/* * 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_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_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_recv_coroutines_enter_all(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) { 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 = { .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; } static void nbd_teardown_connection(NbdClientSession *client) { struct nbd_request request = { .type = NBD_CMD_DISC, .from = 0, .len = 0 }; nbd_send_request(client->sock, &request); /* finish any pending coroutines */ shutdown(client->sock, 2); nbd_recv_coroutines_enter_all(client); qemu_aio_set_fd_handler(client->sock, NULL, NULL, NULL); closesocket(client->sock); client->sock = -1; } void nbd_client_session_close(NbdClientSession *client) { if (!client->bs) { return; } 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); qemu_aio_set_fd_handler(sock, nbd_reply_ready, NULL, client); logout("Established connection with NBD server\n"); return 0; }