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