6dd844db4a
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 <lcapitulino@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
120 lines
2.9 KiB
C
120 lines
2.9 KiB
C
/*
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* Serving QEMU block devices via NBD
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*
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* Copyright (c) 2012 Red Hat, Inc.
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*
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* Author: Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or
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* later. See the COPYING file in the top-level directory.
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*/
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#include "blockdev.h"
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#include "hw/block-common.h"
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#include "monitor.h"
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#include "qerror.h"
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#include "sysemu.h"
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#include "qmp-commands.h"
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#include "trace.h"
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#include "nbd.h"
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#include "qemu_socket.h"
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static int server_fd = -1;
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static void nbd_accept(void *opaque)
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{
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struct sockaddr_in addr;
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socklen_t addr_len = sizeof(addr);
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int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
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if (fd >= 0) {
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nbd_client_new(NULL, fd, nbd_client_put);
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}
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}
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void qmp_nbd_server_start(SocketAddress *addr, Error **errp)
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{
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if (server_fd != -1) {
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error_setg(errp, "NBD server already running");
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return;
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}
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server_fd = socket_listen(addr, errp);
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if (server_fd != -1) {
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qemu_set_fd_handler2(server_fd, NULL, nbd_accept, NULL, NULL);
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}
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}
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/* Hook into the BlockDriverState notifiers to close the export when
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* the file is closed.
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*/
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typedef struct NBDCloseNotifier {
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Notifier n;
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NBDExport *exp;
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QTAILQ_ENTRY(NBDCloseNotifier) next;
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} NBDCloseNotifier;
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static QTAILQ_HEAD(, NBDCloseNotifier) close_notifiers =
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QTAILQ_HEAD_INITIALIZER(close_notifiers);
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static void nbd_close_notifier(Notifier *n, void *data)
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{
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NBDCloseNotifier *cn = DO_UPCAST(NBDCloseNotifier, n, n);
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notifier_remove(&cn->n);
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QTAILQ_REMOVE(&close_notifiers, cn, next);
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nbd_export_close(cn->exp);
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nbd_export_put(cn->exp);
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g_free(cn);
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}
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static void nbd_server_put_ref(NBDExport *exp)
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{
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BlockDriverState *bs = nbd_export_get_blockdev(exp);
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drive_put_ref(drive_get_by_blockdev(bs));
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}
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void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
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Error **errp)
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{
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BlockDriverState *bs;
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NBDExport *exp;
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NBDCloseNotifier *n;
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if (nbd_export_find(device)) {
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error_setg(errp, "NBD server already exporting device '%s'", device);
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return;
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}
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bs = bdrv_find(device);
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if (!bs) {
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error_set(errp, QERR_DEVICE_NOT_FOUND, device);
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return;
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}
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exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY,
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nbd_server_put_ref);
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nbd_export_set_name(exp, device);
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drive_get_ref(drive_get_by_blockdev(bs));
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n = g_malloc0(sizeof(NBDCloseNotifier));
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n->n.notify = nbd_close_notifier;
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n->exp = exp;
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bdrv_add_close_notifier(bs, &n->n);
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QTAILQ_INSERT_TAIL(&close_notifiers, n, next);
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}
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void qmp_nbd_server_stop(Error **errp)
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{
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while (!QTAILQ_EMPTY(&close_notifiers)) {
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NBDCloseNotifier *cn = QTAILQ_FIRST(&close_notifiers);
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nbd_close_notifier(&cn->n, nbd_export_get_blockdev(cn->exp));
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}
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qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL);
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close(server_fd);
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server_fd = -1;
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}
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