bdev/virtio/rpc: allow listing created devices

Listing them through get_bdevs is not enough. Some
devices might not have any LUNs presented while expecting
some to be hotplugged in the future.

```
$ rpc.py get_virtio_scsi_devs
[
  {
    "virtio": {
      "vq_count": 18,
      "type": "user",
      "socket": "/tmp/vhost.0",
      "vq_size": 512
    },
    "name": "VirtioScsi0"
  }
]
```

Change-Id: I56857d7a0637300beba39a8d83a98447f1f74ce7
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/405182
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Pawel Wodkowski <pawelx.wodkowski@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>

lib/bdev/virtio/bdev_virtio.h

@@ -116,6 +116,13 @@ int bdev_virtio_pci_scsi_dev_create(const char *name, struct spdk_pci_addr *pci_
 void bdev_virtio_scsi_dev_remove(const char *name,
 				 bdev_virtio_remove_cb cb_fn, void *cb_arg);
 
+/**
+ * List all created Virtio-SCSI devices.
+ *
+ * \param write_ctx JSON context to write into
+ */
+void bdev_virtio_scsi_dev_list(struct spdk_json_write_ctx *write_ctx);
+
 /**
  * Connect to a vhost-user Unix domain socket and create a Virtio BLK bdev.
  *

lib/bdev/virtio/bdev_virtio_rpc.c

@@ -265,6 +265,28 @@ invalid:
 }
 SPDK_RPC_REGISTER("remove_virtio_scsi_bdev", spdk_rpc_remove_virtio_scsi_bdev);
 
+static void
+spdk_rpc_get_virtio_scsi_devs(struct spdk_jsonrpc_request *request,
+			      const struct spdk_json_val *params)
+{
+	struct spdk_json_write_ctx *w;
+
+	if (params != NULL) {
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS,
+						 "get_virtio_scsi_devs requires no parameters");
+		return;
+	}
+
+	w = spdk_jsonrpc_begin_result(request);
+	if (w == NULL) {
+		return;
+	}
+
+	bdev_virtio_scsi_dev_list(w);
+	spdk_jsonrpc_end_result(request, w);
+}
+SPDK_RPC_REGISTER("get_virtio_scsi_devs", spdk_rpc_get_virtio_scsi_devs)
+
 struct rpc_construct_virtio_blk_dev {
 	char *path;
 	char *pci_address;

lib/bdev/virtio/bdev_virtio_scsi.c

@@ -1933,4 +1933,27 @@ bdev_virtio_scsi_dev_remove(const char *name, bdev_virtio_remove_cb cb_fn, void
 	pthread_mutex_unlock(&g_virtio_scsi_mutex);
 }
 
+void
+bdev_virtio_scsi_dev_list(struct spdk_json_write_ctx *w)
+{
+	struct virtio_scsi_dev *svdev;
+
+	spdk_json_write_array_begin(w);
+
+	pthread_mutex_lock(&g_virtio_scsi_mutex);
+	TAILQ_FOREACH(svdev, &g_virtio_scsi_devs, tailq) {
+		spdk_json_write_object_begin(w);
+
+		spdk_json_write_name(w, "name");
+		spdk_json_write_string(w, svdev->vdev.name);
+
+		virtio_dev_dump_json_config(&svdev->vdev, w);
+
+		spdk_json_write_object_end(w);
+	}
+	pthread_mutex_unlock(&g_virtio_scsi_mutex);
+
+	spdk_json_write_array_end(w);
+}
+
 SPDK_LOG_REGISTER_COMPONENT("virtio", SPDK_LOG_VIRTIO)

scripts/rpc.py

@@ -762,6 +762,12 @@ if __name__ == "__main__":
     It will be inhereted by all created bdevs, which are named n the following format: <name>t<target_id>""")
     p.set_defaults(func=construct_virtio_pci_scsi_bdev)
 
+    def get_virtio_scsi_devs(args):
+        print_dict(rpc.vhost.get_virtio_scsi_devs(args))
+
+    p = subparsers.add_parser('get_virtio_scsi_devs', help='List all Virtio-SCSI devices.')
+    p.set_defaults(func=get_virtio_scsi_devs)
+
     def remove_virtio_scsi_bdev(args):
         rpc.vhost.remove_virtio_scsi_bdev(args)
 

scripts/rpc/vhost.py

@@ -79,6 +79,10 @@ def remove_virtio_scsi_bdev(args):
     return args.client.call('remove_virtio_scsi_bdev', params)
 
 
+def get_virtio_scsi_devs(args):
+    return args.client.call('get_virtio_scsi_devs')
+
+
 def construct_virtio_user_blk_bdev(args):
     params = {
         'path': args.path,