blockdev-nbd.c

   1 /*
   2  * Serving QEMU block devices via NBD
   3  *
   4  * Copyright (c) 2012 Red Hat, Inc.
   5  *
   6  * Author: Paolo Bonzini <pbonzini@redhat.com>
   7  *
   8  * This work is licensed under the terms of the GNU GPL, version 2 or
   9  * later.  See the COPYING file in the top-level directory.
  10  */
  11
  12 #include "qemu/osdep.h"
  13 #include "sysemu/blockdev.h"
  14 #include "sysemu/block-backend.h"
  15 #include "hw/block/block.h"
  16 #include "qapi/qmp/qerror.h"
  17 #include "sysemu/sysemu.h"
  18 #include "qmp-commands.h"
  19 #include "trace.h"
  20 #include "block/nbd.h"
  21 #include "io/channel-socket.h"
  22
  23 static QIOChannelSocket *server_ioc;
  24 static int server_watch = -1;
  25
  26 static gboolean nbd_accept(QIOChannel *ioc, GIOCondition condition,
  27                            gpointer opaque)
  28 {
  29     QIOChannelSocket *cioc;
  30
  31     cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
  32                                      NULL);
  33     if (!cioc) {
  34         return TRUE;
  35     }
  36
  37     nbd_client_new(NULL, cioc, nbd_client_put);
  38     object_unref(OBJECT(cioc));
  39     return TRUE;
  40 }
  41
  42 void qmp_nbd_server_start(SocketAddress *addr, Error **errp)
  43 {
  44     if (server_ioc) {
  45         error_setg(errp, "NBD server already running");
  46         return;
  47     }
  48
  49     server_ioc = qio_channel_socket_new();
  50     if (qio_channel_socket_listen_sync(server_ioc, addr, errp) < 0) {
  51         return;
  52     }
  53
  54     server_watch = qio_channel_add_watch(QIO_CHANNEL(server_ioc),
  55                                          G_IO_IN,
  56                                          nbd_accept,
  57                                          NULL,
  58                                          NULL);
  59 }
  60
  61 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
  62                         Error **errp)
  63 {
  64     BlockBackend *blk;
  65     NBDExport *exp;
  66
  67     if (!server_ioc) {
  68         error_setg(errp, "NBD server not running");
  69         return;
  70     }
  71
  72     if (nbd_export_find(device)) {
  73         error_setg(errp, "NBD server already exporting device '%s'", device);
  74         return;
  75     }
  76
  77     blk = blk_by_name(device);
  78     if (!blk) {
  79         error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
  80                   "Device '%s' not found", device);
  81         return;
  82     }
  83     if (!blk_is_inserted(blk)) {
  84         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
  85         return;
  86     }
  87
  88     if (!has_writable) {
  89         writable = false;
  90     }
  91     if (blk_is_read_only(blk)) {
  92         writable = false;
  93     }
  94
  95     exp = nbd_export_new(blk, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, NULL,
  96                          errp);
  97     if (!exp) {
  98         return;
  99     }
 100
 101     nbd_export_set_name(exp, device);
 102
 103     /* The list of named exports has a strong reference to this export now and
 104      * our only way of accessing it is through nbd_export_find(), so we can drop
 105      * the strong reference that is @exp. */
 106     nbd_export_put(exp);
 107 }
 108
 109 void qmp_nbd_server_stop(Error **errp)
 110 {
 111     nbd_export_close_all();
 112
 113     if (server_watch != -1) {
 114         g_source_remove(server_watch);
 115         server_watch = -1;
 116     }
 117     if (server_ioc) {
 118         object_unref(OBJECT(server_ioc));
 119         server_ioc = NULL;
 120     }
 121 }