block/nbd-client.c

   1 /*
   2  * QEMU Block driver for  NBD
   3  *
   4  * Copyright (C) 2008 Bull S.A.S.
   5  *     Author: Laurent Vivier <Laurent.Vivier@bull.net>
   6  *
   7  * Some parts:
   8  *    Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws>
   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 "qemu/osdep.h"
  30 #include "nbd-client.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
  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]);
  42         }
  43     }
  44 }
  45
  46 static void nbd_teardown_connection(BlockDriverState *bs)
  47 {
  48     NbdClientSession *client = nbd_get_client_session(bs);
  49
  50     if (!client->ioc) { /* Already closed */
  51         return;
  52     }
  53
  54     /* finish any pending coroutines */
  55     qio_channel_shutdown(client->ioc,
  56                          QIO_CHANNEL_SHUTDOWN_BOTH,
  57                          NULL);
  58     nbd_recv_coroutines_enter_all(client);
  59
  60     nbd_client_detach_aio_context(bs);
  61     object_unref(OBJECT(client->sioc));
  62     client->sioc = NULL;
  63     object_unref(OBJECT(client->ioc));
  64     client->ioc = NULL;
  65 }
  66
  67 static void nbd_reply_ready(void *opaque)
  68 {
  69     BlockDriverState *bs = opaque;
  70     NbdClientSession *s = nbd_get_client_session(bs);
  71     uint64_t i;
  72     int ret;
  73
  74     if (!s->ioc) { /* Already closed */
  75         return;
  76     }
  77
  78     if (s->reply.handle == 0) {
  79         /* No reply already in flight.  Fetch a header.  It is possible
  80          * that another thread has done the same thing in parallel, so
  81          * the socket is not readable anymore.
  82          */
  83         ret = nbd_receive_reply(s->ioc, &s->reply);
  84         if (ret == -EAGAIN) {
  85             return;
  86         }
  87         if (ret < 0) {
  88             s->reply.handle = 0;
  89             goto fail;
  90         }
  91     }
  92
  93     /* There's no need for a mutex on the receive side, because the
  94      * handler acts as a synchronization point and ensures that only
  95      * one coroutine is called until the reply finishes.  */
  96     i = HANDLE_TO_INDEX(s, s->reply.handle);
  97     if (i >= MAX_NBD_REQUESTS) {
  98         goto fail;
  99     }
 100
 101     if (s->recv_coroutine[i]) {
 102         qemu_coroutine_enter(s->recv_coroutine[i]);
 103         return;
 104     }
 105
 106 fail:
 107     nbd_teardown_connection(bs);
 108 }
 109
 110 static void nbd_restart_write(void *opaque)
 111 {
 112     BlockDriverState *bs = opaque;
 113
 114     qemu_coroutine_enter(nbd_get_client_session(bs)->send_coroutine);
 115 }
 116
 117 static int nbd_co_send_request(BlockDriverState *bs,
 118                                struct nbd_request *request,
 119                                QEMUIOVector *qiov)
 120 {
 121     NbdClientSession *s = nbd_get_client_session(bs);
 122     AioContext *aio_context;
 123     int rc, ret, i;
 124
 125     qemu_co_mutex_lock(&s->send_mutex);
 126
 127     for (i = 0; i < MAX_NBD_REQUESTS; i++) {
 128         if (s->recv_coroutine[i] == NULL) {
 129             s->recv_coroutine[i] = qemu_coroutine_self();
 130             break;
 131         }
 132     }
 133
 134     g_assert(qemu_in_coroutine());
 135     assert(i < MAX_NBD_REQUESTS);
 136     request->handle = INDEX_TO_HANDLE(s, i);
 137
 138     if (!s->ioc) {
 139         qemu_co_mutex_unlock(&s->send_mutex);
 140         return -EPIPE;
 141     }
 142
 143     s->send_coroutine = qemu_coroutine_self();
 144     aio_context = bdrv_get_aio_context(bs);
 145
 146     aio_set_fd_handler(aio_context, s->sioc->fd, false,
 147                        nbd_reply_ready, nbd_restart_write, bs);
 148     if (qiov) {
 149         qio_channel_set_cork(s->ioc, true);
 150         rc = nbd_send_request(s->ioc, request);
 151         if (rc >= 0) {
 152             ret = nbd_wr_syncv(s->ioc, qiov->iov, qiov->niov, request->len,
 153                                false);
 154             if (ret != request->len) {
 155                 rc = -EIO;
 156             }
 157         }
 158         qio_channel_set_cork(s->ioc, false);
 159     } else {
 160         rc = nbd_send_request(s->ioc, request);
 161     }
 162     aio_set_fd_handler(aio_context, s->sioc->fd, false,
 163                        nbd_reply_ready, NULL, bs);
 164     s->send_coroutine = NULL;
 165     qemu_co_mutex_unlock(&s->send_mutex);
 166     return rc;
 167 }
 168
 169 static void nbd_co_receive_reply(NbdClientSession *s,
 170                                  struct nbd_request *request,
 171                                  struct nbd_reply *reply,
 172                                  QEMUIOVector *qiov)
 173 {
 174     int ret;
 175
 176     /* Wait until we're woken up by the read handler.  TODO: perhaps
 177      * peek at the next reply and avoid yielding if it's ours?  */
 178     qemu_coroutine_yield();
 179     *reply = s->reply;
 180     if (reply->handle != request->handle ||
 181         !s->ioc) {
 182         reply->error = EIO;
 183     } else {
 184         if (qiov && reply->error == 0) {
 185             ret = nbd_wr_syncv(s->ioc, qiov->iov, qiov->niov, request->len,
 186                                true);
 187             if (ret != request->len) {
 188                 reply->error = EIO;
 189             }
 190         }
 191
 192         /* Tell the read handler to read another header.  */
 193         s->reply.handle = 0;
 194     }
 195 }
 196
 197 static void nbd_coroutine_start(NbdClientSession *s,
 198    struct nbd_request *request)
 199 {
 200     /* Poor man semaphore.  The free_sema is locked when no other request
 201      * can be accepted, and unlocked after receiving one reply.  */
 202     if (s->in_flight >= MAX_NBD_REQUESTS - 1) {
 203         qemu_co_mutex_lock(&s->free_sema);
 204         assert(s->in_flight < MAX_NBD_REQUESTS);
 205     }
 206     s->in_flight++;
 207
 208     /* s->recv_coroutine[i] is set as soon as we get the send_lock.  */
 209 }
 210
 211 static void nbd_coroutine_end(NbdClientSession *s,
 212     struct nbd_request *request)
 213 {
 214     int i = HANDLE_TO_INDEX(s, request->handle);
 215     s->recv_coroutine[i] = NULL;
 216     if (s->in_flight-- == MAX_NBD_REQUESTS) {
 217         qemu_co_mutex_unlock(&s->free_sema);
 218     }
 219 }
 220
 221 int nbd_client_co_readv(BlockDriverState *bs, int64_t sector_num,
 222                         int nb_sectors, QEMUIOVector *qiov)
 223 {
 224     NbdClientSession *client = nbd_get_client_session(bs);
 225     struct nbd_request request = { .type = NBD_CMD_READ };
 226     struct nbd_reply reply;
 227     ssize_t ret;
 228
 229     assert(nb_sectors <= NBD_MAX_SECTORS);
 230     request.from = sector_num * 512;
 231     request.len = nb_sectors * 512;
 232
 233     nbd_coroutine_start(client, &request);
 234     ret = nbd_co_send_request(bs, &request, NULL);
 235     if (ret < 0) {
 236         reply.error = -ret;
 237     } else {
 238         nbd_co_receive_reply(client, &request, &reply, qiov);
 239     }
 240     nbd_coroutine_end(client, &request);
 241     return -reply.error;
 242
 243 }
 244
 245 int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num,
 246                          int nb_sectors, QEMUIOVector *qiov, int flags)
 247 {
 248     NbdClientSession *client = nbd_get_client_session(bs);
 249     struct nbd_request request = { .type = NBD_CMD_WRITE };
 250     struct nbd_reply reply;
 251     ssize_t ret;
 252
 253     if (flags & BDRV_REQ_FUA) {
 254         assert(client->nbdflags & NBD_FLAG_SEND_FUA);
 255         request.type |= NBD_CMD_FLAG_FUA;
 256     }
 257
 258     assert(nb_sectors <= NBD_MAX_SECTORS);
 259     request.from = sector_num * 512;
 260     request.len = nb_sectors * 512;
 261
 262     nbd_coroutine_start(client, &request);
 263     ret = nbd_co_send_request(bs, &request, qiov);
 264     if (ret < 0) {
 265         reply.error = -ret;
 266     } else {
 267         nbd_co_receive_reply(client, &request, &reply, NULL);
 268     }
 269     nbd_coroutine_end(client, &request);
 270     return -reply.error;
 271 }
 272
 273 int nbd_client_co_flush(BlockDriverState *bs)
 274 {
 275     NbdClientSession *client = nbd_get_client_session(bs);
 276     struct nbd_request request = { .type = NBD_CMD_FLUSH };
 277     struct nbd_reply reply;
 278     ssize_t ret;
 279
 280     if (!(client->nbdflags & NBD_FLAG_SEND_FLUSH)) {
 281         return 0;
 282     }
 283
 284     request.from = 0;
 285     request.len = 0;
 286
 287     nbd_coroutine_start(client, &request);
 288     ret = nbd_co_send_request(bs, &request, NULL);
 289     if (ret < 0) {
 290         reply.error = -ret;
 291     } else {
 292         nbd_co_receive_reply(client, &request, &reply, NULL);
 293     }
 294     nbd_coroutine_end(client, &request);
 295     return -reply.error;
 296 }
 297
 298 int nbd_client_co_discard(BlockDriverState *bs, int64_t sector_num,
 299                           int nb_sectors)
 300 {
 301     NbdClientSession *client = nbd_get_client_session(bs);
 302     struct nbd_request request = { .type = NBD_CMD_TRIM };
 303     struct nbd_reply reply;
 304     ssize_t ret;
 305
 306     if (!(client->nbdflags & NBD_FLAG_SEND_TRIM)) {
 307         return 0;
 308     }
 309     request.from = sector_num * 512;
 310     request.len = nb_sectors * 512;
 311
 312     nbd_coroutine_start(client, &request);
 313     ret = nbd_co_send_request(bs, &request, NULL);
 314     if (ret < 0) {
 315         reply.error = -ret;
 316     } else {
 317         nbd_co_receive_reply(client, &request, &reply, NULL);
 318     }
 319     nbd_coroutine_end(client, &request);
 320     return -reply.error;
 321
 322 }
 323
 324 void nbd_client_detach_aio_context(BlockDriverState *bs)
 325 {
 326     aio_set_fd_handler(bdrv_get_aio_context(bs),
 327                        nbd_get_client_session(bs)->sioc->fd,
 328                        false, NULL, NULL, NULL);
 329 }
 330
 331 void nbd_client_attach_aio_context(BlockDriverState *bs,
 332                                    AioContext *new_context)
 333 {
 334     aio_set_fd_handler(new_context, nbd_get_client_session(bs)->sioc->fd,
 335                        false, nbd_reply_ready, NULL, bs);
 336 }
 337
 338 void nbd_client_close(BlockDriverState *bs)
 339 {
 340     NbdClientSession *client = nbd_get_client_session(bs);
 341     struct nbd_request request = {
 342         .type = NBD_CMD_DISC,
 343         .from = 0,
 344         .len = 0
 345     };
 346
 347     if (client->ioc == NULL) {
 348         return;
 349     }
 350
 351     nbd_send_request(client->ioc, &request);
 352
 353     nbd_teardown_connection(bs);
 354 }
 355
 356 int nbd_client_init(BlockDriverState *bs,
 357                     QIOChannelSocket *sioc,
 358                     const char *export,
 359                     QCryptoTLSCreds *tlscreds,
 360                     const char *hostname,
 361                     Error **errp)
 362 {
 363     NbdClientSession *client = nbd_get_client_session(bs);
 364     int ret;
 365
 366     /* NBD handshake */
 367     logout("session init %s\n", export);
 368     qio_channel_set_blocking(QIO_CHANNEL(sioc), true, NULL);
 369
 370     ret = nbd_receive_negotiate(QIO_CHANNEL(sioc), export,
 371                                 &client->nbdflags,
 372                                 tlscreds, hostname,
 373                                 &client->ioc,
 374                                 &client->size, errp);
 375     if (ret < 0) {
 376         logout("Failed to negotiate with the NBD server\n");
 377         return ret;
 378     }
 379     if (client->nbdflags & NBD_FLAG_SEND_FUA) {
 380         bs->supported_write_flags = BDRV_REQ_FUA;
 381     }
 382
 383     qemu_co_mutex_init(&client->send_mutex);
 384     qemu_co_mutex_init(&client->free_sema);
 385     client->sioc = sioc;
 386     object_ref(OBJECT(client->sioc));
 387
 388     if (!client->ioc) {
 389         client->ioc = QIO_CHANNEL(sioc);
 390         object_ref(OBJECT(client->ioc));
 391     }
 392
 393     /* Now that we're connected, set the socket to be non-blocking and
 394      * kick the reply mechanism.  */
 395     qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL);
 396
 397     nbd_client_attach_aio_context(bs, bdrv_get_aio_context(bs));
 398
 399     logout("Established connection with NBD server\n");
 400     return 0;
 401 }