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qemu/nbd/server.c
Kevin Wolf cd7fca952c nbd-server: Use a separate BlockBackend 
The builtin NBD server uses its own BlockBackend now instead of reusing
the monitor/guest device one.

This means that it has its own writethrough setting now. The builtin
NBD server always uses writeback caching now regardless of whether the
guest device has WCE enabled. qemu-nbd respects the cache mode given on
the command line.

We still need to keep a reference to the monitor BB because we put an
eject notifier on it, but we don't use it for any I/O.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-09-05 19:06:47 +02:00

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/*
* 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 "qapi/error.h"
#include "nbd-internal.h"
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 EINVAL:
default:
return NBD_EINVAL;
}
}
/* Definitions for opaque data types */
typedef struct NBDRequest NBDRequest;
struct NBDRequest {
QSIMPLEQ_ENTRY(NBDRequest) entry;
NBDClient *client;
uint8_t *data;
bool complete;
};
struct NBDExport {
int refcount;
void (*close)(NBDExport *exp);
BlockBackend *blk;
char *name;
off_t dev_offset;
off_t size;
uint16_t nbdflags;
QTAILQ_HEAD(, NBDClient) clients;
QTAILQ_ENTRY(NBDExport) next;
AioContext *ctx;
BlockBackend *eject_notifier_blk;
Notifier eject_notifier;
};
static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
struct NBDClient {
int refcount;
void (*close)(NBDClient *client);
NBDExport *exp;
QCryptoTLSCreds *tlscreds;
char *tlsaclname;
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 can_read;
QTAILQ_ENTRY(NBDClient) next;
int nb_requests;
bool closing;
};
/* That's all folks */
static void nbd_set_handlers(NBDClient *client);
static void nbd_unset_handlers(NBDClient *client);
static void nbd_update_can_read(NBDClient *client);
static gboolean nbd_negotiate_continue(QIOChannel *ioc,
GIOCondition condition,
void *opaque)
{
qemu_coroutine_enter(opaque);
return TRUE;
}
static ssize_t nbd_negotiate_read(QIOChannel *ioc, void *buffer, size_t size)
{
ssize_t ret;
guint watch;
assert(qemu_in_coroutine());
/* Negotiation are always in main loop. */
watch = qio_channel_add_watch(ioc,
G_IO_IN,
nbd_negotiate_continue,
qemu_coroutine_self(),
NULL);
ret = read_sync(ioc, buffer, size);
g_source_remove(watch);
return ret;
}
static ssize_t nbd_negotiate_write(QIOChannel *ioc, void *buffer, size_t size)
{
ssize_t ret;
guint watch;
assert(qemu_in_coroutine());
/* Negotiation are always in main loop. */
watch = qio_channel_add_watch(ioc,
G_IO_OUT,
nbd_negotiate_continue,
qemu_coroutine_self(),
NULL);
ret = write_sync(ioc, buffer, size);
g_source_remove(watch);
return ret;
}
static ssize_t nbd_negotiate_drop_sync(QIOChannel *ioc, size_t size)
{
ssize_t ret, dropped = size;
uint8_t *buffer = g_malloc(MIN(65536, size));
while (size > 0) {
ret = nbd_negotiate_read(ioc, buffer, MIN(65536, size));
if (ret < 0) {
g_free(buffer);
return ret;
}
assert(ret <= size);
size -= ret;
}
g_free(buffer);
return dropped;
}
/* 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 int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt)
{
uint64_t magic;
uint32_t len;
TRACE("Reply opt=%" PRIx32 " type=%" PRIx32, type, opt);
magic = cpu_to_be64(NBD_REP_MAGIC);
if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("write failed (rep magic)");
return -EINVAL;
}
opt = cpu_to_be32(opt);
if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
LOG("write failed (rep opt)");
return -EINVAL;
}
type = cpu_to_be32(type);
if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
LOG("write failed (rep type)");
return -EINVAL;
}
len = cpu_to_be32(0);
if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
LOG("write failed (rep data length)");
return -EINVAL;
}
return 0;
}
static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
{
uint64_t magic, name_len;
uint32_t opt, type, len;
TRACE("Advertising export name '%s'", exp->name ? exp->name : "");
name_len = strlen(exp->name);
magic = cpu_to_be64(NBD_REP_MAGIC);
if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("write failed (magic)");
return -EINVAL;
}
opt = cpu_to_be32(NBD_OPT_LIST);
if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
LOG("write failed (opt)");
return -EINVAL;
}
type = cpu_to_be32(NBD_REP_SERVER);
if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
LOG("write failed (reply type)");
return -EINVAL;
}
len = cpu_to_be32(name_len + sizeof(len));
if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
LOG("write failed (length)");
return -EINVAL;
}
len = cpu_to_be32(name_len);
if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
LOG("write failed (length)");
return -EINVAL;
}
if (nbd_negotiate_write(ioc, exp->name, name_len) != name_len) {
LOG("write failed (buffer)");
return -EINVAL;
}
return 0;
}
static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length)
{
NBDExport *exp;
if (length) {
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
return -EIO;
}
return nbd_negotiate_send_rep(client->ioc,
NBD_REP_ERR_INVALID, NBD_OPT_LIST);
}
/* For each export, send a NBD_REP_SERVER reply. */
QTAILQ_FOREACH(exp, &exports, next) {
if (nbd_negotiate_send_rep_list(client->ioc, exp)) {
return -EINVAL;
}
}
/* Finish with a NBD_REP_ACK. */
return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST);
}
static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length)
{
int rc = -EINVAL;
char name[NBD_MAX_NAME_SIZE + 1];
/* Client sends:
[20 .. xx] export name (length bytes)
*/
TRACE("Checking length");
if (length >= sizeof(name)) {
LOG("Bad length received");
goto fail;
}
if (nbd_negotiate_read(client->ioc, name, length) != length) {
LOG("read failed");
goto fail;
}
name[length] = '\0';
TRACE("Client requested export '%s'", name);
client->exp = nbd_export_find(name);
if (!client->exp) {
LOG("export not found");
goto fail;
}
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
nbd_export_get(client->exp);
rc = 0;
fail:
return rc;
}
static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
uint32_t length)
{
QIOChannel *ioc;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
TRACE("Setting up TLS");
ioc = client->ioc;
if (length) {
if (nbd_negotiate_drop_sync(ioc, length) != length) {
return NULL;
}
nbd_negotiate_send_rep(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS);
return NULL;
}
if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
NBD_OPT_STARTTLS) < 0) {
return NULL;
}
tioc = qio_channel_tls_new_server(ioc,
client->tlscreds,
client->tlsaclname,
NULL);
if (!tioc) {
return NULL;
}
TRACE("Starting TLS handshake");
data.loop = g_main_loop_new(g_main_context_default(), FALSE);
qio_channel_tls_handshake(tioc,
nbd_tls_handshake,
&data,
NULL);
if (!data.complete) {
g_main_loop_run(data.loop);
}
g_main_loop_unref(data.loop);
if (data.error) {
object_unref(OBJECT(tioc));
error_free(data.error);
return NULL;
}
return QIO_CHANNEL(tioc);
}
static int nbd_negotiate_options(NBDClient *client)
{
uint32_t flags;
bool fixedNewstyle = false;
/* Client sends:
[ 0 .. 3] client flags
[ 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_negotiate_read(client->ioc, &flags, sizeof(flags)) !=
sizeof(flags)) {
LOG("read failed");
return -EIO;
}
TRACE("Checking client flags");
be32_to_cpus(&flags);
if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
TRACE("Client supports fixed newstyle handshake");
fixedNewstyle = true;
flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
}
if (flags != 0) {
TRACE("Unknown client flags 0x%" PRIx32 " received", flags);
return -EIO;
}
while (1) {
int ret;
uint32_t clientflags, length;
uint64_t magic;
if (nbd_negotiate_read(client->ioc, &magic, sizeof(magic)) !=
sizeof(magic)) {
LOG("read failed");
return -EINVAL;
}
TRACE("Checking opts magic");
if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
LOG("Bad magic received");
return -EINVAL;
}
if (nbd_negotiate_read(client->ioc, &clientflags,
sizeof(clientflags)) != sizeof(clientflags)) {
LOG("read failed");
return -EINVAL;
}
clientflags = be32_to_cpu(clientflags);
if (nbd_negotiate_read(client->ioc, &length, sizeof(length)) !=
sizeof(length)) {
LOG("read failed");
return -EINVAL;
}
length = be32_to_cpu(length);
TRACE("Checking option 0x%" PRIx32, clientflags);
if (client->tlscreds &&
client->ioc == (QIOChannel *)client->sioc) {
QIOChannel *tioc;
if (!fixedNewstyle) {
TRACE("Unsupported option 0x%" PRIx32, clientflags);
return -EINVAL;
}
switch (clientflags) {
case NBD_OPT_STARTTLS:
tioc = nbd_negotiate_handle_starttls(client, length);
if (!tioc) {
return -EIO;
}
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 */
TRACE("Option 0x%x not permitted before TLS", clientflags);
return -EINVAL;
default:
TRACE("Option 0x%" PRIx32 " not permitted before TLS",
clientflags);
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
return -EIO;
}
ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_TLS_REQD,
clientflags);
if (ret < 0) {
return ret;
}
break;
}
} else if (fixedNewstyle) {
switch (clientflags) {
case NBD_OPT_LIST:
ret = nbd_negotiate_handle_list(client, length);
if (ret < 0) {
return ret;
}
break;
case NBD_OPT_ABORT:
return -EINVAL;
case NBD_OPT_EXPORT_NAME:
return nbd_negotiate_handle_export_name(client, length);
case NBD_OPT_STARTTLS:
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
return -EIO;
}
if (client->tlscreds) {
TRACE("TLS already enabled");
ret = nbd_negotiate_send_rep(client->ioc,
NBD_REP_ERR_INVALID,
clientflags);
} else {
TRACE("TLS not configured");
ret = nbd_negotiate_send_rep(client->ioc,
NBD_REP_ERR_POLICY,
clientflags);
}
if (ret < 0) {
return ret;
}
break;
default:
TRACE("Unsupported option 0x%" PRIx32, clientflags);
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
return -EIO;
}
ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_UNSUP,
clientflags);
if (ret < 0) {
return ret;
}
break;
}
} else {
/*
* If broken new-style we should drop the connection
* for anything except NBD_OPT_EXPORT_NAME
*/
switch (clientflags) {
case NBD_OPT_EXPORT_NAME:
return nbd_negotiate_handle_export_name(client, length);
default:
TRACE("Unsupported option 0x%" PRIx32, clientflags);
return -EINVAL;
}
}
}
}
typedef struct {
NBDClient *client;
Coroutine *co;
} NBDClientNewData;
static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
{
NBDClient *client = data->client;
char buf[8 + 8 + 8 + 128];
int rc;
const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
bool oldStyle;
/* Old style negotiation header without options
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_CLIENT_MAGIC)
[16 .. 23] size
[24 .. 25] server flags (0)
[26 .. 27] export flags
[28 .. 151] reserved (0)
New style negotiation header with options
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_OPTS_MAGIC)
[16 .. 17] server flags (0)
....options sent....
[18 .. 25] size
[26 .. 27] export flags
[28 .. 151] reserved (0)
*/
qio_channel_set_blocking(client->ioc, false, NULL);
rc = -EINVAL;
TRACE("Beginning negotiation.");
memset(buf, 0, sizeof(buf));
memcpy(buf, "NBDMAGIC", 8);
oldStyle = client->exp != NULL && !client->tlscreds;
if (oldStyle) {
TRACE("advertising size %" PRIu64 " and flags %x",
client->exp->size, client->exp->nbdflags | myflags);
stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
stq_be_p(buf + 16, client->exp->size);
stw_be_p(buf + 26, client->exp->nbdflags | myflags);
} else {
stq_be_p(buf + 8, NBD_OPTS_MAGIC);
stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE);
}
if (oldStyle) {
if (client->tlscreds) {
TRACE("TLS cannot be enabled with oldstyle protocol");
goto fail;
}
if (nbd_negotiate_write(client->ioc, buf, sizeof(buf)) != sizeof(buf)) {
LOG("write failed");
goto fail;
}
} else {
if (nbd_negotiate_write(client->ioc, buf, 18) != 18) {
LOG("write failed");
goto fail;
}
rc = nbd_negotiate_options(client);
if (rc != 0) {
LOG("option negotiation failed");
goto fail;
}
TRACE("advertising size %" PRIu64 " and flags %x",
client->exp->size, client->exp->nbdflags | myflags);
stq_be_p(buf + 18, client->exp->size);
stw_be_p(buf + 26, client->exp->nbdflags | myflags);
if (nbd_negotiate_write(client->ioc, buf + 18, sizeof(buf) - 18) !=
sizeof(buf) - 18) {
LOG("write failed");
goto fail;
}
}
TRACE("Negotiation succeeded.");
rc = 0;
fail:
return rc;
}
static ssize_t nbd_receive_request(QIOChannel *ioc, struct nbd_request *request)
{
uint8_t buf[NBD_REQUEST_SIZE];
uint32_t magic;
ssize_t ret;
ret = read_sync(ioc, buf, sizeof(buf));
if (ret < 0) {
return ret;
}
if (ret != sizeof(buf)) {
LOG("read failed");
return -EINVAL;
}
/* Request
[ 0 .. 3] magic (NBD_REQUEST_MAGIC)
[ 4 .. 7] type (0 == READ, 1 == WRITE)
[ 8 .. 15] handle
[16 .. 23] from
[24 .. 27] len
*/
magic = ldl_be_p(buf);
request->type = ldl_be_p(buf + 4);
request->handle = ldq_be_p(buf + 8);
request->from = ldq_be_p(buf + 16);
request->len = ldl_be_p(buf + 24);
TRACE("Got request: { magic = 0x%" PRIx32 ", .type = %" PRIx32
", from = %" PRIu64 " , len = %" PRIu32 " }",
magic, request->type, request->from, request->len);
if (magic != NBD_REQUEST_MAGIC) {
LOG("invalid magic (got 0x%" PRIx32 ")", magic);
return -EINVAL;
}
return 0;
}
static ssize_t nbd_send_reply(QIOChannel *ioc, struct nbd_reply *reply)
{
uint8_t buf[NBD_REPLY_SIZE];
ssize_t ret;
reply->error = system_errno_to_nbd_errno(reply->error);
TRACE("Sending response to client: { .error = %" PRId32
", handle = %" PRIu64 " }",
reply->error, reply->handle);
/* Reply
[ 0 .. 3] magic (NBD_REPLY_MAGIC)
[ 4 .. 7] error (0 == no error)
[ 7 .. 15] handle
*/
stl_be_p(buf, NBD_REPLY_MAGIC);
stl_be_p(buf + 4, reply->error);
stq_be_p(buf + 8, reply->handle);
ret = write_sync(ioc, buf, sizeof(buf));
if (ret < 0) {
return ret;
}
if (ret != sizeof(buf)) {
LOG("writing to socket failed");
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);
nbd_unset_handlers(client);
object_unref(OBJECT(client->sioc));
object_unref(OBJECT(client->ioc));
if (client->tlscreds) {
object_unref(OBJECT(client->tlscreds));
}
g_free(client->tlsaclname);
if (client->exp) {
QTAILQ_REMOVE(&client->exp->clients, client, next);
nbd_export_put(client->exp);
}
g_free(client);
}
}
static void client_close(NBDClient *client)
{
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) {
client->close(client);
}
}
static NBDRequest *nbd_request_get(NBDClient *client)
{
NBDRequest *req;
assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
client->nb_requests++;
nbd_update_can_read(client);
req = g_new0(NBDRequest, 1);
nbd_client_get(client);
req->client = client;
return req;
}
static void nbd_request_put(NBDRequest *req)
{
NBDClient *client = req->client;
if (req->data) {
qemu_vfree(req->data);
}
g_free(req);
client->nb_requests--;
nbd_update_can_read(client);
nbd_client_put(client);
}
static void blk_aio_attached(AioContext *ctx, void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
TRACE("Export %s: Attaching clients to AIO context %p\n", exp->name, ctx);
exp->ctx = ctx;
QTAILQ_FOREACH(client, &exp->clients, next) {
nbd_set_handlers(client);
}
}
static void blk_aio_detach(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
QTAILQ_FOREACH(client, &exp->clients, next) {
nbd_unset_handlers(client);
}
exp->ctx = NULL;
}
static void nbd_eject_notifier(Notifier *n, void *data)
{
NBDExport *exp = container_of(n, NBDExport, eject_notifier);
nbd_export_close(exp);
}
NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
uint16_t nbdflags, void (*close)(NBDExport *),
bool writethrough, BlockBackend *on_eject_blk,
Error **errp)
{
BlockBackend *blk;
NBDExport *exp = g_malloc0(sizeof(NBDExport));
blk = blk_new();
blk_insert_bs(blk, bs);
blk_set_enable_write_cache(blk, !writethrough);
exp->refcount = 1;
QTAILQ_INIT(&exp->clients);
exp->blk = blk;
exp->dev_offset = dev_offset;
exp->nbdflags = nbdflags;
exp->size = size < 0 ? blk_getlength(blk) : size;
if (exp->size < 0) {
error_setg_errno(errp, -exp->size,
"Failed to determine the NBD export's length");
goto fail;
}
exp->size -= exp->size % BDRV_SECTOR_SIZE;
exp->close = close;
exp->ctx = blk_get_aio_context(blk);
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
if (on_eject_blk) {
blk_ref(on_eject_blk);
exp->eject_notifier_blk = on_eject_blk;
exp->eject_notifier.notify = nbd_eject_notifier;
blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier);
}
/*
* NBD exports are used for non-shared storage migration. Make sure
* that BDRV_O_INACTIVE is cleared and the image is ready for write
* access since the export could be available before migration handover.
*/
aio_context_acquire(exp->ctx);
blk_invalidate_cache(blk, NULL);
aio_context_release(exp->ctx);
return exp;
fail:
blk_unref(blk);
g_free(exp);
return NULL;
}
NBDExport *nbd_export_find(const char *name)
{
NBDExport *exp;
QTAILQ_FOREACH(exp, &exports, next) {
if (strcmp(name, exp->name) == 0) {
return exp;
}
}
return NULL;
}
void nbd_export_set_name(NBDExport *exp, const char *name)
{
if (exp->name == name) {
return;
}
nbd_export_get(exp);
if (exp->name != NULL) {
g_free(exp->name);
exp->name = NULL;
QTAILQ_REMOVE(&exports, exp, next);
nbd_export_put(exp);
}
if (name != NULL) {
nbd_export_get(exp);
exp->name = g_strdup(name);
QTAILQ_INSERT_TAIL(&exports, exp, next);
}
nbd_export_put(exp);
}
void nbd_export_close(NBDExport *exp)
{
NBDClient *client, *next;
nbd_export_get(exp);
QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
client_close(client);
}
nbd_export_set_name(exp, NULL);
nbd_export_put(exp);
}
void nbd_export_get(NBDExport *exp)
{
assert(exp->refcount > 0);
exp->refcount++;
}
void nbd_export_put(NBDExport *exp)
{
assert(exp->refcount > 0);
if (exp->refcount == 1) {
nbd_export_close(exp);
}
if (--exp->refcount == 0) {
assert(exp->name == NULL);
if (exp->close) {
exp->close(exp);
}
if (exp->blk) {
if (exp->eject_notifier_blk) {
notifier_remove(&exp->eject_notifier);
blk_unref(exp->eject_notifier_blk);
}
blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
blk_aio_detach, exp);
blk_unref(exp->blk);
exp->blk = NULL;
}
g_free(exp);
}
}
BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
{
return exp->blk;
}
void nbd_export_close_all(void)
{
NBDExport *exp, *next;
QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
nbd_export_close(exp);
}
}
static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply,
int len)
{
NBDClient *client = req->client;
ssize_t rc, ret;
g_assert(qemu_in_coroutine());
qemu_co_mutex_lock(&client->send_lock);
client->send_coroutine = qemu_coroutine_self();
nbd_set_handlers(client);
if (!len) {
rc = nbd_send_reply(client->ioc, reply);
} else {
qio_channel_set_cork(client->ioc, true);
rc = nbd_send_reply(client->ioc, reply);
if (rc >= 0) {
ret = write_sync(client->ioc, req->data, len);
if (ret != len) {
rc = -EIO;
}
}
qio_channel_set_cork(client->ioc, false);
}
client->send_coroutine = NULL;
nbd_set_handlers(client);
qemu_co_mutex_unlock(&client->send_lock);
return rc;
}
/* Collect a client request. Return 0 if request looks valid, -EAGAIN
* to keep trying the collection, -EIO to drop connection right away,
* 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 ssize_t nbd_co_receive_request(NBDRequest *req,
struct nbd_request *request)
{
NBDClient *client = req->client;
uint32_t command;
ssize_t rc;
g_assert(qemu_in_coroutine());
client->recv_coroutine = qemu_coroutine_self();
nbd_update_can_read(client);
rc = nbd_receive_request(client->ioc, request);
if (rc < 0) {
if (rc != -EAGAIN) {
rc = -EIO;
}
goto out;
}
TRACE("Decoding type");
command = request->type & NBD_CMD_MASK_COMMAND;
if (command != NBD_CMD_WRITE) {
/* No payload, we are ready to read the next request. */
req->complete = true;
}
if (command == NBD_CMD_DISC) {
/* Special case: we're going to disconnect without a reply,
* whether or not flags, from, or len are bogus */
TRACE("Request type is DISCONNECT");
rc = -EIO;
goto out;
}
/* Check for sanity in the parameters, part 1. Defer as many
* checks as possible until after reading any NBD_CMD_WRITE
* payload, so we can try and keep the connection alive. */
if ((request->from + request->len) < request->from) {
LOG("integer overflow detected, you're probably being attacked");
rc = -EINVAL;
goto out;
}
if (command == NBD_CMD_READ || command == NBD_CMD_WRITE) {
if (request->len > NBD_MAX_BUFFER_SIZE) {
LOG("len (%" PRIu32" ) is larger than max len (%u)",
request->len, NBD_MAX_BUFFER_SIZE);
rc = -EINVAL;
goto out;
}
req->data = blk_try_blockalign(client->exp->blk, request->len);
if (req->data == NULL) {
rc = -ENOMEM;
goto out;
}
}
if (command == NBD_CMD_WRITE) {
TRACE("Reading %" PRIu32 " byte(s)", request->len);
if (read_sync(client->ioc, req->data, request->len) != request->len) {
LOG("reading from socket failed");
rc = -EIO;
goto out;
}
req->complete = true;
}
/* Sanity checks, part 2. */
if (request->from + request->len > client->exp->size) {
LOG("operation past EOF; From: %" PRIu64 ", Len: %" PRIu32
", Size: %" PRIu64, request->from, request->len,
(uint64_t)client->exp->size);
rc = command == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
goto out;
}
if (request->type & ~NBD_CMD_MASK_COMMAND & ~NBD_CMD_FLAG_FUA) {
LOG("unsupported flags (got 0x%x)",
request->type & ~NBD_CMD_MASK_COMMAND);
rc = -EINVAL;
goto out;
}
rc = 0;
out:
client->recv_coroutine = NULL;
nbd_update_can_read(client);
return rc;
}
static void nbd_trip(void *opaque)
{
NBDClient *client = opaque;
NBDExport *exp = client->exp;
NBDRequest *req;
struct nbd_request request;
struct nbd_reply reply;
ssize_t ret;
uint32_t command;
int flags;
TRACE("Reading request.");
if (client->closing) {
return;
}
req = nbd_request_get(client);
ret = nbd_co_receive_request(req, &request);
if (ret == -EAGAIN) {
goto done;
}
if (ret == -EIO) {
goto out;
}
reply.handle = request.handle;
reply.error = 0;
if (ret < 0) {
reply.error = -ret;
goto error_reply;
}
command = request.type & NBD_CMD_MASK_COMMAND;
if (client->closing) {
/*
* The client may be closed when we are blocked in
* nbd_co_receive_request()
*/
goto done;
}
switch (command) {
case NBD_CMD_READ:
TRACE("Request type is READ");
if (request.type & NBD_CMD_FLAG_FUA) {
ret = blk_co_flush(exp->blk);
if (ret < 0) {
LOG("flush failed");
reply.error = -ret;
goto error_reply;
}
}
ret = blk_pread(exp->blk, request.from + exp->dev_offset,
req->data, request.len);
if (ret < 0) {
LOG("reading from file failed");
reply.error = -ret;
goto error_reply;
}
TRACE("Read %" PRIu32" byte(s)", request.len);
if (nbd_co_send_reply(req, &reply, request.len) < 0)
goto out;
break;
case NBD_CMD_WRITE:
TRACE("Request type is WRITE");
if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
TRACE("Server is read-only, return error");
reply.error = EROFS;
goto error_reply;
}
TRACE("Writing to device");
flags = 0;
if (request.type & NBD_CMD_FLAG_FUA) {
flags |= BDRV_REQ_FUA;
}
ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
req->data, request.len, flags);
if (ret < 0) {
LOG("writing to file failed");
reply.error = -ret;
goto error_reply;
}
if (nbd_co_send_reply(req, &reply, 0) < 0) {
goto out;
}
break;
case NBD_CMD_DISC:
/* unreachable, thanks to special case in nbd_co_receive_request() */
abort();
case NBD_CMD_FLUSH:
TRACE("Request type is FLUSH");
ret = blk_co_flush(exp->blk);
if (ret < 0) {
LOG("flush failed");
reply.error = -ret;
}
if (nbd_co_send_reply(req, &reply, 0) < 0) {
goto out;
}
break;
case NBD_CMD_TRIM:
TRACE("Request type is TRIM");
ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset,
request.len);
if (ret < 0) {
LOG("discard failed");
reply.error = -ret;
}
if (nbd_co_send_reply(req, &reply, 0) < 0) {
goto out;
}
break;
default:
LOG("invalid request type (%" PRIu32 ") received", request.type);
reply.error = EINVAL;
error_reply:
/* We must disconnect after NBD_CMD_WRITE if we did not
* read the payload.
*/
if (nbd_co_send_reply(req, &reply, 0) < 0 || !req->complete) {
goto out;
}
break;
}
TRACE("Request/Reply complete");
done:
nbd_request_put(req);
return;
out:
nbd_request_put(req);
client_close(client);
}
static void nbd_read(void *opaque)
{
NBDClient *client = opaque;
if (client->recv_coroutine) {
qemu_coroutine_enter(client->recv_coroutine);
} else {
qemu_coroutine_enter(qemu_coroutine_create(nbd_trip, client));
}
}
static void nbd_restart_write(void *opaque)
{
NBDClient *client = opaque;
qemu_coroutine_enter(client->send_coroutine);
}
static void nbd_set_handlers(NBDClient *client)
{
if (client->exp && client->exp->ctx) {
aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
true,
client->can_read ? nbd_read : NULL,
client->send_coroutine ? nbd_restart_write : NULL,
client);
}
}
static void nbd_unset_handlers(NBDClient *client)
{
if (client->exp && client->exp->ctx) {
aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
true, NULL, NULL, NULL);
}
}
static void nbd_update_can_read(NBDClient *client)
{
bool can_read = client->recv_coroutine ||
client->nb_requests < MAX_NBD_REQUESTS;
if (can_read != client->can_read) {
client->can_read = can_read;
nbd_set_handlers(client);
/* There is no need to invoke aio_notify(), since aio_set_fd_handler()
* in nbd_set_handlers() will have taken care of that */
}
}
static coroutine_fn void nbd_co_client_start(void *opaque)
{
NBDClientNewData *data = opaque;
NBDClient *client = data->client;
NBDExport *exp = client->exp;
if (exp) {
nbd_export_get(exp);
}
if (nbd_negotiate(data)) {
client_close(client);
goto out;
}
qemu_co_mutex_init(&client->send_lock);
nbd_set_handlers(client);
if (exp) {
QTAILQ_INSERT_TAIL(&exp->clients, client, next);
}
out:
g_free(data);
}
void nbd_client_new(NBDExport *exp,
QIOChannelSocket *sioc,
QCryptoTLSCreds *tlscreds,
const char *tlsaclname,
void (*close_fn)(NBDClient *))
{
NBDClient *client;
NBDClientNewData *data = g_new(NBDClientNewData, 1);
client = g_malloc0(sizeof(NBDClient));
client->refcount = 1;
client->exp = exp;
client->tlscreds = tlscreds;
if (tlscreds) {
object_ref(OBJECT(client->tlscreds));
}
client->tlsaclname = g_strdup(tlsaclname);
client->sioc = sioc;
object_ref(OBJECT(client->sioc));
client->ioc = QIO_CHANNEL(sioc);
object_ref(OBJECT(client->ioc));
client->can_read = true;
client->close = close_fn;
data->client = client;
data->co = qemu_coroutine_create(nbd_co_client_start, data);
qemu_coroutine_enter(data->co);
}
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