nvme-tcp-offload: Add device scan implementation

As part of create_ctrl(), it scans the registered devices and calls
the claim_dev op on each of them, to find the first devices that matches
the connection params. Once the correct devices is found (claim_dev
returns true), we raise the refcnt of that device and return that device
as the device to be used for ctrl currently being created.

Acked-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: Dean Balandin <dbalandin@marvell.com>
Signed-off-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
Signed-off-by: Omkar Kulkarni <okulkarni@marvell.com>
Signed-off-by: Michal Kalderon <mkalderon@marvell.com>
Signed-off-by: Ariel Elior <aelior@marvell.com>
Signed-off-by: Shai Malin <smalin@marvell.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/nvme/host/tcp-offload.c

@@ -13,6 +13,11 @@
 static LIST_HEAD(nvme_tcp_ofld_devices);
 static DEFINE_MUTEX(nvme_tcp_ofld_devices_mutex);
 
+static inline struct nvme_tcp_ofld_ctrl *to_tcp_ofld_ctrl(struct nvme_ctrl *nctrl)
+{
+	return container_of(nctrl, struct nvme_tcp_ofld_ctrl, nctrl);
+}
+
 /**
  * nvme_tcp_ofld_register_dev() - NVMeTCP Offload Library registration
  * function.
@@ -96,6 +101,77 @@ void nvme_tcp_ofld_req_done(struct nvme_tcp_ofld_req *req,
 	/* Placeholder - complete request with/without error */
 }
 
+static struct nvme_tcp_ofld_dev *
+nvme_tcp_ofld_lookup_dev(struct nvme_tcp_ofld_ctrl *ctrl)
+{
+	struct nvme_tcp_ofld_dev *dev;
+
+	mutex_lock(&nvme_tcp_ofld_devices_mutex);
+	list_for_each_entry(dev, &nvme_tcp_ofld_devices, entry) {
+		if (dev->ops->claim_dev(dev, ctrl))
+			goto out;
+	}
+
+	dev = NULL;
+out:
+	mutex_unlock(&nvme_tcp_ofld_devices_mutex);
+
+	return dev;
+}
+
+static struct nvme_ctrl *
+nvme_tcp_ofld_create_ctrl(struct device *ndev, struct nvmf_ctrl_options *opts)
+{
+	struct nvme_tcp_ofld_ctrl *ctrl;
+	struct nvme_tcp_ofld_dev *dev;
+	struct nvme_ctrl *nctrl;
+	int rc = 0;
+
+	ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
+	if (!ctrl)
+		return ERR_PTR(-ENOMEM);
+
+	nctrl = &ctrl->nctrl;
+
+	/* Init nvme_tcp_ofld_ctrl and nvme_ctrl params based on received opts */
+
+	/* Find device that can reach the dest addr */
+	dev = nvme_tcp_ofld_lookup_dev(ctrl);
+	if (!dev) {
+		pr_info("no device found for addr %s:%s.\n",
+			opts->traddr, opts->trsvcid);
+		rc = -EINVAL;
+		goto out_free_ctrl;
+	}
+
+	/* Increase driver refcnt */
+	if (!try_module_get(dev->ops->module)) {
+		pr_err("try_module_get failed\n");
+		dev = NULL;
+		goto out_free_ctrl;
+	}
+
+	ctrl->dev = dev;
+
+	if (ctrl->dev->ops->max_hw_sectors)
+		nctrl->max_hw_sectors = ctrl->dev->ops->max_hw_sectors;
+	if (ctrl->dev->ops->max_segments)
+		nctrl->max_segments = ctrl->dev->ops->max_segments;
+
+	/* Init queues */
+
+	/* Call nvme_init_ctrl */
+
+	/* Setup ctrl */
+
+	return nctrl;
+
+out_free_ctrl:
+	kfree(ctrl);
+
+	return ERR_PTR(rc);
+}
+
 static struct nvmf_transport_ops nvme_tcp_ofld_transport = {
 	.name		= "tcp_offload",
 	.module		= THIS_MODULE,
@@ -105,6 +181,7 @@ static struct nvmf_transport_ops nvme_tcp_ofld_transport = {
 			  NVMF_OPT_RECONNECT_DELAY | NVMF_OPT_HDR_DIGEST |
 			  NVMF_OPT_DATA_DIGEST | NVMF_OPT_NR_POLL_QUEUES |
 			  NVMF_OPT_TOS,
+	.create_ctrl	= nvme_tcp_ofld_create_ctrl,
 };
 
 static int __init nvme_tcp_ofld_init_module(void)