virtio_blk: added virtio_blk_get_transports RPC

This patch adds virtio_blk_get_transports matching the
virtio_blk_create_transport RPC. Allowing for querying
existing virtio_blk transports and displaying their options.

Signed-off-by: Krystyna Szybalska <krystyna.szybalska@gmail.com>
Change-Id: I0ec49c5f2ad11962feb5087dd376407ad125c349
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16303
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

doc/jsonrpc.md

@@ -8911,6 +8911,43 @@ Example response:
 }
 ~~~
 
+### virtio_blk_get_transports {#rpc_virtio_blk_get_transports}
+
+#### Parameters
+
+The user may specify no parameters in order to list all transports,
+or a transport name may be specified.
+
+Name                        | Optional | Type        | Description
+--------------------------- | -------- | ------------| -----------
+name                        | Optional | string      | Transport name.
+
+#### Example
+
+Example request:
+
+~~~json
+{
+  "jsonrpc": "2.0",
+  "method": "virtio_blk_get_transports",
+  "id": 1
+}
+~~~
+
+Example response:
+
+~~~json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": [
+    {
+      "name": "vhost_user_blk"
+    }
+  ]
+}
+~~~
+
 ### vhost_create_blk_controller {#rpc_vhost_create_blk_controller}
 
 Create vhost block controller

lib/vhost/vhost.c

@@ -13,6 +13,8 @@
 #include "spdk/barrier.h"
 #include "spdk/vhost.h"
 #include "vhost_internal.h"
+#include "spdk/queue.h"
+
 
 static struct spdk_cpuset g_vhost_core_mask;
 
@@ -450,6 +452,46 @@ virtio_blk_transport_create(const char *transport_name,
 	return 0;
 }
 
+struct spdk_virtio_blk_transport *
+virtio_blk_transport_get_first(void)
+{
+	return TAILQ_FIRST(&g_virtio_blk_transports);
+}
+
+struct spdk_virtio_blk_transport *
+virtio_blk_transport_get_next(struct spdk_virtio_blk_transport *transport)
+{
+	return TAILQ_NEXT(transport, tailq);
+}
+
+void
+virtio_blk_transport_dump_opts(struct spdk_virtio_blk_transport *transport,
+			       struct spdk_json_write_ctx *w)
+{
+	spdk_json_write_object_begin(w);
+
+	spdk_json_write_named_string(w, "name", transport->ops->name);
+
+	if (transport->ops->dump_opts) {
+		transport->ops->dump_opts(transport, w);
+	}
+
+	spdk_json_write_object_end(w);
+}
+
+struct spdk_virtio_blk_transport *
+virtio_blk_tgt_get_transport(const char *transport_name)
+{
+	struct spdk_virtio_blk_transport *transport;
+
+	TAILQ_FOREACH(transport, &g_virtio_blk_transports, tailq) {
+		if (strcasecmp(transport->ops->name, transport_name) == 0) {
+			return transport;
+		}
+	}
+	return NULL;
+}
+
 int
 virtio_blk_transport_destroy(struct spdk_virtio_blk_transport *transport,
 			     spdk_vhost_fini_cb cb_fn)

lib/vhost/vhost_internal.h

@@ -586,7 +586,12 @@ void virtio_blk_transport_register(const struct spdk_virtio_blk_transport_ops *o
 int virtio_blk_transport_create(const char *transport_name, const struct spdk_json_val *params);
 int virtio_blk_transport_destroy(struct spdk_virtio_blk_transport *transport,
 				 spdk_vhost_fini_cb cb_fn);
-
+struct spdk_virtio_blk_transport *virtio_blk_transport_get_first(void);
+struct spdk_virtio_blk_transport *virtio_blk_transport_get_next(
+	struct spdk_virtio_blk_transport *transport);
+void virtio_blk_transport_dump_opts(struct spdk_virtio_blk_transport *transport,
+				    struct spdk_json_write_ctx *w);
+struct spdk_virtio_blk_transport *virtio_blk_tgt_get_transport(const char *transport_name);
 const struct spdk_virtio_blk_transport_ops *virtio_blk_get_transport_ops(
 	const char *transport_name);
 

lib/vhost/vhost_rpc.c

@@ -10,7 +10,7 @@
 #include "spdk/util.h"
 #include "spdk/string.h"
 #include "spdk/env.h"
-
+#include "spdk/log.h"
 #include "spdk/scsi.h"
 #include "spdk/vhost.h"
 #include "vhost_internal.h"
@@ -472,6 +472,60 @@ invalid:
 SPDK_RPC_REGISTER("vhost_controller_set_coalescing", rpc_vhost_controller_set_coalescing,
 		  SPDK_RPC_RUNTIME)
 
+struct rpc_get_transport {
+	char *name;
+};
+
+static const struct spdk_json_object_decoder rpc_get_transport_decoders[] = {
+	{"name", offsetof(struct rpc_get_transport, name), spdk_json_decode_string, true},
+};
+
+static void
+rpc_virtio_blk_get_transports(struct spdk_jsonrpc_request *request,
+			      const struct spdk_json_val *params)
+{
+	struct rpc_get_transport req = { 0 };
+	struct spdk_json_write_ctx *w;
+	struct spdk_virtio_blk_transport *transport = NULL;
+
+	if (params) {
+		if (spdk_json_decode_object(params, rpc_get_transport_decoders,
+					    SPDK_COUNTOF(rpc_get_transport_decoders),
+					    &req)) {
+			SPDK_ERRLOG("spdk_json_decode_object failed\n");
+			spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS, "Invalid parameters");
+			return;
+		}
+	}
+
+	if (req.name) {
+		transport = virtio_blk_tgt_get_transport(req.name);
+		if (transport == NULL) {
+			SPDK_ERRLOG("transport '%s' does not exist\n", req.name);
+			spdk_jsonrpc_send_error_response(request, -ENODEV, spdk_strerror(ENODEV));
+			free(req.name);
+			return;
+		}
+	}
+
+	w = spdk_jsonrpc_begin_result(request);
+	spdk_json_write_array_begin(w);
+
+	if (transport) {
+		virtio_blk_transport_dump_opts(transport, w);
+	} else {
+		for (transport = virtio_blk_transport_get_first(); transport != NULL;
+		     transport = virtio_blk_transport_get_next(transport)) {
+			virtio_blk_transport_dump_opts(transport, w);
+		}
+	}
+
+	spdk_json_write_array_end(w);
+	spdk_jsonrpc_end_result(request, w);
+	free(req.name);
+}
+SPDK_RPC_REGISTER("virtio_blk_get_transports", rpc_virtio_blk_get_transports, SPDK_RPC_RUNTIME)
+
 struct rpc_virtio_blk_create_transport {
 	char *name;
 };

python/spdk/rpc/vhost.py

@@ -20,6 +20,23 @@ def vhost_controller_set_coalescing(client, ctrlr, delay_base_us, iops_threshold
     return client.call('vhost_controller_set_coalescing', params)
 
 
+def virtio_blk_get_transports(client, name=None):
+    """Get list of virtio-blk transports.
+    Args:
+        name: name of the virtio-blk transport (optional).
+
+    Returns:
+        List of virtio-blk transport objects.
+    """
+
+    params = {}
+
+    if name:
+        params['name'] = name
+
+    return client.call('virtio_blk_get_transports', params)
+
+
 def virtio_blk_create_transport(client, **params):
     """Create virtio blk transport.
     Args:

scripts/rpc.py

@@ -2601,6 +2601,13 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
     p.add_argument('name', help='transport name')
     p.set_defaults(func=virtio_blk_create_transport)
 
+    def virtio_blk_get_transports(args):
+        print_dict(rpc.vhost.virtio_blk_get_transports(args.client, name=args.name))
+
+    p = subparsers.add_parser('virtio_blk_get_transports', help='Display virtio-blk transports or requested transport')
+    p.add_argument('--name', help='Transport name (optional)', type=str)
+    p.set_defaults(func=virtio_blk_get_transports)
+
     def vhost_create_scsi_controller(args):
         rpc.vhost.vhost_create_scsi_controller(args.client,
                                                ctrlr=args.ctrlr,