx>
---
 drivers/nvme/host/fc.c         | 25 +++++++++++++++++++++++++
 include/linux/nvme-fc-driver.h |  7 +++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index b08a61ca283f..078895809098 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -16,6 +16,7 @@
 #include <linux/nvme-fc.h>
 #include "fc.h"
 #include <scsi/scsi_transport_fc.h>
+#include <linux/blk-mq-pci.h>
 
 /* *************************** Data Structures/Defines ****************** */
 
@@ -2839,6 +2840,29 @@ nvme_fc_complete_rq(struct request *rq)
 	nvme_fc_ctrl_put(ctrl);
 }
 
+static int nvme_fc_map_queues(struct blk_mq_tag_set *set)
+{
+	int i;
+	struct nvme_fc_ctrl *ctrl;
+	struct blk_mq_queue_map *map = NULL;
+
+	ctrl = set->driver_data;
+	for (i = 0; i < set->nr_maps; i++) {
+		map = &set->map[i];
+
+		if (!map->nr_queues) {
+			WARN_ON(i == HCTX_TYPE_DEFAULT);
+			continue;
+		}
+
+		/* Call LLDD map queue functionality if defined */
+		if (ctrl->lport->ops->map_queues)
+			ctrl->lport->ops->map_queues(&ctrl->lport->localport, map);
+		else
+			blk_mq_map_queues(map);
+	}
+	return 0;
+}
 
 static const struct blk_mq_ops nvme_fc_mq_ops = {
 	.queue_rq	= nvme_fc_queue_rq,
@@ -2847,6 +2871,7 @@ static const struct blk_mq_ops nvme_fc_mq_ops = {
 	.exit_request	= nvme_fc_exit_request,
 	.init_hctx	= nvme_fc_init_hctx,
 	.timeout	= nvme_fc_timeout,
+	.map_queues	= nvme_fc_map_queues,
 };
 
 static int
diff --git a/include/linux/nvme-fc-driver.h b/include/linux/nvme-fc-driver.h
index 2a38f2b477a5..cb909edb76c4 100644
--- a/include/linux/nvme-fc-driver.h
+++ b/include/linux/nvme-fc-driver.h
@@ -7,6 +7,7 @@
 #define _NVME_FC_DRIVER_H 1
 
 #include <linux/scatterlist.h>
+#include <linux/blk-mq.h>
 
 
 /*
@@ -497,6 +498,8 @@ struct nvme_fc_port_template {
 	int	(*xmt_ls_rsp)(struct nvme_fc_local_port *localport,
 				struct nvme_fc_remote_port *rport,
 				struct nvmefc_ls_rsp *ls_rsp);
+	void	(*map_queues)(struct nvme_fc_local_port *localport,
+			      struct blk_mq_queue_map *map);
 
 	u32	max_hw_queues;
 	u16	max_sgl_segments;
@@ -779,6 +782,10 @@ struct nvmet_fc_target_port {
  *       LS received.
  *       Entrypoint is Mandatory.
  *
+ * @map_queues: This functions lets the driver expose the queue mapping
+ *	 to the block layer.
+ *       Entrypoint is Optional.
+ *
  * @fcp_op:  Called to perform a data transfer or transmit a response.
  *       The nvmefc_tgt_fcp_req structure is the same LLDD-supplied
  *       exchange structure specified in the nvmet_fc_rcv_fcp_req() call
-- 
2.23.1