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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 "blockdev.h"
13#include "hw/block-common.h"
14#include "monitor.h"
15#include "qerror.h"
16#include "sysemu.h"
17#include "qmp-commands.h"
18#include "trace.h"
19#include "nbd.h"
20#include "qemu_socket.h"
21
22static int server_fd = -1;
23
24static 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) {
31 nbd_client_new(NULL, fd, nbd_client_put);
32 }
33}
34
35void qmp_nbd_server_start(SocketAddress *addr, Error **errp)
36{
37 if (server_fd != -1) {
38 error_setg(errp, "NBD server already running");
39 return;
40 }
41
42 server_fd = socket_listen(addr, errp);
43 if (server_fd != -1) {
44 qemu_set_fd_handler2(server_fd, NULL, nbd_accept, NULL, NULL);
45 }
46}
47
48/* Hook into the BlockDriverState notifiers to close the export when
49 * the file is closed.
50 */
51typedef struct NBDCloseNotifier {
52 Notifier n;
53 NBDExport *exp;
54 QTAILQ_ENTRY(NBDCloseNotifier) next;
55} NBDCloseNotifier;
56
57static QTAILQ_HEAD(, NBDCloseNotifier) close_notifiers =
58 QTAILQ_HEAD_INITIALIZER(close_notifiers);
59
60static void nbd_close_notifier(Notifier *n, void *data)
61{
62 NBDCloseNotifier *cn = DO_UPCAST(NBDCloseNotifier, n, n);
63
64 notifier_remove(&cn->n);
65 QTAILQ_REMOVE(&close_notifiers, cn, next);
66
67 nbd_export_close(cn->exp);
68 nbd_export_put(cn->exp);
69 g_free(cn);
70}
71
72static void nbd_server_put_ref(NBDExport *exp)
73{
74 BlockDriverState *bs = nbd_export_get_blockdev(exp);
75 drive_put_ref(drive_get_by_blockdev(bs));
76}
77
78void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
79 Error **errp)
80{
81 BlockDriverState *bs;
82 NBDExport *exp;
83 NBDCloseNotifier *n;
84
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85 if (server_fd == -1) {
86 error_setg(errp, "NBD server not running");
87 return;
88 }
89
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90 if (nbd_export_find(device)) {
91 error_setg(errp, "NBD server already exporting device '%s'", device);
92 return;
93 }
94
95 bs = bdrv_find(device);
96 if (!bs) {
97 error_set(errp, QERR_DEVICE_NOT_FOUND, device);
98 return;
99 }
100
e6444734 101 if (!has_writable) {
f3313d23 102 writable = false;
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103 }
104 if (bdrv_is_read_only(bs)) {
105 writable = false;
106 }
107
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108 exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY,
109 nbd_server_put_ref);
110
111 nbd_export_set_name(exp, device);
112 drive_get_ref(drive_get_by_blockdev(bs));
113
114 n = g_malloc0(sizeof(NBDCloseNotifier));
115 n->n.notify = nbd_close_notifier;
116 n->exp = exp;
117 bdrv_add_close_notifier(bs, &n->n);
118 QTAILQ_INSERT_TAIL(&close_notifiers, n, next);
119}
120
121void qmp_nbd_server_stop(Error **errp)
122{
123 while (!QTAILQ_EMPTY(&close_notifiers)) {
124 NBDCloseNotifier *cn = QTAILQ_FIRST(&close_notifiers);
125 nbd_close_notifier(&cn->n, nbd_export_get_blockdev(cn->exp));
126 }
127
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128 if (server_fd != -1) {
129 qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL);
130 close(server_fd);
131 server_fd = -1;
132 }
6dd844db 133}