cmd/mount_zfs/mount_zfs.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Copyright (c) 2011 Lawrence Livermore National Security, LLC.
  25  */
  26
  27 #include <libintl.h>
  28 #include <unistd.h>
  29 #include <sys/file.h>
  30 #include <sys/mount.h>
  31 #include <sys/mntent.h>
  32 #include <sys/stat.h>
  33 #include <libzfs.h>
  34 #include <locale.h>
  35 #include <getopt.h>
  36 #include <fcntl.h>
  37
  38 #define ZS_COMMENT      0x00000000      /* comment */
  39 #define ZS_ZFSUTIL      0x00000001      /* caller is zfs(8) */
  40
  41 libzfs_handle_t *g_zfs;
  42
  43 typedef struct option_map {
  44         const char *name;
  45         unsigned long mntmask;
  46         unsigned long zfsmask;
  47 } option_map_t;
  48
  49 static const option_map_t option_map[] = {
  50         /* Canonicalized filesystem independent options from mount(8) */
  51         { MNTOPT_NOAUTO,        MS_COMMENT,     ZS_COMMENT      },
  52         { MNTOPT_DEFAULTS,      MS_COMMENT,     ZS_COMMENT      },
  53         { MNTOPT_NODEVICES,     MS_NODEV,       ZS_COMMENT      },
  54         { MNTOPT_DIRSYNC,       MS_DIRSYNC,     ZS_COMMENT      },
  55         { MNTOPT_NOEXEC,        MS_NOEXEC,      ZS_COMMENT      },
  56         { MNTOPT_GROUP,         MS_GROUP,       ZS_COMMENT      },
  57         { MNTOPT_NETDEV,        MS_COMMENT,     ZS_COMMENT      },
  58         { MNTOPT_NOFAIL,        MS_COMMENT,     ZS_COMMENT      },
  59         { MNTOPT_NOSUID,        MS_NOSUID,      ZS_COMMENT      },
  60         { MNTOPT_OWNER,         MS_OWNER,       ZS_COMMENT      },
  61         { MNTOPT_REMOUNT,       MS_REMOUNT,     ZS_COMMENT      },
  62         { MNTOPT_RO,            MS_RDONLY,      ZS_COMMENT      },
  63         { MNTOPT_RW,            MS_COMMENT,     ZS_COMMENT      },
  64         { MNTOPT_SYNC,          MS_SYNCHRONOUS, ZS_COMMENT      },
  65         { MNTOPT_USER,          MS_USERS,       ZS_COMMENT      },
  66         { MNTOPT_USERS,         MS_USERS,       ZS_COMMENT      },
  67         /* acl flags passed with util-linux-2.24 mount command */
  68         { MNTOPT_ACL,           MS_POSIXACL,    ZS_COMMENT      },
  69         { MNTOPT_NOACL,         MS_COMMENT,     ZS_COMMENT      },
  70         { MNTOPT_POSIXACL,      MS_POSIXACL,    ZS_COMMENT      },
  71 #ifdef MS_NOATIME
  72         { MNTOPT_NOATIME,       MS_NOATIME,     ZS_COMMENT      },
  73 #endif
  74 #ifdef MS_NODIRATIME
  75         { MNTOPT_NODIRATIME,    MS_NODIRATIME,  ZS_COMMENT      },
  76 #endif
  77 #ifdef MS_RELATIME
  78         { MNTOPT_RELATIME,      MS_RELATIME,    ZS_COMMENT      },
  79 #endif
  80 #ifdef MS_STRICTATIME
  81         { MNTOPT_STRICTATIME,   MS_STRICTATIME, ZS_COMMENT      },
  82 #endif
  83 #ifdef MS_LAZYTIME
  84         { MNTOPT_LAZYTIME,      MS_LAZYTIME,    ZS_COMMENT      },
  85 #endif
  86         { MNTOPT_CONTEXT,       MS_COMMENT,     ZS_COMMENT      },
  87         { MNTOPT_FSCONTEXT,     MS_COMMENT,     ZS_COMMENT      },
  88         { MNTOPT_DEFCONTEXT,    MS_COMMENT,     ZS_COMMENT      },
  89         { MNTOPT_ROOTCONTEXT,   MS_COMMENT,     ZS_COMMENT      },
  90 #ifdef MS_I_VERSION
  91         { MNTOPT_IVERSION,      MS_I_VERSION,   ZS_COMMENT      },
  92 #endif
  93 #ifdef MS_MANDLOCK
  94         { MNTOPT_NBMAND,        MS_MANDLOCK,    ZS_COMMENT      },
  95 #endif
  96         /* Valid options not found in mount(8) */
  97         { MNTOPT_BIND,          MS_BIND,        ZS_COMMENT      },
  98 #ifdef MS_REC
  99         { MNTOPT_RBIND,         MS_BIND|MS_REC, ZS_COMMENT      },
 100 #endif
 101         { MNTOPT_COMMENT,       MS_COMMENT,     ZS_COMMENT      },
 102 #ifdef MS_NOSUB
 103         { MNTOPT_NOSUB,         MS_NOSUB,       ZS_COMMENT      },
 104 #endif
 105 #ifdef MS_SILENT
 106         { MNTOPT_QUIET,         MS_SILENT,      ZS_COMMENT      },
 107 #endif
 108         /* Custom zfs options */
 109         { MNTOPT_XATTR,         MS_COMMENT,     ZS_COMMENT      },
 110         { MNTOPT_NOXATTR,       MS_COMMENT,     ZS_COMMENT      },
 111         { MNTOPT_ZFSUTIL,       MS_COMMENT,     ZS_ZFSUTIL      },
 112         { NULL,                 0,              0               } };
 113
 114 /*
 115  * Break the mount option in to a name/value pair.  The name is
 116  * validated against the option map and mount flags set accordingly.
 117  */
 118 static int
 119 parse_option(char *mntopt, unsigned long *mntflags,
 120     unsigned long *zfsflags, int sloppy)
 121 {
 122         const option_map_t *opt;
 123         char *ptr, *name, *value = NULL;
 124         int error = 0;
 125
 126         name = strdup(mntopt);
 127         if (name == NULL)
 128                 return (ENOMEM);
 129
 130         for (ptr = name; ptr && *ptr; ptr++) {
 131                 if (*ptr == '=') {
 132                         *ptr = '\0';
 133                         value = ptr+1;
 134                         VERIFY3P(value, !=, NULL);
 135                         break;
 136                 }
 137         }
 138
 139         for (opt = option_map; opt->name != NULL; opt++) {
 140                 if (strncmp(name, opt->name, strlen(name)) == 0) {
 141                         *mntflags |= opt->mntmask;
 142                         *zfsflags |= opt->zfsmask;
 143                         error = 0;
 144                         goto out;
 145                 }
 146         }
 147
 148         if (!sloppy)
 149                 error = ENOENT;
 150 out:
 151         /* If required further process on the value may be done here */
 152         free(name);
 153         return (error);
 154 }
 155
 156 /*
 157  * Translate the mount option string in to MS_* mount flags for the
 158  * kernel vfs.  When sloppy is non-zero unknown options will be ignored
 159  * otherwise they are considered fatal are copied in to badopt.
 160  */
 161 static int
 162 parse_options(char *mntopts, unsigned long *mntflags, unsigned long *zfsflags,
 163     int sloppy, char *badopt, char *mtabopt)
 164 {
 165         int error = 0, quote = 0, flag = 0, count = 0;
 166         char *ptr, *opt, *opts;
 167
 168         opts = strdup(mntopts);
 169         if (opts == NULL)
 170                 return (ENOMEM);
 171
 172         *mntflags = 0;
 173         opt = NULL;
 174
 175         /*
 176          * Scan through all mount options which must be comma delimited.
 177          * We must be careful to notice regions which are double quoted
 178          * and skip commas in these regions.  Each option is then checked
 179          * to determine if it is a known option.
 180          */
 181         for (ptr = opts; ptr && !flag; ptr++) {
 182                 if (opt == NULL)
 183                         opt = ptr;
 184
 185                 if (*ptr == '"')
 186                         quote = !quote;
 187
 188                 if (quote)
 189                         continue;
 190
 191                 if (*ptr == '\0')
 192                         flag = 1;
 193
 194                 if ((*ptr == ',') || (*ptr == '\0')) {
 195                         *ptr = '\0';
 196
 197                         error = parse_option(opt, mntflags, zfsflags, sloppy);
 198                         if (error) {
 199                                 strcpy(badopt, opt);
 200                                 goto out;
 201
 202                         }
 203
 204                         if (!(*mntflags & MS_REMOUNT) &&
 205                             !(*zfsflags & ZS_ZFSUTIL)) {
 206                                 if (count > 0)
 207                                         strlcat(mtabopt, ",", MNT_LINE_MAX);
 208
 209                                 strlcat(mtabopt, opt, MNT_LINE_MAX);
 210                                 count++;
 211                         }
 212
 213                         opt = NULL;
 214                 }
 215         }
 216
 217 out:
 218         free(opts);
 219         return (error);
 220 }
 221
 222 /*
 223  * Return the pool/dataset to mount given the name passed to mount.  This
 224  * is expected to be of the form pool/dataset, however may also refer to
 225  * a block device if that device contains a valid zfs label.
 226  */
 227 static char *
 228 parse_dataset(char *dataset)
 229 {
 230         char cwd[PATH_MAX];
 231         struct stat64 statbuf;
 232         int error;
 233         int len;
 234
 235         /*
 236          * We expect a pool/dataset to be provided, however if we're
 237          * given a device which is a member of a zpool we attempt to
 238          * extract the pool name stored in the label.  Given the pool
 239          * name we can mount the root dataset.
 240          */
 241         error = stat64(dataset, &statbuf);
 242         if (error == 0) {
 243                 nvlist_t *config;
 244                 char *name;
 245                 int fd;
 246
 247                 fd = open(dataset, O_RDONLY);
 248                 if (fd < 0)
 249                         goto out;
 250
 251                 error = zpool_read_label(fd, &config, NULL);
 252                 (void) close(fd);
 253                 if (error)
 254                         goto out;
 255
 256                 error = nvlist_lookup_string(config,
 257                     ZPOOL_CONFIG_POOL_NAME, &name);
 258                 if (error) {
 259                         nvlist_free(config);
 260                 } else {
 261                         dataset = strdup(name);
 262                         nvlist_free(config);
 263                         return (dataset);
 264                 }
 265         }
 266 out:
 267         /*
 268          * If a file or directory in your current working directory is
 269          * named 'dataset' then mount(8) will prepend your current working
 270          * directory to the dataset.  There is no way to prevent this
 271          * behavior so we simply check for it and strip the prepended
 272          * patch when it is added.
 273          */
 274         if (getcwd(cwd, PATH_MAX) == NULL)
 275                 return (dataset);
 276
 277         len = strlen(cwd);
 278
 279         /* Do not add one when cwd already ends in a trailing '/' */
 280         if (strncmp(cwd, dataset, len) == 0)
 281                 return (dataset + len + (cwd[len-1] != '/'));
 282
 283         return (dataset);
 284 }
 285
 286 /*
 287  * Update the mtab_* code to use the libmount library when it is commonly
 288  * available otherwise fallback to legacy mode.  The mount(8) utility will
 289  * manage the lock file for us to prevent racing updates to /etc/mtab.
 290  */
 291 static int
 292 mtab_is_writeable(void)
 293 {
 294         struct stat st;
 295         int error, fd;
 296
 297         error = lstat("/etc/mtab", &st);
 298         if (error || S_ISLNK(st.st_mode))
 299                 return (0);
 300
 301         fd = open("/etc/mtab", O_RDWR | O_CREAT, 0644);
 302         if (fd < 0)
 303                 return (0);
 304
 305         close(fd);
 306         return (1);
 307 }
 308
 309 static int
 310 mtab_update(char *dataset, char *mntpoint, char *type, char *mntopts)
 311 {
 312         struct mntent mnt;
 313         FILE *fp;
 314         int error;
 315
 316         mnt.mnt_fsname = dataset;
 317         mnt.mnt_dir = mntpoint;
 318         mnt.mnt_type = type;
 319         mnt.mnt_opts = mntopts ? mntopts : "";
 320         mnt.mnt_freq = 0;
 321         mnt.mnt_passno = 0;
 322
 323         fp = setmntent("/etc/mtab", "a+");
 324         if (!fp) {
 325                 (void) fprintf(stderr, gettext(
 326                     "filesystem '%s' was mounted, but /etc/mtab "
 327                     "could not be opened due to error %d\n"),
 328                     dataset, errno);
 329                 return (MOUNT_FILEIO);
 330         }
 331
 332         error = addmntent(fp, &mnt);
 333         if (error) {
 334                 (void) fprintf(stderr, gettext(
 335                     "filesystem '%s' was mounted, but /etc/mtab "
 336                     "could not be updated due to error %d\n"),
 337                     dataset, errno);
 338                 return (MOUNT_FILEIO);
 339         }
 340
 341         (void) endmntent(fp);
 342
 343         return (MOUNT_SUCCESS);
 344 }
 345
 346 static void
 347 append_mntopt(const char *name, const char *val, char *mntopts,
 348     char *mtabopt, boolean_t quote)
 349 {
 350         char tmp[MNT_LINE_MAX];
 351
 352         snprintf(tmp, MNT_LINE_MAX, quote ? ",%s=\"%s\"" : ",%s=%s", name, val);
 353
 354         if (mntopts)
 355                 strlcat(mntopts, tmp, MNT_LINE_MAX);
 356
 357         if (mtabopt)
 358                 strlcat(mtabopt, tmp, MNT_LINE_MAX);
 359 }
 360
 361 static void
 362 zfs_selinux_setcontext(zfs_handle_t *zhp, zfs_prop_t zpt, const char *name,
 363     char *mntopts, char *mtabopt)
 364 {
 365         char context[ZFS_MAXPROPLEN];
 366
 367         if (zfs_prop_get(zhp, zpt, context, sizeof (context),
 368             NULL, NULL, 0, B_FALSE) == 0) {
 369                 if (strcmp(context, "none") != 0)
 370                         append_mntopt(name, context, mntopts, mtabopt, B_TRUE);
 371         }
 372 }
 373
 374 int
 375 main(int argc, char **argv)
 376 {
 377         zfs_handle_t *zhp;
 378         char prop[ZFS_MAXPROPLEN];
 379         uint64_t zfs_version = 0;
 380         char mntopts[MNT_LINE_MAX] = { '\0' };
 381         char badopt[MNT_LINE_MAX] = { '\0' };
 382         char mtabopt[MNT_LINE_MAX] = { '\0' };
 383         char mntpoint[PATH_MAX];
 384         char *dataset;
 385         unsigned long mntflags = 0, zfsflags = 0, remount = 0;
 386         int sloppy = 0, fake = 0, verbose = 0, nomtab = 0, zfsutil = 0;
 387         int error, c;
 388
 389         (void) setlocale(LC_ALL, "");
 390         (void) textdomain(TEXT_DOMAIN);
 391
 392         opterr = 0;
 393
 394         /* check options */
 395         while ((c = getopt_long(argc, argv, "sfnvo:h?", 0, 0)) != -1) {
 396                 switch (c) {
 397                 case 's':
 398                         sloppy = 1;
 399                         break;
 400                 case 'f':
 401                         fake = 1;
 402                         break;
 403                 case 'n':
 404                         nomtab = 1;
 405                         break;
 406                 case 'v':
 407                         verbose++;
 408                         break;
 409                 case 'o':
 410                         (void) strlcpy(mntopts, optarg, sizeof (mntopts));
 411                         break;
 412                 case 'h':
 413                 case '?':
 414                         (void) fprintf(stderr, gettext("Invalid option '%c'\n"),
 415                             optopt);
 416                         (void) fprintf(stderr, gettext("Usage: mount.zfs "
 417                             "[-sfnv] [-o options] <dataset> <mountpoint>\n"));
 418                         return (MOUNT_USAGE);
 419                 }
 420         }
 421
 422         argc -= optind;
 423         argv += optind;
 424
 425         /* check that we only have two arguments */
 426         if (argc != 2) {
 427                 if (argc == 0)
 428                         (void) fprintf(stderr, gettext("missing dataset "
 429                             "argument\n"));
 430                 else if (argc == 1)
 431                         (void) fprintf(stderr,
 432                             gettext("missing mountpoint argument\n"));
 433                 else
 434                         (void) fprintf(stderr, gettext("too many arguments\n"));
 435                 (void) fprintf(stderr, "usage: mount <dataset> <mountpoint>\n");
 436                 return (MOUNT_USAGE);
 437         }
 438
 439         dataset = parse_dataset(argv[0]);
 440
 441         /* canonicalize the mount point */
 442         if (realpath(argv[1], mntpoint) == NULL) {
 443                 (void) fprintf(stderr, gettext("filesystem '%s' cannot be "
 444                     "mounted at '%s' due to canonicalization error %d.\n"),
 445                     dataset, argv[1], errno);
 446                 return (MOUNT_SYSERR);
 447         }
 448
 449         /* validate mount options and set mntflags */
 450         error = parse_options(mntopts, &mntflags, &zfsflags, sloppy,
 451             badopt, mtabopt);
 452         if (error) {
 453                 switch (error) {
 454                 case ENOMEM:
 455                         (void) fprintf(stderr, gettext("filesystem '%s' "
 456                             "cannot be mounted due to a memory allocation "
 457                             "failure.\n"), dataset);
 458                         return (MOUNT_SYSERR);
 459                 case ENOENT:
 460                         (void) fprintf(stderr, gettext("filesystem '%s' "
 461                             "cannot be mounted due to invalid option "
 462                             "'%s'.\n"), dataset, badopt);
 463                         (void) fprintf(stderr, gettext("Use the '-s' option "
 464                             "to ignore the bad mount option.\n"));
 465                         return (MOUNT_USAGE);
 466                 default:
 467                         (void) fprintf(stderr, gettext("filesystem '%s' "
 468                             "cannot be mounted due to internal error %d.\n"),
 469                             dataset, error);
 470                         return (MOUNT_SOFTWARE);
 471                 }
 472         }
 473
 474         if (verbose)
 475                 (void) fprintf(stdout, gettext("mount.zfs:\n"
 476                     "  dataset:    \"%s\"\n  mountpoint: \"%s\"\n"
 477                     "  mountflags: 0x%lx\n  zfsflags:   0x%lx\n"
 478                     "  mountopts:  \"%s\"\n  mtabopts:   \"%s\"\n"),
 479                     dataset, mntpoint, mntflags, zfsflags, mntopts, mtabopt);
 480
 481         if (mntflags & MS_REMOUNT) {
 482                 nomtab = 1;
 483                 remount = 1;
 484         }
 485
 486         if (zfsflags & ZS_ZFSUTIL)
 487                 zfsutil = 1;
 488
 489         if ((g_zfs = libzfs_init()) == NULL) {
 490                 (void) fprintf(stderr, "%s", libzfs_error_init(errno));
 491                 return (MOUNT_SYSERR);
 492         }
 493
 494         /* try to open the dataset to access the mount point */
 495         if ((zhp = zfs_open(g_zfs, dataset,
 496             ZFS_TYPE_FILESYSTEM | ZFS_TYPE_SNAPSHOT)) == NULL) {
 497                 (void) fprintf(stderr, gettext("filesystem '%s' cannot be "
 498                     "mounted, unable to open the dataset\n"), dataset);
 499                 libzfs_fini(g_zfs);
 500                 return (MOUNT_USAGE);
 501         }
 502
 503         /*
 504          * Checks to see if the ZFS_PROP_SELINUX_CONTEXT exists
 505          * if it does, create a tmp variable in case it's needed
 506          * checks to see if the selinux context is set to the default
 507          * if it is, allow the setting of the other context properties
 508          * this is needed because the 'context' property overrides others
 509          * if it is not the default, set the 'context' property
 510          */
 511         if (zfs_prop_get(zhp, ZFS_PROP_SELINUX_CONTEXT, prop, sizeof (prop),
 512             NULL, NULL, 0, B_FALSE) == 0) {
 513                 if (strcmp(prop, "none") == 0) {
 514                         zfs_selinux_setcontext(zhp, ZFS_PROP_SELINUX_FSCONTEXT,
 515                             MNTOPT_FSCONTEXT, mntopts, mtabopt);
 516                         zfs_selinux_setcontext(zhp, ZFS_PROP_SELINUX_DEFCONTEXT,
 517                             MNTOPT_DEFCONTEXT, mntopts, mtabopt);
 518                         zfs_selinux_setcontext(zhp,
 519                             ZFS_PROP_SELINUX_ROOTCONTEXT, MNTOPT_ROOTCONTEXT,
 520                             mntopts, mtabopt);
 521                 } else {
 522                         append_mntopt(MNTOPT_CONTEXT, prop,
 523                             mntopts, mtabopt, B_TRUE);
 524                 }
 525         }
 526
 527         /* A hint used to determine an auto-mounted snapshot mount point */
 528         append_mntopt(MNTOPT_MNTPOINT, mntpoint, mntopts, NULL, B_FALSE);
 529
 530         /* treat all snapshots as legacy mount points */
 531         if (zfs_get_type(zhp) == ZFS_TYPE_SNAPSHOT)
 532                 (void) strlcpy(prop, ZFS_MOUNTPOINT_LEGACY, ZFS_MAXPROPLEN);
 533         else
 534                 (void) zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, prop,
 535                     sizeof (prop), NULL, NULL, 0, B_FALSE);
 536
 537         /*
 538          * Fetch the max supported zfs version in case we get ENOTSUP
 539          * back from the mount command, since we need the zfs handle
 540          * to do so.
 541          */
 542         zfs_version = zfs_prop_get_int(zhp, ZFS_PROP_VERSION);
 543         if (zfs_version == 0) {
 544                 fprintf(stderr, gettext("unable to fetch "
 545                     "ZFS version for filesystem '%s'\n"), dataset);
 546                 return (MOUNT_SYSERR);
 547         }
 548
 549         zfs_close(zhp);
 550         libzfs_fini(g_zfs);
 551
 552         /*
 553          * Legacy mount points may only be mounted using 'mount', never using
 554          * 'zfs mount'.  However, since 'zfs mount' actually invokes 'mount'
 555          * we differentiate the two cases using the 'zfsutil' mount option.
 556          * This mount option should only be supplied by the 'zfs mount' util.
 557          *
 558          * The only exception to the above rule is '-o remount' which is
 559          * always allowed for non-legacy datasets.  This is done because when
 560          * using zfs as your root file system both rc.sysinit/umountroot and
 561          * systemd depend on 'mount -o remount <mountpoint>' to work.
 562          */
 563         if (zfsutil && (strcmp(prop, ZFS_MOUNTPOINT_LEGACY) == 0)) {
 564                 (void) fprintf(stderr, gettext(
 565                     "filesystem '%s' cannot be mounted using 'zfs mount'.\n"
 566                     "Use 'zfs set mountpoint=%s' or 'mount -t zfs %s %s'.\n"
 567                     "See zfs(8) for more information.\n"),
 568                     dataset, mntpoint, dataset, mntpoint);
 569                 return (MOUNT_USAGE);
 570         }
 571
 572         if (!zfsutil && !(remount || fake) &&
 573             strcmp(prop, ZFS_MOUNTPOINT_LEGACY)) {
 574                 (void) fprintf(stderr, gettext(
 575                     "filesystem '%s' cannot be mounted using 'mount'.\n"
 576                     "Use 'zfs set mountpoint=%s' or 'zfs mount %s'.\n"
 577                     "See zfs(8) for more information.\n"),
 578                     dataset, "legacy", dataset);
 579                 return (MOUNT_USAGE);
 580         }
 581
 582         if (!fake) {
 583                 error = mount(dataset, mntpoint, MNTTYPE_ZFS,
 584                     mntflags, mntopts);
 585         }
 586
 587         if (error) {
 588                 switch (errno) {
 589                 case ENOENT:
 590                         (void) fprintf(stderr, gettext("mount point "
 591                             "'%s' does not exist\n"), mntpoint);
 592                         return (MOUNT_SYSERR);
 593                 case EBUSY:
 594                         (void) fprintf(stderr, gettext("filesystem "
 595                             "'%s' is already mounted\n"), dataset);
 596                         return (MOUNT_BUSY);
 597                 case ENOTSUP:
 598                         if (zfs_version > ZPL_VERSION) {
 599                                 (void) fprintf(stderr,
 600                                     gettext("filesystem '%s' (v%d) is not "
 601                                     "supported by this implementation of "
 602                                     "ZFS (max v%d).\n"), dataset,
 603                                     (int)zfs_version, (int)ZPL_VERSION);
 604                         } else {
 605                                 (void) fprintf(stderr,
 606                                     gettext("filesystem '%s' mount "
 607                                     "failed for unknown reason.\n"), dataset);
 608                         }
 609                         return (MOUNT_SYSERR);
 610 #ifdef MS_MANDLOCK
 611                 case EPERM:
 612                         if (mntflags & MS_MANDLOCK) {
 613                                 (void) fprintf(stderr, gettext("filesystem "
 614                                     "'%s' has the 'nbmand=on' property set, "
 615                                     "this mount\noption may be disabled in "
 616                                     "your kernel.  Use 'zfs set nbmand=off'\n"
 617                                     "to disable this option and try to "
 618                                     "mount the filesystem again.\n"), dataset);
 619                                 return (MOUNT_SYSERR);
 620                         }
 621                         /* fallthru */
 622 #endif
 623                 default:
 624                         (void) fprintf(stderr, gettext("filesystem "
 625                             "'%s' can not be mounted: %s\n"), dataset,
 626                             strerror(errno));
 627                         return (MOUNT_USAGE);
 628                 }
 629         }
 630
 631         if (!nomtab && mtab_is_writeable()) {
 632                 error = mtab_update(dataset, mntpoint, MNTTYPE_ZFS, mtabopt);
 633                 if (error)
 634                         return (error);
 635         }
 636
 637         return (MOUNT_SUCCESS);
 638 }