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 "sysemu/blockdev.h" 13 #include "hw/block/block.h" 14 #include "monitor/monitor.h" 15 #include "qapi/qmp/qerror.h" 16 #include "sysemu/sysemu.h" 17 #include "qmp-commands.h" 18 #include "trace.h" 19 #include "block/nbd.h" 20 #include "qemu/sockets.h" 21 22 static int server_fd = -1; 23 24 static void nbd_accept(void *opaque) 25 { 26 struct sockaddr_in addr; 27 socklen_t addr_len = sizeof(addr); 28 29 int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len); 30 if (fd >= 0) { 31 nbd_client_new(NULL, fd, nbd_client_put); 32 } 33 } 34 35 void qmp_nbd_server_start(SocketAddress *addr, Error **errp) 36 { 37 if (server_fd != -1) { 38 error_setg(errp, "NBD server already running"); 39 return; 40 } 41 42 server_fd = socket_listen(addr, errp); 43 if (server_fd != -1) { 44 qemu_set_fd_handler2(server_fd, NULL, nbd_accept, NULL, NULL); 45 } 46 } 47 48 /* Hook into the BlockDriverState notifiers to close the export when 49 * the file is closed. 50 */ 51 typedef struct NBDCloseNotifier { 52 Notifier n; 53 NBDExport *exp; 54 QTAILQ_ENTRY(NBDCloseNotifier) next; 55 } NBDCloseNotifier; 56 57 static QTAILQ_HEAD(, NBDCloseNotifier) close_notifiers = 58 QTAILQ_HEAD_INITIALIZER(close_notifiers); 59 60 static void nbd_close_notifier(Notifier *n, void *data) 61 { 62 NBDCloseNotifier *cn = DO_UPCAST(NBDCloseNotifier, n, n); 63 64 notifier_remove(&cn->n); 65 QTAILQ_REMOVE(&close_notifiers, cn, next); 66 67 nbd_export_close(cn->exp); 68 nbd_export_put(cn->exp); 69 g_free(cn); 70 } 71 72 static void nbd_server_put_ref(NBDExport *exp) 73 { 74 BlockDriverState *bs = nbd_export_get_blockdev(exp); 75 drive_put_ref(drive_get_by_blockdev(bs)); 76 } 77 78 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable, 79 Error **errp) 80 { 81 BlockDriverState *bs; 82 NBDExport *exp; 83 NBDCloseNotifier *n; 84 85 if (server_fd == -1) { 86 error_setg(errp, "NBD server not running"); 87 return; 88 } 89 90 if (nbd_export_find(device)) { 91 error_setg(errp, "NBD server already exporting device '%s'", device); 92 return; 93 } 94 95 bs = bdrv_find(device); 96 if (!bs) { 97 error_set(errp, QERR_DEVICE_NOT_FOUND, device); 98 return; 99 } 100 101 if (!has_writable) { 102 writable = false; 103 } 104 if (bdrv_is_read_only(bs)) { 105 writable = false; 106 } 107 108 exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, 109 nbd_server_put_ref); 110 111 nbd_export_set_name(exp, device); 112 drive_get_ref(drive_get_by_blockdev(bs)); 113 114 n = g_malloc0(sizeof(NBDCloseNotifier)); 115 n->n.notify = nbd_close_notifier; 116 n->exp = exp; 117 bdrv_add_close_notifier(bs, &n->n); 118 QTAILQ_INSERT_TAIL(&close_notifiers, n, next); 119 } 120 121 void qmp_nbd_server_stop(Error **errp) 122 { 123 while (!QTAILQ_EMPTY(&close_notifiers)) { 124 NBDCloseNotifier *cn = QTAILQ_FIRST(&close_notifiers); 125 nbd_close_notifier(&cn->n, nbd_export_get_blockdev(cn->exp)); 126 } 127 128 if (server_fd != -1) { 129 qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL); 130 close(server_fd); 131 server_fd = -1; 132 } 133 } 134