vbdev/passthru: add the construct_passthru_bdev RPC method

Add the RPC method to construct a passthru bdev.

The usage as following:

usage:
rpc.py construct_passthru_bdev [-h] -b BASE_BDEV_NAME -p PASSTHRU_BDEV_NAME

Change-Id: I87bcfde499a9f0c2f5758e36e6772e0fc2928d20
Signed-off-by: GangCao <gang.cao@intel.com>
Reviewed-on: https://review.gerrithub.io/406891
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

lib/bdev/passthru/Makefile

@@ -36,7 +36,7 @@ include $(SPDK_ROOT_DIR)/mk/spdk.common.mk
 
 CFLAGS += -I$(SPDK_ROOT_DIR)/lib/bdev/
 
-C_SRCS = vbdev_passthru.c
+C_SRCS = vbdev_passthru.c vbdev_passthru_rpc.c
 LIBNAME = vbdev_passthru
 
 include $(SPDK_ROOT_DIR)/mk/spdk.lib.mk

lib/bdev/passthru/vbdev_passthru.c

@@ -416,6 +416,24 @@ vbdev_passthru_get_spdk_running_config(FILE *fp)
 	fprintf(fp, "\n");
 }
 
+/* Called when SPDK wants to output the bdev specific methods. */
+static void
+vbdev_passthru_write_json_config(struct spdk_bdev *bdev, struct spdk_json_write_ctx *w)
+{
+	struct vbdev_passthru *pt_node = SPDK_CONTAINEROF(bdev, struct vbdev_passthru, pt_bdev);
+
+	spdk_json_write_object_begin(w);
+
+	spdk_json_write_named_string(w, "method", "construct_passthru_bdev");
+
+	spdk_json_write_named_object_begin(w, "params");
+	spdk_json_write_named_string(w, "base_bdev_name", spdk_bdev_get_name(pt_node->base_bdev));
+	spdk_json_write_named_string(w, "passthru_bdev_name", spdk_bdev_get_name(bdev));
+	spdk_json_write_object_end(w);
+
+	spdk_json_write_object_end(w);
+}
+
 /* When we regsiter our bdev this is how we specify our entry points. */
 static const struct spdk_bdev_fn_table vbdev_passthru_fn_table = {
 	.destruct		= vbdev_passthru_destruct,
@@ -423,6 +441,7 @@ static const struct spdk_bdev_fn_table vbdev_passthru_fn_table = {
 	.io_type_supported	= vbdev_passthru_io_type_supported,
 	.get_io_channel		= vbdev_passthru_get_io_channel,
 	.dump_info_json		= vbdev_passthru_info_config_json,
+	.write_config_json	= vbdev_passthru_write_json_config,
 };
 
 /* Called when the underlying base bdev goes away. */

lib/bdev/passthru/vbdev_passthru_rpc.c

@@ -0,0 +1,100 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright (c) Intel Corporation.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "vbdev_passthru.h"
+#include "spdk/rpc.h"
+#include "spdk/util.h"
+
+#include "spdk_internal/log.h"
+
+/* Structure to hold the parameters for this RPC method. */
+struct rpc_construct_passthru {
+	char *base_bdev_name;
+	char *passthru_bdev_name;
+};
+
+/* Free the allocated memory resource after the RPC handling. */
+static void
+free_rpc_construct_passthru(struct rpc_construct_passthru *r)
+{
+	free(r->base_bdev_name);
+	free(r->passthru_bdev_name);
+}
+
+/* Structure to decode the input parameters for this RPC method. */
+static const struct spdk_json_object_decoder rpc_construct_passthru_decoders[] = {
+	{"base_bdev_name", offsetof(struct rpc_construct_passthru, base_bdev_name), spdk_json_decode_string},
+	{"passthru_bdev_name", offsetof(struct rpc_construct_passthru, passthru_bdev_name), spdk_json_decode_string},
+};
+
+/* Decode the parameters for this RPC method and properly construct the passthru
+ * device. Error status returned in the failed cases.
+ */
+static void
+spdk_rpc_construct_passthru_bdev(struct spdk_jsonrpc_request *request,
+				 const struct spdk_json_val *params)
+{
+	struct rpc_construct_passthru req = {NULL};
+	struct spdk_json_write_ctx *w;
+	int rc;
+
+	if (spdk_json_decode_object(params, rpc_construct_passthru_decoders,
+				    SPDK_COUNTOF(rpc_construct_passthru_decoders),
+				    &req)) {
+		SPDK_DEBUGLOG(SPDK_LOG_VBDEV_PASSTHRU, "spdk_json_decode_object failed\n");
+		goto invalid;
+	}
+
+	rc = create_passthru_disk(req.base_bdev_name, req.passthru_bdev_name);
+	if (rc != 0) {
+		goto invalid;
+	}
+
+	w = spdk_jsonrpc_begin_result(request);
+	if (w == NULL) {
+		free_rpc_construct_passthru(&req);
+		return;
+	}
+
+	spdk_json_write_array_begin(w);
+	spdk_json_write_string(w, req.passthru_bdev_name);
+	spdk_json_write_array_end(w);
+	spdk_jsonrpc_end_result(request, w);
+	free_rpc_construct_passthru(&req);
+	return;
+
+invalid:
+	free_rpc_construct_passthru(&req);
+	spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS, "Invalid parameters");
+}
+SPDK_RPC_REGISTER("construct_passthru_bdev", spdk_rpc_construct_passthru_bdev)

scripts/rpc.py

@@ -171,6 +171,16 @@ if __name__ == "__main__":
     p.add_argument('-n', '--name', help='Block device name', required=True)
     p.set_defaults(func=construct_pmem_bdev)
 
+    @call_cmd
+    def construct_passthru_bdev(args):
+        print_array(rpc.bdev.construct_passthru_bdev(args.client, args))
+
+    p = subparsers.add_parser('construct_passthru_bdev',
+                              help='Add a pass through bdev on existing bdev')
+    p.add_argument('-b', '--base-bdev-name', help="Name of the existing bdev", required=True)
+    p.add_argument('-p', '--passthru-bdev-name', help="Name of the passthru bdev", required=True)
+    p.set_defaults(func=construct_passthru_bdev)
+
     @call_cmd
     def get_bdevs(args):
         print_dict(rpc.bdev.get_bdevs(args.client, args))

scripts/rpc/bdev.py

@@ -70,6 +70,14 @@ def construct_pmem_bdev(client, args):
     return client.call('construct_pmem_bdev', params)
 
 
+def construct_passthru_bdev(client, args):
+    params = {
+        'base_bdev_name': args.base_bdev_name,
+        'passthru_bdev_name': args.passthru_bdev_name,
+    }
+    return client.call('construct_passthru_bdev', params)
+
+
 def construct_split_vbdev(client, args):
     params = {
         'base_bdev': args.base_bdev,