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f1426881a8
qemu/nbd/server.c
Eric Blake f1426881a8 nbd/server: Request TCP_NODELAY 
Nagle's algorithm adds latency in order to reduce network packet
overhead on small packets.  But when we are already using corking to
merge smaller packets into transactional requests, the extra delay
from TCP defaults just gets in the way (see recent commit bd2cd4a4).

For reference, qemu as an NBD client already requests TCP_NODELAY (see
nbd_connect() in nbd/client-connection.c); as does libnbd as a client
[1], and nbdkit as a server [2].  Furthermore, the NBD spec recommends
the use of TCP_NODELAY [3].

[1] https://gitlab.com/nbdkit/libnbd/-/blob/a48a1142/generator/states-connect.c#L39
[2] https://gitlab.com/nbdkit/nbdkit/-/blob/45b72f5b/server/sockets.c#L430
[3] https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md#protocol-phases

CC: Florian Westphal <fw@strlen.de>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20230404004047.142086-1-eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
2023-04-04 08:13:15 -05:00

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/*
* Copyright (C) 2016-2022 Red Hat, Inc.
* 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);
/* NBDExportMetaContexts represents a list of contexts to be exported,
* as selected by NBD_OPT_SET_META_CONTEXT. Also used for
* NBD_OPT_LIST_META_CONTEXT. */
typedef struct NBDExportMetaContexts {
NBDExport *exp;
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
*/
} NBDExportMetaContexts;
struct NBDClient {
int refcount;
void (*close_fn)(NBDClient *client, bool negotiated);
NBDExport *exp;
QCryptoTLSCreds *tlscreds;
char *tlsauthz;
QIOChannelSocket *sioc; /* The underlying data channel */
QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
Coroutine *recv_coroutine;
CoMutex send_lock;
Coroutine *send_coroutine;
bool read_yielding;
bool quiescing;
QTAILQ_ENTRY(NBDClient) next;
int nb_requests;
bool closing;
uint32_t check_align; /* If non-zero, check for aligned client requests */
bool structured_reply;
NBDExportMetaContexts export_meta;
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 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 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 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 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 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 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 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 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 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 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 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 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 void nbd_check_meta_export(NBDClient *client)
{
if (client->exp != client->export_meta.exp) {
client->export_meta.count = 0;
}
}
/* Send a reply to NBD_OPT_EXPORT_NAME.
* Return -errno on error, 0 on success. */
static 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->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;
}
myflags = client->exp->nbdflags;
if (client->structured_reply) {
myflags |= NBD_FLAG_SEND_DF;
}
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);
nbd_check_meta_export(client);
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 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 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 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);
}
/* 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->structured_reply) {
myflags |= NBD_FLAG_SEND_DF;
}
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);
nbd_check_meta_export(client);
rc = 1;
}
return rc;
}
/* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
* new channel for all further (now-encrypted) communication. */
static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
Error **errp)
{
QIOChannel *ioc;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData 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.loop = g_main_loop_new(g_main_context_default(), FALSE);
qio_channel_tls_handshake(tioc,
nbd_tls_handshake,
&data,
NULL,
NULL);
if (!data.complete) {
g_main_loop_run(data.loop);
}
g_main_loop_unref(data.loop);
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 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 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 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 bool nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *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 bool nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *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 int nbd_negotiate_meta_query(NBDClient *client,
NBDExportMetaContexts *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 int nbd_negotiate_meta_queries(NBDClient *client,
NBDExportMetaContexts *meta, 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;
NBDExportMetaContexts local_meta = {0};
uint32_t nb_queries;
size_t i;
size_t count = 0;
if (client->opt == NBD_OPT_SET_META_CONTEXT && !client->structured_reply) {
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;
}
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,
* errp is not set
*/
static 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
*/
if (nbd_read32(client->ioc, &flags, "flags", errp) < 0) {
return -EIO;
}
trace_nbd_negotiate_options_flags(flags);
if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
fixedNewstyle = true;
flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
}
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 = QIO_CHANNEL(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->structured_reply) {
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->structured_reply = true;
}
break;
case NBD_OPT_LIST_META_CONTEXT:
case NBD_OPT_SET_META_CONTEXT:
ret = nbd_negotiate_meta_queries(client, &client->export_meta,
errp);
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,
* 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....
*/
qio_channel_set_blocking(client->ioc, false, NULL);
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);
if (nbd_write(client->ioc, buf, 18, errp) < 0) {
error_prepend(errp, "write failed: ");
return -EINVAL;
}
ret = nbd_negotiate_options(client, errp);
if (ret != 0) {
if (ret < 0) {
error_prepend(errp, "option negotiation failed: ");
}
return ret;
}
/* Attach the channel to the same AioContext as the export */
if (client->exp && client->exp->common.ctx) {
qio_channel_attach_aio_context(client->ioc, client->exp->common.ctx);
}
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) {
client->read_yielding = true;
qio_channel_yield(client->ioc, G_IO_IN);
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 nbd_receive_request(NBDClient *client, NBDRequest *request,
Error **errp)
{
uint8_t buf[NBD_REQUEST_SIZE];
uint32_t magic;
int ret;
ret = nbd_read_eof(client, buf, sizeof(buf), errp);
if (ret < 0) {
return ret;
}
if (ret == 0) {
return -EIO;
}
/* Request
[ 0 .. 3] magic (NBD_REQUEST_MAGIC)
[ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
[ 6 .. 7] type (NBD_CMD_READ, ...)
[ 8 .. 15] handle
[16 .. 23] from
[24 .. 27] len
*/
magic = ldl_be_p(buf);
request->flags = lduw_be_p(buf + 4);
request->type = lduw_be_p(buf + 6);
request->handle = ldq_be_p(buf + 8);
request->from = ldq_be_p(buf + 16);
request->len = ldl_be_p(buf + 24);
trace_nbd_receive_request(magic, request->flags, request->type,
request->from, request->len);
if (magic != NBD_REQUEST_MAGIC) {
error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
return -EINVAL;
}
return 0;
}
#define MAX_NBD_REQUESTS 16
void nbd_client_get(NBDClient *client)
{
client->refcount++;
}
void nbd_client_put(NBDClient *client)
{
if (--client->refcount == 0) {
/* The last reference should be dropped by client->close,
* which is called by client_close.
*/
assert(client->closing);
qio_channel_detach_aio_context(client->ioc);
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->export_meta.bitmaps);
g_free(client);
}
}
static void client_close(NBDClient *client, bool negotiated)
{
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);
}
}
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);
nbd_client_get(client);
req->client = client;
return req;
}
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);
nbd_client_put(client);
}
static void blk_aio_attached(AioContext *ctx, void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
trace_nbd_blk_aio_attached(exp->name, ctx);
exp->common.ctx = ctx;
QTAILQ_FOREACH(client, &exp->clients, next) {
qio_channel_attach_aio_context(client->ioc, ctx);
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;
NBDClient *client;
trace_nbd_blk_aio_detach(exp->name, exp->common.ctx);
QTAILQ_FOREACH(client, &exp->clients, next) {
qio_channel_detach_aio_context(client->ioc);
}
exp->common.ctx = NULL;
}
static void nbd_drained_begin(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
QTAILQ_FOREACH(client, &exp->clients, next) {
client->quiescing = true;
}
}
static void nbd_drained_end(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
QTAILQ_FOREACH(client, &exp->clients, next) {
client->quiescing = false;
nbd_client_receive_next_request(client);
}
}
static bool nbd_drained_poll(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
QTAILQ_FOREACH(client, &exp->clients, next) {
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.
*/
if (client->recv_coroutine != NULL && client->read_yielding) {
qemu_aio_coroutine_enter(exp->common.ctx,
client->recv_coroutine);
}
return true;
}
}
return false;
}
static void nbd_eject_notifier(Notifier *n, void *data)
{
NBDExport *exp = container_of(n, NBDExport, eject_notifier);
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,
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;
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;
}
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);
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);
return 0;
fail:
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 NbdServerRemoveNode 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->common.blk) {
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),
.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 handle)
{
stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC);
stl_be_p(&reply->error, error);
stq_be_p(&reply->handle, handle);
}
static int nbd_co_send_simple_reply(NBDClient *client,
uint64_t handle,
uint32_t error,
void *data,
size_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}
};
trace_nbd_co_send_simple_reply(handle, nbd_err, nbd_err_lookup(nbd_err),
len);
set_be_simple_reply(&reply, nbd_err, handle);
return nbd_co_send_iov(client, iov, len ? 2 : 1, errp);
}
static inline void set_be_chunk(NBDStructuredReplyChunk *chunk, uint16_t flags,
uint16_t type, uint64_t handle, uint32_t length)
{
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->handle, handle);
stl_be_p(&chunk->length, length);
}
static int coroutine_fn nbd_co_send_structured_done(NBDClient *client,
uint64_t handle,
Error **errp)
{
NBDStructuredReplyChunk chunk;
struct iovec iov[] = {
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
};
trace_nbd_co_send_structured_done(handle);
set_be_chunk(&chunk, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_NONE, handle, 0);
return nbd_co_send_iov(client, iov, 1, errp);
}
static int coroutine_fn nbd_co_send_structured_read(NBDClient *client,
uint64_t handle,
uint64_t offset,
void *data,
size_t size,
bool final,
Error **errp)
{
NBDStructuredReadData chunk;
struct iovec iov[] = {
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
{.iov_base = data, .iov_len = size}
};
assert(size);
trace_nbd_co_send_structured_read(handle, offset, data, size);
set_be_chunk(&chunk.h, final ? NBD_REPLY_FLAG_DONE : 0,
NBD_REPLY_TYPE_OFFSET_DATA, handle,
sizeof(chunk) - sizeof(chunk.h) + size);
stq_be_p(&chunk.offset, offset);
return nbd_co_send_iov(client, iov, 2, errp);
}
static int coroutine_fn nbd_co_send_structured_error(NBDClient *client,
uint64_t handle,
uint32_t error,
const char *msg,
Error **errp)
{
NBDStructuredError chunk;
int nbd_err = system_errno_to_nbd_errno(error);
struct iovec iov[] = {
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
{.iov_base = (char *)msg, .iov_len = msg ? strlen(msg) : 0},
};
assert(nbd_err);
trace_nbd_co_send_structured_error(handle, nbd_err,
nbd_err_lookup(nbd_err), msg ? msg : "");
set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_ERROR, handle,
sizeof(chunk) - sizeof(chunk.h) + iov[1].iov_len);
stl_be_p(&chunk.error, nbd_err);
stw_be_p(&chunk.message_length, iov[1].iov_len);
return nbd_co_send_iov(client, iov, 1 + !!iov[1].iov_len, 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,
uint64_t handle,
uint64_t offset,
uint8_t *data,
size_t size,
Error **errp)
{
int ret = 0;
NBDExport *exp = client->exp;
size_t progress = 0;
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_structured_error(client, handle, -status, msg,
errp);
g_free(msg);
return ret;
}
assert(pnum && pnum <= size - progress);
final = progress + pnum == size;
if (status & BDRV_BLOCK_ZERO) {
NBDStructuredReadHole chunk;
struct iovec iov[] = {
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
};
trace_nbd_co_send_structured_read_hole(handle, offset + progress,
pnum);
set_be_chunk(&chunk.h, final ? NBD_REPLY_FLAG_DONE : 0,
NBD_REPLY_TYPE_OFFSET_HOLE,
handle, sizeof(chunk) - sizeof(chunk.h));
stq_be_p(&chunk.offset, offset + progress);
stl_be_p(&chunk.length, pnum);
ret = nbd_co_send_iov(client, iov, 1, errp);
} else {
ret = blk_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_structured_read(client, handle, offset + progress,
data + progress, pnum, final,
errp);
}
if (ret < 0) {
break;
}
progress += pnum;
}
return ret;
}
typedef struct NBDExtentArray {
NBDExtent *extents;
unsigned int nb_alloc;
unsigned int count;
uint64_t total_length;
bool can_add;
bool converted_to_be;
} NBDExtentArray;
static NBDExtentArray *nbd_extent_array_new(unsigned int nb_alloc)
{
NBDExtentArray *ea = g_new0(NBDExtentArray, 1);
ea->nb_alloc = nb_alloc;
ea->extents = g_new(NBDExtent, nb_alloc);
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);
ea->can_add = false;
ea->converted_to_be = true;
for (i = 0; i < ea->count; i++) {
ea->extents[i].flags = cpu_to_be32(ea->extents[i].flags);
ea->extents[i].length = cpu_to_be32(ea->extents[i].length);
}
}
/*
* 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,
uint32_t length, uint32_t flags)
{
assert(ea->can_add);
if (!length) {
return 0;
}
/* Extend previous extent if flags are the same */
if (ea->count > 0 && flags == ea->extents[ea->count - 1].flags) {
uint64_t sum = (uint64_t)length + ea->extents[ea->count - 1].length;
if (sum <= UINT32_MAX) {
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] = (NBDExtent) {.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 nbd_co_send_extents(NBDClient *client, uint64_t handle,
NBDExtentArray *ea,
bool last, uint32_t context_id, Error **errp)
{
NBDStructuredMeta chunk;
struct iovec iov[] = {
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
{.iov_base = ea->extents, .iov_len = ea->count * sizeof(ea->extents[0])}
};
nbd_extent_array_convert_to_be(ea);
trace_nbd_co_send_extents(handle, ea->count, context_id, ea->total_length,
last);
set_be_chunk(&chunk.h, last ? NBD_REPLY_FLAG_DONE : 0,
NBD_REPLY_TYPE_BLOCK_STATUS,
handle, sizeof(chunk) - sizeof(chunk.h) + iov[1].iov_len);
stl_be_p(&chunk.context_id, context_id);
return nbd_co_send_iov(client, iov, 2, 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, uint64_t handle,
BlockBackend *blk, uint64_t offset,
uint32_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);
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_structured_error(
client, handle, -ret, "can't get block status", errp);
}
return nbd_co_send_extents(client, handle, 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;
bdrv_dirty_bitmap_lock(bitmap);
for (start = offset;
bdrv_dirty_bitmap_next_dirty_area(bitmap, start, end, INT32_MAX,
&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 nbd_co_send_bitmap(NBDClient *client, uint64_t handle,
BdrvDirtyBitmap *bitmap, uint64_t offset,
uint32_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);
bitmap_to_extents(bitmap, offset, length, ea);
return nbd_co_send_extents(client, handle, ea, last, context_id, 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 nbd_co_receive_request(NBDRequestData *req, NBDRequest *request,
Error **errp)
{
NBDClient *client = req->client;
int valid_flags;
int ret;
g_assert(qemu_in_coroutine());
assert(client->recv_coroutine == qemu_coroutine_self());
ret = nbd_receive_request(client, request, errp);
if (ret < 0) {
return ret;
}
trace_nbd_co_receive_request_decode_type(request->handle, request->type,
nbd_cmd_lookup(request->type));
if (request->type != NBD_CMD_WRITE) {
/* No payload, we are ready to read the next request. */
req->complete = true;
}
if (request->type == NBD_CMD_DISC) {
/* Special case: we're going to disconnect without a reply,
* whether or not flags, from, or len are bogus */
return -EIO;
}
if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE ||
request->type == NBD_CMD_CACHE)
{
if (request->len > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)",
request->len, NBD_MAX_BUFFER_SIZE);
return -EINVAL;
}
if (request->type != NBD_CMD_CACHE) {
req->data = blk_try_blockalign(client->exp->common.blk,
request->len);
if (req->data == NULL) {
error_setg(errp, "No memory");
return -ENOMEM;
}
}
}
if (request->type == NBD_CMD_WRITE) {
if (nbd_read(client->ioc, req->data, request->len, "CMD_WRITE data",
errp) < 0)
{
return -EIO;
}
req->complete = true;
trace_nbd_co_receive_request_payload_received(request->handle,
request->len);
}
/* Sanity checks. */
if (client->exp->nbdflags & NBD_FLAG_READ_ONLY &&
(request->type == NBD_CMD_WRITE ||
request->type == NBD_CMD_WRITE_ZEROES ||
request->type == NBD_CMD_TRIM)) {
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: %" PRIu32
", 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);
}
valid_flags = NBD_CMD_FLAG_FUA;
if (request->type == NBD_CMD_READ && client->structured_reply) {
valid_flags |= NBD_CMD_FLAG_DF;
} else if (request->type == NBD_CMD_WRITE_ZEROES) {
valid_flags |= NBD_CMD_FLAG_NO_HOLE | NBD_CMD_FLAG_FAST_ZERO;
} else if (request->type == NBD_CMD_BLOCK_STATUS) {
valid_flags |= NBD_CMD_FLAG_REQ_ONE;
}
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,
uint64_t handle,
int ret,
const char *error_msg,
Error **errp)
{
if (client->structured_reply && ret < 0) {
return nbd_co_send_structured_error(client, handle, -ret, error_msg,
errp);
} else {
return nbd_co_send_simple_reply(client, handle, 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);
/* 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->handle, ret,
"flush failed", errp);
}
}
if (client->structured_reply && !(request->flags & NBD_CMD_FLAG_DF) &&
request->len)
{
return nbd_co_send_sparse_read(client, request->handle, request->from,
data, request->len, errp);
}
ret = blk_pread(exp->common.blk, request->from, request->len, data, 0);
if (ret < 0) {
return nbd_send_generic_reply(client, request->handle, ret,
"reading from file failed", errp);
}
if (client->structured_reply) {
if (request->len) {
return nbd_co_send_structured_read(client, request->handle,
request->from, data,
request->len, true, errp);
} else {
return nbd_co_send_structured_done(client, request->handle, errp);
}
} else {
return nbd_co_send_simple_reply(client, request->handle, 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->handle, 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;
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;
}
ret = blk_pwrite(exp->common.blk, request->from, request->len, data,
flags);
return nbd_send_generic_reply(client, request->handle, 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_pwrite_zeroes(exp->common.blk, request->from, request->len,
flags);
return nbd_send_generic_reply(client, request->handle, 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->handle, ret,
"flush failed", errp);
case NBD_CMD_TRIM:
ret = blk_co_pdiscard(exp->common.blk, request->from, request->len);
if (ret >= 0 && request->flags & NBD_CMD_FLAG_FUA) {
ret = blk_co_flush(exp->common.blk);
}
return nbd_send_generic_reply(client, request->handle, ret,
"discard failed", errp);
case NBD_CMD_BLOCK_STATUS:
if (!request->len) {
return nbd_send_generic_reply(client, request->handle, -EINVAL,
"need non-zero length", errp);
}
if (client->export_meta.count) {
bool dont_fragment = request->flags & NBD_CMD_FLAG_REQ_ONE;
int contexts_remaining = client->export_meta.count;
if (client->export_meta.base_allocation) {
ret = nbd_co_send_block_status(client, request->handle,
exp->common.blk,
request->from,
request->len, dont_fragment,
!--contexts_remaining,
NBD_META_ID_BASE_ALLOCATION,
errp);
if (ret < 0) {
return ret;
}
}
if (client->export_meta.allocation_depth) {
ret = nbd_co_send_block_status(client, request->handle,
exp->common.blk,
request->from, request->len,
dont_fragment,
!--contexts_remaining,
NBD_META_ID_ALLOCATION_DEPTH,
errp);
if (ret < 0) {
return ret;
}
}
for (i = 0; i < client->exp->nr_export_bitmaps; i++) {
if (!client->export_meta.bitmaps[i]) {
continue;
}
ret = nbd_co_send_bitmap(client, request->handle,
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 {
return nbd_send_generic_reply(client, request->handle, -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->handle, -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)
{
NBDClient *client = opaque;
NBDRequestData *req;
NBDRequest request = { 0 }; /* GCC thinks it can be used uninitialized */
int ret;
Error *local_err = NULL;
trace_nbd_trip();
if (client->closing) {
nbd_client_put(client);
return;
}
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.
*/
nbd_client_put(client);
client->recv_coroutine = NULL;
aio_wait_kick();
return;
}
req = nbd_request_get(client);
ret = nbd_co_receive_request(req, &request, &local_err);
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) {
assert(client->quiescing);
goto done;
}
nbd_client_receive_next_request(client);
if (ret == -EIO) {
goto disconnect;
}
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.handle, -EINVAL,
error_get_pretty(export_err), &local_err);
error_free(export_err);
} else {
ret = nbd_handle_request(client, &request, req->data, &local_err);
}
if (ret < 0) {
error_prepend(&local_err, "Failed to send reply: ");
goto disconnect;
}
/* We must disconnect after NBD_CMD_WRITE if we did not
* read the payload.
*/
if (!req->complete) {
error_setg(&local_err, "Request handling failed in intermediate state");
goto disconnect;
}
qio_channel_set_cork(client->ioc, false);
done:
nbd_request_put(req);
nbd_client_put(client);
return;
disconnect:
if (local_err) {
error_reportf_err(local_err, "Disconnect client, due to: ");
}
nbd_request_put(req);
client_close(client, true);
nbd_client_put(client);
}
static void nbd_client_receive_next_request(NBDClient *client)
{
if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS &&
!client->quiescing) {
nbd_client_get(client);
client->recv_coroutine = qemu_coroutine_create(nbd_trip, client);
aio_co_schedule(client->exp->common.ctx, client->recv_coroutine);
}
}
static coroutine_fn void nbd_co_client_start(void *opaque)
{
NBDClient *client = opaque;
Error *local_err = NULL;
qemu_co_mutex_init(&client->send_lock);
if (nbd_negotiate(client, &local_err)) {
if (local_err) {
error_report_err(local_err);
}
client_close(client, false);
return;
}
nbd_client_receive_next_request(client);
}
/*
* Create a new client listener using the given channel @sioc.
* Begin servicing it in a coroutine. When the connection closes, call
* @close_fn with an indication of whether the client completed negotiation.
*/
void nbd_client_new(QIOChannelSocket *sioc,
QCryptoTLSCreds *tlscreds,
const char *tlsauthz,
void (*close_fn)(NBDClient *, bool))
{
NBDClient *client;
Coroutine *co;
client = g_new0(NBDClient, 1);
client->refcount = 1;
client->tlscreds = tlscreds;
if (tlscreds) {
object_ref(OBJECT(client->tlscreds));
}
client->tlsauthz = g_strdup(tlsauthz);
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;
co = qemu_coroutine_create(nbd_co_client_start, client);
qemu_coroutine_enter(co);
}
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