From 6dd844db4a49a367cc15cd0e8bfb72cfc6652766 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 22 Aug 2012 16:43:07 +0200 Subject: qmp: add NBD server commands Adding an NBD server inside QEMU is trivial, since all the logic is in nbd.c and can be shared easily between qemu-nbd and QEMU itself. The main difference is that qemu-nbd serves a single unnamed export, while QEMU serves named exports. Acked-by: Luiz Capitulino Signed-off-by: Paolo Bonzini --- blockdev-nbd.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) create mode 100644 blockdev-nbd.c (limited to 'blockdev-nbd.c') diff --git a/blockdev-nbd.c b/blockdev-nbd.c new file mode 100644 index 0000000000..8031813071 --- /dev/null +++ b/blockdev-nbd.c @@ -0,0 +1,119 @@ +/* + * Serving QEMU block devices via NBD + * + * Copyright (c) 2012 Red Hat, Inc. + * + * Author: Paolo Bonzini + * + * 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 "blockdev.h" +#include "hw/block-common.h" +#include "monitor.h" +#include "qerror.h" +#include "sysemu.h" +#include "qmp-commands.h" +#include "trace.h" +#include "nbd.h" +#include "qemu_socket.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); + } +} + +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 BlockDriverState notifiers to close the export when + * the file 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); +} + +static void nbd_server_put_ref(NBDExport *exp) +{ + BlockDriverState *bs = nbd_export_get_blockdev(exp); + drive_put_ref(drive_get_by_blockdev(bs)); +} + +void qmp_nbd_server_add(const char *device, bool has_writable, bool writable, + Error **errp) +{ + BlockDriverState *bs; + NBDExport *exp; + NBDCloseNotifier *n; + + if (nbd_export_find(device)) { + error_setg(errp, "NBD server already exporting device '%s'", device); + return; + } + + bs = bdrv_find(device); + if (!bs) { + error_set(errp, QERR_DEVICE_NOT_FOUND, device); + return; + } + + exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, + nbd_server_put_ref); + + nbd_export_set_name(exp, device); + drive_get_ref(drive_get_by_blockdev(bs)); + + n = g_malloc0(sizeof(NBDCloseNotifier)); + n->n.notify = nbd_close_notifier; + n->exp = exp; + bdrv_add_close_notifier(bs, &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)); + } + + qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL); + close(server_fd); + server_fd = -1; +} -- cgit v1.2.1