sys/kern/subr_diskmbr.c

   1 /*-
   2  * Copyright (c) 1994 Bruce D. Evans.
   3  * All rights reserved.
   4  *
   5  * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  *      from: @(#)ufs_disksubr.c        7.16 (Berkeley) 5/4/91
  37  *      from: ufs_disksubr.c,v 1.8 1994/06/07 01:21:39 phk Exp $
  38  * $FreeBSD: src/sys/kern/subr_diskmbr.c,v 1.45 2000/01/28 10:22:07 bde Exp $
  39  * $DragonFly: src/sys/kern/subr_diskmbr.c,v 1.26 2007/06/19 06:07:57 dillon Exp $
  40  */
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/buf.h>
  45 #include <sys/conf.h>
  46 #include <sys/diskslice.h>
  47 #define DOSPTYP_EXTENDED        5
  48 #define DOSPTYP_EXTENDEDX       15
  49 #define DOSPTYP_ONTRACK         84
  50 #include <sys/diskslice.h>
  51 #include <sys/diskmbr.h>
  52 #include <sys/disk.h>
  53 #include <sys/malloc.h>
  54 #include <sys/syslog.h>
  55 #include <sys/device.h>
  56
  57 #define TRACE(str)      do { if (dsi_debug) kprintf str; } while (0)
  58
  59 static volatile u_char dsi_debug;
  60
  61 /*
  62  * This is what we have embedded in every boot1 for supporting the bogus
  63  * "Dangerously Dedicated" mode. However, the old table is broken because
  64  * it has an illegal geometry in it - it specifies 256 heads (heads = end
  65  * head + 1) which causes nasty stuff when that wraps to zero in bios code.
  66  * eg: divide by zero etc. This caused the dead-thinkpad problem, numerous
  67  * SCSI bios crashes, EFI to crash, etc.
  68  *
  69  * We still have to recognize the old table though, even though we stopped
  70  * inflicting it upon the world.
  71  */
  72 static struct dos_partition historical_bogus_partition_table[NDOSPART] = {
  73         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  74         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  75         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  76         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 255, 255, 255, 0, 50000, },
  77 };
  78 static struct dos_partition historical_bogus_partition_table_fixed[NDOSPART] = {
  79         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  80         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  81         { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  82         { 0x80, 0, 1, 0, DOSPTYP_386BSD, 254, 255, 255, 0, 50000, },
  83 };
  84
  85 static int check_part (char *sname, struct dos_partition *dp,
  86                            u_int64_t offset, int nsectors, int ntracks,
  87                            u_int64_t mbr_offset);
  88 static void mbr_extended (cdev_t dev, struct disk_info *info,
  89                               struct diskslices *ssp, u_int64_t ext_offset,
  90                               u_int64_t ext_size, u_int64_t base_ext_offset,
  91                               int nsectors, int ntracks, u_int64_t mbr_offset,
  92                               int level);
  93 static int mbr_setslice (char *sname, struct disk_info *info,
  94                              struct diskslice *sp, struct dos_partition *dp,
  95                              u_int64_t br_offset);
  96
  97
  98 int
  99 mbrinit(cdev_t dev, struct disk_info *info, struct diskslices **sspp)
 100 {
 101         struct buf *bp;
 102         u_char  *cp;
 103         int     dospart;
 104         struct dos_partition *dp;
 105         struct dos_partition *dp0;
 106         struct dos_partition dpcopy[NDOSPART];
 107         int     error;
 108         int     max_ncyls;
 109         int     max_nsectors;
 110         int     max_ntracks;
 111         u_int64_t mbr_offset;
 112         char    partname[2];
 113         u_long  secpercyl;
 114         char    *sname;
 115         struct diskslice *sp;
 116         struct diskslices *ssp;
 117         cdev_t wdev;
 118
 119         mbr_offset = DOSBBSECTOR;
 120 reread_mbr:
 121         if (info->d_media_blksize & DEV_BMASK)
 122                 return (EIO);
 123         /* Read master boot record. */
 124         wdev = dkmodpart(dkmodslice(dev, WHOLE_DISK_SLICE), WHOLE_SLICE_PART);
 125         bp = geteblk((int)info->d_media_blksize);
 126         bp->b_bio1.bio_offset = (off_t)mbr_offset * info->d_media_blksize;
 127         bp->b_bcount = info->d_media_blksize;
 128         bp->b_cmd = BUF_CMD_READ;
 129         dev_dstrategy(wdev, &bp->b_bio1);
 130         if (biowait(bp) != 0) {
 131                 diskerr(&bp->b_bio1, wdev,
 132                         "reading primary partition table: error",
 133                         LOG_PRINTF, 0);
 134                 kprintf("\n");
 135                 error = EIO;
 136                 goto done;
 137         }
 138
 139         /* Weakly verify it. */
 140         cp = bp->b_data;
 141         sname = dsname(dev, dkunit(dev), WHOLE_DISK_SLICE, WHOLE_SLICE_PART, partname);
 142         if (cp[0x1FE] != 0x55 || cp[0x1FF] != 0xAA) {
 143                 if (bootverbose)
 144                         kprintf("%s: invalid primary partition table: no magic\n",
 145                                sname);
 146                 error = EINVAL;
 147                 goto done;
 148         }
 149
 150         /* Make a copy of the partition table to avoid alignment problems. */
 151         memcpy(&dpcopy[0], cp + DOSPARTOFF, sizeof(dpcopy));
 152
 153         dp0 = &dpcopy[0];
 154
 155         /*
 156          * Check for "Ontrack Diskmanager" or GPT.  If a GPT is found in
 157          * the first dos partition, ignore the rest of the MBR and go
 158          * to GPT processing.
 159          */
 160         for (dospart = 0, dp = dp0; dospart < NDOSPART; dospart++, dp++) {
 161                 if (dospart == 0 &&
 162                     (dp->dp_typ == DOSPTYP_PMBR || dp->dp_typ == DOSPTYP_GPT)) {
 163                         if (bootverbose)
 164                                 kprintf(
 165             "%s: Found GPT in slice #%d\n", sname, dospart + 1);
 166                         error = gptinit(dev, info, sspp);
 167                         goto done;
 168                 }
 169
 170                 if (dp->dp_typ == DOSPTYP_ONTRACK) {
 171                         if (bootverbose)
 172                                 kprintf(
 173             "%s: Found \"Ontrack Disk Manager\" on this disk.\n", sname);
 174                         bp->b_flags |= B_INVAL | B_AGE;
 175                         brelse(bp);
 176                         mbr_offset = 63;
 177                         goto reread_mbr;
 178                 }
 179         }
 180
 181         if (bcmp(dp0, historical_bogus_partition_table,
 182                  sizeof historical_bogus_partition_table) == 0 ||
 183             bcmp(dp0, historical_bogus_partition_table_fixed,
 184                  sizeof historical_bogus_partition_table_fixed) == 0) {
 185 #if 0
 186                 TRACE(("%s: invalid primary partition table: historical\n",
 187                        sname));
 188 #endif /* 0 */
 189                 if (bootverbose)
 190                         kprintf(
 191      "%s: invalid primary partition table: Dangerously Dedicated (ignored)\n",
 192                                sname);
 193                 error = EINVAL;
 194                 goto done;
 195         }
 196
 197         /* Guess the geometry. */
 198         /*
 199          * TODO:
 200          * Perhaps skip entries with 0 size.
 201          * Perhaps only look at entries of type DOSPTYP_386BSD.
 202          */
 203         max_ncyls = 0;
 204         max_nsectors = 0;
 205         max_ntracks = 0;
 206         for (dospart = 0, dp = dp0; dospart < NDOSPART; dospart++, dp++) {
 207                 int     ncyls;
 208                 int     nsectors;
 209                 int     ntracks;
 210
 211                 ncyls = DPCYL(dp->dp_ecyl, dp->dp_esect) + 1;
 212                 if (max_ncyls < ncyls)
 213                         max_ncyls = ncyls;
 214                 nsectors = DPSECT(dp->dp_esect);
 215                 if (max_nsectors < nsectors)
 216                         max_nsectors = nsectors;
 217                 ntracks = dp->dp_ehd + 1;
 218                 if (max_ntracks < ntracks)
 219                         max_ntracks = ntracks;
 220         }
 221
 222         /*
 223          * Check that we have guessed the geometry right by checking the
 224          * partition entries.
 225          */
 226         /*
 227          * TODO:
 228          * As above.
 229          * Check for overlaps.
 230          * Check against d_secperunit if the latter is reliable.
 231          */
 232         error = 0;
 233         for (dospart = 0, dp = dp0; dospart < NDOSPART; dospart++, dp++) {
 234                 if (dp->dp_scyl == 0 && dp->dp_shd == 0 && dp->dp_ssect == 0
 235                     && dp->dp_start == 0 && dp->dp_size == 0)
 236                         continue;
 237                 sname = dsname(dev, dkunit(dev), BASE_SLICE + dospart,
 238                                WHOLE_SLICE_PART, partname);
 239
 240                 /*
 241                  * Temporarily ignore errors from this check.  We could
 242                  * simplify things by accepting the table eariler if we
 243                  * always ignore errors here.  Perhaps we should always
 244                  * accept the table if the magic is right but not let
 245                  * bad entries affect the geometry.
 246                  */
 247                 check_part(sname, dp, mbr_offset, max_nsectors, max_ntracks,
 248                            mbr_offset);
 249         }
 250         if (error != 0)
 251                 goto done;
 252
 253         /*
 254          * Accept the DOS partition table.
 255          *
 256          * Adjust the disk information structure with updated CHS
 257          * conversion parameters, but only use values extracted from
 258          * the primary partition table.
 259          *
 260          * NOTE!  Regardless of our having to deal with this old cruft,
 261          * we do not screw around with the info->d_media* parameters.
 262          */
 263         secpercyl = (u_long)max_nsectors * max_ntracks;
 264         if (secpercyl != 0 && mbr_offset == DOSBBSECTOR) {
 265                 info->d_secpertrack = max_nsectors;
 266                 info->d_nheads = max_ntracks;
 267                 info->d_secpercyl = secpercyl;
 268                 info->d_ncylinders = info->d_media_blocks / secpercyl;
 269         }
 270
 271         /*
 272          * We are passed a pointer to a suitably initialized minimal
 273          * slices "struct" with no dangling pointers in it.  Replace it
 274          * by a maximal one.  This usually oversizes the "struct", but
 275          * enlarging it while searching for logical drives would be
 276          * inconvenient.
 277          */
 278         kfree(*sspp, M_DEVBUF);
 279         ssp = dsmakeslicestruct(MAX_SLICES, info);
 280         *sspp = ssp;
 281
 282         /* Initialize normal slices. */
 283         sp = &ssp->dss_slices[BASE_SLICE];
 284         for (dospart = 0, dp = dp0; dospart < NDOSPART; dospart++, dp++, sp++) {
 285                 sname = dsname(dev, dkunit(dev), BASE_SLICE + dospart,
 286                                WHOLE_SLICE_PART, partname);
 287                 (void)mbr_setslice(sname, info, sp, dp, mbr_offset);
 288         }
 289         ssp->dss_nslices = BASE_SLICE + NDOSPART;
 290
 291         /* Handle extended partitions. */
 292         sp -= NDOSPART;
 293         for (dospart = 0; dospart < NDOSPART; dospart++, sp++) {
 294                 if (sp->ds_type == DOSPTYP_EXTENDED ||
 295                     sp->ds_type == DOSPTYP_EXTENDEDX) {
 296                         mbr_extended(wdev, info, ssp,
 297                                      sp->ds_offset, sp->ds_size, sp->ds_offset,
 298                                      max_nsectors, max_ntracks, mbr_offset, 1);
 299                 }
 300         }
 301
 302         /*
 303          * mbr_extended() abuses ssp->dss_nslices for the number of slices
 304          * that would be found if there were no limit on the number of slices
 305          * in *ssp.  Cut it back now.
 306          */
 307         if (ssp->dss_nslices > MAX_SLICES)
 308                 ssp->dss_nslices = MAX_SLICES;
 309
 310 done:
 311         bp->b_flags |= B_INVAL | B_AGE;
 312         brelse(bp);
 313         if (error == EINVAL)
 314                 error = 0;
 315         return (error);
 316 }
 317
 318 static int
 319 check_part(char *sname, struct dos_partition *dp, u_int64_t offset,
 320             int nsectors, int ntracks, u_int64_t mbr_offset)
 321 {
 322         int     chs_ecyl;
 323         int     chs_esect;
 324         int     chs_scyl;
 325         int     chs_ssect;
 326         int     error;
 327         u_long  secpercyl;
 328         u_int64_t esector;
 329         u_int64_t esector1;
 330         u_int64_t ssector;
 331         u_int64_t ssector1;
 332
 333         secpercyl = (u_long)nsectors * ntracks;
 334         chs_scyl = DPCYL(dp->dp_scyl, dp->dp_ssect);
 335         chs_ssect = DPSECT(dp->dp_ssect);
 336         ssector = chs_ssect - 1 + dp->dp_shd * nsectors + chs_scyl * secpercyl
 337                   + mbr_offset;
 338         ssector1 = offset + dp->dp_start;
 339
 340         /*
 341          * If ssector1 is on a cylinder >= 1024, then ssector can't be right.
 342          * Allow the C/H/S for it to be 1023/ntracks-1/nsectors, or correct
 343          * apart from the cylinder being reduced modulo 1024.  Always allow
 344          * 1023/255/63, because this is the official way to represent
 345          * pure-LBA for the starting position.
 346          */
 347         if ((ssector < ssector1
 348              && ((chs_ssect == nsectors && dp->dp_shd == ntracks - 1
 349                   && chs_scyl == 1023)
 350                  || (secpercyl != 0
 351                      && (ssector1 - ssector) % (1024 * secpercyl) == 0)))
 352             || (dp->dp_scyl == 255 && dp->dp_shd == 255
 353                 && dp->dp_ssect == 255)) {
 354                 TRACE(("%s: C/H/S start %d/%d/%d, start %llu: allow\n",
 355                        sname, chs_scyl, dp->dp_shd, chs_ssect, ssector1));
 356                 ssector = ssector1;
 357         }
 358
 359         chs_ecyl = DPCYL(dp->dp_ecyl, dp->dp_esect);
 360         chs_esect = DPSECT(dp->dp_esect);
 361         esector = chs_esect - 1 + dp->dp_ehd * nsectors + chs_ecyl * secpercyl
 362                   + mbr_offset;
 363         esector1 = ssector1 + dp->dp_size - 1;
 364
 365         /*
 366          * Allow certain bogus C/H/S values for esector, as above. However,
 367          * heads == 255 isn't really legal and causes some BIOS crashes. The
 368          * correct value to indicate a pure-LBA end is 1023/heads-1/sectors -
 369          * usually 1023/254/63. "heads" is base 0, "sectors" is base 1.
 370          */
 371         if ((esector < esector1
 372              && ((chs_esect == nsectors && dp->dp_ehd == ntracks - 1
 373                   && chs_ecyl == 1023)
 374                  || (secpercyl != 0
 375                      && (esector1 - esector) % (1024 * secpercyl) == 0)))
 376             || (dp->dp_ecyl == 255 && dp->dp_ehd == 255
 377                 && dp->dp_esect == 255)) {
 378                 TRACE(("%s: C/H/S end %d/%d/%d, end %llu: allow\n",
 379                        sname, chs_ecyl, dp->dp_ehd, chs_esect, esector1));
 380                 esector = esector1;
 381         }
 382
 383         error = (ssector == ssector1 && esector == esector1) ? 0 : EINVAL;
 384         if (bootverbose)
 385                 kprintf("%s: type 0x%x, start %llu, end = %llu, size %lu %s\n",
 386                        sname, dp->dp_typ, ssector1, esector1,
 387                        (u_long)dp->dp_size, error ? "" : ": OK");
 388         if (ssector != ssector1 && bootverbose)
 389                 kprintf("%s: C/H/S start %d/%d/%d (%llu) != start %llu: invalid\n",
 390                        sname, chs_scyl, dp->dp_shd, chs_ssect,
 391                        ssector, ssector1);
 392         if (esector != esector1 && bootverbose)
 393                 kprintf("%s: C/H/S end %d/%d/%d (%llu) != end %llu: invalid\n",
 394                        sname, chs_ecyl, dp->dp_ehd, chs_esect,
 395                        esector, esector1);
 396         return (error);
 397 }
 398
 399 static
 400 void
 401 mbr_extended(cdev_t dev, struct disk_info *info, struct diskslices *ssp,
 402             u_int64_t ext_offset, u_int64_t ext_size, u_int64_t base_ext_offset,
 403             int nsectors, int ntracks, u_int64_t mbr_offset, int level)
 404 {
 405         struct buf *bp;
 406         u_char  *cp;
 407         int     dospart;
 408         struct dos_partition *dp;
 409         struct dos_partition dpcopy[NDOSPART];
 410         u_int64_t ext_offsets[NDOSPART];
 411         u_int64_t ext_sizes[NDOSPART];
 412         char    partname[2];
 413         int     slice;
 414         char    *sname;
 415         struct diskslice *sp;
 416
 417         if (level >= 16) {
 418                 kprintf(
 419         "%s: excessive recursion in search for slices; aborting search\n",
 420                        devtoname(dev));
 421                 return;
 422         }
 423
 424         /* Read extended boot record. */
 425         bp = geteblk((int)info->d_media_blksize);
 426         bp->b_bio1.bio_offset = (off_t)ext_offset * info->d_media_blksize;
 427         bp->b_bcount = info->d_media_blksize;
 428         bp->b_cmd = BUF_CMD_READ;
 429         dev_dstrategy(dev, &bp->b_bio1);
 430         if (biowait(bp) != 0) {
 431                 diskerr(&bp->b_bio1, dev,
 432                         "reading extended partition table: error",
 433                         LOG_PRINTF, 0);
 434                 kprintf("\n");
 435                 goto done;
 436         }
 437
 438         /* Weakly verify it. */
 439         cp = bp->b_data;
 440         if (cp[0x1FE] != 0x55 || cp[0x1FF] != 0xAA) {
 441                 sname = dsname(dev, dkunit(dev), WHOLE_DISK_SLICE, WHOLE_SLICE_PART,
 442                                partname);
 443                 if (bootverbose)
 444                         kprintf("%s: invalid extended partition table: no magic\n",
 445                                sname);
 446                 goto done;
 447         }
 448
 449         /* Make a copy of the partition table to avoid alignment problems. */
 450         memcpy(&dpcopy[0], cp + DOSPARTOFF, sizeof(dpcopy));
 451
 452         slice = ssp->dss_nslices;
 453         for (dospart = 0, dp = &dpcopy[0]; dospart < NDOSPART;
 454             dospart++, dp++) {
 455                 ext_sizes[dospart] = 0;
 456                 if (dp->dp_scyl == 0 && dp->dp_shd == 0 && dp->dp_ssect == 0
 457                     && dp->dp_start == 0 && dp->dp_size == 0)
 458                         continue;
 459                 if (dp->dp_typ == DOSPTYP_EXTENDED ||
 460                     dp->dp_typ == DOSPTYP_EXTENDEDX) {
 461                         static char buf[32];
 462
 463                         sname = dsname(dev, dkunit(dev), WHOLE_DISK_SLICE,
 464                                        WHOLE_SLICE_PART, partname);
 465                         ksnprintf(buf, sizeof(buf), "%s", sname);
 466                         if (strlen(buf) < sizeof buf - 11)
 467                                 strcat(buf, "<extended>");
 468                         check_part(buf, dp, base_ext_offset, nsectors,
 469                                    ntracks, mbr_offset);
 470                         ext_offsets[dospart] = base_ext_offset + dp->dp_start;
 471                         ext_sizes[dospart] = dp->dp_size;
 472                 } else {
 473                         sname = dsname(dev, dkunit(dev), slice, WHOLE_SLICE_PART,
 474                                        partname);
 475                         check_part(sname, dp, ext_offset, nsectors, ntracks,
 476                                    mbr_offset);
 477                         if (slice >= MAX_SLICES) {
 478                                 kprintf("%s: too many slices\n", sname);
 479                                 slice++;
 480                                 continue;
 481                         }
 482                         sp = &ssp->dss_slices[slice];
 483                         if (mbr_setslice(sname, info, sp, dp, ext_offset) != 0)
 484                                 continue;
 485                         slice++;
 486                 }
 487         }
 488         ssp->dss_nslices = slice;
 489
 490         /* If we found any more slices, recursively find all the subslices. */
 491         for (dospart = 0; dospart < NDOSPART; dospart++) {
 492                 if (ext_sizes[dospart] != 0) {
 493                         mbr_extended(dev, info, ssp, ext_offsets[dospart],
 494                                      ext_sizes[dospart], base_ext_offset,
 495                                      nsectors, ntracks, mbr_offset, ++level);
 496                 }
 497         }
 498
 499 done:
 500         bp->b_flags |= B_INVAL | B_AGE;
 501         brelse(bp);
 502 }
 503
 504 static int
 505 mbr_setslice(char *sname, struct disk_info *info, struct diskslice *sp,
 506             struct dos_partition *dp, u_int64_t br_offset)
 507 {
 508         u_int64_t       offset;
 509         u_int64_t       size;
 510
 511         offset = br_offset + dp->dp_start;
 512         if (offset > info->d_media_blocks || offset < br_offset) {
 513                 kprintf(
 514                 "%s: slice starts beyond end of the disk: rejecting it\n",
 515                        sname);
 516                 return (1);
 517         }
 518         size = info->d_media_blocks - offset;
 519         if (size >= dp->dp_size)
 520                 size = dp->dp_size;
 521         else
 522                 kprintf(
 523 "%s: slice extends beyond end of disk: truncating from %lu to %llu sectors\n",
 524                        sname, (u_long)dp->dp_size, size);
 525         sp->ds_offset = offset;
 526         sp->ds_size = size;
 527         sp->ds_type = dp->dp_typ;
 528         bzero(&sp->ds_type_uuid, sizeof(sp->ds_type_uuid));
 529         bzero(&sp->ds_stor_uuid, sizeof(sp->ds_type_uuid));
 530
 531         /*
 532          * Slices do not overlap with the parent (if any).
 533          */
 534         sp->ds_reserved = 0;
 535         return (0);
 536 }