[qemu.git] / block / nbd-client.c

/*
 * QEMU Block driver for  NBD
 *
 * Copyright (C) 2008 Bull S.A.S.
 *     Author: Laurent Vivier <[email protected]>
 *
 * Some parts:
 *    Copyright (C) 2007 Anthony Liguori <[email protected]>
 *
 * 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 "nbd-client.h"
#include "qemu/sockets.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]) {
            qemu_coroutine_enter(s->recv_coroutine[i], NULL);
        }
    }
}

static void nbd_teardown_connection(NbdClientSession *client)
{
    /* finish any pending coroutines */
    shutdown(client->sock, 2);
    nbd_recv_coroutines_enter_all(client);

    nbd_client_session_detach_aio_context(client);
    closesocket(client->sock);
    client->sock = -1;
}

static void nbd_reply_ready(void *opaque)
{
    NbdClientSession *s = opaque;
    uint64_t i;
    int ret;

    if (s->reply.handle == 0) {
        /* No reply already in flight.  Fetch a header.  It is possible
         * that another thread has done the same thing in parallel, so
         * the socket is not readable anymore.
         */
        ret = nbd_receive_reply(s->sock, &s->reply);
        if (ret == -EAGAIN) {
            return;
        }
        if (ret < 0) {
            s->reply.handle = 0;
            goto fail;
        }
    }

    /* 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) {
        goto fail;
    }

    if (s->recv_coroutine[i]) {
        qemu_coroutine_enter(s->recv_coroutine[i], NULL);
        return;
    }

fail:
    nbd_teardown_connection(s);
}

static void nbd_restart_write(void *opaque)
{
    NbdClientSession *s = opaque;

    qemu_coroutine_enter(s->send_coroutine, NULL);
}

static int nbd_co_send_request(NbdClientSession *s,
    struct nbd_request *request,
    QEMUIOVector *qiov, int offset)
{
    AioContext *aio_context;
    int rc, ret;

    qemu_co_mutex_lock(&s->send_mutex);
    s->send_coroutine = qemu_coroutine_self();
    aio_context = bdrv_get_aio_context(s->bs);
    aio_set_fd_handler(aio_context, s->sock,
                       nbd_reply_ready, nbd_restart_write, s);
    if (qiov) {
        if (!s->is_unix) {
            socket_set_cork(s->sock, 1);
        }
        rc = nbd_send_request(s->sock, request);
        if (rc >= 0) {
            ret = qemu_co_sendv(s->sock, qiov->iov, qiov->niov,
                                offset, request->len);
            if (ret != request->len) {
                rc = -EIO;
            }
        }
        if (!s->is_unix) {
            socket_set_cork(s->sock, 0);
        }
    } else {
        rc = nbd_send_request(s->sock, request);
    }
    aio_set_fd_handler(aio_context, s->sock, nbd_reply_ready, NULL, s);
    s->send_coroutine = NULL;
    qemu_co_mutex_unlock(&s->send_mutex);
    return rc;
}

static void nbd_co_receive_reply(NbdClientSession *s,
    struct nbd_request *request, struct nbd_reply *reply,
    QEMUIOVector *qiov, int offset)
{
    int ret;

    /* Wait until we're woken up by the read handler.  TODO: perhaps
     * peek at the next reply and avoid yielding if it's ours?  */
    qemu_coroutine_yield();
    *reply = s->reply;
    if (reply->handle != request->handle) {
        reply->error = EIO;
    } else {
        if (qiov && reply->error == 0) {
            ret = qemu_co_recvv(s->sock, qiov->iov, qiov->niov,
                                offset, request->len);
            if (ret != request->len) {
                reply->error = EIO;
            }
        }

        /* Tell the read handler to read another header.  */
        s->reply.handle = 0;
    }
}

static void nbd_coroutine_start(NbdClientSession *s,
   struct nbd_request *request)
{
    int i;

    /* Poor man semaphore.  The free_sema is locked when no other request
     * can be accepted, and unlocked after receiving one reply.  */
    if (s->in_flight >= MAX_NBD_REQUESTS - 1) {
        qemu_co_mutex_lock(&s->free_sema);
        assert(s->in_flight < MAX_NBD_REQUESTS);
    }
    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;
        }
    }

    assert(i < MAX_NBD_REQUESTS);
    request->handle = INDEX_TO_HANDLE(s, i);
}

static void nbd_coroutine_end(NbdClientSession *s,
    struct nbd_request *request)
{
    int i = HANDLE_TO_INDEX(s, request->handle);
    s->recv_coroutine[i] = NULL;
    if (s->in_flight-- == MAX_NBD_REQUESTS) {
        qemu_co_mutex_unlock(&s->free_sema);
    }
}

static int nbd_co_readv_1(NbdClientSession *client, int64_t sector_num,
                          int nb_sectors, QEMUIOVector *qiov,
                          int offset)
{
    struct nbd_request request = { .type = NBD_CMD_READ };
    struct nbd_reply reply;
    ssize_t ret;

    request.from = sector_num * 512;
    request.len = nb_sectors * 512;

    nbd_coroutine_start(client, &request);
    ret = nbd_co_send_request(client, &request, NULL, 0);
    if (ret < 0) {
        reply.error = -ret;
    } else {
        nbd_co_receive_reply(client, &request, &reply, qiov, offset);
    }
    nbd_coroutine_end(client, &request);
    return -reply.error;

}

static int nbd_co_writev_1(NbdClientSession *client, int64_t sector_num,
                           int nb_sectors, QEMUIOVector *qiov,
                           int offset)
{
    struct nbd_request request = { .type = NBD_CMD_WRITE };
    struct nbd_reply reply;
    ssize_t ret;

    if (!bdrv_enable_write_cache(client->bs) &&
        (client->nbdflags & NBD_FLAG_SEND_FUA)) {
        request.type |= NBD_CMD_FLAG_FUA;
    }

    request.from = sector_num * 512;
    request.len = nb_sectors * 512;

    nbd_coroutine_start(client, &request);
    ret = nbd_co_send_request(client, &request, qiov, offset);
    if (ret < 0) {
        reply.error = -ret;
    } else {
        nbd_co_receive_reply(client, &request, &reply, NULL, 0);
    }
    nbd_coroutine_end(client, &request);
    return -reply.error;
}

/* qemu-nbd has a limit of slightly less than 1M per request.  Try to
 * remain aligned to 4K. */
#define NBD_MAX_SECTORS 2040

int nbd_client_session_co_readv(NbdClientSession *client, int64_t sector_num,
    int nb_sectors, QEMUIOVector *qiov)
{
    int offset = 0;
    int ret;
    while (nb_sectors > NBD_MAX_SECTORS) {
        ret = nbd_co_readv_1(client, sector_num,
                             NBD_MAX_SECTORS, qiov, offset);
        if (ret < 0) {
            return ret;
        }
        offset += NBD_MAX_SECTORS * 512;
        sector_num += NBD_MAX_SECTORS;
        nb_sectors -= NBD_MAX_SECTORS;
    }
    return nbd_co_readv_1(client, sector_num, nb_sectors, qiov, offset);
}

int nbd_client_session_co_writev(NbdClientSession *client, int64_t sector_num,
                                 int nb_sectors, QEMUIOVector *qiov)
{
    int offset = 0;
    int ret;
    while (nb_sectors > NBD_MAX_SECTORS) {
        ret = nbd_co_writev_1(client, sector_num,
                              NBD_MAX_SECTORS, qiov, offset);
        if (ret < 0) {
            return ret;
        }
        offset += NBD_MAX_SECTORS * 512;
        sector_num += NBD_MAX_SECTORS;
        nb_sectors -= NBD_MAX_SECTORS;
    }
    return nbd_co_writev_1(client, sector_num, nb_sectors, qiov, offset);
}

int nbd_client_session_co_flush(NbdClientSession *client)
{
    struct nbd_request request = { .type = NBD_CMD_FLUSH };
    struct nbd_reply reply;
    ssize_t ret;

    if (!(client->nbdflags & NBD_FLAG_SEND_FLUSH)) {
        return 0;
    }

    if (client->nbdflags & NBD_FLAG_SEND_FUA) {
        request.type |= NBD_CMD_FLAG_FUA;
    }

    request.from = 0;
    request.len = 0;

    nbd_coroutine_start(client, &request);
    ret = nbd_co_send_request(client, &request, NULL, 0);
    if (ret < 0) {
        reply.error = -ret;
    } else {
        nbd_co_receive_reply(client, &request, &reply, NULL, 0);
    }
    nbd_coroutine_end(client, &request);
    return -reply.error;
}

int nbd_client_session_co_discard(NbdClientSession *client, int64_t sector_num,
    int nb_sectors)
{
    struct nbd_request request = { .type = NBD_CMD_TRIM };
    struct nbd_reply reply;
    ssize_t ret;

    if (!(client->nbdflags & NBD_FLAG_SEND_TRIM)) {
        return 0;
    }
    request.from = sector_num * 512;
    request.len = nb_sectors * 512;

    nbd_coroutine_start(client, &request);
    ret = nbd_co_send_request(client, &request, NULL, 0);
    if (ret < 0) {
        reply.error = -ret;
    } else {
        nbd_co_receive_reply(client, &request, &reply, NULL, 0);
    }
    nbd_coroutine_end(client, &request);
    return -reply.error;

}

void nbd_client_session_detach_aio_context(NbdClientSession *client)
{
    aio_set_fd_handler(bdrv_get_aio_context(client->bs), client->sock,
                       NULL, NULL, NULL);
}

void nbd_client_session_attach_aio_context(NbdClientSession *client,
                                           AioContext *new_context)
{
    aio_set_fd_handler(new_context, client->sock,
                       nbd_reply_ready, NULL, client);
}

void nbd_client_session_close(NbdClientSession *client)
{
    struct nbd_request request = {
        .type = NBD_CMD_DISC,
        .from = 0,
        .len = 0
    };

    if (!client->bs) {
        return;
    }
    if (client->sock == -1) {
        return;
    }

    nbd_send_request(client->sock, &request);

    nbd_teardown_connection(client);
    client->bs = NULL;
}

int nbd_client_session_init(NbdClientSession *client, BlockDriverState *bs,
    int sock, const char *export)
{
    int ret;

    /* NBD handshake */
    logout("session init %s\n", export);
    qemu_set_block(sock);
    ret = nbd_receive_negotiate(sock, export,
                                &client->nbdflags, &client->size,
                                &client->blocksize);
    if (ret < 0) {
        logout("Failed to negotiate with the NBD server\n");
        closesocket(sock);
        return ret;
    }

    qemu_co_mutex_init(&client->send_mutex);
    qemu_co_mutex_init(&client->free_sema);
    client->bs = bs;
    client->sock = sock;

    /* Now that we're connected, set the socket to be non-blocking and
     * kick the reply mechanism.  */
    qemu_set_nonblock(sock);
    nbd_client_session_attach_aio_context(client, bdrv_get_aio_context(bs));

    logout("Established connection with NBD server\n");
    return 0;
}
Commit	Line	Data
2302c1ca MAL	1	/*
	2	* QEMU Block driver for NBD
	3	*
	4	* Copyright (C) 2008 Bull S.A.S.
	5	* Author: Laurent Vivier <[email protected]>
	6	*
	7	* Some parts:
	8	* Copyright (C) 2007 Anthony Liguori <[email protected]>
	9	*
	10	* Permission is hereby granted, free of charge, to any person obtaining a copy
	11	* of this software and associated documentation files (the "Software"), to deal
	12	* in the Software without restriction, including without limitation the rights
	13	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	14	* copies of the Software, and to permit persons to whom the Software is
	15	* furnished to do so, subject to the following conditions:
	16	*
	17	* The above copyright notice and this permission notice shall be included in
	18	* all copies or substantial portions of the Software.
	19	*
	20	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	21	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	22	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	23	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	24	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	25	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	26	* THE SOFTWARE.
	27	*/
	28
	29	#include "nbd-client.h"
	30	#include "qemu/sockets.h"
	31
	32	#define HANDLE_TO_INDEX(bs, handle) ((handle) ^ ((uint64_t)(intptr_t)bs))
	33	#define INDEX_TO_HANDLE(bs, index) ((index) ^ ((uint64_t)(intptr_t)bs))
	34
69152c09 MAL	35	static void nbd_recv_coroutines_enter_all(NbdClientSession *s)
	36	{
	37	int i;
	38
	39	for (i = 0; i < MAX_NBD_REQUESTS; i++) {
	40	if (s->recv_coroutine[i]) {
	41	qemu_coroutine_enter(s->recv_coroutine[i], NULL);
	42	}
	43	}
	44	}
	45
4a41a2d6 SH	46	static void nbd_teardown_connection(NbdClientSession *client)
	47	{
	48	/* finish any pending coroutines */
	49	shutdown(client->sock, 2);
	50	nbd_recv_coroutines_enter_all(client);
	51
69447cd8	52	nbd_client_session_detach_aio_context(client);
4a41a2d6 SH	53	closesocket(client->sock);
	54	client->sock = -1;
	55	}
	56
2302c1ca MAL	57	static void nbd_reply_ready(void *opaque)
	58	{
	59	NbdClientSession *s = opaque;
	60	uint64_t i;
	61	int ret;
	62
	63	if (s->reply.handle == 0) {
	64	/* No reply already in flight. Fetch a header. It is possible
	65	* that another thread has done the same thing in parallel, so
	66	* the socket is not readable anymore.
	67	*/
	68	ret = nbd_receive_reply(s->sock, &s->reply);
	69	if (ret == -EAGAIN) {
	70	return;
	71	}
	72	if (ret < 0) {
	73	s->reply.handle = 0;
	74	goto fail;
	75	}
	76	}
	77
	78	/* There's no need for a mutex on the receive side, because the
	79	* handler acts as a synchronization point and ensures that only
	80	* one coroutine is called until the reply finishes. */
	81	i = HANDLE_TO_INDEX(s, s->reply.handle);
	82	if (i >= MAX_NBD_REQUESTS) {
	83	goto fail;
	84	}
	85
	86	if (s->recv_coroutine[i]) {
	87	qemu_coroutine_enter(s->recv_coroutine[i], NULL);
	88	return;
	89	}
	90
	91	fail:
4a41a2d6	92	nbd_teardown_connection(s);
2302c1ca MAL	93	}
	94
	95	static void nbd_restart_write(void *opaque)
	96	{
	97	NbdClientSession *s = opaque;
	98
	99	qemu_coroutine_enter(s->send_coroutine, NULL);
	100	}
	101
	102	static int nbd_co_send_request(NbdClientSession *s,
	103	struct nbd_request *request,
	104	QEMUIOVector *qiov, int offset)
	105	{
69447cd8	106	AioContext *aio_context;
2302c1ca MAL	107	int rc, ret;
	108
	109	qemu_co_mutex_lock(&s->send_mutex);
	110	s->send_coroutine = qemu_coroutine_self();
69447cd8 SH	111	aio_context = bdrv_get_aio_context(s->bs);
	112	aio_set_fd_handler(aio_context, s->sock,
	113	nbd_reply_ready, nbd_restart_write, s);
2302c1ca MAL	114	if (qiov) {
	115	if (!s->is_unix) {
	116	socket_set_cork(s->sock, 1);
	117	}
	118	rc = nbd_send_request(s->sock, request);
	119	if (rc >= 0) {
	120	ret = qemu_co_sendv(s->sock, qiov->iov, qiov->niov,
	121	offset, request->len);
	122	if (ret != request->len) {
	123	rc = -EIO;
	124	}
	125	}
	126	if (!s->is_unix) {
	127	socket_set_cork(s->sock, 0);
	128	}
	129	} else {
	130	rc = nbd_send_request(s->sock, request);
	131	}
69447cd8	132	aio_set_fd_handler(aio_context, s->sock, nbd_reply_ready, NULL, s);
2302c1ca MAL	133	s->send_coroutine = NULL;
	134	qemu_co_mutex_unlock(&s->send_mutex);
	135	return rc;
	136	}
	137
	138	static void nbd_co_receive_reply(NbdClientSession *s,
	139	struct nbd_request request, struct nbd_reply reply,
	140	QEMUIOVector *qiov, int offset)
	141	{
	142	int ret;
	143
	144	/* Wait until we're woken up by the read handler. TODO: perhaps
	145	* peek at the next reply and avoid yielding if it's ours? */
	146	qemu_coroutine_yield();
	147	*reply = s->reply;
	148	if (reply->handle != request->handle) {
	149	reply->error = EIO;
	150	} else {
	151	if (qiov && reply->error == 0) {
	152	ret = qemu_co_recvv(s->sock, qiov->iov, qiov->niov,
	153	offset, request->len);
	154	if (ret != request->len) {
	155	reply->error = EIO;
	156	}
	157	}
	158
	159	/* Tell the read handler to read another header. */
	160	s->reply.handle = 0;
	161	}
	162	}
	163
	164	static void nbd_coroutine_start(NbdClientSession *s,
	165	struct nbd_request *request)
	166	{
	167	int i;
	168
	169	/* Poor man semaphore. The free_sema is locked when no other request
	170	* can be accepted, and unlocked after receiving one reply. */
	171	if (s->in_flight >= MAX_NBD_REQUESTS - 1) {
	172	qemu_co_mutex_lock(&s->free_sema);
	173	assert(s->in_flight < MAX_NBD_REQUESTS);
	174	}
	175	s->in_flight++;
	176
	177	for (i = 0; i < MAX_NBD_REQUESTS; i++) {
	178	if (s->recv_coroutine[i] == NULL) {
	179	s->recv_coroutine[i] = qemu_coroutine_self();
	180	break;
	181	}
	182	}
	183
	184	assert(i < MAX_NBD_REQUESTS);
	185	request->handle = INDEX_TO_HANDLE(s, i);
	186	}
	187
	188	static void nbd_coroutine_end(NbdClientSession *s,
	189	struct nbd_request *request)
	190	{
	191	int i = HANDLE_TO_INDEX(s, request->handle);
	192	s->recv_coroutine[i] = NULL;
	193	if (s->in_flight-- == MAX_NBD_REQUESTS) {
	194	qemu_co_mutex_unlock(&s->free_sema);
	195	}
	196	}
197
198	static int nbd_co_readv_1(NbdClientSession *client, int64_t sector_num,
199	int nb_sectors, QEMUIOVector *qiov,
200	int offset)
201	{
b1b27b64	202	struct nbd_request request = { .type = NBD_CMD_READ };
2302c1ca MAL	203	struct nbd_reply reply;
	204	ssize_t ret;
	205
2302c1ca MAL	206	request.from = sector_num * 512;
	207	request.len = nb_sectors * 512;
	208
	209	nbd_coroutine_start(client, &request);
	210	ret = nbd_co_send_request(client, &request, NULL, 0);
	211	if (ret < 0) {
	212	reply.error = -ret;
	213	} else {
	214	nbd_co_receive_reply(client, &request, &reply, qiov, offset);
	215	}
	216	nbd_coroutine_end(client, &request);
	217	return -reply.error;
	218
	219	}
	220
	221	static int nbd_co_writev_1(NbdClientSession *client, int64_t sector_num,
	222	int nb_sectors, QEMUIOVector *qiov,
	223	int offset)
	224	{
b1b27b64	225	struct nbd_request request = { .type = NBD_CMD_WRITE };
2302c1ca MAL	226	struct nbd_reply reply;
	227	ssize_t ret;
	228
2302c1ca MAL	229	if (!bdrv_enable_write_cache(client->bs) &&
	230	(client->nbdflags & NBD_FLAG_SEND_FUA)) {
	231	request.type \|= NBD_CMD_FLAG_FUA;
	232	}
	233
	234	request.from = sector_num * 512;
	235	request.len = nb_sectors * 512;
	236
	237	nbd_coroutine_start(client, &request);
	238	ret = nbd_co_send_request(client, &request, qiov, offset);
	239	if (ret < 0) {
	240	reply.error = -ret;
	241	} else {
	242	nbd_co_receive_reply(client, &request, &reply, NULL, 0);
	243	}
	244	nbd_coroutine_end(client, &request);
	245	return -reply.error;
	246	}
	247
	248	/* qemu-nbd has a limit of slightly less than 1M per request. Try to
	249	* remain aligned to 4K. */
	250	#define NBD_MAX_SECTORS 2040
	251
	252	int nbd_client_session_co_readv(NbdClientSession *client, int64_t sector_num,
	253	int nb_sectors, QEMUIOVector *qiov)
	254	{
	255	int offset = 0;
	256	int ret;
	257	while (nb_sectors > NBD_MAX_SECTORS) {
	258	ret = nbd_co_readv_1(client, sector_num,
	259	NBD_MAX_SECTORS, qiov, offset);
	260	if (ret < 0) {
	261	return ret;
	262	}
	263	offset += NBD_MAX_SECTORS * 512;
	264	sector_num += NBD_MAX_SECTORS;
	265	nb_sectors -= NBD_MAX_SECTORS;
	266	}
	267	return nbd_co_readv_1(client, sector_num, nb_sectors, qiov, offset);
	268	}
	269
	270	int nbd_client_session_co_writev(NbdClientSession *client, int64_t sector_num,
	271	int nb_sectors, QEMUIOVector *qiov)
	272	{
	273	int offset = 0;
	274	int ret;
	275	while (nb_sectors > NBD_MAX_SECTORS) {
	276	ret = nbd_co_writev_1(client, sector_num,
	277	NBD_MAX_SECTORS, qiov, offset);
	278	if (ret < 0) {
	279	return ret;
	280	}
	281	offset += NBD_MAX_SECTORS * 512;
	282	sector_num += NBD_MAX_SECTORS;
	283	nb_sectors -= NBD_MAX_SECTORS;
	284	}
	285	return nbd_co_writev_1(client, sector_num, nb_sectors, qiov, offset);
	286	}
	287
	288	int nbd_client_session_co_flush(NbdClientSession *client)
	289	{
b1b27b64	290	struct nbd_request request = { .type = NBD_CMD_FLUSH };
2302c1ca MAL	291	struct nbd_reply reply;
	292	ssize_t ret;
	293
	294	if (!(client->nbdflags & NBD_FLAG_SEND_FLUSH)) {
	295	return 0;
	296	}
	297
2302c1ca MAL	298	if (client->nbdflags & NBD_FLAG_SEND_FUA) {
	299	request.type \|= NBD_CMD_FLAG_FUA;
	300	}
	301
	302	request.from = 0;
	303	request.len = 0;
	304
	305	nbd_coroutine_start(client, &request);
	306	ret = nbd_co_send_request(client, &request, NULL, 0);
	307	if (ret < 0) {
	308	reply.error = -ret;
	309	} else {
	310	nbd_co_receive_reply(client, &request, &reply, NULL, 0);
	311	}
	312	nbd_coroutine_end(client, &request);
	313	return -reply.error;
	314	}
	315
	316	int nbd_client_session_co_discard(NbdClientSession *client, int64_t sector_num,
	317	int nb_sectors)
	318	{
b1b27b64	319	struct nbd_request request = { .type = NBD_CMD_TRIM };
2302c1ca MAL	320	struct nbd_reply reply;
	321	ssize_t ret;
	322
	323	if (!(client->nbdflags & NBD_FLAG_SEND_TRIM)) {
	324	return 0;
	325	}
2302c1ca MAL	326	request.from = sector_num * 512;
	327	request.len = nb_sectors * 512;
	328
	329	nbd_coroutine_start(client, &request);
	330	ret = nbd_co_send_request(client, &request, NULL, 0);
	331	if (ret < 0) {
	332	reply.error = -ret;
	333	} else {
	334	nbd_co_receive_reply(client, &request, &reply, NULL, 0);
	335	}
	336	nbd_coroutine_end(client, &request);
	337	return -reply.error;
	338
	339	}
	340
69447cd8 SH	341	void nbd_client_session_detach_aio_context(NbdClientSession *client)
	342	{
	343	aio_set_fd_handler(bdrv_get_aio_context(client->bs), client->sock,
	344	NULL, NULL, NULL);
	345	}
	346
	347	void nbd_client_session_attach_aio_context(NbdClientSession *client,
	348	AioContext *new_context)
	349	{
	350	aio_set_fd_handler(new_context, client->sock,
	351	nbd_reply_ready, NULL, client);
	352	}
	353
4a41a2d6	354	void nbd_client_session_close(NbdClientSession *client)
2302c1ca	355	{
b1b27b64 MAL	356	struct nbd_request request = {
	357	.type = NBD_CMD_DISC,
	358	.from = 0,
	359	.len = 0
	360	};
2302c1ca	361
5ad283eb MAL	362	if (!client->bs) {
	363	return;
	364	}
4a41a2d6 SH	365	if (client->sock == -1) {
	366	return;
	367	}
	368
	369	nbd_send_request(client->sock, &request);
5ad283eb	370
2302c1ca	371	nbd_teardown_connection(client);
5ad283eb	372	client->bs = NULL;
2302c1ca MAL	373	}
2302c1ca MAL	374
e2bc625f MAL	375	int nbd_client_session_init(NbdClientSession client, BlockDriverState bs,
e2bc625f MAL	376	int sock, const char *export)
2302c1ca MAL	377	{
	378	int ret;
	379
	380	/* NBD handshake */
e2bc625f	381	logout("session init %s\n", export);
e53a18e4	382	qemu_set_block(sock);
e2bc625f	383	ret = nbd_receive_negotiate(sock, export,
2302c1ca MAL	384	&client->nbdflags, &client->size,
	385	&client->blocksize);
	386	if (ret < 0) {
	387	logout("Failed to negotiate with the NBD server\n");
	388	closesocket(sock);
	389	return ret;
	390	}
	391
	392	qemu_co_mutex_init(&client->send_mutex);
	393	qemu_co_mutex_init(&client->free_sema);
	394	client->bs = bs;
	395	client->sock = sock;
	396
	397	/* Now that we're connected, set the socket to be non-blocking and
	398	* kick the reply mechanism. */
	399	qemu_set_nonblock(sock);
69447cd8	400	nbd_client_session_attach_aio_context(client, bdrv_get_aio_context(bs));
2302c1ca MAL	401
	402	logout("Established connection with NBD server\n");
	403	return 0;
	404	}