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qemu/qemu/049855b94de5559bc319293c998933d3b25bea8c/./nbd/server.c
blob: e6c47f8c2e3263891138279c219ad78c7d0724f2 [file]
/*
* Copyright Red Hat
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device Server 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 "block/block_int.h"
#include "block/export.h"
#include "block/dirty-bitmap.h"
#include "qapi/error.h"
#include "qemu/queue.h"
#include "trace.h"
#include "nbd-internal.h"
#include "qemu/units.h"
#include "qemu/memalign.h"
#define NBD_META_ID_BASE_ALLOCATION 0
#define NBD_META_ID_ALLOCATION_DEPTH 1
/* Dirty bitmaps use 'NBD_META_ID_DIRTY_BITMAP + i', so keep this id last. */
#define NBD_META_ID_DIRTY_BITMAP 2
/*
* NBD_MAX_BLOCK_STATUS_EXTENTS: 1 MiB of extents data. An empirical
* constant. If an increase is needed, note that the NBD protocol
* recommends no larger than 32 mb, so that the client won't consider
* the reply as a denial of service attack.
*/
#define NBD_MAX_BLOCK_STATUS_EXTENTS (1 * MiB / 8)
static int system_errno_to_nbd_errno(int err)
{
switch (err) {
case 0:
return NBD_SUCCESS;
case EPERM:
case EROFS:
return NBD_EPERM;
case EIO:
return NBD_EIO;
case ENOMEM:
return NBD_ENOMEM;
#ifdef EDQUOT
case EDQUOT:
#endif
case EFBIG:
case ENOSPC:
return NBD_ENOSPC;
case EOVERFLOW:
return NBD_EOVERFLOW;
case ENOTSUP:
#if ENOTSUP != EOPNOTSUPP
case EOPNOTSUPP:
#endif
return NBD_ENOTSUP;
case ESHUTDOWN:
return NBD_ESHUTDOWN;
case EINVAL:
default:
return NBD_EINVAL;
}
}
/* Definitions for opaque data types */
typedef struct NBDRequestData NBDRequestData;
struct NBDRequestData {
NBDClient *client;
uint8_t *data;
bool complete;
};
struct NBDExport {
BlockExport common;
char *name;
char *description;
uint64_t size;
uint16_t nbdflags;
QTAILQ_HEAD(, NBDClient) clients;
QTAILQ_ENTRY(NBDExport) next;
BlockBackend *eject_notifier_blk;
Notifier eject_notifier;
bool allocation_depth;
BdrvDirtyBitmap **export_bitmaps;
size_t nr_export_bitmaps;
};
static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
/*
* NBDMetaContexts represents a list of meta contexts in use,
* as selected by NBD_OPT_SET_META_CONTEXT. Also used for
* NBD_OPT_LIST_META_CONTEXT.
*/
struct NBDMetaContexts {
const NBDExport *exp; /* associated export */
size_t count; /* number of negotiated contexts */
bool base_allocation; /* export base:allocation context (block status) */
bool allocation_depth; /* export qemu:allocation-depth */
bool *bitmaps; /*
* export qemu:dirty-bitmap:<export bitmap name>,
* sized by exp->nr_export_bitmaps
*/
};
struct NBDClient {
int refcount; /* atomic */
void (*close_fn)(NBDClient *client, bool negotiated);
void *owner;
QemuMutex lock;
NBDExport *exp;
QCryptoTLSCreds *tlscreds;
char *tlsauthz;
uint32_t handshake_max_secs;
QIOChannelSocket *sioc; /* The underlying data channel */
QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
Coroutine *recv_coroutine; /* protected by lock */
CoMutex send_lock;
Coroutine *send_coroutine;
bool read_yielding; /* protected by lock */
bool quiescing; /* protected by lock */
QTAILQ_ENTRY(NBDClient) next;
int nb_requests; /* protected by lock */
bool closing; /* protected by lock */
uint32_t check_align; /* If non-zero, check for aligned client requests */
NBDMode mode;
NBDMetaContexts contexts; /* Negotiated meta contexts */
uint32_t opt; /* Current option being negotiated */
uint32_t optlen; /* remaining length of data in ioc for the option being
negotiated now */
};
static void nbd_client_receive_next_request(NBDClient *client);
/* 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)
*/
static inline void set_be_option_rep(NBDOptionReply *rep, uint32_t option,
uint32_t type, uint32_t length)
{
stq_be_p(&rep->magic, NBD_REP_MAGIC);
stl_be_p(&rep->option, option);
stl_be_p(&rep->type, type);
stl_be_p(&rep->length, length);
}
/* Send a reply header, including length, but no payload.
* Return -errno on error, 0 on success. */
static coroutine_fn int
nbd_negotiate_send_rep_len(NBDClient *client, uint32_t type,
uint32_t len, Error **errp)
{
NBDOptionReply rep;
trace_nbd_negotiate_send_rep_len(client->opt, nbd_opt_lookup(client->opt),
type, nbd_rep_lookup(type), len);
assert(len < NBD_MAX_BUFFER_SIZE);
set_be_option_rep(&rep, client->opt, type, len);
return nbd_write(client->ioc, &rep, sizeof(rep), errp);
}
/* Send a reply header with default 0 length.
* Return -errno on error, 0 on success. */
static coroutine_fn int
nbd_negotiate_send_rep(NBDClient *client, uint32_t type, Error **errp)
{
return nbd_negotiate_send_rep_len(client, type, 0, errp);
}
/* Send an error reply.
* Return -errno on error, 0 on success. */
static coroutine_fn int G_GNUC_PRINTF(4, 0)
nbd_negotiate_send_rep_verr(NBDClient *client, uint32_t type,
Error **errp, const char *fmt, va_list va)
{
ERRP_GUARD();
g_autofree char *msg = NULL;
int ret;
size_t len;
msg = g_strdup_vprintf(fmt, va);
len = strlen(msg);
assert(len < NBD_MAX_STRING_SIZE);
trace_nbd_negotiate_send_rep_err(msg);
ret = nbd_negotiate_send_rep_len(client, type, len, errp);
if (ret < 0) {
return ret;
}
if (nbd_write(client->ioc, msg, len, errp) < 0) {
error_prepend(errp, "write failed (error message): ");
return -EIO;
}
return 0;
}
/*
* Return a malloc'd copy of @name suitable for use in an error reply.
*/
static char *
nbd_sanitize_name(const char *name)
{
if (strnlen(name, 80) < 80) {
return g_strdup(name);
}
/* XXX Should we also try to sanitize any control characters? */
return g_strdup_printf("%.80s...", name);
}
/* Send an error reply.
* Return -errno on error, 0 on success. */
static coroutine_fn int G_GNUC_PRINTF(4, 5)
nbd_negotiate_send_rep_err(NBDClient *client, uint32_t type,
Error **errp, const char *fmt, ...)
{
va_list va;
int ret;
va_start(va, fmt);
ret = nbd_negotiate_send_rep_verr(client, type, errp, fmt, va);
va_end(va);
return ret;
}
/* Drop remainder of the current option, and send a reply with the
* given error type and message. Return -errno on read or write
* failure; or 0 if connection is still live. */
static coroutine_fn int G_GNUC_PRINTF(4, 0)
nbd_opt_vdrop(NBDClient *client, uint32_t type, Error **errp,
const char *fmt, va_list va)
{
int ret = nbd_drop(client->ioc, client->optlen, errp);
client->optlen = 0;
if (!ret) {
ret = nbd_negotiate_send_rep_verr(client, type, errp, fmt, va);
}
return ret;
}
static coroutine_fn int G_GNUC_PRINTF(4, 5)
nbd_opt_drop(NBDClient *client, uint32_t type, Error **errp,
const char *fmt, ...)
{
int ret;
va_list va;
va_start(va, fmt);
ret = nbd_opt_vdrop(client, type, errp, fmt, va);
va_end(va);
return ret;
}
static coroutine_fn int G_GNUC_PRINTF(3, 4)
nbd_opt_invalid(NBDClient *client, Error **errp, const char *fmt, ...)
{
int ret;
va_list va;
va_start(va, fmt);
ret = nbd_opt_vdrop(client, NBD_REP_ERR_INVALID, errp, fmt, va);
va_end(va);
return ret;
}
/* Read size bytes from the unparsed payload of the current option.
* If @check_nul, require that no NUL bytes appear in buffer.
* Return -errno on I/O error, 0 if option was completely handled by
* sending a reply about inconsistent lengths, or 1 on success. */
static coroutine_fn int
nbd_opt_read(NBDClient *client, void *buffer, size_t size,
bool check_nul, Error **errp)
{
if (size > client->optlen) {
return nbd_opt_invalid(client, errp,
"Inconsistent lengths in option %s",
nbd_opt_lookup(client->opt));
}
client->optlen -= size;
if (qio_channel_read_all(client->ioc, buffer, size, errp) < 0) {
return -EIO;
}
if (check_nul && strnlen(buffer, size) != size) {
return nbd_opt_invalid(client, errp,
"Unexpected embedded NUL in option %s",
nbd_opt_lookup(client->opt));
}
return 1;
}
/* Drop size bytes from the unparsed payload of the current option.
* Return -errno on I/O error, 0 if option was completely handled by
* sending a reply about inconsistent lengths, or 1 on success. */
static coroutine_fn int
nbd_opt_skip(NBDClient *client, size_t size, Error **errp)
{
if (size > client->optlen) {
return nbd_opt_invalid(client, errp,
"Inconsistent lengths in option %s",
nbd_opt_lookup(client->opt));
}
client->optlen -= size;
return nbd_drop(client->ioc, size, errp) < 0 ? -EIO : 1;
}
/* nbd_opt_read_name
*
* Read a string with the format:
* uint32_t len (<= NBD_MAX_STRING_SIZE)
* len bytes string (not 0-terminated)
*
* On success, @name will be allocated.
* If @length is non-null, it will be set to the actual string length.
*
* Return -errno on I/O error, 0 if option was completely handled by
* sending a reply about inconsistent lengths, or 1 on success.
*/
static coroutine_fn int
nbd_opt_read_name(NBDClient *client, char **name, uint32_t *length,
Error **errp)
{
int ret;
uint32_t len;
g_autofree char *local_name = NULL;
*name = NULL;
ret = nbd_opt_read(client, &len, sizeof(len), false, errp);
if (ret <= 0) {
return ret;
}
len = cpu_to_be32(len);
if (len > NBD_MAX_STRING_SIZE) {
return nbd_opt_invalid(client, errp,
"Invalid name length: %" PRIu32, len);
}
local_name = g_malloc(len + 1);
ret = nbd_opt_read(client, local_name, len, true, errp);
if (ret <= 0) {
return ret;
}
local_name[len] = '\0';
if (length) {
*length = len;
}
*name = g_steal_pointer(&local_name);
return 1;
}
/* Send a single NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
* Return -errno on error, 0 on success. */
static coroutine_fn int
nbd_negotiate_send_rep_list(NBDClient *client, NBDExport *exp, Error **errp)
{
ERRP_GUARD();
size_t name_len, desc_len;
uint32_t len;
const char *name = exp->name ? exp->name : "";
const char *desc = exp->description ? exp->description : "";
QIOChannel *ioc = client->ioc;
int ret;
trace_nbd_negotiate_send_rep_list(name, desc);
name_len = strlen(name);
desc_len = strlen(desc);
assert(name_len <= NBD_MAX_STRING_SIZE && desc_len <= NBD_MAX_STRING_SIZE);
len = name_len + desc_len + sizeof(len);
ret = nbd_negotiate_send_rep_len(client, NBD_REP_SERVER, len, errp);
if (ret < 0) {
return ret;
}
len = cpu_to_be32(name_len);
if (nbd_write(ioc, &len, sizeof(len), errp) < 0) {
error_prepend(errp, "write failed (name length): ");
return -EINVAL;
}
if (nbd_write(ioc, name, name_len, errp) < 0) {
error_prepend(errp, "write failed (name buffer): ");
return -EINVAL;
}
if (nbd_write(ioc, desc, desc_len, errp) < 0) {
error_prepend(errp, "write failed (description buffer): ");
return -EINVAL;
}
return 0;
}
/* Process the NBD_OPT_LIST command, with a potential series of replies.
* Return -errno on error, 0 on success. */
static coroutine_fn int
nbd_negotiate_handle_list(NBDClient *client, Error **errp)
{
NBDExport *exp;
assert(client->opt == NBD_OPT_LIST);
/* For each export, send a NBD_REP_SERVER reply. */
QTAILQ_FOREACH(exp, &exports, next) {
if (nbd_negotiate_send_rep_list(client, exp, errp)) {
return -EINVAL;
}
}
/* Finish with a NBD_REP_ACK. */
return nbd_negotiate_send_rep(client, NBD_REP_ACK, errp);
}
static coroutine_fn void
nbd_check_meta_export(NBDClient *client, NBDExport *exp)
{
if (exp != client->contexts.exp) {
client->contexts.count = 0;
}
}
/* Send a reply to NBD_OPT_EXPORT_NAME.
* Return -errno on error, 0 on success. */
static coroutine_fn int
nbd_negotiate_handle_export_name(NBDClient *client, bool no_zeroes,
Error **errp)
{
ERRP_GUARD();
g_autofree char *name = NULL;
char buf[NBD_REPLY_EXPORT_NAME_SIZE] = "";
size_t len;
int ret;
uint16_t myflags;
/* Client sends:
[20 .. xx] export name (length bytes)
Server replies:
[ 0 .. 7] size
[ 8 .. 9] export flags
[10 .. 133] reserved (0) [unless no_zeroes]
*/
trace_nbd_negotiate_handle_export_name();
if (client->mode >= NBD_MODE_EXTENDED) {
error_setg(errp, "Extended headers already negotiated");
return -EINVAL;
}
if (client->optlen > NBD_MAX_STRING_SIZE) {
error_setg(errp, "Bad length received");
return -EINVAL;
}
name = g_malloc(client->optlen + 1);
if (nbd_read(client->ioc, name, client->optlen, "export name", errp) < 0) {
return -EIO;
}
name[client->optlen] = '\0';
client->optlen = 0;
trace_nbd_negotiate_handle_export_name_request(name);
client->exp = nbd_export_find(name);
if (!client->exp) {
error_setg(errp, "export not found");
return -EINVAL;
}
nbd_check_meta_export(client, client->exp);
myflags = client->exp->nbdflags;
if (client->mode >= NBD_MODE_STRUCTURED) {
myflags |= NBD_FLAG_SEND_DF;
}
if (client->mode >= NBD_MODE_EXTENDED && client->contexts.count) {
myflags |= NBD_FLAG_BLOCK_STAT_PAYLOAD;
}
trace_nbd_negotiate_new_style_size_flags(client->exp->size, myflags);
stq_be_p(buf, client->exp->size);
stw_be_p(buf + 8, myflags);
len = no_zeroes ? 10 : sizeof(buf);
ret = nbd_write(client->ioc, buf, len, errp);
if (ret < 0) {
error_prepend(errp, "write failed: ");
return ret;
}
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
blk_exp_ref(&client->exp->common);
return 0;
}
/* Send a single NBD_REP_INFO, with a buffer @buf of @length bytes.
* The buffer does NOT include the info type prefix.
* Return -errno on error, 0 if ready to send more. */
static coroutine_fn int
nbd_negotiate_send_info(NBDClient *client, uint16_t info, uint32_t length,
void *buf, Error **errp)
{
int rc;
trace_nbd_negotiate_send_info(info, nbd_info_lookup(info), length);
rc = nbd_negotiate_send_rep_len(client, NBD_REP_INFO,
sizeof(info) + length, errp);
if (rc < 0) {
return rc;
}
info = cpu_to_be16(info);
if (nbd_write(client->ioc, &info, sizeof(info), errp) < 0) {
return -EIO;
}
if (nbd_write(client->ioc, buf, length, errp) < 0) {
return -EIO;
}
return 0;
}
/* nbd_reject_length: Handle any unexpected payload.
* @fatal requests that we quit talking to the client, even if we are able
* to successfully send an error reply.
* Return:
* -errno transmission error occurred or @fatal was requested, errp is set
* 0 error message successfully sent to client, errp is not set
*/
static coroutine_fn int
nbd_reject_length(NBDClient *client, bool fatal, Error **errp)
{
int ret;
assert(client->optlen);
ret = nbd_opt_invalid(client, errp, "option '%s' has unexpected length",
nbd_opt_lookup(client->opt));
if (fatal && !ret) {
error_setg(errp, "option '%s' has unexpected length",
nbd_opt_lookup(client->opt));
return -EINVAL;
}
return ret;
}
/* Handle NBD_OPT_INFO and NBD_OPT_GO.
* Return -errno on error, 0 if ready for next option, and 1 to move
* into transmission phase. */
static coroutine_fn int
nbd_negotiate_handle_info(NBDClient *client, Error **errp)
{
int rc;
g_autofree char *name = NULL;
NBDExport *exp;
uint16_t requests;
uint16_t request;
uint32_t namelen = 0;
bool sendname = false;
bool blocksize = false;
uint32_t sizes[3];
char buf[sizeof(uint64_t) + sizeof(uint16_t)];
uint32_t check_align = 0;
uint16_t myflags;
/* Client sends:
4 bytes: L, name length (can be 0)
L bytes: export name
2 bytes: N, number of requests (can be 0)
N * 2 bytes: N requests
*/
rc = nbd_opt_read_name(client, &name, &namelen, errp);
if (rc <= 0) {
return rc;
}
trace_nbd_negotiate_handle_export_name_request(name);
rc = nbd_opt_read(client, &requests, sizeof(requests), false, errp);
if (rc <= 0) {
return rc;
}
requests = be16_to_cpu(requests);
trace_nbd_negotiate_handle_info_requests(requests);
while (requests--) {
rc = nbd_opt_read(client, &request, sizeof(request), false, errp);
if (rc <= 0) {
return rc;
}
request = be16_to_cpu(request);
trace_nbd_negotiate_handle_info_request(request,
nbd_info_lookup(request));
/* We care about NBD_INFO_NAME and NBD_INFO_BLOCK_SIZE;
* everything else is either a request we don't know or
* something we send regardless of request */
switch (request) {
case NBD_INFO_NAME:
sendname = true;
break;
case NBD_INFO_BLOCK_SIZE:
blocksize = true;
break;
}
}
if (client->optlen) {
return nbd_reject_length(client, false, errp);
}
exp = nbd_export_find(name);
if (!exp) {
g_autofree char *sane_name = nbd_sanitize_name(name);
return nbd_negotiate_send_rep_err(client, NBD_REP_ERR_UNKNOWN,
errp, "export '%s' not present",
sane_name);
}
if (client->opt == NBD_OPT_GO) {
nbd_check_meta_export(client, exp);
}
/* Don't bother sending NBD_INFO_NAME unless client requested it */
if (sendname) {
rc = nbd_negotiate_send_info(client, NBD_INFO_NAME, namelen, name,
errp);
if (rc < 0) {
return rc;
}
}
/* Send NBD_INFO_DESCRIPTION only if available, regardless of
* client request */
if (exp->description) {
size_t len = strlen(exp->description);
assert(len <= NBD_MAX_STRING_SIZE);
rc = nbd_negotiate_send_info(client, NBD_INFO_DESCRIPTION,
len, exp->description, errp);
if (rc < 0) {
return rc;
}
}
/* Send NBD_INFO_BLOCK_SIZE always, but tweak the minimum size
* according to whether the client requested it, and according to
* whether this is OPT_INFO or OPT_GO. */
/* minimum - 1 for back-compat, or actual if client will obey it. */
if (client->opt == NBD_OPT_INFO || blocksize) {
check_align = sizes[0] = blk_get_request_alignment(exp->common.blk);
} else {
sizes[0] = 1;
}
assert(sizes[0] <= NBD_MAX_BUFFER_SIZE);
/* preferred - Hard-code to 4096 for now.
* TODO: is blk_bs(blk)->bl.opt_transfer appropriate? */
sizes[1] = MAX(4096, sizes[0]);
/* maximum - At most 32M, but smaller as appropriate. */
sizes[2] = MIN(blk_get_max_transfer(exp->common.blk), NBD_MAX_BUFFER_SIZE);
trace_nbd_negotiate_handle_info_block_size(sizes[0], sizes[1], sizes[2]);
sizes[0] = cpu_to_be32(sizes[0]);
sizes[1] = cpu_to_be32(sizes[1]);
sizes[2] = cpu_to_be32(sizes[2]);
rc = nbd_negotiate_send_info(client, NBD_INFO_BLOCK_SIZE,
sizeof(sizes), sizes, errp);
if (rc < 0) {
return rc;
}
/* Send NBD_INFO_EXPORT always */
myflags = exp->nbdflags;
if (client->mode >= NBD_MODE_STRUCTURED) {
myflags |= NBD_FLAG_SEND_DF;
}
if (client->mode >= NBD_MODE_EXTENDED &&
(client->contexts.count || client->opt == NBD_OPT_INFO)) {
myflags |= NBD_FLAG_BLOCK_STAT_PAYLOAD;
}
trace_nbd_negotiate_new_style_size_flags(exp->size, myflags);
stq_be_p(buf, exp->size);
stw_be_p(buf + 8, myflags);
rc = nbd_negotiate_send_info(client, NBD_INFO_EXPORT,
sizeof(buf), buf, errp);
if (rc < 0) {
return rc;
}
/*
* If the client is just asking for NBD_OPT_INFO, but forgot to
* request block sizes in a situation that would impact
* performance, then return an error. But for NBD_OPT_GO, we
* tolerate all clients, regardless of alignments.
*/
if (client->opt == NBD_OPT_INFO && !blocksize &&
blk_get_request_alignment(exp->common.blk) > 1) {
return nbd_negotiate_send_rep_err(client,
NBD_REP_ERR_BLOCK_SIZE_REQD,
errp,
"request NBD_INFO_BLOCK_SIZE to "
"use this export");
}
/* Final reply */
rc = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp);
if (rc < 0) {
return rc;
}
if (client->opt == NBD_OPT_GO) {
client->exp = exp;
client->check_align = check_align;
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
blk_exp_ref(&client->exp->common);
rc = 1;
}
return rc;
}
/* Callback to learn when QIO TLS upgrade is complete */
struct NBDTLSServerHandshakeData {
bool complete;
Error *error;
Coroutine *co;
};
static void
nbd_server_tls_handshake(QIOTask *task, void *opaque)
{
struct NBDTLSServerHandshakeData *data = opaque;
qio_task_propagate_error(task, &data->error);
data->complete = true;
if (!qemu_coroutine_entered(data->co)) {
aio_co_wake(data->co);
}
}
/* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
* new channel for all further (now-encrypted) communication. */
static coroutine_fn QIOChannel *
nbd_negotiate_handle_starttls(NBDClient *client, Error **errp)
{
QIOChannel *ioc;
QIOChannelTLS *tioc;
struct NBDTLSServerHandshakeData data = { 0 };
assert(client->opt == NBD_OPT_STARTTLS);
trace_nbd_negotiate_handle_starttls();
ioc = client->ioc;
if (nbd_negotiate_send_rep(client, NBD_REP_ACK, errp) < 0) {
return NULL;
}
tioc = qio_channel_tls_new_server(ioc,
client->tlscreds,
client->tlsauthz,
errp);
if (!tioc) {
return NULL;
}
qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls");
trace_nbd_negotiate_handle_starttls_handshake();
data.co = qemu_coroutine_self();
qio_channel_tls_handshake(tioc,
nbd_server_tls_handshake,
&data,
NULL,
NULL);
if (!data.complete) {
qemu_coroutine_yield();
assert(data.complete);
}
if (data.error) {
object_unref(OBJECT(tioc));
error_propagate(errp, data.error);
return NULL;
}
return QIO_CHANNEL(tioc);
}
/* nbd_negotiate_send_meta_context
*
* Send one chunk of reply to NBD_OPT_{LIST,SET}_META_CONTEXT
*
* For NBD_OPT_LIST_META_CONTEXT @context_id is ignored, 0 is used instead.
*/
static coroutine_fn int
nbd_negotiate_send_meta_context(NBDClient *client, const char *context,
uint32_t context_id, Error **errp)
{
NBDOptionReplyMetaContext opt;
struct iovec iov[] = {
{.iov_base = &opt, .iov_len = sizeof(opt)},
{.iov_base = (void *)context, .iov_len = strlen(context)}
};
assert(iov[1].iov_len <= NBD_MAX_STRING_SIZE);
if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
context_id = 0;
}
trace_nbd_negotiate_meta_query_reply(context, context_id);
set_be_option_rep(&opt.h, client->opt, NBD_REP_META_CONTEXT,
sizeof(opt) - sizeof(opt.h) + iov[1].iov_len);
stl_be_p(&opt.context_id, context_id);
return qio_channel_writev_all(client->ioc, iov, 2, errp) < 0 ? -EIO : 0;
}
/*
* Return true if @query matches @pattern, or if @query is empty when
* the @client is performing _LIST_.
*/
static coroutine_fn bool
nbd_meta_empty_or_pattern(NBDClient *client, const char *pattern,
const char *query)
{
if (!*query) {
trace_nbd_negotiate_meta_query_parse("empty");
return client->opt == NBD_OPT_LIST_META_CONTEXT;
}
if (strcmp(query, pattern) == 0) {
trace_nbd_negotiate_meta_query_parse(pattern);
return true;
}
trace_nbd_negotiate_meta_query_skip("pattern not matched");
return false;
}
/*
* Return true and adjust @str in place if it begins with @prefix.
*/
static coroutine_fn bool
nbd_strshift(const char **str, const char *prefix)
{
size_t len = strlen(prefix);
if (strncmp(*str, prefix, len) == 0) {
*str += len;
return true;
}
return false;
}
/* nbd_meta_base_query
*
* Handle queries to 'base' namespace. For now, only the base:allocation
* context is available. Return true if @query has been handled.
*/
static coroutine_fn bool
nbd_meta_base_query(NBDClient *client, NBDMetaContexts *meta,
const char *query)
{
if (!nbd_strshift(&query, "base:")) {
return false;
}
trace_nbd_negotiate_meta_query_parse("base:");
if (nbd_meta_empty_or_pattern(client, "allocation", query)) {
meta->base_allocation = true;
}
return true;
}
/* nbd_meta_qemu_query
*
* Handle queries to 'qemu' namespace. For now, only the qemu:dirty-bitmap:
* and qemu:allocation-depth contexts are available. Return true if @query
* has been handled.
*/
static coroutine_fn bool
nbd_meta_qemu_query(NBDClient *client, NBDMetaContexts *meta,
const char *query)
{
size_t i;
if (!nbd_strshift(&query, "qemu:")) {
return false;
}
trace_nbd_negotiate_meta_query_parse("qemu:");
if (!*query) {
if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
meta->allocation_depth = meta->exp->allocation_depth;
if (meta->exp->nr_export_bitmaps) {
memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
}
}
trace_nbd_negotiate_meta_query_parse("empty");
return true;
}
if (strcmp(query, "allocation-depth") == 0) {
trace_nbd_negotiate_meta_query_parse("allocation-depth");
meta->allocation_depth = meta->exp->allocation_depth;
return true;
}
if (nbd_strshift(&query, "dirty-bitmap:")) {
trace_nbd_negotiate_meta_query_parse("dirty-bitmap:");
if (!*query) {
if (client->opt == NBD_OPT_LIST_META_CONTEXT &&
meta->exp->nr_export_bitmaps) {
memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
}
trace_nbd_negotiate_meta_query_parse("empty");
return true;
}
for (i = 0; i < meta->exp->nr_export_bitmaps; i++) {
const char *bm_name;
bm_name = bdrv_dirty_bitmap_name(meta->exp->export_bitmaps[i]);
if (strcmp(bm_name, query) == 0) {
meta->bitmaps[i] = true;
trace_nbd_negotiate_meta_query_parse(query);
return true;
}
}
trace_nbd_negotiate_meta_query_skip("no dirty-bitmap match");
return true;
}
trace_nbd_negotiate_meta_query_skip("unknown qemu context");
return true;
}
/* nbd_negotiate_meta_query
*
* Parse namespace name and call corresponding function to parse body of the
* query.
*
* The only supported namespaces are 'base' and 'qemu'.
*
* Return -errno on I/O error, 0 if option was completely handled by
* sending a reply about inconsistent lengths, or 1 on success. */
static coroutine_fn int
nbd_negotiate_meta_query(NBDClient *client,
NBDMetaContexts *meta, Error **errp)
{
int ret;
g_autofree char *query = NULL;
uint32_t len;
ret = nbd_opt_read(client, &len, sizeof(len), false, errp);
if (ret <= 0) {
return ret;
}
len = cpu_to_be32(len);
if (len > NBD_MAX_STRING_SIZE) {
trace_nbd_negotiate_meta_query_skip("length too long");
return nbd_opt_skip(client, len, errp);
}
query = g_malloc(len + 1);
ret = nbd_opt_read(client, query, len, true, errp);
if (ret <= 0) {
return ret;
}
query[len] = '\0';
if (nbd_meta_base_query(client, meta, query)) {
return 1;
}
if (nbd_meta_qemu_query(client, meta, query)) {
return 1;
}
trace_nbd_negotiate_meta_query_skip("unknown namespace");
return 1;
}
/* nbd_negotiate_meta_queries
* Handle NBD_OPT_LIST_META_CONTEXT and NBD_OPT_SET_META_CONTEXT
*
* Return -errno on I/O error, or 0 if option was completely handled. */
static coroutine_fn int
nbd_negotiate_meta_queries(NBDClient *client, Error **errp)
{
int ret;
g_autofree char *export_name = NULL;
/* Mark unused to work around https://bugs.llvm.org/show_bug.cgi?id=3888 */
g_autofree G_GNUC_UNUSED bool *bitmaps = NULL;
NBDMetaContexts local_meta = {0};
NBDMetaContexts *meta;
uint32_t nb_queries;
size_t i;
size_t count = 0;
if (client->opt == NBD_OPT_SET_META_CONTEXT &&
client->mode < NBD_MODE_STRUCTURED) {
return nbd_opt_invalid(client, errp,
"request option '%s' when structured reply "
"is not negotiated",
nbd_opt_lookup(client->opt));
}
if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
/* Only change the caller's meta on SET. */
meta = &local_meta;
} else {
meta = &client->contexts;
}
g_free(meta->bitmaps);
memset(meta, 0, sizeof(*meta));
ret = nbd_opt_read_name(client, &export_name, NULL, errp);
if (ret <= 0) {
return ret;
}
meta->exp = nbd_export_find(export_name);
if (meta->exp == NULL) {
g_autofree char *sane_name = nbd_sanitize_name(export_name);
return nbd_opt_drop(client, NBD_REP_ERR_UNKNOWN, errp,
"export '%s' not present", sane_name);
}
meta->bitmaps = g_new0(bool, meta->exp->nr_export_bitmaps);
if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
bitmaps = meta->bitmaps;
}
ret = nbd_opt_read(client, &nb_queries, sizeof(nb_queries), false, errp);
if (ret <= 0) {
return ret;
}
nb_queries = cpu_to_be32(nb_queries);
trace_nbd_negotiate_meta_context(nbd_opt_lookup(client->opt),
export_name, nb_queries);
if (client->opt == NBD_OPT_LIST_META_CONTEXT && !nb_queries) {
/* enable all known contexts */
meta->base_allocation = true;
meta->allocation_depth = meta->exp->allocation_depth;
if (meta->exp->nr_export_bitmaps) {
memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
}
} else {
for (i = 0; i < nb_queries; ++i) {
ret = nbd_negotiate_meta_query(client, meta, errp);
if (ret <= 0) {
return ret;
}
}
}
if (meta->base_allocation) {
ret = nbd_negotiate_send_meta_context(client, "base:allocation",
NBD_META_ID_BASE_ALLOCATION,
errp);
if (ret < 0) {
return ret;
}
count++;
}
if (meta->allocation_depth) {
ret = nbd_negotiate_send_meta_context(client, "qemu:allocation-depth",
NBD_META_ID_ALLOCATION_DEPTH,
errp);
if (ret < 0) {
return ret;
}
count++;
}
for (i = 0; i < meta->exp->nr_export_bitmaps; i++) {
const char *bm_name;
g_autofree char *context = NULL;
if (!meta->bitmaps[i]) {
continue;
}
bm_name = bdrv_dirty_bitmap_name(meta->exp->export_bitmaps[i]);
context = g_strdup_printf("qemu:dirty-bitmap:%s", bm_name);
ret = nbd_negotiate_send_meta_context(client, context,
NBD_META_ID_DIRTY_BITMAP + i,
errp);
if (ret < 0) {
return ret;
}
count++;
}
ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp);
if (ret == 0) {
meta->count = count;
}
return ret;
}
/* nbd_negotiate_options
* Process all NBD_OPT_* client option commands, during fixed newstyle
* negotiation.
* Return:
* -errno on error, errp is set
* 0 on successful negotiation, errp is not set
* 1 if client sent NBD_OPT_ABORT (i.e. on valid disconnect) or never
* wrote anything (i.e. port probe); errp is not set
*/
static coroutine_fn int
nbd_negotiate_options(NBDClient *client, Error **errp)
{
uint32_t flags;
bool fixedNewstyle = false;
bool no_zeroes = false;
/* Client sends:
[ 0 .. 3] client flags
Then we loop until NBD_OPT_EXPORT_NAME or NBD_OPT_GO:
[ 0 .. 7] NBD_OPTS_MAGIC
[ 8 .. 11] NBD option
[12 .. 15] Data length
... Rest of request
[ 0 .. 7] NBD_OPTS_MAGIC
[ 8 .. 11] Second NBD option
[12 .. 15] Data length
... Rest of request
*/
/*
* Intentionally ignore errors on this first read - we do not want
* to be noisy about a mere port probe, but only for clients that
* start talking the protocol and then quit abruptly.
*/
if (nbd_read32(client->ioc, &flags, "flags", NULL) < 0) {
return 1;
}
client->mode = NBD_MODE_EXPORT_NAME;
trace_nbd_negotiate_options_flags(flags);
if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
fixedNewstyle = true;
flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
client->mode = NBD_MODE_SIMPLE;
}
if (flags & NBD_FLAG_C_NO_ZEROES) {
no_zeroes = true;
flags &= ~NBD_FLAG_C_NO_ZEROES;
}
if (flags != 0) {
error_setg(errp, "Unknown client flags 0x%" PRIx32 " received", flags);
return -EINVAL;
}
while (1) {
int ret;
uint32_t option, length;
uint64_t magic;
if (nbd_read64(client->ioc, &magic, "opts magic", errp) < 0) {
return -EINVAL;
}
trace_nbd_negotiate_options_check_magic(magic);
if (magic != NBD_OPTS_MAGIC) {
error_setg(errp, "Bad magic received");
return -EINVAL;
}
if (nbd_read32(client->ioc, &option, "option", errp) < 0) {
return -EINVAL;
}
client->opt = option;
if (nbd_read32(client->ioc, &length, "option length", errp) < 0) {
return -EINVAL;
}
assert(!client->optlen);
client->optlen = length;
if (length > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "len (%" PRIu32 ") is larger than max len (%u)",
length, NBD_MAX_BUFFER_SIZE);
return -EINVAL;
}
trace_nbd_negotiate_options_check_option(option,
nbd_opt_lookup(option));
if (client->tlscreds &&
client->ioc == (QIOChannel *)client->sioc) {
QIOChannel *tioc;
if (!fixedNewstyle) {
error_setg(errp, "Unsupported option 0x%" PRIx32, option);
return -EINVAL;
}
switch (option) {
case NBD_OPT_STARTTLS:
if (length) {
/* Unconditionally drop the connection if the client
* can't start a TLS negotiation correctly */
return nbd_reject_length(client, true, errp);
}
tioc = nbd_negotiate_handle_starttls(client, errp);
if (!tioc) {
return -EIO;
}
ret = 0;
object_unref(OBJECT(client->ioc));
client->ioc = tioc;
break;
case NBD_OPT_EXPORT_NAME:
/* No way to return an error to client, so drop connection */
error_setg(errp, "Option 0x%x not permitted before TLS",
option);
return -EINVAL;
default:
/* Let the client keep trying, unless they asked to
* quit. Always try to give an error back to the
* client; but when replying to OPT_ABORT, be aware
* that the client may hang up before receiving the
* error, in which case we are fine ignoring the
* resulting EPIPE. */
ret = nbd_opt_drop(client, NBD_REP_ERR_TLS_REQD,
option == NBD_OPT_ABORT ? NULL : errp,
"Option 0x%" PRIx32
" not permitted before TLS", option);
if (option == NBD_OPT_ABORT) {
return 1;
}
break;
}
} else if (fixedNewstyle) {
switch (option) {
case NBD_OPT_LIST:
if (length) {
ret = nbd_reject_length(client, false, errp);
} else {
ret = nbd_negotiate_handle_list(client, errp);
}
break;
case NBD_OPT_ABORT:
/* NBD spec says we must try to reply before
* disconnecting, but that we must also tolerate
* guests that don't wait for our reply. */
nbd_negotiate_send_rep(client, NBD_REP_ACK, NULL);
return 1;
case NBD_OPT_EXPORT_NAME:
return nbd_negotiate_handle_export_name(client, no_zeroes,
errp);
case NBD_OPT_INFO:
case NBD_OPT_GO:
ret = nbd_negotiate_handle_info(client, errp);
if (ret == 1) {
assert(option == NBD_OPT_GO);
return 0;
}
break;
case NBD_OPT_STARTTLS:
if (length) {
ret = nbd_reject_length(client, false, errp);
} else if (client->tlscreds) {
ret = nbd_negotiate_send_rep_err(client,
NBD_REP_ERR_INVALID, errp,
"TLS already enabled");
} else {
ret = nbd_negotiate_send_rep_err(client,
NBD_REP_ERR_POLICY, errp,
"TLS not configured");
}
break;
case NBD_OPT_STRUCTURED_REPLY:
if (length) {
ret = nbd_reject_length(client, false, errp);
} else if (client->mode >= NBD_MODE_EXTENDED) {
ret = nbd_negotiate_send_rep_err(
client, NBD_REP_ERR_EXT_HEADER_REQD, errp,
"extended headers already negotiated");
} else if (client->mode >= NBD_MODE_STRUCTURED) {
ret = nbd_negotiate_send_rep_err(
client, NBD_REP_ERR_INVALID, errp,
"structured reply already negotiated");
} else {
ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp);
client->mode = NBD_MODE_STRUCTURED;
}
break;
case NBD_OPT_LIST_META_CONTEXT:
case NBD_OPT_SET_META_CONTEXT:
ret = nbd_negotiate_meta_queries(client, errp);
break;
case NBD_OPT_EXTENDED_HEADERS:
if (length) {
ret = nbd_reject_length(client, false, errp);
} else if (client->mode >= NBD_MODE_EXTENDED) {
ret = nbd_negotiate_send_rep_err(
client, NBD_REP_ERR_INVALID, errp,
"extended headers already negotiated");
} else {
ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp);
client->mode = NBD_MODE_EXTENDED;
}
break;
default:
ret = nbd_opt_drop(client, NBD_REP_ERR_UNSUP, errp,
"Unsupported option %" PRIu32 " (%s)",
option, nbd_opt_lookup(option));
break;
}
} else {
/*
* If broken new-style we should drop the connection
* for anything except NBD_OPT_EXPORT_NAME
*/
switch (option) {
case NBD_OPT_EXPORT_NAME:
return nbd_negotiate_handle_export_name(client, no_zeroes,
errp);
default:
error_setg(errp, "Unsupported option %" PRIu32 " (%s)",
option, nbd_opt_lookup(option));
return -EINVAL;
}
}
if (ret < 0) {
return ret;
}
}
}
/* nbd_negotiate
* Return:
* -errno on error, errp is set
* 0 on successful negotiation, errp is not set
* 1 if client sent NBD_OPT_ABORT (i.e. on valid disconnect) or never
* wrote anything (i.e. port probe); errp is not set
*/
static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp)
{
ERRP_GUARD();
char buf[NBD_OLDSTYLE_NEGOTIATE_SIZE] = "";
int ret;
/* Old style negotiation header, no room for options
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_CLIENT_MAGIC)
[16 .. 23] size
[24 .. 27] export flags (zero-extended)
[28 .. 151] reserved (0)
New style negotiation header, client can send options
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_OPTS_MAGIC)
[16 .. 17] server flags (0)
....options sent, ending in NBD_OPT_EXPORT_NAME or NBD_OPT_GO....
*/
if (!qio_channel_set_blocking(client->ioc, false, errp)) {
return -EINVAL;
}
qio_channel_set_follow_coroutine_ctx(client->ioc, true);
trace_nbd_negotiate_begin();
memcpy(buf, "NBDMAGIC", 8);
stq_be_p(buf + 8, NBD_OPTS_MAGIC);
stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES);
/*
* Be silent about failure to write our greeting: there is nothing
* wrong with a client testing if our port is alive.
*/
if (nbd_write(client->ioc, buf, 18, NULL) < 0) {
return 1;
}
ret = nbd_negotiate_options(client, errp);
if (ret != 0) {
if (ret < 0) {
error_prepend(errp, "option negotiation failed: ");
}
return ret;
}
assert(!client->optlen);
trace_nbd_negotiate_success();
return 0;
}
/* nbd_read_eof
* Tries to read @size bytes from @ioc. This is a local implementation of
* qio_channel_readv_all_eof. We have it here because we need it to be
* interruptible and to know when the coroutine is yielding.
* Returns 1 on success
* 0 on eof, when no data was read (errp is not set)
* negative errno on failure (errp is set)
*/
static inline int coroutine_fn
nbd_read_eof(NBDClient *client, void *buffer, size_t size, Error **errp)
{
bool partial = false;
assert(size);
while (size > 0) {
struct iovec iov = { .iov_base = buffer, .iov_len = size };
ssize_t len;
len = qio_channel_readv(client->ioc, &iov, 1, errp);
if (len == QIO_CHANNEL_ERR_BLOCK) {
WITH_QEMU_LOCK_GUARD(&client->lock) {
client->read_yielding = true;
/* Prompt main loop thread to re-run nbd_drained_poll() */
aio_wait_kick();
}
qio_channel_yield(client->ioc, G_IO_IN);
WITH_QEMU_LOCK_GUARD(&client->lock) {
client->read_yielding = false;
if (client->quiescing) {
return -EAGAIN;
}
}
continue;
} else if (len < 0) {
return -EIO;
} else if (len == 0) {
if (partial) {
error_setg(errp,
"Unexpected end-of-file before all bytes were read");
return -EIO;
} else {
return 0;
}
}
partial = true;
size -= len;
buffer = (uint8_t *) buffer + len;
}
return 1;
}
static int coroutine_fn nbd_receive_request(NBDClient *client, NBDRequest *request,
Error **errp)
{
uint8_t buf[NBD_EXTENDED_REQUEST_SIZE];
uint32_t magic, expect;
int ret;
size_t size = client->mode >= NBD_MODE_EXTENDED ?
NBD_EXTENDED_REQUEST_SIZE : NBD_REQUEST_SIZE;
ret = nbd_read_eof(client, buf, size, errp);
if (ret < 0) {
return ret;
}
if (ret == 0) {
return -EIO;
}
/*
* Compact request
* [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
* [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
* [ 6 .. 7] type (NBD_CMD_READ, ...)
* [ 8 .. 15] cookie
* [16 .. 23] from
* [24 .. 27] len
* Extended request
* [ 0 .. 3] magic (NBD_EXTENDED_REQUEST_MAGIC)
* [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, NBD_CMD_FLAG_PAYLOAD_LEN, ...)
* [ 6 .. 7] type (NBD_CMD_READ, ...)
* [ 8 .. 15] cookie
* [16 .. 23] from
* [24 .. 31] len
*/
magic = ldl_be_p(buf);
request->flags = lduw_be_p(buf + 4);
request->type = lduw_be_p(buf + 6);
request->cookie = ldq_be_p(buf + 8);
request->from = ldq_be_p(buf + 16);
if (client->mode >= NBD_MODE_EXTENDED) {
request->len = ldq_be_p(buf + 24);
expect = NBD_EXTENDED_REQUEST_MAGIC;
} else {
request->len = (uint32_t)ldl_be_p(buf + 24); /* widen 32 to 64 bits */
expect = NBD_REQUEST_MAGIC;
}
trace_nbd_receive_request(magic, request->flags, request->type,
request->from, request->len);
if (magic != expect) {
error_setg(errp, "invalid magic (got 0x%" PRIx32 ", expected 0x%"
PRIx32 ")", magic, expect);
return -EINVAL;
}
return 0;
}
#define MAX_NBD_REQUESTS 16
/* Runs in export AioContext and main loop thread */
void nbd_client_get(NBDClient *client)
{
qatomic_inc(&client->refcount);
}
void nbd_client_put(NBDClient *client)
{
assert(qemu_in_main_thread());
if (qatomic_fetch_dec(&client->refcount) == 1) {
/* The last reference should be dropped by client->close,
* which is called by client_close.
*/
assert(client->closing);
object_unref(OBJECT(client->sioc));
object_unref(OBJECT(client->ioc));
if (client->tlscreds) {
object_unref(OBJECT(client->tlscreds));
}
g_free(client->tlsauthz);
if (client->exp) {
QTAILQ_REMOVE(&client->exp->clients, client, next);
blk_exp_unref(&client->exp->common);
}
g_free(client->contexts.bitmaps);
qemu_mutex_destroy(&client->lock);
g_free(client);
}
}
/*
* Tries to release the reference to @client, but only if other references
* remain. This is an optimization for the common case where we want to avoid
* the expense of scheduling nbd_client_put() in the main loop thread.
*
* Returns true upon success or false if the reference was not released because
* it is the last reference.
*/
static bool nbd_client_put_nonzero(NBDClient *client)
{
int old = qatomic_read(&client->refcount);
int expected;
do {
if (old == 1) {
return false;
}
expected = old;
old = qatomic_cmpxchg(&client->refcount, expected, expected - 1);
} while (old != expected);
return true;
}
static void client_close(NBDClient *client, bool negotiated)
{
assert(qemu_in_main_thread());
WITH_QEMU_LOCK_GUARD(&client->lock) {
if (client->closing) {
return;
}
client->closing = true;
}
/* Force requests to finish. They will drop their own references,
* then we'll close the socket and free the NBDClient.
*/
qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
NULL);
/* Also tell the client, so that they release their reference. */
if (client->close_fn) {
client->close_fn(client, negotiated);
}
}
/* Runs in export AioContext with client->lock held */
static NBDRequestData *nbd_request_get(NBDClient *client)
{
NBDRequestData *req;
assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
client->nb_requests++;
req = g_new0(NBDRequestData, 1);
req->client = client;
return req;
}
/* Runs in export AioContext with client->lock held */
static void nbd_request_put(NBDRequestData *req)
{
NBDClient *client = req->client;
if (req->data) {
qemu_vfree(req->data);
}
g_free(req);
client->nb_requests--;
if (client->quiescing && client->nb_requests == 0) {
aio_wait_kick();
}
nbd_client_receive_next_request(client);
}
static void blk_aio_attached(AioContext *ctx, void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
assert(qemu_in_main_thread());
trace_nbd_blk_aio_attached(exp->name, ctx);
exp->common.ctx = ctx;
QTAILQ_FOREACH(client, &exp->clients, next) {
WITH_QEMU_LOCK_GUARD(&client->lock) {
assert(client->nb_requests == 0);
assert(client->recv_coroutine == NULL);
assert(client->send_coroutine == NULL);
}
}
}
static void blk_aio_detach(void *opaque)
{
NBDExport *exp = opaque;
assert(qemu_in_main_thread());
trace_nbd_blk_aio_detach(exp->name, exp->common.ctx);
exp->common.ctx = NULL;
}
static void nbd_drained_begin(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
assert(qemu_in_main_thread());
QTAILQ_FOREACH(client, &exp->clients, next) {
WITH_QEMU_LOCK_GUARD(&client->lock) {
client->quiescing = true;
}
}
}
static void nbd_drained_end(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
assert(qemu_in_main_thread());
QTAILQ_FOREACH(client, &exp->clients, next) {
WITH_QEMU_LOCK_GUARD(&client->lock) {
client->quiescing = false;
nbd_client_receive_next_request(client);
}
}
}
/* Runs in export AioContext */
static void nbd_wake_read_bh(void *opaque)
{
NBDClient *client = opaque;
qio_channel_wake_read(client->ioc);
}
static bool nbd_drained_poll(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
assert(qemu_in_main_thread());
QTAILQ_FOREACH(client, &exp->clients, next) {
WITH_QEMU_LOCK_GUARD(&client->lock) {
if (client->nb_requests != 0) {
/*
* If there's a coroutine waiting for a request on nbd_read_eof()
* enter it here so we don't depend on the client to wake it up.
*
* Schedule a BH in the export AioContext to avoid missing the
* wake up due to the race between qio_channel_wake_read() and
* qio_channel_yield().
*/
if (client->recv_coroutine != NULL && client->read_yielding) {
aio_bh_schedule_oneshot(nbd_export_aio_context(client->exp),
nbd_wake_read_bh, client);
}
return true;
}
}
}
return false;
}
static void nbd_eject_notifier(Notifier *n, void *data)
{
NBDExport *exp = container_of(n, NBDExport, eject_notifier);
assert(qemu_in_main_thread());
blk_exp_request_shutdown(&exp->common);
}
void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk)
{
NBDExport *nbd_exp = container_of(exp, NBDExport, common);
assert(exp->drv == &blk_exp_nbd);
assert(nbd_exp->eject_notifier_blk == NULL);
blk_ref(blk);
nbd_exp->eject_notifier_blk = blk;
nbd_exp->eject_notifier.notify = nbd_eject_notifier;
blk_add_remove_bs_notifier(blk, &nbd_exp->eject_notifier);
}
static const BlockDevOps nbd_block_ops = {
.drained_begin = nbd_drained_begin,
.drained_end = nbd_drained_end,
.drained_poll = nbd_drained_poll,
};
static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
AioContext *const *multithread, size_t mt_count,
Error **errp)
{
NBDExport *exp = container_of(blk_exp, NBDExport, common);
BlockExportOptionsNbd *arg = &exp_args->u.nbd;
const char *name = arg->name ?: exp_args->node_name;
BlockBackend *blk = blk_exp->blk;
int64_t size;
uint64_t perm, shared_perm;
bool readonly = !exp_args->writable;
BlockDirtyBitmapOrStrList *bitmaps;
size_t i;
int ret;
GLOBAL_STATE_CODE();
assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
if (!nbd_server_is_running()) {
error_setg(errp, "NBD server not running");
return -EINVAL;
}
if (strlen(name) > NBD_MAX_STRING_SIZE) {
error_setg(errp, "export name '%s' too long", name);
return -EINVAL;
}
if (arg->description && strlen(arg->description) > NBD_MAX_STRING_SIZE) {
error_setg(errp, "description '%s' too long", arg->description);
return -EINVAL;
}
if (nbd_export_find(name)) {
error_setg(errp, "NBD server already has export named '%s'", name);
return -EEXIST;
}
if (multithread) {
error_setg(errp, "NBD export does not support multi-threading");
return -EINVAL;
}
size = blk_getlength(blk);
if (size < 0) {
error_setg_errno(errp, -size,
"Failed to determine the NBD export's length");
return size;
}
/* Don't allow resize while the NBD server is running, otherwise we don't
* care what happens with the node. */
blk_get_perm(blk, &perm, &shared_perm);
ret = blk_set_perm(blk, perm, shared_perm & ~BLK_PERM_RESIZE, errp);
if (ret < 0) {
return ret;
}
QTAILQ_INIT(&exp->clients);
exp->name = g_strdup(name);
exp->description = g_strdup(arg->description);
exp->nbdflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_FLUSH |
NBD_FLAG_SEND_FUA | NBD_FLAG_SEND_CACHE);
if (nbd_server_max_connections() != 1) {
exp->nbdflags |= NBD_FLAG_CAN_MULTI_CONN;
}
if (readonly) {
exp->nbdflags |= NBD_FLAG_READ_ONLY;
} else {
exp->nbdflags |= (NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES |
NBD_FLAG_SEND_FAST_ZERO);
}
exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
bdrv_graph_rdlock_main_loop();
for (bitmaps = arg->bitmaps; bitmaps; bitmaps = bitmaps->next) {
exp->nr_export_bitmaps++;
}
exp->export_bitmaps = g_new0(BdrvDirtyBitmap *, exp->nr_export_bitmaps);
for (i = 0, bitmaps = arg->bitmaps; bitmaps;
i++, bitmaps = bitmaps->next)
{
const char *bitmap;
BlockDriverState *bs = blk_bs(blk);
BdrvDirtyBitmap *bm = NULL;
switch (bitmaps->value->type) {
case QTYPE_QSTRING:
bitmap = bitmaps->value->u.local;
while (bs) {
bm = bdrv_find_dirty_bitmap(bs, bitmap);
if (bm != NULL) {
break;
}
bs = bdrv_filter_or_cow_bs(bs);
}
if (bm == NULL) {
ret = -ENOENT;
error_setg(errp, "Bitmap '%s' is not found",
bitmaps->value->u.local);
goto fail;
}
if (readonly && bdrv_is_writable(bs) &&
bdrv_dirty_bitmap_enabled(bm)) {
ret = -EINVAL;
error_setg(errp, "Enabled bitmap '%s' incompatible with "
"readonly export", bitmap);
goto fail;
}
break;
case QTYPE_QDICT:
bitmap = bitmaps->value->u.external.name;
bm = block_dirty_bitmap_lookup(bitmaps->value->u.external.node,
bitmap, NULL, errp);
if (!bm) {
ret = -ENOENT;
goto fail;
}
break;
default:
abort();
}
assert(bm);
if (bdrv_dirty_bitmap_check(bm, BDRV_BITMAP_ALLOW_RO, errp)) {
ret = -EINVAL;
goto fail;
}
exp->export_bitmaps[i] = bm;
assert(strlen(bitmap) <= BDRV_BITMAP_MAX_NAME_SIZE);
}
/* Mark bitmaps busy in a separate loop, to simplify roll-back concerns. */
for (i = 0; i < exp->nr_export_bitmaps; i++) {
bdrv_dirty_bitmap_set_busy(exp->export_bitmaps[i], true);
}
exp->allocation_depth = arg->allocation_depth;
/*
* We need to inhibit request queuing in the block layer to ensure we can
* be properly quiesced when entering a drained section, as our coroutines
* servicing pending requests might enter blk_pread().
*/
blk_set_disable_request_queuing(blk, true);
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
blk_set_dev_ops(blk, &nbd_block_ops, exp);
QTAILQ_INSERT_TAIL(&exports, exp, next);
bdrv_graph_rdunlock_main_loop();
return 0;
fail:
bdrv_graph_rdunlock_main_loop();
g_free(exp->export_bitmaps);
g_free(exp->name);
g_free(exp->description);
return ret;
}
NBDExport *nbd_export_find(const char *name)
{
NBDExport *exp;
QTAILQ_FOREACH(exp, &exports, next) {
if (strcmp(name, exp->name) == 0) {
return exp;
}
}
return NULL;
}
AioContext *
nbd_export_aio_context(NBDExport *exp)
{
return exp->common.ctx;
}
static void nbd_export_request_shutdown(BlockExport *blk_exp)
{
NBDExport *exp = container_of(blk_exp, NBDExport, common);
NBDClient *client, *next;
blk_exp_ref(&exp->common);
/*
* TODO: Should we expand QMP BlockExportRemoveMode enum to allow a
* close mode that stops advertising the export to new clients but
* still permits existing clients to run to completion? Because of
* that possibility, nbd_export_close() can be called more than
* once on an export.
*/
QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
client_close(client, true);
}
if (exp->name) {
g_free(exp->name);
exp->name = NULL;
QTAILQ_REMOVE(&exports, exp, next);
}
blk_exp_unref(&exp->common);
}
static void nbd_export_delete(BlockExport *blk_exp)
{
size_t i;
NBDExport *exp = container_of(blk_exp, NBDExport, common);
assert(exp->name == NULL);
assert(QTAILQ_EMPTY(&exp->clients));
g_free(exp->description);
exp->description = NULL;
if (exp->eject_notifier_blk) {
notifier_remove(&exp->eject_notifier);
blk_unref(exp->eject_notifier_blk);
}
blk_remove_aio_context_notifier(exp->common.blk, blk_aio_attached,
blk_aio_detach, exp);
blk_set_disable_request_queuing(exp->common.blk, false);
for (i = 0; i < exp->nr_export_bitmaps; i++) {
bdrv_dirty_bitmap_set_busy(exp->export_bitmaps[i], false);
}
}
const BlockExportDriver blk_exp_nbd = {
.type = BLOCK_EXPORT_TYPE_NBD,
.instance_size = sizeof(NBDExport),
.supports_inactive = true,
.create = nbd_export_create,
.delete = nbd_export_delete,
.request_shutdown = nbd_export_request_shutdown,
};
static int coroutine_fn nbd_co_send_iov(NBDClient *client, struct iovec *iov,
unsigned niov, Error **errp)
{
int ret;
g_assert(qemu_in_coroutine());
qemu_co_mutex_lock(&client->send_lock);
client->send_coroutine = qemu_coroutine_self();
ret = qio_channel_writev_all(client->ioc, iov, niov, errp) < 0 ? -EIO : 0;
client->send_coroutine = NULL;
qemu_co_mutex_unlock(&client->send_lock);
return ret;
}
static inline void set_be_simple_reply(NBDSimpleReply *reply, uint64_t error,
uint64_t cookie)
{
stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC);
stl_be_p(&reply->error, error);
stq_be_p(&reply->cookie, cookie);
}
static int coroutine_fn nbd_co_send_simple_reply(NBDClient *client,
NBDRequest *request,
uint32_t error,
void *data,
uint64_t len,
Error **errp)
{
NBDSimpleReply reply;
int nbd_err = system_errno_to_nbd_errno(error);
struct iovec iov[] = {
{.iov_base = &reply, .iov_len = sizeof(reply)},
{.iov_base = data, .iov_len = len}
};
assert(!len || !nbd_err);
assert(len <= NBD_MAX_BUFFER_SIZE);
assert(client->mode < NBD_MODE_STRUCTURED ||
(client->mode == NBD_MODE_STRUCTURED &&
request->type != NBD_CMD_READ));
trace_nbd_co_send_simple_reply(request->cookie, nbd_err,
nbd_err_lookup(nbd_err), len);
set_be_simple_reply(&reply, nbd_err, request->cookie);
return nbd_co_send_iov(client, iov, 2, errp);
}
/*
* Prepare the header of a reply chunk for network transmission.
*
* On input, @iov is partially initialized: iov[0].iov_base must point
* to an uninitialized NBDReply, while the remaining @niov elements
* (if any) must be ready for transmission. This function then
* populates iov[0] for transmission.
*/
static inline void set_be_chunk(NBDClient *client, struct iovec *iov,
size_t niov, uint16_t flags, uint16_t type,
NBDRequest *request)
{
size_t i, length = 0;
for (i = 1; i < niov; i++) {
length += iov[i].iov_len;
}
assert(length <= NBD_MAX_BUFFER_SIZE + sizeof(NBDStructuredReadData));
if (client->mode >= NBD_MODE_EXTENDED) {
NBDExtendedReplyChunk *chunk = iov->iov_base;
iov[0].iov_len = sizeof(*chunk);
stl_be_p(&chunk->magic, NBD_EXTENDED_REPLY_MAGIC);
stw_be_p(&chunk->flags, flags);
stw_be_p(&chunk->type, type);
stq_be_p(&chunk->cookie, request->cookie);
stq_be_p(&chunk->offset, request->from);
stq_be_p(&chunk->length, length);
} else {
NBDStructuredReplyChunk *chunk = iov->iov_base;
iov[0].iov_len = sizeof(*chunk);
stl_be_p(&chunk->magic, NBD_STRUCTURED_REPLY_MAGIC);
stw_be_p(&chunk->flags, flags);
stw_be_p(&chunk->type, type);
stq_be_p(&chunk->cookie, request->cookie);
stl_be_p(&chunk->length, length);
}
}
static int coroutine_fn nbd_co_send_chunk_done(NBDClient *client,
NBDRequest *request,
Error **errp)
{
NBDReply hdr;
struct iovec iov[] = {
{.iov_base = &hdr},
};
trace_nbd_co_send_chunk_done(request->cookie);
set_be_chunk(client, iov, 1, NBD_REPLY_FLAG_DONE,
NBD_REPLY_TYPE_NONE, request);
return nbd_co_send_iov(client, iov, 1, errp);
}
static int coroutine_fn nbd_co_send_chunk_read(NBDClient *client,
NBDRequest *request,
uint64_t offset,
void *data,
uint64_t size,
bool final,
Error **errp)
{
NBDReply hdr;
NBDStructuredReadData chunk;
struct iovec iov[] = {
{.iov_base = &hdr},
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
{.iov_base = data, .iov_len = size}
};
assert(size && size <= NBD_MAX_BUFFER_SIZE);
trace_nbd_co_send_chunk_read(request->cookie, offset, data, size);
set_be_chunk(client, iov, 3, final ? NBD_REPLY_FLAG_DONE : 0,
NBD_REPLY_TYPE_OFFSET_DATA, request);
stq_be_p(&chunk.offset, offset);
return nbd_co_send_iov(client, iov, 3, errp);
}
static int coroutine_fn nbd_co_send_chunk_error(NBDClient *client,
NBDRequest *request,
uint32_t error,
const char *msg,
Error **errp)
{
NBDReply hdr;
NBDStructuredError chunk;
int nbd_err = system_errno_to_nbd_errno(error);
struct iovec iov[] = {
{.iov_base = &hdr},
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
{.iov_base = (char *)msg, .iov_len = msg ? strlen(msg) : 0},
};
assert(nbd_err);
trace_nbd_co_send_chunk_error(request->cookie, nbd_err,
nbd_err_lookup(nbd_err), msg ? msg : "");
set_be_chunk(client, iov, 3, NBD_REPLY_FLAG_DONE,
NBD_REPLY_TYPE_ERROR, request);
stl_be_p(&chunk.error, nbd_err);
stw_be_p(&chunk.message_length, iov[2].iov_len);
return nbd_co_send_iov(client, iov, 3, errp);
}
/* Do a sparse read and send the structured reply to the client.
* Returns -errno if sending fails. blk_co_block_status_above() failure is
* reported to the client, at which point this function succeeds.
*/
static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client,
NBDRequest *request,
uint64_t offset,
uint8_t *data,
uint64_t size,
Error **errp)
{
int ret = 0;
NBDExport *exp = client->exp;
size_t progress = 0;
assert(size <= NBD_MAX_BUFFER_SIZE);
while (progress < size) {
int64_t pnum;
int status = blk_co_block_status_above(exp->common.blk, NULL,
offset + progress,
size - progress, &pnum, NULL,
NULL);
bool final;
if (status < 0) {
char *msg = g_strdup_printf("unable to check for holes: %s",
strerror(-status));
ret = nbd_co_send_chunk_error(client, request, -status, msg, errp);
g_free(msg);
return ret;
}
assert(pnum && pnum <= size - progress);
final = progress + pnum == size;
if (status & BDRV_BLOCK_ZERO) {
NBDReply hdr;
NBDStructuredReadHole chunk;
struct iovec iov[] = {
{.iov_base = &hdr},
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
};
trace_nbd_co_send_chunk_read_hole(request->cookie,
offset + progress, pnum);
set_be_chunk(client, iov, 2,
final ? NBD_REPLY_FLAG_DONE : 0,
NBD_REPLY_TYPE_OFFSET_HOLE, request);
stq_be_p(&chunk.offset, offset + progress);
stl_be_p(&chunk.length, pnum);
ret = nbd_co_send_iov(client, iov, 2, errp);
} else {
ret = blk_co_pread(exp->common.blk, offset + progress, pnum,
data + progress, 0);
if (ret < 0) {
error_setg_errno(errp, -ret, "reading from file failed");
break;
}
ret = nbd_co_send_chunk_read(client, request, offset + progress,
data + progress, pnum, final, errp);
}
if (ret < 0) {
break;
}
progress += pnum;
}
return ret;
}
typedef struct NBDExtentArray {
NBDExtent64 *extents;
unsigned int nb_alloc;
unsigned int count;
uint64_t total_length;
bool extended;
bool can_add;
bool converted_to_be;
} NBDExtentArray;
static NBDExtentArray *nbd_extent_array_new(unsigned int nb_alloc,
NBDMode mode)
{
NBDExtentArray *ea = g_new0(NBDExtentArray, 1);
assert(mode >= NBD_MODE_STRUCTURED);
ea->nb_alloc = nb_alloc;
ea->extents = g_new(NBDExtent64, nb_alloc);
ea->extended = mode >= NBD_MODE_EXTENDED;
ea->can_add = true;
return ea;
}
static void nbd_extent_array_free(NBDExtentArray *ea)
{
g_free(ea->extents);
g_free(ea);
}
G_DEFINE_AUTOPTR_CLEANUP_FUNC(NBDExtentArray, nbd_extent_array_free)
/* Further modifications of the array after conversion are abandoned */
static void nbd_extent_array_convert_to_be(NBDExtentArray *ea)
{
int i;
assert(!ea->converted_to_be);
assert(ea->extended);
ea->can_add = false;
ea->converted_to_be = true;
for (i = 0; i < ea->count; i++) {
ea->extents[i].length = cpu_to_be64(ea->extents[i].length);
ea->extents[i].flags = cpu_to_be64(ea->extents[i].flags);
}
}
/* Further modifications of the array after conversion are abandoned */
static NBDExtent32 *nbd_extent_array_convert_to_narrow(NBDExtentArray *ea)
{
int i;
NBDExtent32 *extents = g_new(NBDExtent32, ea->count);
assert(!ea->converted_to_be);
assert(!ea->extended);
ea->can_add = false;
ea->converted_to_be = true;
for (i = 0; i < ea->count; i++) {
assert((ea->extents[i].length | ea->extents[i].flags) <= UINT32_MAX);
extents[i].length = cpu_to_be32(ea->extents[i].length);
extents[i].flags = cpu_to_be32(ea->extents[i].flags);
}
return extents;
}
/*
* Add extent to NBDExtentArray. If extent can't be added (no available space),
* return -1.
* For safety, when returning -1 for the first time, .can_add is set to false,
* and further calls to nbd_extent_array_add() will crash.
* (this avoids the situation where a caller ignores failure to add one extent,
* where adding another extent that would squash into the last array entry
* would result in an incorrect range reported to the client)
*/
static int nbd_extent_array_add(NBDExtentArray *ea,
uint64_t length, uint32_t flags)
{
assert(ea->can_add);
if (!length) {
return 0;
}
if (!ea->extended) {
assert(length <= UINT32_MAX);
}
/* Extend previous extent if flags are the same */
if (ea->count > 0 && flags == ea->extents[ea->count - 1].flags) {
uint64_t sum = length + ea->extents[ea->count - 1].length;
/*
* sum cannot overflow: the block layer bounds image size at
* 2^63, and ea->extents[].length comes from the block layer.
*/
assert(sum >= length);
if (sum <= UINT32_MAX || ea->extended) {
ea->extents[ea->count - 1].length = sum;
ea->total_length += length;
return 0;
}
}
if (ea->count >= ea->nb_alloc) {
ea->can_add = false;
return -1;
}
ea->total_length += length;
ea->extents[ea->count] = (NBDExtent64) {.length = length, .flags = flags};
ea->count++;
return 0;
}
static int coroutine_fn blockstatus_to_extents(BlockBackend *blk,
uint64_t offset, uint64_t bytes,
NBDExtentArray *ea)
{
while (bytes) {
uint32_t flags;
int64_t num;
int ret = blk_co_block_status_above(blk, NULL, offset, bytes, &num,
NULL, NULL);
if (ret < 0) {
return ret;
}
flags = (ret & BDRV_BLOCK_DATA ? 0 : NBD_STATE_HOLE) |
(ret & BDRV_BLOCK_ZERO ? NBD_STATE_ZERO : 0);
if (nbd_extent_array_add(ea, num, flags) < 0) {
return 0;
}
offset += num;
bytes -= num;
}
return 0;
}
static int coroutine_fn blockalloc_to_extents(BlockBackend *blk,
uint64_t offset, uint64_t bytes,
NBDExtentArray *ea)
{
while (bytes) {
int64_t num;
int ret = blk_co_is_allocated_above(blk, NULL, false, offset, bytes,
&num);
if (ret < 0) {
return ret;
}
if (nbd_extent_array_add(ea, num, ret) < 0) {
return 0;
}
offset += num;
bytes -= num;
}
return 0;
}
/*
* nbd_co_send_extents
*
* @ea is converted to BE by the function
* @last controls whether NBD_REPLY_FLAG_DONE is sent.
*/
static int coroutine_fn
nbd_co_send_extents(NBDClient *client, NBDRequest *request, NBDExtentArray *ea,
bool last, uint32_t context_id, Error **errp)
{
NBDReply hdr;
NBDStructuredMeta meta;
NBDExtendedMeta meta_ext;
g_autofree NBDExtent32 *extents = NULL;
uint16_t type;
struct iovec iov[] = { {.iov_base = &hdr}, {0}, {0} };
if (client->mode >= NBD_MODE_EXTENDED) {
type = NBD_REPLY_TYPE_BLOCK_STATUS_EXT;
iov[1].iov_base = &meta_ext;
iov[1].iov_len = sizeof(meta_ext);
stl_be_p(&meta_ext.context_id, context_id);
stl_be_p(&meta_ext.count, ea->count);
nbd_extent_array_convert_to_be(ea);
iov[2].iov_base = ea->extents;
iov[2].iov_len = ea->count * sizeof(ea->extents[0]);
} else {
type = NBD_REPLY_TYPE_BLOCK_STATUS;
iov[1].iov_base = &meta;
iov[1].iov_len = sizeof(meta);
stl_be_p(&meta.context_id, context_id);
extents = nbd_extent_array_convert_to_narrow(ea);
iov[2].iov_base = extents;
iov[2].iov_len = ea->count * sizeof(extents[0]);
}
trace_nbd_co_send_extents(request->cookie, ea->count, context_id,
ea->total_length, last);
set_be_chunk(client, iov, 3, last ? NBD_REPLY_FLAG_DONE : 0, type,
request);
return nbd_co_send_iov(client, iov, 3, errp);
}
/* Get block status from the exported device and send it to the client */
static int
coroutine_fn nbd_co_send_block_status(NBDClient *client, NBDRequest *request,
BlockBackend *blk, uint64_t offset,
uint64_t length, bool dont_fragment,
bool last, uint32_t context_id,
Error **errp)
{
int ret;
unsigned int nb_extents = dont_fragment ? 1 : NBD_MAX_BLOCK_STATUS_EXTENTS;
g_autoptr(NBDExtentArray) ea =
nbd_extent_array_new(nb_extents, client->mode);
if (context_id == NBD_META_ID_BASE_ALLOCATION) {
ret = blockstatus_to_extents(blk, offset, length, ea);
} else {
ret = blockalloc_to_extents(blk, offset, length, ea);
}
if (ret < 0) {
return nbd_co_send_chunk_error(client, request, -ret,
"can't get block status", errp);
}
return nbd_co_send_extents(client, request, ea, last, context_id, errp);
}
/* Populate @ea from a dirty bitmap. */
static void bitmap_to_extents(BdrvDirtyBitmap *bitmap,
uint64_t offset, uint64_t length,
NBDExtentArray *es)
{
int64_t start, dirty_start, dirty_count;
int64_t end = offset + length;
bool full = false;
int64_t bound = es->extended ? INT64_MAX : INT32_MAX;
bdrv_dirty_bitmap_lock(bitmap);
for (start = offset;
bdrv_dirty_bitmap_next_dirty_area(bitmap, start, end, bound,
&dirty_start, &dirty_count);
start = dirty_start + dirty_count)
{
if ((nbd_extent_array_add(es, dirty_start - start, 0) < 0) ||
(nbd_extent_array_add(es, dirty_count, NBD_STATE_DIRTY) < 0))
{
full = true;
break;
}
}
if (!full) {
/* last non dirty extent, nothing to do if array is now full */
(void) nbd_extent_array_add(es, end - start, 0);
}
bdrv_dirty_bitmap_unlock(bitmap);
}
static int coroutine_fn nbd_co_send_bitmap(NBDClient *client,
NBDRequest *request,
BdrvDirtyBitmap *bitmap,
uint64_t offset,
uint64_t length, bool dont_fragment,
bool last, uint32_t context_id,
Error **errp)
{
unsigned int nb_extents = dont_fragment ? 1 : NBD_MAX_BLOCK_STATUS_EXTENTS;
g_autoptr(NBDExtentArray) ea =
nbd_extent_array_new(nb_extents, client->mode);
bitmap_to_extents(bitmap, offset, length, ea);
return nbd_co_send_extents(client, request, ea, last, context_id, errp);
}
/*
* nbd_co_block_status_payload_read
* Called when a client wants a subset of negotiated contexts via a
* BLOCK_STATUS payload. Check the payload for valid length and
* contents. On success, return 0 with request updated to effective
* length. If request was invalid but all payload consumed, return 0
* with request->len and request->contexts->count set to 0 (which will
* trigger an appropriate NBD_EINVAL response later on). Return
* negative errno if the payload was not fully consumed.
*/
static int
nbd_co_block_status_payload_read(NBDClient *client, NBDRequest *request,
Error **errp)
{
uint64_t payload_len = request->len;
g_autofree char *buf = NULL;
size_t count, i, nr_bitmaps;
uint32_t id;
if (payload_len > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "len (%" PRIu64 ") is larger than max len (%u)",
request->len, NBD_MAX_BUFFER_SIZE);
return -EINVAL;
}
assert(client->contexts.exp == client->exp);
nr_bitmaps = client->exp->nr_export_bitmaps;
request->contexts = g_new0(NBDMetaContexts, 1);
request->contexts->exp = client->exp;
if (payload_len % sizeof(uint32_t) ||
payload_len < sizeof(NBDBlockStatusPayload) ||
payload_len > (sizeof(NBDBlockStatusPayload) +
sizeof(id) * client->contexts.count)) {
goto skip;
}
buf = g_malloc(payload_len);
if (nbd_read(client->ioc, buf, payload_len,
"CMD_BLOCK_STATUS data", errp) < 0) {
return -EIO;
}
trace_nbd_co_receive_request_payload_received(request->cookie,
payload_len);
request->contexts->bitmaps = g_new0(bool, nr_bitmaps);
count = (payload_len - sizeof(NBDBlockStatusPayload)) / sizeof(id);
payload_len = 0;
for (i = 0; i < count; i++) {
id = ldl_be_p(buf + sizeof(NBDBlockStatusPayload) + sizeof(id) * i);
if (id == NBD_META_ID_BASE_ALLOCATION) {
if (!client->contexts.base_allocation ||
request->contexts->base_allocation) {
goto skip;
}
request->contexts->base_allocation = true;
} else if (id == NBD_META_ID_ALLOCATION_DEPTH) {
if (!client->contexts.allocation_depth ||
request->contexts->allocation_depth) {
goto skip;
}
request->contexts->allocation_depth = true;
} else {
unsigned idx = id - NBD_META_ID_DIRTY_BITMAP;
if (idx >= nr_bitmaps || !client->contexts.bitmaps[idx] ||
request->contexts->bitmaps[idx]) {
goto skip;
}
request->contexts->bitmaps[idx] = true;
}
}
request->len = ldq_be_p(buf);
request->contexts->count = count;
return 0;
skip:
trace_nbd_co_receive_block_status_payload_compliance(request->from,
request->len);
request->len = request->contexts->count = 0;
return nbd_drop(client->ioc, payload_len, errp);
}
/* nbd_co_receive_request
* Collect a client request. Return 0 if request looks valid, -EIO to drop
* connection right away, -EAGAIN to indicate we were interrupted and the
* channel should be quiesced, and any other negative value to report an error
* to the client (although the caller may still need to disconnect after
* reporting the error).
*/
static int coroutine_fn nbd_co_receive_request(NBDRequestData *req,
NBDRequest *request,
Error **errp)
{
NBDClient *client = req->client;
bool extended_with_payload;
bool check_length = false;
bool check_rofs = false;
bool allocate_buffer = false;
bool payload_okay = false;
uint64_t payload_len = 0;
int valid_flags = NBD_CMD_FLAG_FUA;
int ret;
g_assert(qemu_in_coroutine());
ret = nbd_receive_request(client, request, errp);
if (ret < 0) {
return ret;
}
trace_nbd_co_receive_request_decode_type(request->cookie, request->type,
nbd_cmd_lookup(request->type));
extended_with_payload = client->mode >= NBD_MODE_EXTENDED &&
request->flags & NBD_CMD_FLAG_PAYLOAD_LEN;
if (extended_with_payload) {
payload_len = request->len;
check_length = true;
}
switch (request->type) {
case NBD_CMD_DISC:
/* Special case: we're going to disconnect without a reply,
* whether or not flags, from, or len are bogus */
req->complete = true;
return -EIO;
case NBD_CMD_READ:
if (client->mode >= NBD_MODE_STRUCTURED) {
valid_flags |= NBD_CMD_FLAG_DF;
}
check_length = true;
allocate_buffer = true;
break;
case NBD_CMD_WRITE:
if (client->mode >= NBD_MODE_EXTENDED) {
if (!extended_with_payload) {
/* The client is noncompliant. Trace it, but proceed. */
trace_nbd_co_receive_ext_payload_compliance(request->from,
request->len);
}
valid_flags |= NBD_CMD_FLAG_PAYLOAD_LEN;
}
payload_okay = true;
payload_len = request->len;
check_length = true;
allocate_buffer = true;
check_rofs = true;
break;
case NBD_CMD_FLUSH:
break;
case NBD_CMD_TRIM:
check_rofs = true;
break;
case NBD_CMD_CACHE:
break;
case NBD_CMD_WRITE_ZEROES:
valid_flags |= NBD_CMD_FLAG_NO_HOLE | NBD_CMD_FLAG_FAST_ZERO;
check_rofs = true;
break;
case NBD_CMD_BLOCK_STATUS:
if (extended_with_payload) {
ret = nbd_co_block_status_payload_read(client, request, errp);
if (ret < 0) {
return ret;
}
/* payload now consumed */
check_length = false;
payload_len = 0;
valid_flags |= NBD_CMD_FLAG_PAYLOAD_LEN;
} else {
request->contexts = &client->contexts;
}
valid_flags |= NBD_CMD_FLAG_REQ_ONE;
break;
default:
/* Unrecognized, will fail later */
;
}
/* Payload and buffer handling. */
if (!payload_len) {
req->complete = true;
}
if (check_length && request->len > NBD_MAX_BUFFER_SIZE) {
/* READ, WRITE */
error_setg(errp, "len (%" PRIu64 ") is larger than max len (%u)",
request->len, NBD_MAX_BUFFER_SIZE);
return -EINVAL;
}
if (payload_len && !payload_okay) {
/*
* For now, we don't support payloads on other commands; but
* we can keep the connection alive by ignoring the payload.
* We will fail the command later with NBD_EINVAL for the use
* of an unsupported flag (and not for access beyond bounds).
*/
assert(request->type != NBD_CMD_WRITE);
request->len = 0;
}
if (allocate_buffer) {
/* READ, WRITE */
req->data = blk_try_blockalign(client->exp->common.blk,
request->len);
if (req->data == NULL) {
error_setg(errp, "No memory");
return -ENOMEM;
}
}
if (payload_len) {
if (payload_okay) {
/* WRITE */
assert(req->data);
ret = nbd_read(client->ioc, req->data, payload_len,
"CMD_WRITE data", errp);
} else {
ret = nbd_drop(client->ioc, payload_len, errp);
}
if (ret < 0) {
return -EIO;
}
req->complete = true;
trace_nbd_co_receive_request_payload_received(request->cookie,
payload_len);
}
/* Sanity checks. */
if (client->exp->nbdflags & NBD_FLAG_READ_ONLY && check_rofs) {
/* WRITE, TRIM, WRITE_ZEROES */
error_setg(errp, "Export is read-only");
return -EROFS;
}
if (request->from > client->exp->size ||
request->len > client->exp->size - request->from) {
error_setg(errp, "operation past EOF; From: %" PRIu64 ", Len: %" PRIu64
", Size: %" PRIu64, request->from, request->len,
client->exp->size);
return (request->type == NBD_CMD_WRITE ||
request->type == NBD_CMD_WRITE_ZEROES) ? -ENOSPC : -EINVAL;
}
if (client->check_align && !QEMU_IS_ALIGNED(request->from | request->len,
client->check_align)) {
/*
* The block layer gracefully handles unaligned requests, but
* it's still worth tracing client non-compliance
*/
trace_nbd_co_receive_align_compliance(nbd_cmd_lookup(request->type),
request->from,
request->len,
client->check_align);
}
if (request->flags & ~valid_flags) {
error_setg(errp, "unsupported flags for command %s (got 0x%x)",
nbd_cmd_lookup(request->type), request->flags);
return -EINVAL;
}
return 0;
}
/* Send simple reply without a payload, or a structured error
* @error_msg is ignored if @ret >= 0
* Returns 0 if connection is still live, -errno on failure to talk to client
*/
static coroutine_fn int nbd_send_generic_reply(NBDClient *client,
NBDRequest *request,
int ret,
const char *error_msg,
Error **errp)
{
if (client->mode >= NBD_MODE_STRUCTURED && ret < 0) {
return nbd_co_send_chunk_error(client, request, -ret, error_msg, errp);
} else if (client->mode >= NBD_MODE_EXTENDED) {
return nbd_co_send_chunk_done(client, request, errp);
} else {
return nbd_co_send_simple_reply(client, request, ret < 0 ? -ret : 0,
NULL, 0, errp);
}
}
/* Handle NBD_CMD_READ request.
* Return -errno if sending fails. Other errors are reported directly to the
* client as an error reply. */
static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request,
uint8_t *data, Error **errp)
{
int ret;
NBDExport *exp = client->exp;
assert(request->type == NBD_CMD_READ);
assert(request->len <= NBD_MAX_BUFFER_SIZE);
/* XXX: NBD Protocol only documents use of FUA with WRITE */
if (request->flags & NBD_CMD_FLAG_FUA) {
ret = blk_co_flush(exp->common.blk);
if (ret < 0) {
return nbd_send_generic_reply(client, request, ret,
"flush failed", errp);
}
}
if (client->mode >= NBD_MODE_STRUCTURED &&
!(request->flags & NBD_CMD_FLAG_DF) && request->len)
{
return nbd_co_send_sparse_read(client, request, request->from,
data, request->len, errp);
}
ret = blk_co_pread(exp->common.blk, request->from, request->len, data, 0);
if (ret < 0) {
return nbd_send_generic_reply(client, request, ret,
"reading from file failed", errp);
}
if (client->mode >= NBD_MODE_STRUCTURED) {
if (request->len) {
return nbd_co_send_chunk_read(client, request, request->from, data,
request->len, true, errp);
} else {
return nbd_co_send_chunk_done(client, request, errp);
}
} else {
return nbd_co_send_simple_reply(client, request, 0,
data, request->len, errp);
}
}
/*
* nbd_do_cmd_cache
*
* Handle NBD_CMD_CACHE request.
* Return -errno if sending fails. Other errors are reported directly to the
* client as an error reply.
*/
static coroutine_fn int nbd_do_cmd_cache(NBDClient *client, NBDRequest *request,
Error **errp)
{
int ret;
NBDExport *exp = client->exp;
assert(request->type == NBD_CMD_CACHE);
ret = blk_co_preadv(exp->common.blk, request->from, request->len,
NULL, BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH);
return nbd_send_generic_reply(client, request, ret,
"caching data failed", errp);
}
/* Handle NBD request.
* Return -errno if sending fails. Other errors are reported directly to the
* client as an error reply. */
static coroutine_fn int nbd_handle_request(NBDClient *client,
NBDRequest *request,
uint8_t *data, Error **errp)
{
int ret;
int flags;
NBDExport *exp = client->exp;
char *msg;
size_t i;
bool inactive;
WITH_GRAPH_RDLOCK_GUARD() {
inactive = bdrv_is_inactive(blk_bs(exp->common.blk));
if (inactive) {
switch (request->type) {
case NBD_CMD_READ:
/* These commands are allowed on inactive nodes */
break;
default:
/* Return an error for the rest */
return nbd_send_generic_reply(client, request, -EPERM,
"export is inactive", errp);
}
}
}
switch (request->type) {
case NBD_CMD_CACHE:
return nbd_do_cmd_cache(client, request, errp);
case NBD_CMD_READ:
return nbd_do_cmd_read(client, request, data, errp);
case NBD_CMD_WRITE:
flags = 0;
if (request->flags & NBD_CMD_FLAG_FUA) {
flags |= BDRV_REQ_FUA;
}
assert(request->len <= NBD_MAX_BUFFER_SIZE);
ret = blk_co_pwrite(exp->common.blk, request->from, request->len, data,
flags);
return nbd_send_generic_reply(client, request, ret,
"writing to file failed", errp);
case NBD_CMD_WRITE_ZEROES:
flags = 0;
if (request->flags & NBD_CMD_FLAG_FUA) {
flags |= BDRV_REQ_FUA;
}
if (!(request->flags & NBD_CMD_FLAG_NO_HOLE)) {
flags |= BDRV_REQ_MAY_UNMAP;
}
if (request->flags & NBD_CMD_FLAG_FAST_ZERO) {
flags |= BDRV_REQ_NO_FALLBACK;
}
ret = blk_co_pwrite_zeroes(exp->common.blk, request->from, request->len,
flags);
return nbd_send_generic_reply(client, request, ret,
"writing to file failed", errp);
case NBD_CMD_DISC:
/* unreachable, thanks to special case in nbd_co_receive_request() */
abort();
case NBD_CMD_FLUSH:
ret = blk_co_flush(exp->common.blk);
return nbd_send_generic_reply(client, request, ret,
"flush failed", errp);
case NBD_CMD_TRIM:
ret = blk_co_pdiscard(exp->common.blk, request->from, request->len, 0);
if (ret >= 0 && request->flags & NBD_CMD_FLAG_FUA) {
ret = blk_co_flush(exp->common.blk);
}
return nbd_send_generic_reply(client, request, ret,
"discard failed", errp);
case NBD_CMD_BLOCK_STATUS:
assert(request->contexts);
assert(client->mode >= NBD_MODE_EXTENDED ||
request->len <= UINT32_MAX);
if (request->contexts->count) {
bool dont_fragment = request->flags & NBD_CMD_FLAG_REQ_ONE;
int contexts_remaining = request->contexts->count;
if (!request->len) {
return nbd_send_generic_reply(client, request, -EINVAL,
"need non-zero length", errp);
}
if (request->contexts->base_allocation) {
ret = nbd_co_send_block_status(client, request,
exp->common.blk,
request->from,
request->len, dont_fragment,
!--contexts_remaining,
NBD_META_ID_BASE_ALLOCATION,
errp);
if (ret < 0) {
return ret;
}
}
if (request->contexts->allocation_depth) {
ret = nbd_co_send_block_status(client, request,
exp->common.blk,
request->from, request->len,
dont_fragment,
!--contexts_remaining,
NBD_META_ID_ALLOCATION_DEPTH,
errp);
if (ret < 0) {
return ret;
}
}
assert(request->contexts->exp == client->exp);
for (i = 0; i < client->exp->nr_export_bitmaps; i++) {
if (!request->contexts->bitmaps[i]) {
continue;
}
ret = nbd_co_send_bitmap(client, request,
client->exp->export_bitmaps[i],
request->from, request->len,
dont_fragment, !--contexts_remaining,
NBD_META_ID_DIRTY_BITMAP + i, errp);
if (ret < 0) {
return ret;
}
}
assert(!contexts_remaining);
return 0;
} else if (client->contexts.count) {
return nbd_send_generic_reply(client, request, -EINVAL,
"CMD_BLOCK_STATUS payload not valid",
errp);
} else {
return nbd_send_generic_reply(client, request, -EINVAL,
"CMD_BLOCK_STATUS not negotiated",
errp);
}
default:
msg = g_strdup_printf("invalid request type (%" PRIu32 ") received",
request->type);
ret = nbd_send_generic_reply(client, request, -EINVAL, msg,
errp);
g_free(msg);
return ret;
}
}
/* Owns a reference to the NBDClient passed as opaque. */
static coroutine_fn void nbd_trip(void *opaque)
{
NBDRequestData *req = opaque;
NBDClient *client = req->client;
NBDRequest request = { 0 }; /* GCC thinks it can be used uninitialized */
int ret;
Error *local_err = NULL;
/*
* Note that nbd_client_put() and client_close() must be called from the
* main loop thread. Use aio_co_reschedule_self() to switch AioContext
* before calling these functions.
*/
trace_nbd_trip();
qemu_mutex_lock(&client->lock);
if (client->closing) {
goto done;
}
if (client->quiescing) {
/*
* We're switching between AIO contexts. Don't attempt to receive a new
* request and kick the main context which may be waiting for us.
*/
client->recv_coroutine = NULL;
aio_wait_kick();
goto done;
}
/*
* nbd_co_receive_request() returns -EAGAIN when nbd_drained_begin() has
* set client->quiescing but by the time we get back nbd_drained_end() may
* have already cleared client->quiescing. In that case we try again
* because nothing else will spawn an nbd_trip() coroutine until we set
* client->recv_coroutine = NULL further down.
*/
do {
assert(client->recv_coroutine == qemu_coroutine_self());
qemu_mutex_unlock(&client->lock);
ret = nbd_co_receive_request(req, &request, &local_err);
qemu_mutex_lock(&client->lock);
} while (ret == -EAGAIN && !client->quiescing);
client->recv_coroutine = NULL;
if (client->closing) {
/*
* The client may be closed when we are blocked in
* nbd_co_receive_request()
*/
goto done;
}
if (ret == -EAGAIN) {
goto done;
}
nbd_client_receive_next_request(client);
if (ret == -EIO) {
goto disconnect;
}
qemu_mutex_unlock(&client->lock);
qio_channel_set_cork(client->ioc, true);
if (ret < 0) {
/* It wasn't -EIO, so, according to nbd_co_receive_request()
* semantics, we should return the error to the client. */
Error *export_err = local_err;
local_err = NULL;
ret = nbd_send_generic_reply(client, &request, -EINVAL,
error_get_pretty(export_err), &local_err);
error_free(export_err);
} else {
ret = nbd_handle_request(client, &request, req->data, &local_err);
}
if (request.contexts && request.contexts != &client->contexts) {
assert(request.type == NBD_CMD_BLOCK_STATUS);
g_free(request.contexts->bitmaps);
g_free(request.contexts);
}
qio_channel_set_cork(client->ioc, false);
qemu_mutex_lock(&client->lock);
if (ret < 0) {
error_prepend(&local_err, "Failed to send reply: ");
goto disconnect;
}
/*
* We must disconnect after NBD_CMD_WRITE or BLOCK_STATUS with
* payload if we did not read the payload.
*/
if (!req->complete) {
error_setg(&local_err, "Request handling failed in intermediate state");
goto disconnect;
}
done:
nbd_request_put(req);
qemu_mutex_unlock(&client->lock);
if (!nbd_client_put_nonzero(client)) {
aio_co_reschedule_self(qemu_get_aio_context());
nbd_client_put(client);
}
return;
disconnect:
if (local_err) {
error_reportf_err(local_err, "Disconnect client, due to: ");
}
nbd_request_put(req);
qemu_mutex_unlock(&client->lock);
aio_co_reschedule_self(qemu_get_aio_context());
client_close(client, true);
nbd_client_put(client);
}
/*
* Runs in export AioContext and main loop thread. Caller must hold
* client->lock.
*/
static void nbd_client_receive_next_request(NBDClient *client)
{
NBDRequestData *req;
if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS &&
!client->quiescing) {
nbd_client_get(client);
req = nbd_request_get(client);
client->recv_coroutine = qemu_coroutine_create(nbd_trip, req);
aio_co_schedule(client->exp->common.ctx, client->recv_coroutine);
}
}
static void nbd_handshake_timer_cb(void *opaque)
{
QIOChannel *ioc = opaque;
trace_nbd_handshake_timer_cb();
qio_channel_shutdown(ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
}
static coroutine_fn void nbd_co_client_start(void *opaque)
{
NBDClient *client = opaque;
Error *local_err = NULL;
QEMUTimer *handshake_timer = NULL;
qemu_co_mutex_init(&client->send_lock);
/*
* Create a timer to bound the time spent in negotiation. If the
* timer expires, it is likely nbd_negotiate will fail because the
* socket was shutdown.
*/
if (client->handshake_max_secs > 0) {
handshake_timer = aio_timer_new(qemu_get_aio_context(),
QEMU_CLOCK_REALTIME,
SCALE_NS,
nbd_handshake_timer_cb,
client->sioc);
timer_mod(handshake_timer,
qemu_clock_get_ns(QEMU_CLOCK_REALTIME) +
client->handshake_max_secs * NANOSECONDS_PER_SECOND);
}
if (nbd_negotiate(client, &local_err)) {
if (local_err) {
error_report_err(local_err);
}
timer_free(handshake_timer);
client_close(client, false);
return;
}
timer_free(handshake_timer);
WITH_QEMU_LOCK_GUARD(&client->lock) {
nbd_client_receive_next_request(client);
}
}
/*
* Create a new client listener using the given channel @sioc and @owner.
* Begin servicing it in a coroutine. When the connection closes, call
* @close_fn with an indication of whether the client completed negotiation
* within @handshake_max_secs seconds (0 for unbounded).
*/
void nbd_client_new(QIOChannelSocket *sioc,
uint32_t handshake_max_secs,
QCryptoTLSCreds *tlscreds,
const char *tlsauthz,
void (*close_fn)(NBDClient *, bool),
void *owner)
{
NBDClient *client;
Coroutine *co;
client = g_new0(NBDClient, 1);
qemu_mutex_init(&client->lock);
client->refcount = 1;
client->tlscreds = tlscreds;
if (tlscreds) {
object_ref(OBJECT(client->tlscreds));
}
client->tlsauthz = g_strdup(tlsauthz);
client->handshake_max_secs = handshake_max_secs;
client->sioc = sioc;
qio_channel_set_delay(QIO_CHANNEL(sioc), false);
object_ref(OBJECT(client->sioc));
client->ioc = QIO_CHANNEL(sioc);
object_ref(OBJECT(client->ioc));
client->close_fn = close_fn;
client->owner = owner;
nbd_set_socket_send_buffer(sioc);
co = qemu_coroutine_create(nbd_co_client_start, client);
qemu_coroutine_enter(co);
}
void *
nbd_client_owner(NBDClient *client)
{
return client->owner;
}