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qemu/block/nbd-client.c

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/*
* QEMU Block driver for NBD
*
* Copyright (C) 2016 Red Hat, Inc.
* Copyright (C) 2008 Bull S.A.S.
* Author: Laurent Vivier <Laurent.Vivier@bull.net>
*
* Some parts:
* Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "nbd-client.h"
#define HANDLE_TO_INDEX(bs, handle) ((handle) ^ ((uint64_t)(intptr_t)bs))
#define INDEX_TO_HANDLE(bs, index) ((index) ^ ((uint64_t)(intptr_t)bs))
static void nbd_recv_coroutines_enter_all(NBDClientSession *s)
{
int i;
for (i = 0; i < MAX_NBD_REQUESTS; i++) {
if (s->recv_coroutine[i]) {
aio_co_wake(s->recv_coroutine[i]);
}
}
}
static void nbd_teardown_connection(BlockDriverState *bs)
{
NBDClientSession *client = nbd_get_client_session(bs);
if (!client->ioc) { /* Already closed */
return;
}
/* finish any pending coroutines */
qio_channel_shutdown(client->ioc,
QIO_CHANNEL_SHUTDOWN_BOTH,
NULL);
BDRV_POLL_WHILE(bs, client->read_reply_co);
nbd_client_detach_aio_context(bs);
object_unref(OBJECT(client->sioc));
client->sioc = NULL;
object_unref(OBJECT(client->ioc));
client->ioc = NULL;
}
static coroutine_fn void nbd_read_reply_entry(void *opaque)
{
NBDClientSession *s = opaque;
uint64_t i;
int ret;
Error *local_err = NULL;
for (;;) {
assert(s->reply.handle == 0);
ret = nbd_receive_reply(s->ioc, &s->reply, &local_err);
if (ret < 0) {
error_report_err(local_err);
}
if (ret <= 0) {
break;
}
/* There's no need for a mutex on the receive side, because the
* handler acts as a synchronization point and ensures that only
* one coroutine is called until the reply finishes.
*/
i = HANDLE_TO_INDEX(s, s->reply.handle);
if (i >= MAX_NBD_REQUESTS || !s->recv_coroutine[i]) {
break;
}
/* We're woken up by the recv_coroutine itself. Note that there
* is no race between yielding and reentering read_reply_co. This
* is because:
*
* - if recv_coroutine[i] runs on the same AioContext, it is only
* entered after we yield
*
* - if recv_coroutine[i] runs on a different AioContext, reentering
* read_reply_co happens through a bottom half, which can only
* run after we yield.
*/
aio_co_wake(s->recv_coroutine[i]);
qemu_coroutine_yield();
}
nbd_recv_coroutines_enter_all(s);
s->read_reply_co = NULL;
}
static int nbd_co_send_request(BlockDriverState *bs,
NBDRequest *request,
QEMUIOVector *qiov)
{
NBDClientSession *s = nbd_get_client_session(bs);
int rc, ret, i;
qemu_co_mutex_lock(&s->send_mutex);
while (s->in_flight == MAX_NBD_REQUESTS) {
qemu_co_queue_wait(&s->free_sema, &s->send_mutex);
}
s->in_flight++;
for (i = 0; i < MAX_NBD_REQUESTS; i++) {
if (s->recv_coroutine[i] == NULL) {
s->recv_coroutine[i] = qemu_coroutine_self();
break;
}
}
g_assert(qemu_in_coroutine());
assert(i < MAX_NBD_REQUESTS);
request->handle = INDEX_TO_HANDLE(s, i);
if (!s->ioc) {
qemu_co_mutex_unlock(&s->send_mutex);
return -EPIPE;
}
if (qiov) {
qio_channel_set_cork(s->ioc, true);
rc = nbd_send_request(s->ioc, request);
if (rc >= 0) {
ret = nbd_rwv(s->ioc, qiov->iov, qiov->niov, request->len, false,
NULL);
if (ret != request->len) {
rc = -EIO;
}
}
qio_channel_set_cork(s->ioc, false);
} else {
rc = nbd_send_request(s->ioc, request);
}
qemu_co_mutex_unlock(&s->send_mutex);
return rc;
}
static void nbd_co_receive_reply(NBDClientSession *s,
NBDRequest *request,
NBDReply *reply,
QEMUIOVector *qiov)
{
int ret;
/* Wait until we're woken up by nbd_read_reply_entry. */
qemu_coroutine_yield();
*reply = s->reply;
if (reply->handle != request->handle ||
!s->ioc) {
reply->error = EIO;
} else {
if (qiov && reply->error == 0) {
ret = nbd_rwv(s->ioc, qiov->iov, qiov->niov, request->len, true,
NULL);
if (ret != request->len) {
reply->error = EIO;
}
}
/* Tell the read handler to read another header. */
s->reply.handle = 0;
}
}
static void nbd_coroutine_end(BlockDriverState *bs,
NBDRequest *request)
{
NBDClientSession *s = nbd_get_client_session(bs);
int i = HANDLE_TO_INDEX(s, request->handle);
s->recv_coroutine[i] = NULL;
/* Kick the read_reply_co to get the next reply. */
if (s->read_reply_co) {
aio_co_wake(s->read_reply_co);
}
qemu_co_mutex_lock(&s->send_mutex);
s->in_flight--;
qemu_co_queue_next(&s->free_sema);
qemu_co_mutex_unlock(&s->send_mutex);
}
int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int flags)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = {
.type = NBD_CMD_READ,
.from = offset,
.len = bytes,
};
NBDReply reply;
ssize_t ret;
assert(bytes <= NBD_MAX_BUFFER_SIZE);
assert(!flags);
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
reply.error = -ret;
} else {
nbd_co_receive_reply(client, &request, &reply, qiov);
}
nbd_coroutine_end(bs, &request);
return -reply.error;
}
int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int flags)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = {
.type = NBD_CMD_WRITE,
.from = offset,
.len = bytes,
};
NBDReply reply;
ssize_t ret;
if (flags & BDRV_REQ_FUA) {
assert(client->nbdflags & NBD_FLAG_SEND_FUA);
request.flags |= NBD_CMD_FLAG_FUA;
}
assert(bytes <= NBD_MAX_BUFFER_SIZE);
ret = nbd_co_send_request(bs, &request, qiov);
if (ret < 0) {
reply.error = -ret;
} else {
nbd_co_receive_reply(client, &request, &reply, NULL);
}
nbd_coroutine_end(bs, &request);
return -reply.error;
}
int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
int bytes, BdrvRequestFlags flags)
{
ssize_t ret;
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = {
.type = NBD_CMD_WRITE_ZEROES,
.from = offset,
.len = bytes,
};
NBDReply reply;
if (!(client->nbdflags & NBD_FLAG_SEND_WRITE_ZEROES)) {
return -ENOTSUP;
}
if (flags & BDRV_REQ_FUA) {
assert(client->nbdflags & NBD_FLAG_SEND_FUA);
request.flags |= NBD_CMD_FLAG_FUA;
}
if (!(flags & BDRV_REQ_MAY_UNMAP)) {
request.flags |= NBD_CMD_FLAG_NO_HOLE;
}
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
reply.error = -ret;
} else {
nbd_co_receive_reply(client, &request, &reply, NULL);
}
nbd_coroutine_end(bs, &request);
return -reply.error;
}
int nbd_client_co_flush(BlockDriverState *bs)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = { .type = NBD_CMD_FLUSH };
NBDReply reply;
ssize_t ret;
if (!(client->nbdflags & NBD_FLAG_SEND_FLUSH)) {
return 0;
}
request.from = 0;
request.len = 0;
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
reply.error = -ret;
} else {
nbd_co_receive_reply(client, &request, &reply, NULL);
}
nbd_coroutine_end(bs, &request);
return -reply.error;
}
int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = {
.type = NBD_CMD_TRIM,
.from = offset,
.len = bytes,
};
NBDReply reply;
ssize_t ret;
if (!(client->nbdflags & NBD_FLAG_SEND_TRIM)) {
return 0;
}
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
reply.error = -ret;
} else {
nbd_co_receive_reply(client, &request, &reply, NULL);
}
nbd_coroutine_end(bs, &request);
return -reply.error;
}
void nbd_client_detach_aio_context(BlockDriverState *bs)
{
NBDClientSession *client = nbd_get_client_session(bs);
qio_channel_detach_aio_context(QIO_CHANNEL(client->ioc));
}
void nbd_client_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
NBDClientSession *client = nbd_get_client_session(bs);
qio_channel_attach_aio_context(QIO_CHANNEL(client->ioc), new_context);
aio_co_schedule(new_context, client->read_reply_co);
}
void nbd_client_close(BlockDriverState *bs)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = { .type = NBD_CMD_DISC };
if (client->ioc == NULL) {
return;
}
nbd_send_request(client->ioc, &request);
nbd_teardown_connection(bs);
}
int nbd_client_init(BlockDriverState *bs,
QIOChannelSocket *sioc,
const char *export,
QCryptoTLSCreds *tlscreds,
const char *hostname,
Error **errp)
{
NBDClientSession *client = nbd_get_client_session(bs);
int ret;
/* NBD handshake */
logout("session init %s\n", export);
qio_channel_set_blocking(QIO_CHANNEL(sioc), true, NULL);
ret = nbd_receive_negotiate(QIO_CHANNEL(sioc), export,
&client->nbdflags,
tlscreds, hostname,
&client->ioc,
&client->size, errp);
if (ret < 0) {
logout("Failed to negotiate with the NBD server\n");
return ret;
}
if (client->nbdflags & NBD_FLAG_SEND_FUA) {
bs->supported_write_flags = BDRV_REQ_FUA;
bs->supported_zero_flags |= BDRV_REQ_FUA;
}
if (client->nbdflags & NBD_FLAG_SEND_WRITE_ZEROES) {
bs->supported_zero_flags |= BDRV_REQ_MAY_UNMAP;
}
qemu_co_mutex_init(&client->send_mutex);
qemu_co_queue_init(&client->free_sema);
client->sioc = sioc;
object_ref(OBJECT(client->sioc));
if (!client->ioc) {
client->ioc = QIO_CHANNEL(sioc);
object_ref(OBJECT(client->ioc));
}
/* Now that we're connected, set the socket to be non-blocking and
* kick the reply mechanism. */
qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL);
client->read_reply_co = qemu_coroutine_create(nbd_read_reply_entry, client);
nbd_client_attach_aio_context(bs, bdrv_get_aio_context(bs));
logout("Established connection with NBD server\n");
return 0;
}
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