We only have one caller that wants to export a bitmap name, which it does right after creation of the export. But there is still a brief window of time where an NBD client could see the export but not the dirty bitmap, which a robust client would have to interpret as meaning the entire image should be treated as dirty. Better is to eliminate the window entirely, by inlining nbd_export_bitmap() into nbd_export_new(), and refusing to create the bitmap in the first place if the requested bitmap can't be located. We also no longer need logic for setting a different bitmap name compared to the bitmap being exported. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190111194720.15671-8-eblake@redhat.com>
227 lines
5.6 KiB
C
227 lines
5.6 KiB
C
/*
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* Serving QEMU block devices via NBD
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*
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* Copyright (c) 2012 Red Hat, Inc.
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*
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* Author: Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or
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* later. See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "sysemu/blockdev.h"
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#include "sysemu/block-backend.h"
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#include "hw/block/block.h"
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#include "qapi/error.h"
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#include "qapi/qapi-commands-block.h"
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#include "sysemu/sysemu.h"
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#include "block/nbd.h"
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#include "io/channel-socket.h"
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#include "io/net-listener.h"
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typedef struct NBDServerData {
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QIONetListener *listener;
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QCryptoTLSCreds *tlscreds;
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} NBDServerData;
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static NBDServerData *nbd_server;
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static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
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{
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nbd_client_put(client);
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}
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static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
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gpointer opaque)
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{
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qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
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nbd_client_new(cioc, nbd_server->tlscreds, NULL,
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nbd_blockdev_client_closed);
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}
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static void nbd_server_free(NBDServerData *server)
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{
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if (!server) {
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return;
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}
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qio_net_listener_disconnect(server->listener);
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object_unref(OBJECT(server->listener));
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if (server->tlscreds) {
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object_unref(OBJECT(server->tlscreds));
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}
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g_free(server);
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}
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static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
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{
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Object *obj;
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QCryptoTLSCreds *creds;
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obj = object_resolve_path_component(
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object_get_objects_root(), id);
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if (!obj) {
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error_setg(errp, "No TLS credentials with id '%s'",
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id);
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return NULL;
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}
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creds = (QCryptoTLSCreds *)
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object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
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if (!creds) {
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error_setg(errp, "Object with id '%s' is not TLS credentials",
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id);
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return NULL;
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}
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if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
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error_setg(errp,
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"Expecting TLS credentials with a server endpoint");
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return NULL;
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}
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object_ref(obj);
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return creds;
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}
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void nbd_server_start(SocketAddress *addr, const char *tls_creds,
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Error **errp)
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{
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if (nbd_server) {
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error_setg(errp, "NBD server already running");
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return;
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}
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nbd_server = g_new0(NBDServerData, 1);
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nbd_server->listener = qio_net_listener_new();
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qio_net_listener_set_name(nbd_server->listener,
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"nbd-listener");
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if (qio_net_listener_open_sync(nbd_server->listener, addr, errp) < 0) {
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goto error;
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}
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if (tls_creds) {
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nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
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if (!nbd_server->tlscreds) {
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goto error;
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}
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/* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */
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if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
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error_setg(errp, "TLS is only supported with IPv4/IPv6");
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goto error;
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}
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}
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qio_net_listener_set_client_func(nbd_server->listener,
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nbd_accept,
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NULL,
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NULL);
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return;
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error:
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nbd_server_free(nbd_server);
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nbd_server = NULL;
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}
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void qmp_nbd_server_start(SocketAddressLegacy *addr,
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bool has_tls_creds, const char *tls_creds,
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Error **errp)
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{
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SocketAddress *addr_flat = socket_address_flatten(addr);
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nbd_server_start(addr_flat, tls_creds, errp);
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qapi_free_SocketAddress(addr_flat);
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}
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void qmp_nbd_server_add(const char *device, bool has_name, const char *name,
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bool has_writable, bool writable,
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bool has_bitmap, const char *bitmap, Error **errp)
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{
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BlockDriverState *bs = NULL;
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BlockBackend *on_eject_blk;
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NBDExport *exp;
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if (!nbd_server) {
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error_setg(errp, "NBD server not running");
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return;
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}
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if (!has_name) {
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name = device;
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}
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if (nbd_export_find(name)) {
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error_setg(errp, "NBD server already has export named '%s'", name);
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return;
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}
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on_eject_blk = blk_by_name(device);
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bs = bdrv_lookup_bs(device, device, errp);
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if (!bs) {
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return;
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}
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if (!has_writable) {
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writable = false;
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}
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if (bdrv_is_read_only(bs)) {
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writable = false;
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}
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exp = nbd_export_new(bs, 0, -1, name, NULL, bitmap,
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writable ? 0 : NBD_FLAG_READ_ONLY,
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NULL, false, on_eject_blk, errp);
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if (!exp) {
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return;
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}
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/* The list of named exports has a strong reference to this export now and
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* our only way of accessing it is through nbd_export_find(), so we can drop
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* the strong reference that is @exp. */
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nbd_export_put(exp);
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}
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void qmp_nbd_server_remove(const char *name,
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bool has_mode, NbdServerRemoveMode mode,
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Error **errp)
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{
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NBDExport *exp;
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if (!nbd_server) {
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error_setg(errp, "NBD server not running");
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return;
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}
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exp = nbd_export_find(name);
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if (exp == NULL) {
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error_setg(errp, "Export '%s' is not found", name);
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return;
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}
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if (!has_mode) {
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mode = NBD_SERVER_REMOVE_MODE_SAFE;
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}
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nbd_export_remove(exp, mode, errp);
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}
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void qmp_nbd_server_stop(Error **errp)
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{
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if (!nbd_server) {
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error_setg(errp, "NBD server not running");
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return;
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}
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nbd_export_close_all();
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nbd_server_free(nbd_server);
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nbd_server = NULL;
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}
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