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[qemu.git] / blockdev-nbd.c
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1 /*
2 * Serving QEMU block devices via NBD
4 * Copyright (c) 2012 Red Hat, Inc.
6 * Author: Paolo Bonzini <pbonzini@redhat.com>
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.
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"
22 static int server_fd = -1;
24 static void nbd_accept(void *opaque)
26 struct sockaddr_in addr;
27 socklen_t addr_len = sizeof(addr);
29 int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
30 if (fd >= 0) {
31 nbd_client_new(NULL, fd, nbd_client_put);
35 void qmp_nbd_server_start(SocketAddress *addr, Error **errp)
37 if (server_fd != -1) {
38 error_setg(errp, "NBD server already running");
39 return;
42 server_fd = socket_listen(addr, errp);
43 if (server_fd != -1) {
44 qemu_set_fd_handler2(server_fd, NULL, nbd_accept, NULL, NULL);
48 /* Hook into the BlockDriverState notifiers to close the export when
49 * the file is closed.
51 typedef struct NBDCloseNotifier {
52 Notifier n;
53 NBDExport *exp;
54 QTAILQ_ENTRY(NBDCloseNotifier) next;
55 } NBDCloseNotifier;
57 static QTAILQ_HEAD(, NBDCloseNotifier) close_notifiers =
58 QTAILQ_HEAD_INITIALIZER(close_notifiers);
60 static void nbd_close_notifier(Notifier *n, void *data)
62 NBDCloseNotifier *cn = DO_UPCAST(NBDCloseNotifier, n, n);
64 notifier_remove(&cn->n);
65 QTAILQ_REMOVE(&close_notifiers, cn, next);
67 nbd_export_close(cn->exp);
68 nbd_export_put(cn->exp);
69 g_free(cn);
72 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
73 Error **errp)
75 BlockDriverState *bs;
76 NBDExport *exp;
77 NBDCloseNotifier *n;
79 if (server_fd == -1) {
80 error_setg(errp, "NBD server not running");
81 return;
84 if (nbd_export_find(device)) {
85 error_setg(errp, "NBD server already exporting device '%s'", device);
86 return;
89 bs = bdrv_find(device);
90 if (!bs) {
91 error_set(errp, QERR_DEVICE_NOT_FOUND, device);
92 return;
95 if (!has_writable) {
96 writable = false;
98 if (bdrv_is_read_only(bs)) {
99 writable = false;
102 exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, NULL);
104 nbd_export_set_name(exp, device);
106 n = g_malloc0(sizeof(NBDCloseNotifier));
107 n->n.notify = nbd_close_notifier;
108 n->exp = exp;
109 bdrv_add_close_notifier(bs, &n->n);
110 QTAILQ_INSERT_TAIL(&close_notifiers, n, next);
113 void qmp_nbd_server_stop(Error **errp)
115 while (!QTAILQ_EMPTY(&close_notifiers)) {
116 NBDCloseNotifier *cn = QTAILQ_FIRST(&close_notifiers);
117 nbd_close_notifier(&cn->n, nbd_export_get_blockdev(cn->exp));
120 if (server_fd != -1) {
121 qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL);
122 close(server_fd);
123 server_fd = -1;