From e02cda008591317b1625707ff8e115a4841aa889 Mon Sep 17 00:00:00 2001
From: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Date: Tue, 10 Oct 2023 11:40:56 +0000
Subject: Introduce Virtio-loopback epsilon release:
Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.
Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9
---
nbd/client-connection.c | 389 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 389 insertions(+)
create mode 100644 nbd/client-connection.c
(limited to 'nbd/client-connection.c')
diff --git a/nbd/client-connection.c b/nbd/client-connection.c
new file mode 100644
index 000000000..695f85575
--- /dev/null
+++ b/nbd/client-connection.c
@@ -0,0 +1,389 @@
+/*
+ * 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 "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;
+ NBDExportInfo initial_info;
+ bool do_negotiation;
+ bool do_retry;
+
+ QemuMutex mutex;
+
+ /*
+ * @sioc and @err represent a connection attempt. While running
+ * is true, they are only used by the connection thread, and mutex
+ * locking is not needed. Once the thread finishes,
+ * nbd_co_establish_connection then steals these pointers while
+ * under the mutex.
+ */
+ NBDExportInfo updated_info;
+ QIOChannelSocket *sioc;
+ QIOChannel *ioc;
+ 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)
+{
+ NBDClientConnection *conn = g_new(NBDClientConnection, 1);
+
+ object_ref(OBJECT(tlscreds));
+ *conn = (NBDClientConnection) {
+ .saddr = QAPI_CLONE(SocketAddress, saddr),
+ .tlscreds = tlscreds,
+ .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);
+ 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,
+ 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,
+ tlscreds ? addr->u.inet.host : NULL,
+ 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) {
+ assert(!conn->sioc);
+ conn->sioc = qio_channel_socket_new();
+
+ qemu_mutex_unlock(&conn->mutex);
+
+ error_free(conn->err);
+ conn->err = NULL;
+ conn->updated_info = conn->initial_info;
+
+ ret = nbd_connect(conn->sioc, conn->saddr,
+ conn->do_negotiation ? &conn->updated_info : NULL,
+ conn->tlscreds, &conn->ioc, &conn->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);
+
+ if (ret < 0) {
+ object_unref(OBJECT(conn->sioc));
+ conn->sioc = NULL;
+ if (conn->do_retry && !conn->detached) {
+ 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;
+ error_free(conn->err);
+ conn->err = NULL;
+ qemu_thread_create(&thread, "nbd-connect",
+ connect_thread_func, conn, QEMU_THREAD_DETACHED);
+ }
+
+ if (!blocking) {
+ 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.
+ */
+ error_setg(errp, "Connection attempt cancelled by other operation");
+ return NULL;
+ } else {
+ error_propagate(errp, conn->err);
+ conn->err = NULL;
+ if (!conn->sioc) {
+ 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);
+ }
+}
--
cgit