diff options
Diffstat (limited to 'block/nbd-client.c')
| -rw-r--r-- | block/nbd-client.c | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/block/nbd-client.c b/block/nbd-client.c new file mode 100644 index 0000000000..1abfc6a7f5 --- /dev/null +++ b/block/nbd-client.c @@ -0,0 +1,372 @@ +/* + * QEMU Block driver for NBD + * + * 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 "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_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: + for (i = 0; i < MAX_NBD_REQUESTS; i++) { + if (s->recv_coroutine[i]) { + qemu_coroutine_enter(s->recv_coroutine[i], NULL); + } + } +} + +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) +{ + int rc, ret; + + qemu_co_mutex_lock(&s->send_mutex); + s->send_coroutine = qemu_coroutine_self(); + qemu_aio_set_fd_handler(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); + } + qemu_aio_set_fd_handler(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; + struct nbd_reply reply; + ssize_t ret; + + request.type = NBD_CMD_READ; + 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; + struct nbd_reply reply; + ssize_t ret; + + request.type = NBD_CMD_WRITE; + 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; + struct nbd_reply reply; + ssize_t ret; + + if (!(client->nbdflags & NBD_FLAG_SEND_FLUSH)) { + return 0; + } + + request.type = NBD_CMD_FLUSH; + 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; + struct nbd_reply reply; + ssize_t ret; + + if (!(client->nbdflags & NBD_FLAG_SEND_TRIM)) { + return 0; + } + request.type = NBD_CMD_TRIM; + 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; + +} + +static void nbd_teardown_connection(NbdClientSession *client) +{ + struct nbd_request request; + + request.type = NBD_CMD_DISC; + request.from = 0; + request.len = 0; + nbd_send_request(client->sock, &request); + + qemu_aio_set_fd_handler(client->sock, NULL, NULL, NULL); + closesocket(client->sock); + client->sock = -1; +} + +void nbd_client_session_close(NbdClientSession *client) +{ + nbd_teardown_connection(client); + g_free(client->export_name); + client->export_name = NULL; +} + +int nbd_client_session_init(NbdClientSession *client, + BlockDriverState *bs, int sock) +{ + int ret; + + /* NBD handshake */ + ret = nbd_receive_negotiate(sock, client->export_name, + &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); + qemu_aio_set_fd_handler(sock, nbd_reply_ready, NULL, client); + + logout("Established connection with NBD server\n"); + return 0; +} |