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 && !nbd_client_new(NULL, fd, nbd_client_put)) { 31 shutdown(fd, 2); 32 close(fd); 33 } 34 } 35 36 void qmp_nbd_server_start(SocketAddress *addr, Error **errp) 37 { 38 if (server_fd != -1) { 39 error_setg(errp, "NBD server already running"); 40 return; 41 } 42 43 server_fd = socket_listen(addr, errp); 44 if (server_fd != -1) { 45 qemu_set_fd_handler2(server_fd, NULL, nbd_accept, NULL, NULL); 46 } 47 } 48 49 /* Hook into the BlockDriverState notifiers to close the export when 50 * the file is closed. 51 */ 52 typedef struct NBDCloseNotifier { 53 Notifier n; 54 NBDExport *exp; 55 QTAILQ_ENTRY(NBDCloseNotifier) next; 56 } NBDCloseNotifier; 57 58 static QTAILQ_HEAD(, NBDCloseNotifier) close_notifiers = 59 QTAILQ_HEAD_INITIALIZER(close_notifiers); 60 61 static void nbd_close_notifier(Notifier *n, void *data) 62 { 63 NBDCloseNotifier *cn = DO_UPCAST(NBDCloseNotifier, n, n); 64 65 notifier_remove(&cn->n); 66 QTAILQ_REMOVE(&close_notifiers, cn, next); 67 68 nbd_export_close(cn->exp); 69 nbd_export_put(cn->exp); 70 g_free(cn); 71 } 72 73 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable, 74 Error **errp) 75 { 76 BlockDriverState *bs; 77 NBDExport *exp; 78 NBDCloseNotifier *n; 79 80 if (server_fd == -1) { 81 error_setg(errp, "NBD server not running"); 82 return; 83 } 84 85 if (nbd_export_find(device)) { 86 error_setg(errp, "NBD server already exporting device '%s'", device); 87 return; 88 } 89 90 bs = bdrv_find(device); 91 if (!bs) { 92 error_set(errp, QERR_DEVICE_NOT_FOUND, device); 93 return; 94 } 95 if (!bdrv_is_inserted(bs)) { 96 error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, device); 97 return; 98 } 99 100 if (!has_writable) { 101 writable = false; 102 } 103 if (bdrv_is_read_only(bs)) { 104 writable = false; 105 } 106 107 exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, NULL); 108 109 nbd_export_set_name(exp, device); 110 111 n = g_malloc0(sizeof(NBDCloseNotifier)); 112 n->n.notify = nbd_close_notifier; 113 n->exp = exp; 114 bdrv_add_close_notifier(bs, &n->n); 115 QTAILQ_INSERT_TAIL(&close_notifiers, n, next); 116 } 117 118 void qmp_nbd_server_stop(Error **errp) 119 { 120 while (!QTAILQ_EMPTY(&close_notifiers)) { 121 NBDCloseNotifier *cn = QTAILQ_FIRST(&close_notifiers); 122 nbd_close_notifier(&cn->n, nbd_export_get_blockdev(cn->exp)); 123 } 124 125 if (server_fd != -1) { 126 qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL); 127 close(server_fd); 128 server_fd = -1; 129 } 130 } 131