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Copy pathblockdev-nbd.c
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133 lines (111 loc) · 3.21 KB
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/*
* 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 "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 (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;
}
bs = bdrv_find(device);
if (!bs) {
error_set(errp, QERR_DEVICE_NOT_FOUND, device);
return;
}
if (!has_writable) {
writable = false;
}
if (bdrv_is_read_only(bs)) {
writable = false;
}
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));
}
if (server_fd != -1) {
qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL);
close(server_fd);
server_fd = -1;
}
}