block/nbd doesn't need underlying sioc channel anymore. So, we can update nbd/client-connection interface to return only one top-most io channel, which is more straight forward. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20210610100802.5888-27-vsementsov@virtuozzo.com> [eblake: squash in Vladimir's fixes for uninit usage caught by clang] Signed-off-by: Eric Blake <eblake@redhat.com>
383 lines
11 KiB
C
383 lines
11 KiB
C
/*
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* QEMU Block driver for NBD
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*
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* Copyright (c) 2021 Virtuozzo International GmbH.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include "block/nbd.h"
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#include "qapi/qapi-visit-sockets.h"
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#include "qapi/clone-visitor.h"
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struct NBDClientConnection {
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/* Initialization constants, never change */
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SocketAddress *saddr; /* address to connect to */
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QCryptoTLSCreds *tlscreds;
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NBDExportInfo initial_info;
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bool do_negotiation;
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bool do_retry;
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QemuMutex mutex;
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/*
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* @sioc and @err represent a connection attempt. While running
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* is true, they are only used by the connection thread, and mutex
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* locking is not needed. Once the thread finishes,
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* nbd_co_establish_connection then steals these pointers while
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* under the mutex.
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*/
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NBDExportInfo updated_info;
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QIOChannelSocket *sioc;
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QIOChannel *ioc;
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Error *err;
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/* All further fields are accessed only under mutex */
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bool running; /* thread is running now */
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bool detached; /* thread is detached and should cleanup the state */
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/*
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* wait_co: if non-NULL, which coroutine to wake in
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* nbd_co_establish_connection() after yield()
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*/
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Coroutine *wait_co;
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};
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/*
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* The function isn't protected by any mutex, only call it when the client
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* connection attempt has not yet started.
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*/
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void nbd_client_connection_enable_retry(NBDClientConnection *conn)
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{
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conn->do_retry = true;
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}
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NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr,
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bool do_negotiation,
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const char *export_name,
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const char *x_dirty_bitmap,
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QCryptoTLSCreds *tlscreds)
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{
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NBDClientConnection *conn = g_new(NBDClientConnection, 1);
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object_ref(OBJECT(tlscreds));
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*conn = (NBDClientConnection) {
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.saddr = QAPI_CLONE(SocketAddress, saddr),
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.tlscreds = tlscreds,
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.do_negotiation = do_negotiation,
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.initial_info.request_sizes = true,
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.initial_info.structured_reply = true,
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.initial_info.base_allocation = true,
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.initial_info.x_dirty_bitmap = g_strdup(x_dirty_bitmap),
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.initial_info.name = g_strdup(export_name ?: "")
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};
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qemu_mutex_init(&conn->mutex);
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return conn;
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}
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static void nbd_client_connection_do_free(NBDClientConnection *conn)
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{
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if (conn->sioc) {
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qio_channel_close(QIO_CHANNEL(conn->sioc), NULL);
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object_unref(OBJECT(conn->sioc));
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}
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error_free(conn->err);
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qapi_free_SocketAddress(conn->saddr);
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object_unref(OBJECT(conn->tlscreds));
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g_free(conn->initial_info.x_dirty_bitmap);
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g_free(conn->initial_info.name);
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g_free(conn);
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}
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/*
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* Connect to @addr and do NBD negotiation if @info is not null. If @tlscreds
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* are given @outioc is returned. @outioc is provided only on success. The call
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* may be cancelled from other thread by simply qio_channel_shutdown(sioc).
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*/
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static int nbd_connect(QIOChannelSocket *sioc, SocketAddress *addr,
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NBDExportInfo *info, QCryptoTLSCreds *tlscreds,
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QIOChannel **outioc, Error **errp)
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{
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int ret;
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if (outioc) {
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*outioc = NULL;
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}
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ret = qio_channel_socket_connect_sync(sioc, addr, errp);
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if (ret < 0) {
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return ret;
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}
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qio_channel_set_delay(QIO_CHANNEL(sioc), false);
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if (!info) {
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return 0;
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}
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ret = nbd_receive_negotiate(NULL, QIO_CHANNEL(sioc), tlscreds,
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tlscreds ? addr->u.inet.host : NULL,
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outioc, info, errp);
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if (ret < 0) {
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/*
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* nbd_receive_negotiate() may setup tls ioc and return it even on
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* failure path. In this case we should use it instead of original
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* channel.
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*/
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if (outioc && *outioc) {
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qio_channel_close(QIO_CHANNEL(*outioc), NULL);
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object_unref(OBJECT(*outioc));
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*outioc = NULL;
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} else {
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qio_channel_close(QIO_CHANNEL(sioc), NULL);
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}
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return ret;
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}
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return 0;
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}
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static void *connect_thread_func(void *opaque)
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{
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NBDClientConnection *conn = opaque;
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int ret;
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bool do_free;
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uint64_t timeout = 1;
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uint64_t max_timeout = 16;
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qemu_mutex_lock(&conn->mutex);
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while (!conn->detached) {
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assert(!conn->sioc);
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conn->sioc = qio_channel_socket_new();
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qemu_mutex_unlock(&conn->mutex);
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error_free(conn->err);
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conn->err = NULL;
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conn->updated_info = conn->initial_info;
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ret = nbd_connect(conn->sioc, conn->saddr,
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conn->do_negotiation ? &conn->updated_info : NULL,
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conn->tlscreds, &conn->ioc, &conn->err);
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/*
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* conn->updated_info will finally be returned to the user. Clear the
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* pointers to our internally allocated strings, which are IN parameters
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* of nbd_receive_negotiate() and therefore nbd_connect(). Caller
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* shoudn't be interested in these fields.
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*/
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conn->updated_info.x_dirty_bitmap = NULL;
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conn->updated_info.name = NULL;
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qemu_mutex_lock(&conn->mutex);
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if (ret < 0) {
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object_unref(OBJECT(conn->sioc));
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conn->sioc = NULL;
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if (conn->do_retry && !conn->detached) {
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qemu_mutex_unlock(&conn->mutex);
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sleep(timeout);
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if (timeout < max_timeout) {
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timeout *= 2;
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}
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qemu_mutex_lock(&conn->mutex);
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continue;
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}
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}
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break;
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}
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/* mutex is locked */
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assert(conn->running);
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conn->running = false;
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if (conn->wait_co) {
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aio_co_wake(conn->wait_co);
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conn->wait_co = NULL;
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}
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do_free = conn->detached;
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qemu_mutex_unlock(&conn->mutex);
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if (do_free) {
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nbd_client_connection_do_free(conn);
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}
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return NULL;
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}
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void nbd_client_connection_release(NBDClientConnection *conn)
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{
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bool do_free = false;
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if (!conn) {
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return;
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}
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WITH_QEMU_LOCK_GUARD(&conn->mutex) {
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assert(!conn->detached);
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if (conn->running) {
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conn->detached = true;
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} else {
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do_free = true;
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}
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if (conn->sioc) {
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qio_channel_shutdown(QIO_CHANNEL(conn->sioc),
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QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
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}
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}
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if (do_free) {
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nbd_client_connection_do_free(conn);
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}
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}
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/*
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* Get a new connection in context of @conn:
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* if the thread is running, wait for completion
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* if the thread already succeeded in the background, and user didn't get the
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* result, just return it now
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* otherwise the thread is not running, so start a thread and wait for
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* completion
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*
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* If @info is not NULL, also do nbd-negotiation after successful connection.
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* In this case info is used only as out parameter, and is fully initialized by
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* nbd_co_establish_connection(). "IN" fields of info as well as related only to
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* nbd_receive_export_list() would be zero (see description of NBDExportInfo in
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* include/block/nbd.h).
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*/
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QIOChannel *coroutine_fn
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nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
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Error **errp)
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{
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QemuThread thread;
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if (conn->do_negotiation) {
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assert(info);
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}
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WITH_QEMU_LOCK_GUARD(&conn->mutex) {
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/*
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* Don't call nbd_co_establish_connection() in several coroutines in
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* parallel. Only one call at once is supported.
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*/
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assert(!conn->wait_co);
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if (!conn->running) {
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if (conn->sioc) {
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/* Previous attempt finally succeeded in background */
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if (conn->do_negotiation) {
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memcpy(info, &conn->updated_info, sizeof(*info));
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if (conn->ioc) {
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/* TLS channel now has own reference to parent */
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object_unref(OBJECT(conn->sioc));
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conn->sioc = NULL;
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return g_steal_pointer(&conn->ioc);
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}
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}
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assert(!conn->ioc);
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return QIO_CHANNEL(g_steal_pointer(&conn->sioc));
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}
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conn->running = true;
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error_free(conn->err);
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conn->err = NULL;
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qemu_thread_create(&thread, "nbd-connect",
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connect_thread_func, conn, QEMU_THREAD_DETACHED);
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}
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conn->wait_co = qemu_coroutine_self();
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}
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/*
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* We are going to wait for connect-thread finish, but
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* nbd_co_establish_connection_cancel() can interrupt.
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*/
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qemu_coroutine_yield();
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WITH_QEMU_LOCK_GUARD(&conn->mutex) {
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if (conn->running) {
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/*
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* The connection attempt was canceled and the coroutine resumed
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* before the connection thread finished its job. Report the
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* attempt as failed, but leave the connection thread running,
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* to reuse it for the next connection attempt.
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*/
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error_setg(errp, "Connection attempt cancelled by other operation");
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return NULL;
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} else {
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error_propagate(errp, conn->err);
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conn->err = NULL;
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if (!conn->sioc) {
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return NULL;
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}
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if (conn->do_negotiation) {
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memcpy(info, &conn->updated_info, sizeof(*info));
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if (conn->ioc) {
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/* TLS channel now has own reference to parent */
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object_unref(OBJECT(conn->sioc));
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conn->sioc = NULL;
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return g_steal_pointer(&conn->ioc);
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}
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}
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assert(!conn->ioc);
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return QIO_CHANNEL(g_steal_pointer(&conn->sioc));
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}
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}
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abort(); /* unreachable */
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}
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/*
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* nbd_co_establish_connection_cancel
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* Cancel nbd_co_establish_connection() asynchronously.
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*
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* Note that this function neither directly stops the thread nor closes the
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* socket, but rather safely wakes nbd_co_establish_connection() which is
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* sleeping in yield()
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*/
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void nbd_co_establish_connection_cancel(NBDClientConnection *conn)
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{
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Coroutine *wait_co;
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WITH_QEMU_LOCK_GUARD(&conn->mutex) {
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wait_co = g_steal_pointer(&conn->wait_co);
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}
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if (wait_co) {
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aio_co_wake(wait_co);
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}
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}
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