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qemu/block/nbd.c
Eric Blake fa778fffdf nbd: Implement NBD_CMD_WRITE_ZEROES on client 
Upstream NBD protocol recently added the ability to efficiently
write zeroes without having to send the zeroes over the wire,
along with a flag to control whether the client wants a hole.

The generic block code takes care of falling back to the obvious
write of lots of zeroes if we return -ENOTSUP because the server
does not have WRITE_ZEROES.

Ideally, since NBD_CMD_WRITE_ZEROES does not involve any data
over the wire, we want to support transactions that are much
larger than the normal 32M limit imposed on NBD_CMD_WRITE.  But
the server may still have a limit smaller than UINT_MAX, so
until experimental NBD protocol additions for advertising various
command sizes is finalized (see [1], [2]), for now we just stick to
the same limits as normal writes.

[1] https://github.com/yoe/nbd/blob/extension-info/doc/proto.md
[2] https://sourceforge.net/p/nbd/mailman/message/35081223/

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-17-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-02 09:28:56 +01:00

619 lines
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/*
* QEMU Block driver for NBD
*
* Copyright (C) 2008 Bull S.A.S.
* Author: Laurent Vivier <Laurent.Vivier@bull.net>
*
* Some parts:
* Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws>
*
* 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-client.h"
#include "qapi/error.h"
#include "qemu/uri.h"
#include "block/block_int.h"
#include "qemu/module.h"
#include "qapi-visit.h"
#include "qapi/qobject-input-visitor.h"
#include "qapi/qobject-output-visitor.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qjson.h"
#include "qapi/qmp/qint.h"
#include "qapi/qmp/qstring.h"
#include "qemu/cutils.h"
#define EN_OPTSTR ":exportname="
typedef struct BDRVNBDState {
NBDClientSession client;
/* For nbd_refresh_filename() */
SocketAddress *saddr;
char *export, *tlscredsid;
} BDRVNBDState;
static int nbd_parse_uri(const char *filename, QDict *options)
{
URI *uri;
const char *p;
QueryParams *qp = NULL;
int ret = 0;
bool is_unix;
uri = uri_parse(filename);
if (!uri) {
return -EINVAL;
}
/* transport */
if (!strcmp(uri->scheme, "nbd")) {
is_unix = false;
} else if (!strcmp(uri->scheme, "nbd+tcp")) {
is_unix = false;
} else if (!strcmp(uri->scheme, "nbd+unix")) {
is_unix = true;
} else {
ret = -EINVAL;
goto out;
}
p = uri->path ? uri->path : "/";
p += strspn(p, "/");
if (p[0]) {
qdict_put(options, "export", qstring_from_str(p));
}
qp = query_params_parse(uri->query);
if (qp->n > 1 || (is_unix && !qp->n) || (!is_unix && qp->n)) {
ret = -EINVAL;
goto out;
}
if (is_unix) {
/* nbd+unix:///export?socket=path */
if (uri->server || uri->port || strcmp(qp->p[0].name, "socket")) {
ret = -EINVAL;
goto out;
}
qdict_put(options, "server.type", qstring_from_str("unix"));
qdict_put(options, "server.data.path",
qstring_from_str(qp->p[0].value));
} else {
QString *host;
char *port_str;
/* nbd[+tcp]://host[:port]/export */
if (!uri->server) {
ret = -EINVAL;
goto out;
}
/* strip braces from literal IPv6 address */
if (uri->server[0] == '[') {
host = qstring_from_substr(uri->server, 1,
strlen(uri->server) - 2);
} else {
host = qstring_from_str(uri->server);
}
qdict_put(options, "server.type", qstring_from_str("inet"));
qdict_put(options, "server.data.host", host);
port_str = g_strdup_printf("%d", uri->port ?: NBD_DEFAULT_PORT);
qdict_put(options, "server.data.port", qstring_from_str(port_str));
g_free(port_str);
}
out:
if (qp) {
query_params_free(qp);
}
uri_free(uri);
return ret;
}
static bool nbd_has_filename_options_conflict(QDict *options, Error **errp)
{
const QDictEntry *e;
for (e = qdict_first(options); e; e = qdict_next(options, e)) {
if (!strcmp(e->key, "host") ||
!strcmp(e->key, "port") ||
!strcmp(e->key, "path") ||
!strcmp(e->key, "export") ||
strstart(e->key, "server.", NULL))
{
error_setg(errp, "Option '%s' cannot be used with a file name",
e->key);
return true;
}
}
return false;
}
static void nbd_parse_filename(const char *filename, QDict *options,
Error **errp)
{
char *file;
char *export_name;
const char *host_spec;
const char *unixpath;
if (nbd_has_filename_options_conflict(options, errp)) {
return;
}
if (strstr(filename, "://")) {
int ret = nbd_parse_uri(filename, options);
if (ret < 0) {
error_setg(errp, "No valid URL specified");
}
return;
}
file = g_strdup(filename);
export_name = strstr(file, EN_OPTSTR);
if (export_name) {
if (export_name[strlen(EN_OPTSTR)] == 0) {
goto out;
}
export_name[0] = 0; /* truncate 'file' */
export_name += strlen(EN_OPTSTR);
qdict_put(options, "export", qstring_from_str(export_name));
}
/* extract the host_spec - fail if it's not nbd:... */
if (!strstart(file, "nbd:", &host_spec)) {
error_setg(errp, "File name string for NBD must start with 'nbd:'");
goto out;
}
if (!*host_spec) {
goto out;
}
/* are we a UNIX or TCP socket? */
if (strstart(host_spec, "unix:", &unixpath)) {
qdict_put(options, "server.type", qstring_from_str("unix"));
qdict_put(options, "server.data.path", qstring_from_str(unixpath));
} else {
InetSocketAddress *addr = NULL;
addr = inet_parse(host_spec, errp);
if (!addr) {
goto out;
}
qdict_put(options, "server.type", qstring_from_str("inet"));
qdict_put(options, "server.data.host", qstring_from_str(addr->host));
qdict_put(options, "server.data.port", qstring_from_str(addr->port));
qapi_free_InetSocketAddress(addr);
}
out:
g_free(file);
}
static bool nbd_process_legacy_socket_options(QDict *output_options,
QemuOpts *legacy_opts,
Error **errp)
{
const char *path = qemu_opt_get(legacy_opts, "path");
const char *host = qemu_opt_get(legacy_opts, "host");
const char *port = qemu_opt_get(legacy_opts, "port");
const QDictEntry *e;
if (!path && !host && !port) {
return true;
}
for (e = qdict_first(output_options); e; e = qdict_next(output_options, e))
{
if (strstart(e->key, "server.", NULL)) {
error_setg(errp, "Cannot use 'server' and path/host/port at the "
"same time");
return false;
}
}
if (path && host) {
error_setg(errp, "path and host may not be used at the same time");
return false;
} else if (path) {
if (port) {
error_setg(errp, "port may not be used without host");
return false;
}
qdict_put(output_options, "server.type", qstring_from_str("unix"));
qdict_put(output_options, "server.data.path", qstring_from_str(path));
} else if (host) {
qdict_put(output_options, "server.type", qstring_from_str("inet"));
qdict_put(output_options, "server.data.host", qstring_from_str(host));
qdict_put(output_options, "server.data.port",
qstring_from_str(port ?: stringify(NBD_DEFAULT_PORT)));
}
return true;
}
static SocketAddress *nbd_config(BDRVNBDState *s, QDict *options, Error **errp)
{
SocketAddress *saddr = NULL;
QDict *addr = NULL;
QObject *crumpled_addr = NULL;
Visitor *iv = NULL;
Error *local_err = NULL;
qdict_extract_subqdict(options, &addr, "server.");
if (!qdict_size(addr)) {
error_setg(errp, "NBD server address missing");
goto done;
}
crumpled_addr = qdict_crumple(addr, errp);
if (!crumpled_addr) {
goto done;
}
iv = qobject_input_visitor_new(crumpled_addr, true);
visit_type_SocketAddress(iv, NULL, &saddr, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto done;
}
s->client.is_unix = saddr->type == SOCKET_ADDRESS_KIND_UNIX;
done:
QDECREF(addr);
qobject_decref(crumpled_addr);
visit_free(iv);
return saddr;
}
NBDClientSession *nbd_get_client_session(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
return &s->client;
}
static QIOChannelSocket *nbd_establish_connection(SocketAddress *saddr,
Error **errp)
{
QIOChannelSocket *sioc;
Error *local_err = NULL;
sioc = qio_channel_socket_new();
qio_channel_set_name(QIO_CHANNEL(sioc), "nbd-client");
qio_channel_socket_connect_sync(sioc,
saddr,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return NULL;
}
qio_channel_set_delay(QIO_CHANNEL(sioc), false);
return sioc;
}
static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
{
Object *obj;
QCryptoTLSCreds *creds;
obj = object_resolve_path_component(
object_get_objects_root(), id);
if (!obj) {
error_setg(errp, "No TLS credentials with id '%s'",
id);
return NULL;
}
creds = (QCryptoTLSCreds *)
object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
if (!creds) {
error_setg(errp, "Object with id '%s' is not TLS credentials",
id);
return NULL;
}
if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT) {
error_setg(errp,
"Expecting TLS credentials with a client endpoint");
return NULL;
}
object_ref(obj);
return creds;
}
static QemuOptsList nbd_runtime_opts = {
.name = "nbd",
.head = QTAILQ_HEAD_INITIALIZER(nbd_runtime_opts.head),
.desc = {
{
.name = "host",
.type = QEMU_OPT_STRING,
.help = "TCP host to connect to",
},
{
.name = "port",
.type = QEMU_OPT_STRING,
.help = "TCP port to connect to",
},
{
.name = "path",
.type = QEMU_OPT_STRING,
.help = "Unix socket path to connect to",
},
{
.name = "export",
.type = QEMU_OPT_STRING,
.help = "Name of the NBD export to open",
},
{
.name = "tls-creds",
.type = QEMU_OPT_STRING,
.help = "ID of the TLS credentials to use",
},
},
};
static int nbd_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVNBDState *s = bs->opaque;
QemuOpts *opts = NULL;
Error *local_err = NULL;
QIOChannelSocket *sioc = NULL;
QCryptoTLSCreds *tlscreds = NULL;
const char *hostname = NULL;
int ret = -EINVAL;
opts = qemu_opts_create(&nbd_runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto error;
}
/* Translate @host, @port, and @path to a SocketAddress */
if (!nbd_process_legacy_socket_options(options, opts, errp)) {
goto error;
}
/* Pop the config into our state object. Exit if invalid. */
s->saddr = nbd_config(s, options, errp);
if (!s->saddr) {
goto error;
}
s->export = g_strdup(qemu_opt_get(opts, "export"));
s->tlscredsid = g_strdup(qemu_opt_get(opts, "tls-creds"));
if (s->tlscredsid) {
tlscreds = nbd_get_tls_creds(s->tlscredsid, errp);
if (!tlscreds) {
goto error;
}
if (s->saddr->type != SOCKET_ADDRESS_KIND_INET) {
error_setg(errp, "TLS only supported over IP sockets");
goto error;
}
hostname = s->saddr->u.inet.data->host;
}
/* establish TCP connection, return error if it fails
* TODO: Configurable retry-until-timeout behaviour.
*/
sioc = nbd_establish_connection(s->saddr, errp);
if (!sioc) {
ret = -ECONNREFUSED;
goto error;
}
/* NBD handshake */
ret = nbd_client_init(bs, sioc, s->export,
tlscreds, hostname, errp);
error:
if (sioc) {
object_unref(OBJECT(sioc));
}
if (tlscreds) {
object_unref(OBJECT(tlscreds));
}
if (ret < 0) {
qapi_free_SocketAddress(s->saddr);
g_free(s->export);
g_free(s->tlscredsid);
}
qemu_opts_del(opts);
return ret;
}
static int nbd_co_flush(BlockDriverState *bs)
{
return nbd_client_co_flush(bs);
}
static void nbd_refresh_limits(BlockDriverState *bs, Error **errp)
{
bs->bl.max_pdiscard = NBD_MAX_BUFFER_SIZE;
bs->bl.max_pwrite_zeroes = NBD_MAX_BUFFER_SIZE;
bs->bl.max_transfer = NBD_MAX_BUFFER_SIZE;
}
static void nbd_close(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
nbd_client_close(bs);
qapi_free_SocketAddress(s->saddr);
g_free(s->export);
g_free(s->tlscredsid);
}
static int64_t nbd_getlength(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
return s->client.size;
}
static void nbd_detach_aio_context(BlockDriverState *bs)
{
nbd_client_detach_aio_context(bs);
}
static void nbd_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
nbd_client_attach_aio_context(bs, new_context);
}
static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
{
BDRVNBDState *s = bs->opaque;
QDict *opts = qdict_new();
QObject *saddr_qdict;
Visitor *ov;
const char *host = NULL, *port = NULL, *path = NULL;
if (s->saddr->type == SOCKET_ADDRESS_KIND_INET) {
const InetSocketAddress *inet = s->saddr->u.inet.data;
if (!inet->has_ipv4 && !inet->has_ipv6 && !inet->has_to) {
host = inet->host;
port = inet->port;
}
} else if (s->saddr->type == SOCKET_ADDRESS_KIND_UNIX) {
path = s->saddr->u.q_unix.data->path;
}
qdict_put(opts, "driver", qstring_from_str("nbd"));
if (path && s->export) {
snprintf(bs->exact_filename, sizeof(bs->exact_filename),
"nbd+unix:///%s?socket=%s", s->export, path);
} else if (path && !s->export) {
snprintf(bs->exact_filename, sizeof(bs->exact_filename),
"nbd+unix://?socket=%s", path);
} else if (host && s->export) {
snprintf(bs->exact_filename, sizeof(bs->exact_filename),
"nbd://%s:%s/%s", host, port, s->export);
} else if (host && !s->export) {
snprintf(bs->exact_filename, sizeof(bs->exact_filename),
"nbd://%s:%s", host, port);
}
ov = qobject_output_visitor_new(&saddr_qdict);
visit_type_SocketAddress(ov, NULL, &s->saddr, &error_abort);
visit_complete(ov, &saddr_qdict);
assert(qobject_type(saddr_qdict) == QTYPE_QDICT);
qdict_put_obj(opts, "server", saddr_qdict);
if (s->export) {
qdict_put(opts, "export", qstring_from_str(s->export));
}
if (s->tlscredsid) {
qdict_put(opts, "tls-creds", qstring_from_str(s->tlscredsid));
}
qdict_flatten(opts);
bs->full_open_options = opts;
}
static BlockDriver bdrv_nbd = {
.format_name = "nbd",
.protocol_name = "nbd",
.instance_size = sizeof(BDRVNBDState),
.bdrv_parse_filename = nbd_parse_filename,
.bdrv_file_open = nbd_open,
.bdrv_co_preadv = nbd_client_co_preadv,
.bdrv_co_pwritev = nbd_client_co_pwritev,
.bdrv_co_pwrite_zeroes = nbd_client_co_pwrite_zeroes,
.bdrv_close = nbd_close,
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_pdiscard = nbd_client_co_pdiscard,
.bdrv_refresh_limits = nbd_refresh_limits,
.bdrv_getlength = nbd_getlength,
.bdrv_detach_aio_context = nbd_detach_aio_context,
.bdrv_attach_aio_context = nbd_attach_aio_context,
.bdrv_refresh_filename = nbd_refresh_filename,
};
static BlockDriver bdrv_nbd_tcp = {
.format_name = "nbd",
.protocol_name = "nbd+tcp",
.instance_size = sizeof(BDRVNBDState),
.bdrv_parse_filename = nbd_parse_filename,
.bdrv_file_open = nbd_open,
.bdrv_co_preadv = nbd_client_co_preadv,
.bdrv_co_pwritev = nbd_client_co_pwritev,
.bdrv_co_pwrite_zeroes = nbd_client_co_pwrite_zeroes,
.bdrv_close = nbd_close,
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_pdiscard = nbd_client_co_pdiscard,
.bdrv_refresh_limits = nbd_refresh_limits,
.bdrv_getlength = nbd_getlength,
.bdrv_detach_aio_context = nbd_detach_aio_context,
.bdrv_attach_aio_context = nbd_attach_aio_context,
.bdrv_refresh_filename = nbd_refresh_filename,
};
static BlockDriver bdrv_nbd_unix = {
.format_name = "nbd",
.protocol_name = "nbd+unix",
.instance_size = sizeof(BDRVNBDState),
.bdrv_parse_filename = nbd_parse_filename,
.bdrv_file_open = nbd_open,
.bdrv_co_preadv = nbd_client_co_preadv,
.bdrv_co_pwritev = nbd_client_co_pwritev,
.bdrv_co_pwrite_zeroes = nbd_client_co_pwrite_zeroes,
.bdrv_close = nbd_close,
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_pdiscard = nbd_client_co_pdiscard,
.bdrv_refresh_limits = nbd_refresh_limits,
.bdrv_getlength = nbd_getlength,
.bdrv_detach_aio_context = nbd_detach_aio_context,
.bdrv_attach_aio_context = nbd_attach_aio_context,
.bdrv_refresh_filename = nbd_refresh_filename,
};
static void bdrv_nbd_init(void)
{
bdrv_register(&bdrv_nbd);
bdrv_register(&bdrv_nbd_tcp);
bdrv_register(&bdrv_nbd_unix);
}
block_init(bdrv_nbd_init);
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