block/nfs.c

   1 /*
   2  * QEMU Block driver for native access to files on NFS shares
   3  *
   4  * Copyright (c) 2014-2016 Peter Lieven <pl@kamp.de>
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26
  27 #include <poll.h>
  28 #include "qemu-common.h"
  29 #include "qemu/config-file.h"
  30 #include "qemu/error-report.h"
  31 #include "qapi/error.h"
  32 #include "block/block_int.h"
  33 #include "trace.h"
  34 #include "qemu/iov.h"
  35 #include "qemu/uri.h"
  36 #include "qemu/cutils.h"
  37 #include "sysemu/sysemu.h"
  38 #include <nfsc/libnfs.h>
  39
  40 #define QEMU_NFS_MAX_READAHEAD_SIZE 1048576
  41 #define QEMU_NFS_MAX_PAGECACHE_SIZE (8388608 / NFS_BLKSIZE)
  42 #define QEMU_NFS_MAX_DEBUG_LEVEL 2
  43
  44 typedef struct NFSClient {
  45     struct nfs_context *context;
  46     struct nfsfh *fh;
  47     int events;
  48     bool has_zero_init;
  49     AioContext *aio_context;
  50     blkcnt_t st_blocks;
  51     bool cache_used;
  52 } NFSClient;
  53
  54 typedef struct NFSRPC {
  55     int ret;
  56     int complete;
  57     QEMUIOVector *iov;
  58     struct stat *st;
  59     Coroutine *co;
  60     QEMUBH *bh;
  61     NFSClient *client;
  62 } NFSRPC;
  63
  64 static void nfs_process_read(void *arg);
  65 static void nfs_process_write(void *arg);
  66
  67 static void nfs_set_events(NFSClient *client)
  68 {
  69     int ev = nfs_which_events(client->context);
  70     if (ev != client->events) {
  71         aio_set_fd_handler(client->aio_context, nfs_get_fd(client->context),
  72                            false,
  73                            (ev & POLLIN) ? nfs_process_read : NULL,
  74                            (ev & POLLOUT) ? nfs_process_write : NULL, client);
  75
  76     }
  77     client->events = ev;
  78 }
  79
  80 static void nfs_process_read(void *arg)
  81 {
  82     NFSClient *client = arg;
  83     nfs_service(client->context, POLLIN);
  84     nfs_set_events(client);
  85 }
  86
  87 static void nfs_process_write(void *arg)
  88 {
  89     NFSClient *client = arg;
  90     nfs_service(client->context, POLLOUT);
  91     nfs_set_events(client);
  92 }
  93
  94 static void nfs_co_init_task(NFSClient *client, NFSRPC *task)
  95 {
  96     *task = (NFSRPC) {
  97         .co             = qemu_coroutine_self(),
  98         .client         = client,
  99     };
 100 }
 101
 102 static void nfs_co_generic_bh_cb(void *opaque)
 103 {
 104     NFSRPC *task = opaque;
 105     task->complete = 1;
 106     qemu_bh_delete(task->bh);
 107     qemu_coroutine_enter(task->co);
 108 }
 109
 110 static void
 111 nfs_co_generic_cb(int ret, struct nfs_context *nfs, void *data,
 112                   void *private_data)
 113 {
 114     NFSRPC *task = private_data;
 115     task->ret = ret;
 116     if (task->ret > 0 && task->iov) {
 117         if (task->ret <= task->iov->size) {
 118             qemu_iovec_from_buf(task->iov, 0, data, task->ret);
 119         } else {
 120             task->ret = -EIO;
 121         }
 122     }
 123     if (task->ret == 0 && task->st) {
 124         memcpy(task->st, data, sizeof(struct stat));
 125     }
 126     if (task->ret < 0) {
 127         error_report("NFS Error: %s", nfs_get_error(nfs));
 128     }
 129     if (task->co) {
 130         task->bh = aio_bh_new(task->client->aio_context,
 131                               nfs_co_generic_bh_cb, task);
 132         qemu_bh_schedule(task->bh);
 133     } else {
 134         task->complete = 1;
 135     }
 136 }
 137
 138 static int coroutine_fn nfs_co_readv(BlockDriverState *bs,
 139                                      int64_t sector_num, int nb_sectors,
 140                                      QEMUIOVector *iov)
 141 {
 142     NFSClient *client = bs->opaque;
 143     NFSRPC task;
 144
 145     nfs_co_init_task(client, &task);
 146     task.iov = iov;
 147
 148     if (nfs_pread_async(client->context, client->fh,
 149                         sector_num * BDRV_SECTOR_SIZE,
 150                         nb_sectors * BDRV_SECTOR_SIZE,
 151                         nfs_co_generic_cb, &task) != 0) {
 152         return -ENOMEM;
 153     }
 154
 155     while (!task.complete) {
 156         nfs_set_events(client);
 157         qemu_coroutine_yield();
 158     }
 159
 160     if (task.ret < 0) {
 161         return task.ret;
 162     }
 163
 164     /* zero pad short reads */
 165     if (task.ret < iov->size) {
 166         qemu_iovec_memset(iov, task.ret, 0, iov->size - task.ret);
 167     }
 168
 169     return 0;
 170 }
 171
 172 static int coroutine_fn nfs_co_writev(BlockDriverState *bs,
 173                                         int64_t sector_num, int nb_sectors,
 174                                         QEMUIOVector *iov)
 175 {
 176     NFSClient *client = bs->opaque;
 177     NFSRPC task;
 178     char *buf = NULL;
 179
 180     nfs_co_init_task(client, &task);
 181
 182     buf = g_try_malloc(nb_sectors * BDRV_SECTOR_SIZE);
 183     if (nb_sectors && buf == NULL) {
 184         return -ENOMEM;
 185     }
 186
 187     qemu_iovec_to_buf(iov, 0, buf, nb_sectors * BDRV_SECTOR_SIZE);
 188
 189     if (nfs_pwrite_async(client->context, client->fh,
 190                          sector_num * BDRV_SECTOR_SIZE,
 191                          nb_sectors * BDRV_SECTOR_SIZE,
 192                          buf, nfs_co_generic_cb, &task) != 0) {
 193         g_free(buf);
 194         return -ENOMEM;
 195     }
 196
 197     while (!task.complete) {
 198         nfs_set_events(client);
 199         qemu_coroutine_yield();
 200     }
 201
 202     g_free(buf);
 203
 204     if (task.ret != nb_sectors * BDRV_SECTOR_SIZE) {
 205         return task.ret < 0 ? task.ret : -EIO;
 206     }
 207
 208     return 0;
 209 }
 210
 211 static int coroutine_fn nfs_co_flush(BlockDriverState *bs)
 212 {
 213     NFSClient *client = bs->opaque;
 214     NFSRPC task;
 215
 216     nfs_co_init_task(client, &task);
 217
 218     if (nfs_fsync_async(client->context, client->fh, nfs_co_generic_cb,
 219                         &task) != 0) {
 220         return -ENOMEM;
 221     }
 222
 223     while (!task.complete) {
 224         nfs_set_events(client);
 225         qemu_coroutine_yield();
 226     }
 227
 228     return task.ret;
 229 }
 230
 231 /* TODO Convert to fine grained options */
 232 static QemuOptsList runtime_opts = {
 233     .name = "nfs",
 234     .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
 235     .desc = {
 236         {
 237             .name = "filename",
 238             .type = QEMU_OPT_STRING,
 239             .help = "URL to the NFS file",
 240         },
 241         { /* end of list */ }
 242     },
 243 };
 244
 245 static void nfs_detach_aio_context(BlockDriverState *bs)
 246 {
 247     NFSClient *client = bs->opaque;
 248
 249     aio_set_fd_handler(client->aio_context, nfs_get_fd(client->context),
 250                        false, NULL, NULL, NULL);
 251     client->events = 0;
 252 }
 253
 254 static void nfs_attach_aio_context(BlockDriverState *bs,
 255                                    AioContext *new_context)
 256 {
 257     NFSClient *client = bs->opaque;
 258
 259     client->aio_context = new_context;
 260     nfs_set_events(client);
 261 }
 262
 263 static void nfs_client_close(NFSClient *client)
 264 {
 265     if (client->context) {
 266         if (client->fh) {
 267             nfs_close(client->context, client->fh);
 268         }
 269         aio_set_fd_handler(client->aio_context, nfs_get_fd(client->context),
 270                            false, NULL, NULL, NULL);
 271         nfs_destroy_context(client->context);
 272     }
 273     memset(client, 0, sizeof(NFSClient));
 274 }
 275
 276 static void nfs_file_close(BlockDriverState *bs)
 277 {
 278     NFSClient *client = bs->opaque;
 279     nfs_client_close(client);
 280 }
 281
 282 static int64_t nfs_client_open(NFSClient *client, const char *filename,
 283                                int flags, Error **errp, int open_flags)
 284 {
 285     int ret = -EINVAL, i;
 286     struct stat st;
 287     URI *uri;
 288     QueryParams *qp = NULL;
 289     char *file = NULL, *strp = NULL;
 290
 291     uri = uri_parse(filename);
 292     if (!uri) {
 293         error_setg(errp, "Invalid URL specified");
 294         goto fail;
 295     }
 296     if (!uri->server) {
 297         error_setg(errp, "Invalid URL specified");
 298         goto fail;
 299     }
 300     strp = strrchr(uri->path, '/');
 301     if (strp == NULL) {
 302         error_setg(errp, "Invalid URL specified");
 303         goto fail;
 304     }
 305     file = g_strdup(strp);
 306     *strp = 0;
 307
 308     client->context = nfs_init_context();
 309     if (client->context == NULL) {
 310         error_setg(errp, "Failed to init NFS context");
 311         goto fail;
 312     }
 313
 314     qp = query_params_parse(uri->query);
 315     for (i = 0; i < qp->n; i++) {
 316         unsigned long long val;
 317         if (!qp->p[i].value) {
 318             error_setg(errp, "Value for NFS parameter expected: %s",
 319                        qp->p[i].name);
 320             goto fail;
 321         }
 322         if (parse_uint_full(qp->p[i].value, &val, 0)) {
 323             error_setg(errp, "Illegal value for NFS parameter: %s",
 324                        qp->p[i].name);
 325             goto fail;
 326         }
 327         if (!strcmp(qp->p[i].name, "uid")) {
 328             nfs_set_uid(client->context, val);
 329         } else if (!strcmp(qp->p[i].name, "gid")) {
 330             nfs_set_gid(client->context, val);
 331         } else if (!strcmp(qp->p[i].name, "tcp-syncnt")) {
 332             nfs_set_tcp_syncnt(client->context, val);
 333 #ifdef LIBNFS_FEATURE_READAHEAD
 334         } else if (!strcmp(qp->p[i].name, "readahead")) {
 335             if (open_flags & BDRV_O_NOCACHE) {
 336                 error_setg(errp, "Cannot enable NFS readahead "
 337                                  "if cache.direct = on");
 338                 goto fail;
 339             }
 340             if (val > QEMU_NFS_MAX_READAHEAD_SIZE) {
 341                 error_report("NFS Warning: Truncating NFS readahead"
 342                              " size to %d", QEMU_NFS_MAX_READAHEAD_SIZE);
 343                 val = QEMU_NFS_MAX_READAHEAD_SIZE;
 344             }
 345             nfs_set_readahead(client->context, val);
 346 #ifdef LIBNFS_FEATURE_PAGECACHE
 347             nfs_set_pagecache_ttl(client->context, 0);
 348 #endif
 349             client->cache_used = true;
 350 #endif
 351 #ifdef LIBNFS_FEATURE_PAGECACHE
 352             nfs_set_pagecache_ttl(client->context, 0);
 353         } else if (!strcmp(qp->p[i].name, "pagecache")) {
 354             if (open_flags & BDRV_O_NOCACHE) {
 355                 error_setg(errp, "Cannot enable NFS pagecache "
 356                                  "if cache.direct = on");
 357                 goto fail;
 358             }
 359             if (val > QEMU_NFS_MAX_PAGECACHE_SIZE) {
 360                 error_report("NFS Warning: Truncating NFS pagecache"
 361                              " size to %d pages", QEMU_NFS_MAX_PAGECACHE_SIZE);
 362                 val = QEMU_NFS_MAX_PAGECACHE_SIZE;
 363             }
 364             nfs_set_pagecache(client->context, val);
 365             nfs_set_pagecache_ttl(client->context, 0);
 366             client->cache_used = true;
 367 #endif
 368 #ifdef LIBNFS_FEATURE_DEBUG
 369         } else if (!strcmp(qp->p[i].name, "debug")) {
 370             /* limit the maximum debug level to avoid potential flooding
 371              * of our log files. */
 372             if (val > QEMU_NFS_MAX_DEBUG_LEVEL) {
 373                 error_report("NFS Warning: Limiting NFS debug level"
 374                              " to %d", QEMU_NFS_MAX_DEBUG_LEVEL);
 375                 val = QEMU_NFS_MAX_DEBUG_LEVEL;
 376             }
 377             nfs_set_debug(client->context, val);
 378 #endif
 379         } else {
 380             error_setg(errp, "Unknown NFS parameter name: %s",
 381                        qp->p[i].name);
 382             goto fail;
 383         }
 384     }
 385
 386     ret = nfs_mount(client->context, uri->server, uri->path);
 387     if (ret < 0) {
 388         error_setg(errp, "Failed to mount nfs share: %s",
 389                    nfs_get_error(client->context));
 390         goto fail;
 391     }
 392
 393     if (flags & O_CREAT) {
 394         ret = nfs_creat(client->context, file, 0600, &client->fh);
 395         if (ret < 0) {
 396             error_setg(errp, "Failed to create file: %s",
 397                        nfs_get_error(client->context));
 398             goto fail;
 399         }
 400     } else {
 401         ret = nfs_open(client->context, file, flags, &client->fh);
 402         if (ret < 0) {
 403             error_setg(errp, "Failed to open file : %s",
 404                        nfs_get_error(client->context));
 405             goto fail;
 406         }
 407     }
 408
 409     ret = nfs_fstat(client->context, client->fh, &st);
 410     if (ret < 0) {
 411         error_setg(errp, "Failed to fstat file: %s",
 412                    nfs_get_error(client->context));
 413         goto fail;
 414     }
 415
 416     ret = DIV_ROUND_UP(st.st_size, BDRV_SECTOR_SIZE);
 417     client->st_blocks = st.st_blocks;
 418     client->has_zero_init = S_ISREG(st.st_mode);
 419     goto out;
 420 fail:
 421     nfs_client_close(client);
 422 out:
 423     if (qp) {
 424         query_params_free(qp);
 425     }
 426     uri_free(uri);
 427     g_free(file);
 428     return ret;
 429 }
 430
 431 static int nfs_file_open(BlockDriverState *bs, QDict *options, int flags,
 432                          Error **errp) {
 433     NFSClient *client = bs->opaque;
 434     int64_t ret;
 435     QemuOpts *opts;
 436     Error *local_err = NULL;
 437
 438     client->aio_context = bdrv_get_aio_context(bs);
 439
 440     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
 441     qemu_opts_absorb_qdict(opts, options, &local_err);
 442     if (local_err) {
 443         error_propagate(errp, local_err);
 444         ret = -EINVAL;
 445         goto out;
 446     }
 447     ret = nfs_client_open(client, qemu_opt_get(opts, "filename"),
 448                           (flags & BDRV_O_RDWR) ? O_RDWR : O_RDONLY,
 449                           errp, bs->open_flags);
 450     if (ret < 0) {
 451         goto out;
 452     }
 453     bs->total_sectors = ret;
 454     ret = 0;
 455 out:
 456     qemu_opts_del(opts);
 457     return ret;
 458 }
 459
 460 static QemuOptsList nfs_create_opts = {
 461     .name = "nfs-create-opts",
 462     .head = QTAILQ_HEAD_INITIALIZER(nfs_create_opts.head),
 463     .desc = {
 464         {
 465             .name = BLOCK_OPT_SIZE,
 466             .type = QEMU_OPT_SIZE,
 467             .help = "Virtual disk size"
 468         },
 469         { /* end of list */ }
 470     }
 471 };
 472
 473 static int nfs_file_create(const char *url, QemuOpts *opts, Error **errp)
 474 {
 475     int ret = 0;
 476     int64_t total_size = 0;
 477     NFSClient *client = g_new0(NFSClient, 1);
 478
 479     client->aio_context = qemu_get_aio_context();
 480
 481     /* Read out options */
 482     total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
 483                           BDRV_SECTOR_SIZE);
 484
 485     ret = nfs_client_open(client, url, O_CREAT, errp, 0);
 486     if (ret < 0) {
 487         goto out;
 488     }
 489     ret = nfs_ftruncate(client->context, client->fh, total_size);
 490     nfs_client_close(client);
 491 out:
 492     g_free(client);
 493     return ret;
 494 }
 495
 496 static int nfs_has_zero_init(BlockDriverState *bs)
 497 {
 498     NFSClient *client = bs->opaque;
 499     return client->has_zero_init;
 500 }
 501
 502 static int64_t nfs_get_allocated_file_size(BlockDriverState *bs)
 503 {
 504     NFSClient *client = bs->opaque;
 505     NFSRPC task = {0};
 506     struct stat st;
 507
 508     if (bdrv_is_read_only(bs) &&
 509         !(bs->open_flags & BDRV_O_NOCACHE)) {
 510         return client->st_blocks * 512;
 511     }
 512
 513     task.st = &st;
 514     if (nfs_fstat_async(client->context, client->fh, nfs_co_generic_cb,
 515                         &task) != 0) {
 516         return -ENOMEM;
 517     }
 518
 519     while (!task.complete) {
 520         nfs_set_events(client);
 521         aio_poll(client->aio_context, true);
 522     }
 523
 524     return (task.ret < 0 ? task.ret : st.st_blocks * 512);
 525 }
 526
 527 static int nfs_file_truncate(BlockDriverState *bs, int64_t offset)
 528 {
 529     NFSClient *client = bs->opaque;
 530     return nfs_ftruncate(client->context, client->fh, offset);
 531 }
 532
 533 /* Note that this will not re-establish a connection with the NFS server
 534  * - it is effectively a NOP.  */
 535 static int nfs_reopen_prepare(BDRVReopenState *state,
 536                               BlockReopenQueue *queue, Error **errp)
 537 {
 538     NFSClient *client = state->bs->opaque;
 539     struct stat st;
 540     int ret = 0;
 541
 542     if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) {
 543         error_setg(errp, "Cannot open a read-only mount as read-write");
 544         return -EACCES;
 545     }
 546
 547     if ((state->flags & BDRV_O_NOCACHE) && client->cache_used) {
 548         error_setg(errp, "Cannot disable cache if libnfs readahead or"
 549                          " pagecache is enabled");
 550         return -EINVAL;
 551     }
 552
 553     /* Update cache for read-only reopens */
 554     if (!(state->flags & BDRV_O_RDWR)) {
 555         ret = nfs_fstat(client->context, client->fh, &st);
 556         if (ret < 0) {
 557             error_setg(errp, "Failed to fstat file: %s",
 558                        nfs_get_error(client->context));
 559             return ret;
 560         }
 561         client->st_blocks = st.st_blocks;
 562     }
 563
 564     return 0;
 565 }
 566
 567 #ifdef LIBNFS_FEATURE_PAGECACHE
 568 static void nfs_invalidate_cache(BlockDriverState *bs,
 569                                  Error **errp)
 570 {
 571     NFSClient *client = bs->opaque;
 572     nfs_pagecache_invalidate(client->context, client->fh);
 573 }
 574 #endif
 575
 576 static BlockDriver bdrv_nfs = {
 577     .format_name                    = "nfs",
 578     .protocol_name                  = "nfs",
 579
 580     .instance_size                  = sizeof(NFSClient),
 581     .bdrv_needs_filename            = true,
 582     .create_opts                    = &nfs_create_opts,
 583
 584     .bdrv_has_zero_init             = nfs_has_zero_init,
 585     .bdrv_get_allocated_file_size   = nfs_get_allocated_file_size,
 586     .bdrv_truncate                  = nfs_file_truncate,
 587
 588     .bdrv_file_open                 = nfs_file_open,
 589     .bdrv_close                     = nfs_file_close,
 590     .bdrv_create                    = nfs_file_create,
 591     .bdrv_reopen_prepare            = nfs_reopen_prepare,
 592
 593     .bdrv_co_readv                  = nfs_co_readv,
 594     .bdrv_co_writev                 = nfs_co_writev,
 595     .bdrv_co_flush_to_disk          = nfs_co_flush,
 596
 597     .bdrv_detach_aio_context        = nfs_detach_aio_context,
 598     .bdrv_attach_aio_context        = nfs_attach_aio_context,
 599
 600 #ifdef LIBNFS_FEATURE_PAGECACHE
 601     .bdrv_invalidate_cache          = nfs_invalidate_cache,
 602 #endif
 603 };
 604
 605 static void nfs_block_init(void)
 606 {
 607     bdrv_register(&bdrv_nfs);
 608 }
 609
 610 block_init(nfs_block_init);