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qemu/nbd/client.c
Eric Blake 081dd1fe36 nbd: Implement NBD_INFO_BLOCK_SIZE on client 
The upstream NBD Protocol has defined a new extension to allow
the server to advertise block sizes to the client, as well as
a way for the client to inform the server whether it intends to
obey block sizes.

When using the block layer as the client, we will obey block
sizes; but when used as 'qemu-nbd -c' to hand off to the
kernel nbd module as the client, we are still waiting for the
kernel to implement a way for us to learn if it will honor
block sizes (perhaps by an addition to sysfs, rather than an
ioctl), as well as any way to tell the kernel what additional
block sizes to obey (NBD_SET_BLKSIZE appears to be accurate
for the minimum size, but preferred and maximum sizes would
probably be new ioctl()s), so until then, we need to make our
request for block sizes conditional.

When using ioctl(NBD_SET_BLKSIZE) to hand off to the kernel,
use the minimum block size as the sector size if it is larger
than 512, which also has the nice effect of cooperating with
(non-qemu) servers that don't do read-modify-write when
exposing a block device with 4k sectors; it might also allow
us to visit a file larger than 2T on a 32-bit kernel.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170707203049.534-10-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-14 12:04:42 +02:00

959 lines
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/*
* Copyright (C) 2016-2017 Red Hat, Inc.
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device Client Side
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; under version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "trace.h"
#include "nbd-internal.h"
static int nbd_errno_to_system_errno(int err)
{
int ret;
switch (err) {
case NBD_SUCCESS:
ret = 0;
break;
case NBD_EPERM:
ret = EPERM;
break;
case NBD_EIO:
ret = EIO;
break;
case NBD_ENOMEM:
ret = ENOMEM;
break;
case NBD_ENOSPC:
ret = ENOSPC;
break;
case NBD_ESHUTDOWN:
ret = ESHUTDOWN;
break;
default:
trace_nbd_unknown_error(err);
/* fallthrough */
case NBD_EINVAL:
ret = EINVAL;
break;
}
return ret;
}
/* Definitions for opaque data types */
static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
/* That's all folks */
/* Basic flow for negotiation
Server Client
Negotiate
or
Server Client
Negotiate #1
Option
Negotiate #2
----
followed by
Server Client
Request
Response
Request
Response
...
...
Request (type == 2)
*/
/* Send an option request.
*
* The request is for option @opt, with @data containing @len bytes of
* additional payload for the request (@len may be -1 to treat @data as
* a C string; and @data may be NULL if @len is 0).
* Return 0 if successful, -1 with errp set if it is impossible to
* continue. */
static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
uint32_t len, const char *data,
Error **errp)
{
nbd_option req;
QEMU_BUILD_BUG_ON(sizeof(req) != 16);
if (len == -1) {
req.length = len = strlen(data);
}
trace_nbd_send_option_request(opt, nbd_opt_lookup(opt), len);
stq_be_p(&req.magic, NBD_OPTS_MAGIC);
stl_be_p(&req.option, opt);
stl_be_p(&req.length, len);
if (nbd_write(ioc, &req, sizeof(req), errp) < 0) {
error_prepend(errp, "Failed to send option request header");
return -1;
}
if (len && nbd_write(ioc, (char *) data, len, errp) < 0) {
error_prepend(errp, "Failed to send option request data");
return -1;
}
return 0;
}
/* Send NBD_OPT_ABORT as a courtesy to let the server know that we are
* not going to attempt further negotiation. */
static void nbd_send_opt_abort(QIOChannel *ioc)
{
/* Technically, a compliant server is supposed to reply to us; but
* older servers disconnected instead. At any rate, we're allowed
* to disconnect without waiting for the server reply, so we don't
* even care if the request makes it to the server, let alone
* waiting around for whether the server replies. */
nbd_send_option_request(ioc, NBD_OPT_ABORT, 0, NULL, NULL);
}
/* Receive the header of an option reply, which should match the given
* opt. Read through the length field, but NOT the length bytes of
* payload. Return 0 if successful, -1 with errp set if it is
* impossible to continue. */
static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
nbd_opt_reply *reply, Error **errp)
{
QEMU_BUILD_BUG_ON(sizeof(*reply) != 20);
if (nbd_read(ioc, reply, sizeof(*reply), errp) < 0) {
error_prepend(errp, "failed to read option reply");
nbd_send_opt_abort(ioc);
return -1;
}
be64_to_cpus(&reply->magic);
be32_to_cpus(&reply->option);
be32_to_cpus(&reply->type);
be32_to_cpus(&reply->length);
trace_nbd_receive_option_reply(reply->option, nbd_opt_lookup(reply->option),
reply->type, nbd_rep_lookup(reply->type),
reply->length);
if (reply->magic != NBD_REP_MAGIC) {
error_setg(errp, "Unexpected option reply magic");
nbd_send_opt_abort(ioc);
return -1;
}
if (reply->option != opt) {
error_setg(errp, "Unexpected option type %x expected %x",
reply->option, opt);
nbd_send_opt_abort(ioc);
return -1;
}
return 0;
}
/* If reply represents success, return 1 without further action.
* If reply represents an error, consume the optional payload of
* the packet on ioc. Then return 0 for unsupported (so the client
* can fall back to other approaches), or -1 with errp set for other
* errors.
*/
static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply,
Error **errp)
{
char *msg = NULL;
int result = -1;
if (!(reply->type & (1 << 31))) {
return 1;
}
if (reply->length) {
if (reply->length > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "server error 0x%" PRIx32
" (%s) message is too long",
reply->type, nbd_rep_lookup(reply->type));
goto cleanup;
}
msg = g_malloc(reply->length + 1);
if (nbd_read(ioc, msg, reply->length, errp) < 0) {
error_prepend(errp, "failed to read option error 0x%" PRIx32
" (%s) message",
reply->type, nbd_rep_lookup(reply->type));
goto cleanup;
}
msg[reply->length] = '\0';
}
switch (reply->type) {
case NBD_REP_ERR_UNSUP:
trace_nbd_reply_err_unsup(reply->option, nbd_opt_lookup(reply->option));
result = 0;
goto cleanup;
case NBD_REP_ERR_POLICY:
error_setg(errp, "Denied by server for option %" PRIx32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_INVALID:
error_setg(errp, "Invalid data length for option %" PRIx32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_PLATFORM:
error_setg(errp, "Server lacks support for option %" PRIx32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_TLS_REQD:
error_setg(errp, "TLS negotiation required before option %" PRIx32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_UNKNOWN:
error_setg(errp, "Requested export not available for option %" PRIx32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_SHUTDOWN:
error_setg(errp, "Server shutting down before option %" PRIx32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_BLOCK_SIZE_REQD:
error_setg(errp, "Server requires INFO_BLOCK_SIZE for option %" PRIx32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
default:
error_setg(errp, "Unknown error code when asking for option %" PRIx32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
}
if (msg) {
error_append_hint(errp, "%s\n", msg);
}
cleanup:
g_free(msg);
if (result < 0) {
nbd_send_opt_abort(ioc);
}
return result;
}
/* Process another portion of the NBD_OPT_LIST reply. Set *@match if
* the current reply matches @want or if the server does not support
* NBD_OPT_LIST, otherwise leave @match alone. Return 0 if iteration
* is complete, positive if more replies are expected, or negative
* with @errp set if an unrecoverable error occurred. */
static int nbd_receive_list(QIOChannel *ioc, const char *want, bool *match,
Error **errp)
{
nbd_opt_reply reply;
uint32_t len;
uint32_t namelen;
char name[NBD_MAX_NAME_SIZE + 1];
int error;
if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) {
return -1;
}
error = nbd_handle_reply_err(ioc, &reply, errp);
if (error <= 0) {
/* The server did not support NBD_OPT_LIST, so set *match on
* the assumption that any name will be accepted. */
*match = true;
return error;
}
len = reply.length;
if (reply.type == NBD_REP_ACK) {
if (len != 0) {
error_setg(errp, "length too long for option end");
nbd_send_opt_abort(ioc);
return -1;
}
return 0;
} else if (reply.type != NBD_REP_SERVER) {
error_setg(errp, "Unexpected reply type %" PRIx32 " expected %x",
reply.type, NBD_REP_SERVER);
nbd_send_opt_abort(ioc);
return -1;
}
if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "incorrect option length %" PRIu32, len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &namelen, sizeof(namelen), errp) < 0) {
error_prepend(errp, "failed to read option name length");
nbd_send_opt_abort(ioc);
return -1;
}
namelen = be32_to_cpu(namelen);
len -= sizeof(namelen);
if (len < namelen) {
error_setg(errp, "incorrect option name length");
nbd_send_opt_abort(ioc);
return -1;
}
if (namelen != strlen(want)) {
if (nbd_drop(ioc, len, errp) < 0) {
error_prepend(errp, "failed to skip export name with wrong length");
nbd_send_opt_abort(ioc);
return -1;
}
return 1;
}
assert(namelen < sizeof(name));
if (nbd_read(ioc, name, namelen, errp) < 0) {
error_prepend(errp, "failed to read export name");
nbd_send_opt_abort(ioc);
return -1;
}
name[namelen] = '\0';
len -= namelen;
if (nbd_drop(ioc, len, errp) < 0) {
error_prepend(errp, "failed to read export description");
nbd_send_opt_abort(ioc);
return -1;
}
if (!strcmp(name, want)) {
*match = true;
}
return 1;
}
/* Returns -1 if NBD_OPT_GO proves the export @wantname cannot be
* used, 0 if NBD_OPT_GO is unsupported (fall back to NBD_OPT_LIST and
* NBD_OPT_EXPORT_NAME in that case), and > 0 if the export is good to
* go (with @info populated). */
static int nbd_opt_go(QIOChannel *ioc, const char *wantname,
NBDExportInfo *info, Error **errp)
{
nbd_opt_reply reply;
uint32_t len = strlen(wantname);
uint16_t type;
int error;
char *buf;
/* The protocol requires that the server send NBD_INFO_EXPORT with
* a non-zero flags (at least NBD_FLAG_HAS_FLAGS must be set); so
* flags still 0 is a witness of a broken server. */
info->flags = 0;
trace_nbd_opt_go_start(wantname);
buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1);
stl_be_p(buf, len);
memcpy(buf + 4, wantname, len);
/* At most one request, everything else up to server */
stw_be_p(buf + 4 + len, info->request_sizes);
if (info->request_sizes) {
stw_be_p(buf + 4 + len + 2, NBD_INFO_BLOCK_SIZE);
}
if (nbd_send_option_request(ioc, NBD_OPT_GO,
4 + len + 2 + 2 * info->request_sizes, buf,
errp) < 0) {
return -1;
}
while (1) {
if (nbd_receive_option_reply(ioc, NBD_OPT_GO, &reply, errp) < 0) {
return -1;
}
error = nbd_handle_reply_err(ioc, &reply, errp);
if (error <= 0) {
return error;
}
len = reply.length;
if (reply.type == NBD_REP_ACK) {
/* Server is done sending info and moved into transmission
phase, but make sure it sent flags */
if (len) {
error_setg(errp, "server sent invalid NBD_REP_ACK");
nbd_send_opt_abort(ioc);
return -1;
}
if (!info->flags) {
error_setg(errp, "broken server omitted NBD_INFO_EXPORT");
nbd_send_opt_abort(ioc);
return -1;
}
trace_nbd_opt_go_success();
return 1;
}
if (reply.type != NBD_REP_INFO) {
error_setg(errp, "unexpected reply type %" PRIx32
" (%s), expected %x",
reply.type, nbd_rep_lookup(reply.type), NBD_REP_INFO);
nbd_send_opt_abort(ioc);
return -1;
}
if (len < sizeof(type)) {
error_setg(errp, "NBD_REP_INFO length %" PRIu32 " is too short",
len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &type, sizeof(type), errp) < 0) {
error_prepend(errp, "failed to read info type");
nbd_send_opt_abort(ioc);
return -1;
}
len -= sizeof(type);
be16_to_cpus(&type);
switch (type) {
case NBD_INFO_EXPORT:
if (len != sizeof(info->size) + sizeof(info->flags)) {
error_setg(errp, "remaining export info len %" PRIu32
" is unexpected size", len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "failed to read info size");
nbd_send_opt_abort(ioc);
return -1;
}
be64_to_cpus(&info->size);
if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
error_prepend(errp, "failed to read info flags");
nbd_send_opt_abort(ioc);
return -1;
}
be16_to_cpus(&info->flags);
trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
break;
case NBD_INFO_BLOCK_SIZE:
if (len != sizeof(info->min_block) * 3) {
error_setg(errp, "remaining export info len %" PRIu32
" is unexpected size", len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->min_block, sizeof(info->min_block),
errp) < 0) {
error_prepend(errp, "failed to read info minimum block size");
nbd_send_opt_abort(ioc);
return -1;
}
be32_to_cpus(&info->min_block);
if (!is_power_of_2(info->min_block)) {
error_setg(errp, "server minimum block size %" PRId32
"is not a power of two", info->min_block);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->opt_block, sizeof(info->opt_block),
errp) < 0) {
error_prepend(errp, "failed to read info preferred block size");
nbd_send_opt_abort(ioc);
return -1;
}
be32_to_cpus(&info->opt_block);
if (!is_power_of_2(info->opt_block) ||
info->opt_block < info->min_block) {
error_setg(errp, "server preferred block size %" PRId32
"is not valid", info->opt_block);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->max_block, sizeof(info->max_block),
errp) < 0) {
error_prepend(errp, "failed to read info maximum block size");
nbd_send_opt_abort(ioc);
return -1;
}
be32_to_cpus(&info->max_block);
trace_nbd_opt_go_info_block_size(info->min_block, info->opt_block,
info->max_block);
break;
default:
trace_nbd_opt_go_info_unknown(type, nbd_info_lookup(type));
if (nbd_drop(ioc, len, errp) < 0) {
error_prepend(errp, "Failed to read info payload");
nbd_send_opt_abort(ioc);
return -1;
}
break;
}
}
}
/* Return -1 on failure, 0 if wantname is an available export. */
static int nbd_receive_query_exports(QIOChannel *ioc,
const char *wantname,
Error **errp)
{
bool foundExport = false;
trace_nbd_receive_query_exports_start(wantname);
if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
return -1;
}
while (1) {
int ret = nbd_receive_list(ioc, wantname, &foundExport, errp);
if (ret < 0) {
/* Server gave unexpected reply */
return -1;
} else if (ret == 0) {
/* Done iterating. */
if (!foundExport) {
error_setg(errp, "No export with name '%s' available",
wantname);
nbd_send_opt_abort(ioc);
return -1;
}
trace_nbd_receive_query_exports_success(wantname);
return 0;
}
}
}
static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
QCryptoTLSCreds *tlscreds,
const char *hostname, Error **errp)
{
nbd_opt_reply reply;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
trace_nbd_receive_starttls_request();
if (nbd_send_option_request(ioc, NBD_OPT_STARTTLS, 0, NULL, errp) < 0) {
return NULL;
}
trace_nbd_receive_starttls_reply();
if (nbd_receive_option_reply(ioc, NBD_OPT_STARTTLS, &reply, errp) < 0) {
return NULL;
}
if (reply.type != NBD_REP_ACK) {
error_setg(errp, "Server rejected request to start TLS %" PRIx32,
reply.type);
nbd_send_opt_abort(ioc);
return NULL;
}
if (reply.length != 0) {
error_setg(errp, "Start TLS response was not zero %" PRIu32,
reply.length);
nbd_send_opt_abort(ioc);
return NULL;
}
trace_nbd_receive_starttls_new_client();
tioc = qio_channel_tls_new_client(ioc, tlscreds, hostname, errp);
if (!tioc) {
return NULL;
}
qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls");
data.loop = g_main_loop_new(g_main_context_default(), FALSE);
trace_nbd_receive_starttls_tls_handshake();
qio_channel_tls_handshake(tioc,
nbd_tls_handshake,
&data,
NULL);
if (!data.complete) {
g_main_loop_run(data.loop);
}
g_main_loop_unref(data.loop);
if (data.error) {
error_propagate(errp, data.error);
object_unref(OBJECT(tioc));
return NULL;
}
return QIO_CHANNEL(tioc);
}
int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
QCryptoTLSCreds *tlscreds, const char *hostname,
QIOChannel **outioc, NBDExportInfo *info,
Error **errp)
{
char buf[256];
uint64_t magic;
int rc;
bool zeroes = true;
trace_nbd_receive_negotiate(tlscreds, hostname ? hostname : "<null>");
rc = -EINVAL;
if (outioc) {
*outioc = NULL;
}
if (tlscreds && !outioc) {
error_setg(errp, "Output I/O channel required for TLS");
goto fail;
}
if (nbd_read(ioc, buf, 8, errp) < 0) {
error_prepend(errp, "Failed to read data");
goto fail;
}
buf[8] = '\0';
if (strlen(buf) == 0) {
error_setg(errp, "Server connection closed unexpectedly");
goto fail;
}
magic = ldq_be_p(buf);
trace_nbd_receive_negotiate_magic(magic);
if (memcmp(buf, "NBDMAGIC", 8) != 0) {
error_setg(errp, "Invalid magic received");
goto fail;
}
if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) {
error_prepend(errp, "Failed to read magic");
goto fail;
}
magic = be64_to_cpu(magic);
trace_nbd_receive_negotiate_magic(magic);
if (magic == NBD_OPTS_MAGIC) {
uint32_t clientflags = 0;
uint16_t globalflags;
bool fixedNewStyle = false;
if (nbd_read(ioc, &globalflags, sizeof(globalflags), errp) < 0) {
error_prepend(errp, "Failed to read server flags");
goto fail;
}
globalflags = be16_to_cpu(globalflags);
trace_nbd_receive_negotiate_server_flags(globalflags);
if (globalflags & NBD_FLAG_FIXED_NEWSTYLE) {
fixedNewStyle = true;
clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE;
}
if (globalflags & NBD_FLAG_NO_ZEROES) {
zeroes = false;
clientflags |= NBD_FLAG_C_NO_ZEROES;
}
/* client requested flags */
clientflags = cpu_to_be32(clientflags);
if (nbd_write(ioc, &clientflags, sizeof(clientflags), errp) < 0) {
error_prepend(errp, "Failed to send clientflags field");
goto fail;
}
if (tlscreds) {
if (fixedNewStyle) {
*outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp);
if (!*outioc) {
goto fail;
}
ioc = *outioc;
} else {
error_setg(errp, "Server does not support STARTTLS");
goto fail;
}
}
if (!name) {
trace_nbd_receive_negotiate_default_name();
name = "";
}
if (fixedNewStyle) {
int result;
/* Try NBD_OPT_GO first - if it works, we are done (it
* also gives us a good message if the server requires
* TLS). If it is not available, fall back to
* NBD_OPT_LIST for nicer error messages about a missing
* export, then use NBD_OPT_EXPORT_NAME. */
result = nbd_opt_go(ioc, name, info, errp);
if (result < 0) {
goto fail;
}
if (result > 0) {
return 0;
}
/* Check our desired export is present in the
* server export list. Since NBD_OPT_EXPORT_NAME
* cannot return an error message, running this
* query gives us better error reporting if the
* export name is not available.
*/
if (nbd_receive_query_exports(ioc, name, errp) < 0) {
goto fail;
}
}
/* write the export name request */
if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, name,
errp) < 0) {
goto fail;
}
/* Read the response */
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length");
goto fail;
}
be64_to_cpus(&info->size);
if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
error_prepend(errp, "Failed to read export flags");
goto fail;
}
be16_to_cpus(&info->flags);
} else if (magic == NBD_CLIENT_MAGIC) {
uint32_t oldflags;
if (name) {
error_setg(errp, "Server does not support export names");
goto fail;
}
if (tlscreds) {
error_setg(errp, "Server does not support STARTTLS");
goto fail;
}
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length");
goto fail;
}
be64_to_cpus(&info->size);
if (nbd_read(ioc, &oldflags, sizeof(oldflags), errp) < 0) {
error_prepend(errp, "Failed to read export flags");
goto fail;
}
be32_to_cpus(&oldflags);
if (oldflags & ~0xffff) {
error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags);
goto fail;
}
info->flags = oldflags;
} else {
error_setg(errp, "Bad magic received");
goto fail;
}
trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
if (zeroes && nbd_drop(ioc, 124, errp) < 0) {
error_prepend(errp, "Failed to read reserved block");
goto fail;
}
rc = 0;
fail:
return rc;
}
#ifdef __linux__
int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
Error **errp)
{
unsigned long sector_size = MAX(BDRV_SECTOR_SIZE, info->min_block);
unsigned long sectors = info->size / sector_size;
/* FIXME: Once the kernel module is patched to honor block sizes,
* and to advertise that fact to user space, we should update the
* hand-off to the kernel to use any block sizes we learned. */
assert(!info->request_sizes);
if (info->size / sector_size != sectors) {
error_setg(errp, "Export size %" PRIu64 " too large for 32-bit kernel",
info->size);
return -E2BIG;
}
trace_nbd_init_set_socket();
if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) {
int serrno = errno;
error_setg(errp, "Failed to set NBD socket");
return -serrno;
}
trace_nbd_init_set_block_size(sector_size);
if (ioctl(fd, NBD_SET_BLKSIZE, sector_size) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting NBD block size");
return -serrno;
}
trace_nbd_init_set_size(sectors);
if (info->size % sector_size) {
trace_nbd_init_trailing_bytes(info->size % sector_size);
}
if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting size (in blocks)");
return -serrno;
}
if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) info->flags) < 0) {
if (errno == ENOTTY) {
int read_only = (info->flags & NBD_FLAG_READ_ONLY) != 0;
trace_nbd_init_set_readonly();
if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting read-only attribute");
return -serrno;
}
} else {
int serrno = errno;
error_setg(errp, "Failed setting flags");
return -serrno;
}
}
trace_nbd_init_finish();
return 0;
}
int nbd_client(int fd)
{
int ret;
int serrno;
trace_nbd_client_loop();
ret = ioctl(fd, NBD_DO_IT);
if (ret < 0 && errno == EPIPE) {
/* NBD_DO_IT normally returns EPIPE when someone has disconnected
* the socket via NBD_DISCONNECT. We do not want to return 1 in
* that case.
*/
ret = 0;
}
serrno = errno;
trace_nbd_client_loop_ret(ret, strerror(serrno));
trace_nbd_client_clear_queue();
ioctl(fd, NBD_CLEAR_QUE);
trace_nbd_client_clear_socket();
ioctl(fd, NBD_CLEAR_SOCK);
errno = serrno;
return ret;
}
int nbd_disconnect(int fd)
{
ioctl(fd, NBD_CLEAR_QUE);
ioctl(fd, NBD_DISCONNECT);
ioctl(fd, NBD_CLEAR_SOCK);
return 0;
}
#else
int nbd_init(int fd, QIOChannelSocket *ioc, NBDExportInfo *info,
Error **errp)
{
error_setg(errp, "nbd_init is only supported on Linux");
return -ENOTSUP;
}
int nbd_client(int fd)
{
return -ENOTSUP;
}
int nbd_disconnect(int fd)
{
return -ENOTSUP;
}
#endif
ssize_t nbd_send_request(QIOChannel *ioc, NBDRequest *request)
{
uint8_t buf[NBD_REQUEST_SIZE];
trace_nbd_send_request(request->from, request->len, request->handle,
request->flags, request->type);
stl_be_p(buf, NBD_REQUEST_MAGIC);
stw_be_p(buf + 4, request->flags);
stw_be_p(buf + 6, request->type);
stq_be_p(buf + 8, request->handle);
stq_be_p(buf + 16, request->from);
stl_be_p(buf + 24, request->len);
return nbd_write(ioc, buf, sizeof(buf), NULL);
}
ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)
{
uint8_t buf[NBD_REPLY_SIZE];
uint32_t magic;
ssize_t ret;
ret = nbd_read_eof(ioc, buf, sizeof(buf), errp);
if (ret <= 0) {
return ret;
}
if (ret != sizeof(buf)) {
error_setg(errp, "read failed");
return -EINVAL;
}
/* Reply
[ 0 .. 3] magic (NBD_REPLY_MAGIC)
[ 4 .. 7] error (0 == no error)
[ 7 .. 15] handle
*/
magic = ldl_be_p(buf);
reply->error = ldl_be_p(buf + 4);
reply->handle = ldq_be_p(buf + 8);
reply->error = nbd_errno_to_system_errno(reply->error);
if (reply->error == ESHUTDOWN) {
/* This works even on mingw which lacks a native ESHUTDOWN */
error_setg(errp, "server shutting down");
return -EINVAL;
}
trace_nbd_receive_reply(magic, reply->error, reply->handle);
if (magic != NBD_REPLY_MAGIC) {
error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
return -EINVAL;
}
return sizeof(buf);
}
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