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-rw-r--r--block/nbd-client.c372
1 files changed, 372 insertions, 0 deletions
diff --git a/block/nbd-client.c b/block/nbd-client.c
new file mode 100644
index 0000000..1abfc6a
--- /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;
+}
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