block/nbd-client.c

   1 /*
   2  * QEMU Block driver for  NBD
   3  *
   4  * Copyright (C) 2016 Red Hat, Inc.
   5  * Copyright (C) 2008 Bull S.A.S.
   6  *     Author: Laurent Vivier <Laurent.Vivier@bull.net>
   7  *
   8  * Some parts:
   9  *    Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws>
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a copy
  12  * of this software and associated documentation files (the "Software"), to deal
  13  * in the Software without restriction, including without limitation the rights
  14  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15  * copies of the Software, and to permit persons to whom the Software is
  16  * furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included in
  19  * all copies or substantial portions of the Software.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  24  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  26  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  27  * THE SOFTWARE.
  28  */
  29
  30 #include "qemu/osdep.h"
  31 #include "qapi/error.h"
  32 #include "nbd-client.h"
  33
  34 #define HANDLE_TO_INDEX(bs, handle) ((handle) ^ (uint64_t)(intptr_t)(bs))
  35 #define INDEX_TO_HANDLE(bs, index)  ((index)  ^ (uint64_t)(intptr_t)(bs))
  36
  37 static void nbd_recv_coroutines_wake_all(NBDClientSession *s)
  38 {
  39     int i;
  40
  41     for (i = 0; i < MAX_NBD_REQUESTS; i++) {
  42         NBDClientRequest *req = &s->requests[i];
  43
  44         if (req->coroutine && req->receiving) {
  45             aio_co_wake(req->coroutine);
  46         }
  47     }
  48 }
  49
  50 static void nbd_teardown_connection(BlockDriverState *bs)
  51 {
  52     NBDClientSession *client = nbd_get_client_session(bs);
  53
  54     if (!client->ioc) { /* Already closed */
  55         return;
  56     }
  57
  58     /* finish any pending coroutines */
  59     qio_channel_shutdown(client->ioc,
  60                          QIO_CHANNEL_SHUTDOWN_BOTH,
  61                          NULL);
  62     BDRV_POLL_WHILE(bs, client->read_reply_co);
  63
  64     nbd_client_detach_aio_context(bs);
  65     object_unref(OBJECT(client->sioc));
  66     client->sioc = NULL;
  67     object_unref(OBJECT(client->ioc));
  68     client->ioc = NULL;
  69 }
  70
  71 static coroutine_fn void nbd_read_reply_entry(void *opaque)
  72 {
  73     NBDClientSession *s = opaque;
  74     uint64_t i;
  75     int ret = 0;
  76     Error *local_err = NULL;
  77
  78     while (!s->quit) {
  79         assert(s->reply.handle == 0);
  80         ret = nbd_receive_reply(s->ioc, &s->reply, &local_err);
  81         if (ret < 0) {
  82             error_report_err(local_err);
  83         }
  84         if (ret <= 0) {
  85             break;
  86         }
  87
  88         /* There's no need for a mutex on the receive side, because the
  89          * handler acts as a synchronization point and ensures that only
  90          * one coroutine is called until the reply finishes.
  91          */
  92         i = HANDLE_TO_INDEX(s, s->reply.handle);
  93         if (i >= MAX_NBD_REQUESTS ||
  94             !s->requests[i].coroutine ||
  95             !s->requests[i].receiving) {
  96             break;
  97         }
  98
  99         /* We're woken up again by the request itself.  Note that there
 100          * is no race between yielding and reentering read_reply_co.  This
 101          * is because:
 102          *
 103          * - if the request runs on the same AioContext, it is only
 104          *   entered after we yield
 105          *
 106          * - if the request runs on a different AioContext, reentering
 107          *   read_reply_co happens through a bottom half, which can only
 108          *   run after we yield.
 109          */
 110         aio_co_wake(s->requests[i].coroutine);
 111         qemu_coroutine_yield();
 112     }
 113
 114     s->quit = true;
 115     nbd_recv_coroutines_wake_all(s);
 116     s->read_reply_co = NULL;
 117 }
 118
 119 static int nbd_co_send_request(BlockDriverState *bs,
 120                                NBDRequest *request,
 121                                QEMUIOVector *qiov)
 122 {
 123     NBDClientSession *s = nbd_get_client_session(bs);
 124     int rc, i;
 125
 126     qemu_co_mutex_lock(&s->send_mutex);
 127     while (s->in_flight == MAX_NBD_REQUESTS) {
 128         qemu_co_queue_wait(&s->free_sema, &s->send_mutex);
 129     }
 130     s->in_flight++;
 131
 132     for (i = 0; i < MAX_NBD_REQUESTS; i++) {
 133         if (s->requests[i].coroutine == NULL) {
 134             break;
 135         }
 136     }
 137
 138     g_assert(qemu_in_coroutine());
 139     assert(i < MAX_NBD_REQUESTS);
 140
 141     s->requests[i].coroutine = qemu_coroutine_self();
 142     s->requests[i].receiving = false;
 143
 144     request->handle = INDEX_TO_HANDLE(s, i);
 145
 146     if (s->quit) {
 147         rc = -EIO;
 148         goto err;
 149     }
 150     if (!s->ioc) {
 151         rc = -EPIPE;
 152         goto err;
 153     }
 154
 155     if (qiov) {
 156         qio_channel_set_cork(s->ioc, true);
 157         rc = nbd_send_request(s->ioc, request);
 158         if (rc >= 0 && !s->quit) {
 159             if (qio_channel_writev_all(s->ioc, qiov->iov, qiov->niov,
 160                                        NULL) < 0) {
 161                 rc = -EIO;
 162             }
 163         } else if (rc >= 0) {
 164             rc = -EIO;
 165         }
 166         qio_channel_set_cork(s->ioc, false);
 167     } else {
 168         rc = nbd_send_request(s->ioc, request);
 169     }
 170
 171 err:
 172     if (rc < 0) {
 173         s->quit = true;
 174         s->requests[i].coroutine = NULL;
 175         s->in_flight--;
 176         qemu_co_queue_next(&s->free_sema);
 177     }
 178     qemu_co_mutex_unlock(&s->send_mutex);
 179     return rc;
 180 }
 181
 182 static int nbd_co_receive_reply(NBDClientSession *s,
 183                                 uint64_t handle,
 184                                 QEMUIOVector *qiov)
 185 {
 186     int ret;
 187     int i = HANDLE_TO_INDEX(s, handle);
 188
 189     /* Wait until we're woken up by nbd_read_reply_entry.  */
 190     s->requests[i].receiving = true;
 191     qemu_coroutine_yield();
 192     s->requests[i].receiving = false;
 193     if (!s->ioc || s->quit) {
 194         ret = -EIO;
 195     } else {
 196         assert(s->reply.handle == handle);
 197         ret = -s->reply.error;
 198         if (qiov && s->reply.error == 0) {
 199             if (qio_channel_readv_all(s->ioc, qiov->iov, qiov->niov,
 200                                       NULL) < 0) {
 201                 ret = -EIO;
 202                 s->quit = true;
 203             }
 204         }
 205
 206         /* Tell the read handler to read another header.  */
 207         s->reply.handle = 0;
 208     }
 209
 210     s->requests[i].coroutine = NULL;
 211
 212     /* Kick the read_reply_co to get the next reply.  */
 213     if (s->read_reply_co) {
 214         aio_co_wake(s->read_reply_co);
 215     }
 216
 217     qemu_co_mutex_lock(&s->send_mutex);
 218     s->in_flight--;
 219     qemu_co_queue_next(&s->free_sema);
 220     qemu_co_mutex_unlock(&s->send_mutex);
 221
 222     return ret;
 223 }
 224
 225 static int nbd_co_request(BlockDriverState *bs,
 226                           NBDRequest *request,
 227                           QEMUIOVector *qiov)
 228 {
 229     NBDClientSession *client = nbd_get_client_session(bs);
 230     int ret;
 231
 232     if (qiov) {
 233         assert(request->type == NBD_CMD_WRITE || request->type == NBD_CMD_READ);
 234         assert(request->len == iov_size(qiov->iov, qiov->niov));
 235     } else {
 236         assert(request->type != NBD_CMD_WRITE && request->type != NBD_CMD_READ);
 237     }
 238     ret = nbd_co_send_request(bs, request,
 239                               request->type == NBD_CMD_WRITE ? qiov : NULL);
 240     if (ret < 0) {
 241         return ret;
 242     }
 243
 244     return nbd_co_receive_reply(client, request->handle,
 245                                 request->type == NBD_CMD_READ ? qiov : NULL);
 246 }
 247
 248 int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
 249                          uint64_t bytes, QEMUIOVector *qiov, int flags)
 250 {
 251     NBDRequest request = {
 252         .type = NBD_CMD_READ,
 253         .from = offset,
 254         .len = bytes,
 255     };
 256
 257     assert(bytes <= NBD_MAX_BUFFER_SIZE);
 258     assert(!flags);
 259
 260     return nbd_co_request(bs, &request, qiov);
 261 }
 262
 263 int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
 264                           uint64_t bytes, QEMUIOVector *qiov, int flags)
 265 {
 266     NBDClientSession *client = nbd_get_client_session(bs);
 267     NBDRequest request = {
 268         .type = NBD_CMD_WRITE,
 269         .from = offset,
 270         .len = bytes,
 271     };
 272
 273     if (flags & BDRV_REQ_FUA) {
 274         assert(client->info.flags & NBD_FLAG_SEND_FUA);
 275         request.flags |= NBD_CMD_FLAG_FUA;
 276     }
 277
 278     assert(bytes <= NBD_MAX_BUFFER_SIZE);
 279
 280     return nbd_co_request(bs, &request, qiov);
 281 }
 282
 283 int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
 284                                 int bytes, BdrvRequestFlags flags)
 285 {
 286     NBDClientSession *client = nbd_get_client_session(bs);
 287     NBDRequest request = {
 288         .type = NBD_CMD_WRITE_ZEROES,
 289         .from = offset,
 290         .len = bytes,
 291     };
 292
 293     if (!(client->info.flags & NBD_FLAG_SEND_WRITE_ZEROES)) {
 294         return -ENOTSUP;
 295     }
 296
 297     if (flags & BDRV_REQ_FUA) {
 298         assert(client->info.flags & NBD_FLAG_SEND_FUA);
 299         request.flags |= NBD_CMD_FLAG_FUA;
 300     }
 301     if (!(flags & BDRV_REQ_MAY_UNMAP)) {
 302         request.flags |= NBD_CMD_FLAG_NO_HOLE;
 303     }
 304
 305     return nbd_co_request(bs, &request, NULL);
 306 }
 307
 308 int nbd_client_co_flush(BlockDriverState *bs)
 309 {
 310     NBDClientSession *client = nbd_get_client_session(bs);
 311     NBDRequest request = { .type = NBD_CMD_FLUSH };
 312
 313     if (!(client->info.flags & NBD_FLAG_SEND_FLUSH)) {
 314         return 0;
 315     }
 316
 317     request.from = 0;
 318     request.len = 0;
 319
 320     return nbd_co_request(bs, &request, NULL);
 321 }
 322
 323 int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes)
 324 {
 325     NBDClientSession *client = nbd_get_client_session(bs);
 326     NBDRequest request = {
 327         .type = NBD_CMD_TRIM,
 328         .from = offset,
 329         .len = bytes,
 330     };
 331
 332     if (!(client->info.flags & NBD_FLAG_SEND_TRIM)) {
 333         return 0;
 334     }
 335
 336     return nbd_co_request(bs, &request, NULL);
 337 }
 338
 339 void nbd_client_detach_aio_context(BlockDriverState *bs)
 340 {
 341     NBDClientSession *client = nbd_get_client_session(bs);
 342     qio_channel_detach_aio_context(QIO_CHANNEL(client->ioc));
 343 }
 344
 345 void nbd_client_attach_aio_context(BlockDriverState *bs,
 346                                    AioContext *new_context)
 347 {
 348     NBDClientSession *client = nbd_get_client_session(bs);
 349     qio_channel_attach_aio_context(QIO_CHANNEL(client->ioc), new_context);
 350     aio_co_schedule(new_context, client->read_reply_co);
 351 }
 352
 353 void nbd_client_close(BlockDriverState *bs)
 354 {
 355     NBDClientSession *client = nbd_get_client_session(bs);
 356     NBDRequest request = { .type = NBD_CMD_DISC };
 357
 358     if (client->ioc == NULL) {
 359         return;
 360     }
 361
 362     nbd_send_request(client->ioc, &request);
 363
 364     nbd_teardown_connection(bs);
 365 }
 366
 367 int nbd_client_init(BlockDriverState *bs,
 368                     QIOChannelSocket *sioc,
 369                     const char *export,
 370                     QCryptoTLSCreds *tlscreds,
 371                     const char *hostname,
 372                     Error **errp)
 373 {
 374     NBDClientSession *client = nbd_get_client_session(bs);
 375     int ret;
 376
 377     /* NBD handshake */
 378     logout("session init %s\n", export);
 379     qio_channel_set_blocking(QIO_CHANNEL(sioc), true, NULL);
 380
 381     client->info.request_sizes = true;
 382     ret = nbd_receive_negotiate(QIO_CHANNEL(sioc), export,
 383                                 tlscreds, hostname,
 384                                 &client->ioc, &client->info, errp);
 385     if (ret < 0) {
 386         logout("Failed to negotiate with the NBD server\n");
 387         return ret;
 388     }
 389     if (client->info.flags & NBD_FLAG_SEND_FUA) {
 390         bs->supported_write_flags = BDRV_REQ_FUA;
 391         bs->supported_zero_flags |= BDRV_REQ_FUA;
 392     }
 393     if (client->info.flags & NBD_FLAG_SEND_WRITE_ZEROES) {
 394         bs->supported_zero_flags |= BDRV_REQ_MAY_UNMAP;
 395     }
 396     if (client->info.min_block > bs->bl.request_alignment) {
 397         bs->bl.request_alignment = client->info.min_block;
 398     }
 399
 400     qemu_co_mutex_init(&client->send_mutex);
 401     qemu_co_queue_init(&client->free_sema);
 402     client->sioc = sioc;
 403     object_ref(OBJECT(client->sioc));
 404
 405     if (!client->ioc) {
 406         client->ioc = QIO_CHANNEL(sioc);
 407         object_ref(OBJECT(client->ioc));
 408     }
 409
 410     /* Now that we're connected, set the socket to be non-blocking and
 411      * kick the reply mechanism.  */
 412     qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL);
 413     client->read_reply_co = qemu_coroutine_create(nbd_read_reply_entry, client);
 414     nbd_client_attach_aio_context(bs, bdrv_get_aio_context(bs));
 415
 416     logout("Established connection with NBD server\n");
 417     return 0;
 418 }