/* * 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 "qemu/osdep.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]) { qemu_coroutine_enter(s->recv_coroutine[i], NULL); } } } 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); nbd_recv_coroutines_enter_all(client); nbd_client_detach_aio_context(bs); object_unref(OBJECT(client->sioc)); client->sioc = NULL; object_unref(OBJECT(client->ioc)); client->ioc = NULL; } static void nbd_reply_ready(void *opaque) { BlockDriverState *bs = opaque; NbdClientSession *s = nbd_get_client_session(bs); uint64_t i; int ret; if (!s->ioc) { /* Already closed */ return; } 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->ioc, &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(bs); } static void nbd_restart_write(void *opaque) { BlockDriverState *bs = opaque; qemu_coroutine_enter(nbd_get_client_session(bs)->send_coroutine, NULL); } static int nbd_co_send_request(BlockDriverState *bs, struct nbd_request *request, QEMUIOVector *qiov, int offset) { NbdClientSession *s = nbd_get_client_session(bs); AioContext *aio_context; int rc, ret, i; qemu_co_mutex_lock(&s->send_mutex); 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; } s->send_coroutine = qemu_coroutine_self(); aio_context = bdrv_get_aio_context(bs); aio_set_fd_handler(aio_context, s->sioc->fd, false, nbd_reply_ready, nbd_restart_write, bs); if (qiov) { qio_channel_set_cork(s->ioc, true); rc = nbd_send_request(s->ioc, request); if (rc >= 0) { ret = nbd_wr_syncv(s->ioc, qiov->iov, qiov->niov, offset, request->len, 0); if (ret != request->len) { rc = -EIO; } } qio_channel_set_cork(s->ioc, false); } else { rc = nbd_send_request(s->ioc, request); } aio_set_fd_handler(aio_context, s->sioc->fd, false, nbd_reply_ready, NULL, bs); 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 || !s->ioc) { reply->error = EIO; } else { if (qiov && reply->error == 0) { ret = nbd_wr_syncv(s->ioc, qiov->iov, qiov->niov, offset, request->len, 1); 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) { /* 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++; /* s->recv_coroutine[i] is set as soon as we get the send_lock. */ } 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(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int offset) { NbdClientSession *client = nbd_get_client_session(bs); 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(bs, &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(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int offset, int flags) { NbdClientSession *client = nbd_get_client_session(bs); struct nbd_request request = { .type = NBD_CMD_WRITE }; struct nbd_reply reply; ssize_t ret; if (flags & BDRV_REQ_FUA) { assert(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(bs, &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; } int nbd_client_co_readv(BlockDriverState *bs, 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(bs, 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(bs, sector_num, nb_sectors, qiov, offset); } int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags) { int offset = 0; int ret; while (nb_sectors > NBD_MAX_SECTORS) { ret = nbd_co_writev_1(bs, sector_num, NBD_MAX_SECTORS, qiov, offset, flags); 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(bs, sector_num, nb_sectors, qiov, offset, flags); } int nbd_client_co_flush(BlockDriverState *bs) { NbdClientSession *client = nbd_get_client_session(bs); struct nbd_request request = { .type = NBD_CMD_FLUSH }; struct nbd_reply reply; ssize_t ret; if (!(client->nbdflags & NBD_FLAG_SEND_FLUSH)) { return 0; } request.from = 0; request.len = 0; nbd_coroutine_start(client, &request); ret = nbd_co_send_request(bs, &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_co_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors) { NbdClientSession *client = nbd_get_client_session(bs); 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(bs, &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_detach_aio_context(BlockDriverState *bs) { aio_set_fd_handler(bdrv_get_aio_context(bs), nbd_get_client_session(bs)->sioc->fd, false, NULL, NULL, NULL); } void nbd_client_attach_aio_context(BlockDriverState *bs, AioContext *new_context) { aio_set_fd_handler(new_context, nbd_get_client_session(bs)->sioc->fd, false, nbd_reply_ready, NULL, bs); } void nbd_client_close(BlockDriverState *bs) { NbdClientSession *client = nbd_get_client_session(bs); struct nbd_request request = { .type = NBD_CMD_DISC, .from = 0, .len = 0 }; 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; } qemu_co_mutex_init(&client->send_mutex); qemu_co_mutex_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); nbd_client_attach_aio_context(bs, bdrv_get_aio_context(bs)); logout("Established connection with NBD server\n"); return 0; }