/*
* QEMU Block driver for NBD
*
* Copyright (c) 2021 Virtuozzo International GmbH.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "trace.h"
#include "block/nbd.h"
#include "qapi/qapi-visit-sockets.h"
#include "qapi/clone-visitor.h"
struct NBDClientConnection {
/* Initialization constants, never change */
SocketAddress *saddr; /* address to connect to */
QCryptoTLSCreds *tlscreds;
char *tlshostname;
NBDExportInfo initial_info;
bool do_negotiation;
bool do_retry;
QemuMutex mutex;
NBDExportInfo updated_info;
/*
* @sioc represents a successful result. While thread is running, @sioc is
* used only by thread and not protected by mutex. When thread is not
* running, @sioc is stolen by nbd_co_establish_connection() under mutex.
*/
QIOChannelSocket *sioc;
QIOChannel *ioc;
/*
* @err represents previous attempt. It may be copied by
* nbd_co_establish_connection() when it reports failure.
*/
Error *err;
/* All further fields are accessed only under mutex */
bool running; /* thread is running now */
bool detached; /* thread is detached and should cleanup the state */
/*
* wait_co: if non-NULL, which coroutine to wake in
* nbd_co_establish_connection() after yield()
*/
Coroutine *wait_co;
};
/*
* The function isn't protected by any mutex, only call it when the client
* connection attempt has not yet started.
*/
void nbd_client_connection_enable_retry(NBDClientConnection *conn)
{
conn->do_retry = true;
}
NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr,
bool do_negotiation,
const char *export_name,
const char *x_dirty_bitmap,
QCryptoTLSCreds *tlscreds,
const char *tlshostname)
{
NBDClientConnection *conn = g_new(NBDClientConnection, 1);
object_ref(OBJECT(tlscreds));
*conn = (NBDClientConnection) {
.saddr = QAPI_CLONE(SocketAddress, saddr),
.tlscreds = tlscreds,
.tlshostname = g_strdup(tlshostname),
.do_negotiation = do_negotiation,
.initial_info.request_sizes = true,
.initial_info.structured_reply = true,
.initial_info.base_allocation = true,
.initial_info.x_dirty_bitmap = g_strdup(x_dirty_bitmap),
.initial_info.name = g_strdup(export_name ?: "")
};
qemu_mutex_init(&conn->mutex);
return conn;
}
static void nbd_client_connection_do_free(NBDClientConnection *conn)
{
if (conn->sioc) {
qio_channel_close(QIO_CHANNEL(conn->sioc), NULL);
object_unref(OBJECT(conn->sioc));
}
error_free(conn->err);
qapi_free_SocketAddress(conn->saddr);
g_free(conn->tlshostname);
object_unref(OBJECT(conn->tlscreds));
g_free(conn->initial_info.x_dirty_bitmap);
g_free(conn->initial_info.name);
g_free(conn);
}
/*
* Connect to @addr and do NBD negotiation if @info is not null. If @tlscreds
* are given @outioc is returned. @outioc is provided only on success. The call
* may be cancelled from other thread by simply qio_channel_shutdown(sioc).
*/
static int nbd_connect(QIOChannelSocket *sioc, SocketAddress *addr,
NBDExportInfo *info, QCryptoTLSCreds *tlscreds,
const char *tlshostname,
QIOChannel **outioc, Error **errp)
{
int ret;
if (outioc) {
*outioc = NULL;
}
ret = qio_channel_socket_connect_sync(sioc, addr, errp);
if (ret < 0) {
return ret;
}
qio_channel_set_delay(QIO_CHANNEL(sioc), false);
if (!info) {
return 0;
}
ret = nbd_receive_negotiate(NULL, QIO_CHANNEL(sioc), tlscreds,
tlshostname,
outioc, info, errp);
if (ret < 0) {
/*
* nbd_receive_negotiate() may setup tls ioc and return it even on
* failure path. In this case we should use it instead of original
* channel.
*/
if (outioc && *outioc) {
qio_channel_close(QIO_CHANNEL(*outioc), NULL);
object_unref(OBJECT(*outioc));
*outioc = NULL;
} else {
qio_channel_close(QIO_CHANNEL(sioc), NULL);
}
return ret;
}
return 0;
}
static void *connect_thread_func(void *opaque)
{
NBDClientConnection *conn = opaque;
int ret;
bool do_free;
uint64_t timeout = 1;
uint64_t max_timeout = 16;
qemu_mutex_lock(&conn->mutex);
while (!conn->detached) {
Error *local_err = NULL;
assert(!conn->sioc);
conn->sioc = qio_channel_socket_new();
qemu_mutex_unlock(&conn->mutex);
conn->updated_info = conn->initial_info;
ret = nbd_connect(conn->sioc, conn->saddr,
conn->do_negotiation ? &conn->updated_info : NULL,
conn->tlscreds, conn->tlshostname,
&conn->ioc, &local_err);
/*
* conn->updated_info will finally be returned to the user. Clear the
* pointers to our internally allocated strings, which are IN parameters
* of nbd_receive_negotiate() and therefore nbd_connect(). Caller
* shoudn't be interested in these fields.
*/
conn->updated_info.x_dirty_bitmap = NULL;
conn->updated_info.name = NULL;
qemu_mutex_lock(&conn->mutex);
error_free(conn->err);
conn->err = NULL;
error_propagate(&conn->err, local_err);
if (ret < 0) {
object_unref(OBJECT(conn->sioc));
conn->sioc = NULL;
if (conn->do_retry && !conn->detached) {
trace_nbd_connect_thread_sleep(timeout);
qemu_mutex_unlock(&conn->mutex);
sleep(timeout);
if (timeout < max_timeout) {
timeout *= 2;
}
qemu_mutex_lock(&conn->mutex);
continue;
}
}
break;
}
/* mutex is locked */
assert(conn->running);
conn->running = false;
if (conn->wait_co) {
aio_co_wake(conn->wait_co);
conn->wait_co = NULL;
}
do_free = conn->detached;
qemu_mutex_unlock(&conn->mutex);
if (do_free) {
nbd_client_connection_do_free(conn);
}
return NULL;
}
void nbd_client_connection_release(NBDClientConnection *conn)
{
bool do_free = false;
if (!conn) {
return;
}
WITH_QEMU_LOCK_GUARD(&conn->mutex) {
assert(!conn->detached);
if (conn->running) {
conn->detached = true;
} else {
do_free = true;
}
if (conn->sioc) {
qio_channel_shutdown(QIO_CHANNEL(conn->sioc),
QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
}
}
if (do_free) {
nbd_client_connection_do_free(conn);
}
}
/*
* Get a new connection in context of @conn:
* if the thread is running, wait for completion
* if the thread already succeeded in the background, and user didn't get the
* result, just return it now
* otherwise the thread is not running, so start a thread and wait for
* completion
*
* If @blocking is false, don't wait for the thread, return immediately.
*
* If @info is not NULL, also do nbd-negotiation after successful connection.
* In this case info is used only as out parameter, and is fully initialized by
* nbd_co_establish_connection(). "IN" fields of info as well as related only to
* nbd_receive_export_list() would be zero (see description of NBDExportInfo in
* include/block/nbd.h).
*/
QIOChannel *coroutine_fn
nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
bool blocking, Error **errp)
{
QemuThread thread;
if (conn->do_negotiation) {
assert(info);
}
WITH_QEMU_LOCK_GUARD(&conn->mutex) {
/*
* Don't call nbd_co_establish_connection() in several coroutines in
* parallel. Only one call at once is supported.
*/
assert(!conn->wait_co);
if (!conn->running) {
if (conn->sioc) {
/* Previous attempt finally succeeded in background */
if (conn->do_negotiation) {
memcpy(info, &conn->updated_info, sizeof(*info));
if (conn->ioc) {
/* TLS channel now has own reference to parent */
object_unref(OBJECT(conn->sioc));
conn->sioc = NULL;
return g_steal_pointer(&conn->ioc);
}
}
assert(!conn->ioc);
return QIO_CHANNEL(g_steal_pointer(&conn->sioc));
}
conn->running = true;
qemu_thread_create(&thread, "nbd-connect",
connect_thread_func, conn, QEMU_THREAD_DETACHED);
}
if (!blocking) {
if (conn->err) {
error_propagate(errp, error_copy(conn->err));
} else {
error_setg(errp, "No connection at the moment");
}
return NULL;
}
conn->wait_co = qemu_coroutine_self();
}
/*
* We are going to wait for connect-thread finish, but
* nbd_co_establish_connection_cancel() can interrupt.
*/
qemu_coroutine_yield();
WITH_QEMU_LOCK_GUARD(&conn->mutex) {
if (conn->running) {
/*
* The connection attempt was canceled and the coroutine resumed
* before the connection thread finished its job. Report the
* attempt as failed, but leave the connection thread running,
* to reuse it for the next connection attempt.
*/
if (conn->err) {
error_propagate(errp, error_copy(conn->err));
} else {
/*
* The only possible case here is cancelling by open_timer
* during nbd_open(). So, the error message is for that case.
* If we have more use cases, we can refactor
* nbd_co_establish_connection_cancel() to take an additional
* parameter cancel_reason, that would be passed than to the
* caller of cancelled nbd_co_establish_connection().
*/
error_setg(errp, "Connection attempt cancelled by timeout");
}
return NULL;
} else {
/* Thread finished. There must be either error or sioc */
assert(!conn->err != !conn->sioc);
if (conn->err) {
error_propagate(errp, error_copy(conn->err));
return NULL;
}
if (conn->do_negotiation) {
memcpy(info, &conn->updated_info, sizeof(*info));
if (conn->ioc) {
/* TLS channel now has own reference to parent */
object_unref(OBJECT(conn->sioc));
conn->sioc = NULL;
return g_steal_pointer(&conn->ioc);
}
}
assert(!conn->ioc);
return QIO_CHANNEL(g_steal_pointer(&conn->sioc));
}
}
abort(); /* unreachable */
}
/*
* nbd_co_establish_connection_cancel
* Cancel nbd_co_establish_connection() asynchronously.
*
* Note that this function neither directly stops the thread nor closes the
* socket, but rather safely wakes nbd_co_establish_connection() which is
* sleeping in yield()
*/
void nbd_co_establish_connection_cancel(NBDClientConnection *conn)
{
Coroutine *wait_co;
WITH_QEMU_LOCK_GUARD(&conn->mutex) {
wait_co = g_steal_pointer(&conn->wait_co);
}
if (wait_co) {
aio_co_wake(wait_co);
}
}
