qemu-storage-daemon: Add --nbd-server option

Add a --nbd-server option to qemu-storage-daemon to start the built-in
NBD server right away. It maps the arguments for nbd-server-start to the
command line, with the exception that it uses SocketAddress instead of
SocketAddressLegacy: New interfaces shouldn't use legacy types, and the
additional nesting would be nasty on the command line.

Example (only with required options):

    --nbd-server addr.type=inet,addr.host=localhost,addr.port=10809

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200224143008.13362-10-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Makefile.objs

@@ -32,7 +32,7 @@ endif # CONFIG_SOFTMMU or CONFIG_TOOLS
 # used for system emulation, too, but specified separately there)
 
 storage-daemon-obj-y = block/ qom/
-storage-daemon-obj-y += blockdev.o iothread.o
+storage-daemon-obj-y += blockdev.o blockdev-nbd.o iothread.o
 
 ######################################################################
 # Target independent part of system emulation. The long term path is to

blockdev-nbd.c

@@ -132,6 +132,11 @@ void nbd_server_start(SocketAddress *addr, const char *tls_creds,
     nbd_server = NULL;
 }
 
+void nbd_server_start_options(NbdServerOptions *arg, Error **errp)
+{
+    nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz, errp);
+}
+
 void qmp_nbd_server_start(SocketAddressLegacy *addr,
                           bool has_tls_creds, const char *tls_creds,
                           bool has_tls_authz, const char *tls_authz,

include/block/nbd.h

@@ -353,6 +353,7 @@ void nbd_client_put(NBDClient *client);
 
 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
                       const char *tls_authz, Error **errp);
+void nbd_server_start_options(NbdServerOptions *arg, Error **errp);
 
 /* nbd_read
  * Reads @size bytes from @ioc. Returns 0 on success.

qapi/block-core.json

@@ -5062,6 +5062,27 @@
              'iothread': 'StrOrNull',
              '*force': 'bool' } }
 
+##
+# @NbdServerOptions:
+#
+# @addr: Address on which to listen.
+# @tls-creds: ID of the TLS credentials object (since 2.6).
+# @tls-authz: ID of the QAuthZ authorization object used to validate
+#             the client's x509 distinguished name. This object is
+#             is only resolved at time of use, so can be deleted and
+#             recreated on the fly while the NBD server is active.
+#             If missing, it will default to denying access (since 4.0).
+#
+# Keep this type consistent with the nbd-server-start arguments. The only
+# intended difference is using SocketAddress instead of SocketAddressLegacy.
+#
+# Since: 4.2
+##
+{ 'struct': 'NbdServerOptions',
+  'data': { 'addr': 'SocketAddress',
+            '*tls-creds': 'str',
+            '*tls-authz': 'str'} }
+
 ##
 # @nbd-server-start:
 #
@@ -5080,6 +5101,9 @@
 #
 # Returns: error if the server is already running.
 #
+# Keep this type consistent with the NbdServerOptions type. The only intended
+# difference is using SocketAddressLegacy instead of SocketAddress.
+#
 # Since: 1.3.0
 ##
 { 'command': 'nbd-server-start',

qemu-storage-daemon.c

@@ -28,11 +28,14 @@
 #include <getopt.h>
 
 #include "block/block.h"
+#include "block/nbd.h"
 #include "crypto/init.h"
 
 #include "qapi/error.h"
-#include "qapi/qapi-visit-block-core.h"
+#include "qapi/qapi-commands-block.h"
 #include "qapi/qapi-commands-block-core.h"
+#include "qapi/qapi-visit-block.h"
+#include "qapi/qapi-visit-block-core.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qobject-input-visitor.h"
 
@@ -67,6 +70,12 @@ static void help(void)
 "             [,driver specific parameters...]\n"
 "                         configure a block backend\n"
 "\n"
+"  --nbd-server addr.type=inet,addr.host=<host>,addr.port=<port>\n"
+"               [,tls-creds=<id>][,tls-authz=<id>]\n"
+"  --nbd-server addr.type=unix,addr.path=<path>\n"
+"               [,tls-creds=<id>][,tls-authz=<id>]\n"
+"                         start an NBD server for exporting block nodes\n"
+"\n"
 "  --object help          list object types that can be added\n"
 "  --object <type>,help   list properties for the given object type\n"
 "  --object <type>[,<property>=<value>...]\n"
@@ -82,6 +91,7 @@ QEMU_HELP_BOTTOM "\n",
 
 enum {
     OPTION_BLOCKDEV = 256,
+    OPTION_NBD_SERVER,
     OPTION_OBJECT,
 };
 
@@ -101,6 +111,7 @@ static void process_options(int argc, char *argv[])
     static const struct option long_options[] = {
         {"blockdev", required_argument, NULL, OPTION_BLOCKDEV},
         {"help", no_argument, NULL, 'h'},
+        {"nbd-server", required_argument, NULL, OPTION_NBD_SERVER},
         {"object", required_argument, NULL, OPTION_OBJECT},
         {"trace", required_argument, NULL, 'T'},
         {"version", no_argument, NULL, 'V'},
@@ -145,6 +156,19 @@ static void process_options(int argc, char *argv[])
                 qapi_free_BlockdevOptions(options);
                 break;
             }
+        case OPTION_NBD_SERVER:
+            {
+                Visitor *v;
+                NbdServerOptions *options;
+
+                v = qobject_input_visitor_new_str(optarg, NULL, &error_fatal);
+                visit_type_NbdServerOptions(v, NULL, &options, &error_fatal);
+                visit_free(v);
+
+                nbd_server_start_options(options, &error_fatal);
+                qapi_free_NbdServerOptions(options);
+                break;
+            }
         case OPTION_OBJECT:
             {
                 QemuOpts *opts;