/* * Serving QEMU block devices via NBD * * Copyright (c) 2012 Red Hat, Inc. * * Author: Paolo Bonzini <pbonzini@redhat.com> * * This work is licensed under the terms of the GNU GPL, version 2 or * later. See the COPYING file in the top-level directory. */ #include "sysemu/blockdev.h" #include "sysemu/block-backend.h" #include "hw/block/block.h" #include "monitor/monitor.h" #include "qapi/qmp/qerror.h" #include "sysemu/sysemu.h" #include "qmp-commands.h" #include "trace.h" #include "block/nbd.h" #include "qemu/sockets.h" static int server_fd = -1; static void nbd_accept(void *opaque) { struct sockaddr_in addr; socklen_t addr_len = sizeof(addr); int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len); if (fd >= 0 && !nbd_client_new(NULL, fd, nbd_client_put)) { shutdown(fd, 2); close(fd); } } void qmp_nbd_server_start(SocketAddress *addr, Error **errp) { if (server_fd != -1) { error_setg(errp, "NBD server already running"); return; } server_fd = socket_listen(addr, errp); if (server_fd != -1) { qemu_set_fd_handler2(server_fd, NULL, nbd_accept, NULL, NULL); } } /* * Hook into the BlockBackend notifiers to close the export when the * backend is closed. */ typedef struct NBDCloseNotifier { Notifier n; NBDExport *exp; QTAILQ_ENTRY(NBDCloseNotifier) next; } NBDCloseNotifier; static QTAILQ_HEAD(, NBDCloseNotifier) close_notifiers = QTAILQ_HEAD_INITIALIZER(close_notifiers); static void nbd_close_notifier(Notifier *n, void *data) { NBDCloseNotifier *cn = DO_UPCAST(NBDCloseNotifier, n, n); notifier_remove(&cn->n); QTAILQ_REMOVE(&close_notifiers, cn, next); nbd_export_close(cn->exp); nbd_export_put(cn->exp); g_free(cn); } void qmp_nbd_server_add(const char *device, bool has_writable, bool writable, Error **errp) { BlockBackend *blk; NBDExport *exp; NBDCloseNotifier *n; if (server_fd == -1) { error_setg(errp, "NBD server not running"); return; } if (nbd_export_find(device)) { error_setg(errp, "NBD server already exporting device '%s'", device); return; } blk = blk_by_name(device); if (!blk) { error_set(errp, QERR_DEVICE_NOT_FOUND, device); return; } if (!blk_is_inserted(blk)) { error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, device); return; } if (!has_writable) { writable = false; } if (blk_is_read_only(blk)) { writable = false; } exp = nbd_export_new(blk, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, NULL, errp); if (!exp) { return; } nbd_export_set_name(exp, device); n = g_new0(NBDCloseNotifier, 1); n->n.notify = nbd_close_notifier; n->exp = exp; blk_add_close_notifier(blk, &n->n); QTAILQ_INSERT_TAIL(&close_notifiers, n, next); } void qmp_nbd_server_stop(Error **errp) { while (!QTAILQ_EMPTY(&close_notifiers)) { NBDCloseNotifier *cn = QTAILQ_FIRST(&close_notifiers); nbd_close_notifier(&cn->n, nbd_export_get_blockdev(cn->exp)); } if (server_fd != -1) { qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL); close(server_fd); server_fd = -1; } }