nbd: add nbd stop rpc

Use soft-disconnection to stop nbd disk
Examople RPC request:
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "stop_nbd_disk",
  "params": {
    "nbd_device": "/dev/nbd0"
  }
}

Change-Id: I3d9161635b4422bbb9895914a03483dbaa6b6386
Signed-off-by: Xiaodong Liu <xiaodong.liu@intel.com>
Reviewed-on: https://review.gerrithub.io/389781
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>

lib/nbd/Makefile

@@ -35,6 +35,6 @@ SPDK_ROOT_DIR := $(abspath $(CURDIR)/../..)
 include $(SPDK_ROOT_DIR)/mk/spdk.common.mk
 
 LIBNAME = nbd
-C_SRCS = nbd.c
+C_SRCS = nbd.c nbd_rpc.c
 
 include $(SPDK_ROOT_DIR)/mk/spdk.lib.mk

lib/nbd/nbd.c

@@ -204,6 +204,17 @@ is_write(enum spdk_bdev_io_type io_type)
 	}
 }
 
+void
+nbd_disconnect(struct spdk_nbd_disk *nbd)
+{
+	/*
+	 * nbd soft-disconnection to terminate transmission phase.
+	 * After receiving this ioctl command, nbd kernel module will send
+	 * a NBD_CMD_DISC type io to nbd server in order to inform server.
+	 */
+	ioctl(nbd->dev_fd, NBD_DISCONNECT);
+}
+
 static void
 _nbd_stop(struct spdk_nbd_disk *nbd)
 {

lib/nbd/nbd_internal.h

@@ -47,4 +47,6 @@ const char *spdk_nbd_disk_get_nbd_path(struct spdk_nbd_disk *nbd);
 
 const char *spdk_nbd_disk_get_bdev_name(struct spdk_nbd_disk *nbd);
 
+void nbd_disconnect(struct spdk_nbd_disk *nbd);
+
 #endif /* SPDK_NBD_INTERNAL_H */

lib/nbd/nbd_rpc.c

@@ -0,0 +1,99 @@
+/*-
+ *   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 "spdk/rpc.h"
+#include "spdk/util.h"
+
+#include <linux/nbd.h>
+
+#include "nbd_internal.h"
+#include "spdk_internal/log.h"
+
+struct rpc_stop_nbd_disk {
+	char *nbd_device;
+};
+
+static void
+free_rpc_stop_nbd_disk(struct rpc_stop_nbd_disk *req)
+{
+	free(req->nbd_device);
+}
+
+static const struct spdk_json_object_decoder rpc_stop_nbd_disk_decoders[] = {
+	{"nbd_device", offsetof(struct rpc_stop_nbd_disk, nbd_device), spdk_json_decode_string},
+};
+
+static void
+spdk_rpc_stop_nbd_disk(struct spdk_jsonrpc_request *request,
+		       const struct spdk_json_val *params)
+{
+	struct rpc_stop_nbd_disk req = {};
+	struct spdk_json_write_ctx *w;
+	struct spdk_nbd_disk *nbd;
+
+	if (spdk_json_decode_object(params, rpc_stop_nbd_disk_decoders,
+				    SPDK_COUNTOF(rpc_stop_nbd_disk_decoders),
+				    &req)) {
+		SPDK_ERRLOG("spdk_json_decode_object failed\n");
+		goto invalid;
+	}
+
+	if (req.nbd_device == NULL) {
+		goto invalid;
+	}
+
+	/* make sure nbd_device is registered */
+	nbd = spdk_nbd_disk_find_by_nbd_path(req.nbd_device);
+	if (!nbd) {
+		goto invalid;
+	}
+
+	nbd_disconnect(nbd);
+
+	free_rpc_stop_nbd_disk(&req);
+
+	w = spdk_jsonrpc_begin_result(request);
+	if (w == NULL) {
+		return;
+	}
+
+	spdk_json_write_bool(w, true);
+	spdk_jsonrpc_end_result(request, w);
+	return;
+
+invalid:
+	free_rpc_stop_nbd_disk(&req);
+	spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS, "Invalid parameters");
+}
+
+SPDK_RPC_REGISTER("stop_nbd_disk", spdk_rpc_stop_nbd_disk)

mk/spdk.app.mk

@@ -43,6 +43,7 @@ SPDK_FILTER_LIB_LIST += $(filter %_rpc,$(SPDK_LIB_LIST))
 #  rather than breaking them out into separate libraries.  So we must also include
 #  these directories in the RPC library list.
 SPDK_FILTER_LIB_LIST += $(filter iscsi,$(SPDK_LIB_LIST))
+SPDK_FILTER_LIB_LIST += $(filter nbd,$(SPDK_LIB_LIST))
 SPDK_FILTER_LIB_LIST += $(filter net,$(SPDK_LIB_LIST))
 SPDK_FILTER_LIB_LIST += $(filter scsi,$(SPDK_LIB_LIST))
 SPDK_FILTER_LIB_LIST += $(filter vhost,$(SPDK_LIB_LIST))

scripts/rpc.py

@@ -604,6 +604,13 @@ p = subparsers.add_parser('delete_bdev', help='Delete a blockdev')
 p.add_argument('bdev_name', help='Blockdev name to be deleted. Example: Malloc0.')
 p.set_defaults(func=delete_bdev)
 
+def stop_nbd_disk(args):
+    params = {'nbd_device': args.nbd_device}
+    jsonrpc_call('stop_nbd_disk', params)
+
+p = subparsers.add_parser('stop_nbd_disk', help='Stop a nbd disk')
+p.add_argument('nbd_device', help='Nbd device name to be stopped. Example: /dev/nbd0.')
+p.set_defaults(func=stop_nbd_disk)
 
 def get_nvmf_subsystems(args):
     print_dict(jsonrpc_call('get_nvmf_subsystems'))