sys/vfs/hammer/hammer_volume.c

   1 /*
   2  * Copyright (c) 2009 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com> and
   6  * Michael Neumann <mneumann@ntecs.de>
   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  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in
  16  *    the documentation and/or other materials provided with the
  17  *    distribution.
  18  * 3. Neither the name of The DragonFly Project nor the names of its
  19  *    contributors may be used to endorse or promote products derived
  20  *    from this software without specific, prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  26  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  */
  36
  37 #include "hammer.h"
  38 #include <sys/fcntl.h>
  39 #include <sys/nlookup.h>
  40 #include <sys/buf.h>
  41
  42 static int
  43 hammer_setup_device(struct vnode **devvpp, const char *dev_path, int ronly);
  44
  45 static void
  46 hammer_close_device(struct vnode **devvpp, int ronly);
  47
  48 static int
  49 hammer_format_volume_header(struct hammer_mount *hmp, struct vnode *devvp,
  50         const char *vol_name, int vol_no, int vol_count,
  51         int64_t vol_size, int64_t boot_area_size, int64_t mem_area_size);
  52
  53 static int
  54 hammer_clear_volume_header(struct vnode *devvp);
  55
  56 static uint64_t
  57 hammer_format_freemap(hammer_transaction_t trans, hammer_volume_t volume);
  58
  59 static int
  60 hammer_free_freemap(hammer_transaction_t trans, hammer_volume_t volume);
  61
  62
  63 int
  64 hammer_ioc_volume_add(hammer_transaction_t trans, hammer_inode_t ip,
  65                 struct hammer_ioc_volume *ioc)
  66 {
  67         struct hammer_mount *hmp = trans->hmp;
  68         struct mount *mp = hmp->mp;
  69         hammer_volume_t volume;
  70         int error;
  71
  72         if (mp->mnt_flag & MNT_RDONLY) {
  73                 kprintf("Cannot add volume to read-only HAMMER filesystem\n");
  74                 return (EINVAL);
  75         }
  76
  77         if (hmp->nvolumes + 1 >= HAMMER_MAX_VOLUMES) {
  78                 kprintf("Max number of HAMMER volumes exceeded\n");
  79                 return (EINVAL);
  80         }
  81
  82         /*
  83          * Find an unused volume number.
  84          */
  85         int free_vol_no = 0;
  86         while (free_vol_no < HAMMER_MAX_VOLUMES &&
  87                RB_LOOKUP(hammer_vol_rb_tree, &hmp->rb_vols_root, free_vol_no)) {
  88                 ++free_vol_no;
  89         }
  90         if (free_vol_no >= HAMMER_MAX_VOLUMES) {
  91                 kprintf("Max number of HAMMER volumes exceeded\n");
  92                 return (EINVAL);
  93         }
  94
  95         struct vnode *devvp = NULL;
  96         error = hammer_setup_device(&devvp, ioc->device_name, 0);
  97         if (error)
  98                 goto end;
  99         KKASSERT(devvp);
 100         error = hammer_format_volume_header(
 101                 hmp,
 102                 devvp,
 103                 hmp->rootvol->ondisk->vol_name,
 104                 free_vol_no,
 105                 hmp->nvolumes+1,
 106                 ioc->vol_size,
 107                 ioc->boot_area_size,
 108                 ioc->mem_area_size);
 109         hammer_close_device(&devvp, 0);
 110         if (error)
 111                 goto end;
 112
 113         error = hammer_install_volume(hmp, ioc->device_name, NULL);
 114         if (error)
 115                 goto end;
 116
 117         hammer_sync_lock_sh(trans);
 118         hammer_lock_ex(&hmp->blkmap_lock);
 119
 120         ++hmp->nvolumes;
 121
 122         /*
 123          * Set each volumes new value of the vol_count field.
 124          */
 125         for (int vol_no = 0; vol_no < HAMMER_MAX_VOLUMES; ++vol_no) {
 126                 volume = hammer_get_volume(hmp, vol_no, &error);
 127                 if (volume == NULL && error == ENOENT) {
 128                         /*
 129                          * Skip unused volume numbers
 130                          */
 131                         error = 0;
 132                         continue;
 133                 }
 134                 KKASSERT(volume != NULL && error == 0);
 135                 hammer_modify_volume_field(trans, volume, vol_count);
 136                 volume->ondisk->vol_count = hmp->nvolumes;
 137                 hammer_modify_volume_done(volume);
 138
 139                 /*
 140                  * Only changes to the header of the root volume
 141                  * are automatically flushed to disk. For all
 142                  * other volumes that we modify we do it here.
 143                  */
 144                 if (volume != trans->rootvol && volume->io.modified) {
 145                         hammer_crc_set_volume(volume->ondisk);
 146                         hammer_io_flush(&volume->io, 0);
 147                 }
 148
 149                 hammer_rel_volume(volume, 0);
 150         }
 151
 152         volume = hammer_get_volume(hmp, free_vol_no, &error);
 153         KKASSERT(volume != NULL && error == 0);
 154
 155         uint64_t total_free_bigblocks =
 156                 hammer_format_freemap(trans, volume);
 157
 158         /*
 159          * Increase the total number of bigblocks
 160          */
 161         hammer_modify_volume_field(trans, trans->rootvol,
 162                 vol0_stat_bigblocks);
 163         trans->rootvol->ondisk->vol0_stat_bigblocks += total_free_bigblocks;
 164         hammer_modify_volume_done(trans->rootvol);
 165
 166         /*
 167          * Increase the number of free bigblocks
 168          * (including the copy in hmp)
 169          */
 170         hammer_modify_volume_field(trans, trans->rootvol,
 171                 vol0_stat_freebigblocks);
 172         trans->rootvol->ondisk->vol0_stat_freebigblocks += total_free_bigblocks;
 173         hmp->copy_stat_freebigblocks =
 174                 trans->rootvol->ondisk->vol0_stat_freebigblocks;
 175         hammer_modify_volume_done(trans->rootvol);
 176
 177         hammer_rel_volume(volume, 0);
 178
 179         hammer_unlock(&hmp->blkmap_lock);
 180         hammer_sync_unlock(trans);
 181
 182 end:
 183         if (error)
 184                 kprintf("An error occurred: %d\n", error);
 185         return (error);
 186 }
 187
 188
 189 /*
 190  * Remove a volume.
 191  */
 192 int
 193 hammer_ioc_volume_del(hammer_transaction_t trans, hammer_inode_t ip,
 194                 struct hammer_ioc_volume *ioc)
 195 {
 196         struct hammer_mount *hmp = trans->hmp;
 197         struct mount *mp = hmp->mp;
 198         hammer_volume_t volume;
 199         int error = 0;
 200
 201         if (mp->mnt_flag & MNT_RDONLY) {
 202                 kprintf("Cannot del volume from read-only HAMMER filesystem\n");
 203                 return (EINVAL);
 204         }
 205
 206
 207         volume = NULL;
 208
 209         /*
 210          * find volume by volname
 211          */
 212         for (int vol_no = 0; vol_no < HAMMER_MAX_VOLUMES; ++vol_no) {
 213                 volume = hammer_get_volume(hmp, vol_no, &error);
 214                 if (volume == NULL && error == ENOENT) {
 215                         /*
 216                          * Skip unused volume numbers
 217                          */
 218                         error = 0;
 219                         continue;
 220                 }
 221                 KKASSERT(volume != NULL && error == 0);
 222                 if (strcmp(volume->vol_name, ioc->device_name) == 0) {
 223                         break;
 224                 }
 225                 hammer_rel_volume(volume, 0);
 226                 volume = NULL;
 227         }
 228
 229         if (volume == NULL) {
 230                 kprintf("Couldn't find volume\n");
 231                 return (EINVAL);
 232         }
 233
 234         if (volume == trans->rootvol) {
 235                 kprintf("Cannot remove root-volume\n");
 236                 hammer_rel_volume(volume, 0);
 237                 return (EINVAL);
 238         }
 239
 240         /*
 241          *
 242          */
 243
 244         hmp->volume_to_remove = volume->vol_no;
 245
 246         struct hammer_ioc_reblock reblock;
 247         bzero(&reblock, sizeof(reblock));
 248
 249         reblock.key_beg.localization = HAMMER_MIN_LOCALIZATION;
 250         reblock.key_beg.obj_id = HAMMER_MIN_OBJID;
 251         reblock.key_end.localization = HAMMER_MAX_LOCALIZATION;
 252         reblock.key_end.obj_id = HAMMER_MAX_OBJID;
 253         reblock.head.flags = HAMMER_IOC_DO_FLAGS;
 254         reblock.free_level = 0;
 255
 256         error = hammer_ioc_reblock(trans, ip, &reblock);
 257
 258         if (reblock.head.flags & HAMMER_IOC_HEAD_INTR) {
 259                 error = EINTR;
 260         }
 261
 262         if (error) {
 263                 if (error == EINTR) {
 264                         kprintf("reblock was interrupted\n");
 265                 } else {
 266                         kprintf("reblock failed: %d\n", error);
 267                 }
 268                 hmp->volume_to_remove = -1;
 269                 hammer_rel_volume(volume, 0);
 270                 return (error);
 271         }
 272
 273         /*
 274          * Sync filesystem
 275          */
 276         int count = 0;
 277         while (hammer_flusher_haswork(hmp)) {
 278                 hammer_flusher_sync(hmp);
 279                 ++count;
 280                 if (count >= 5) {
 281                         if (count == 5)
 282                                 kprintf("HAMMER: flushing.");
 283                         else
 284                                 kprintf(".");
 285                         tsleep(&count, 0, "hmrufl", hz);
 286                 }
 287                 if (count == 30) {
 288                         kprintf("giving up");
 289                         break;
 290                 }
 291         }
 292         kprintf("\n");
 293
 294         hammer_sync_lock_sh(trans);
 295         hammer_lock_ex(&hmp->blkmap_lock);
 296
 297         error = hammer_free_freemap(trans, volume);
 298         if (error) {
 299                 kprintf("Failed to free volume. Volume not empty!\n");
 300                 hmp->volume_to_remove = -1;
 301                 hammer_rel_volume(volume, 0);
 302                 hammer_unlock(&hmp->blkmap_lock);
 303                 hammer_sync_unlock(trans);
 304                 return (error);
 305         }
 306
 307         hmp->volume_to_remove = -1;
 308
 309         hammer_rel_volume(volume, 0);
 310
 311         /*
 312          * Unload buffers
 313          */
 314         RB_SCAN(hammer_buf_rb_tree, &hmp->rb_bufs_root, NULL,
 315                 hammer_unload_buffer, volume);
 316
 317         error = hammer_unload_volume(volume, NULL);
 318         if (error == -1) {
 319                 kprintf("Failed to unload volume\n");
 320                 hammer_unlock(&hmp->blkmap_lock);
 321                 hammer_sync_unlock(trans);
 322                 return (error);
 323         }
 324
 325         volume = NULL;
 326         --hmp->nvolumes;
 327
 328         /*
 329          * Set each volume's new value of the vol_count field.
 330          */
 331         for (int vol_no = 0; vol_no < HAMMER_MAX_VOLUMES; ++vol_no) {
 332                 volume = hammer_get_volume(hmp, vol_no, &error);
 333                 if (volume == NULL && error == ENOENT) {
 334                         /*
 335                          * Skip unused volume numbers
 336                          */
 337                         error = 0;
 338                         continue;
 339                 }
 340
 341                 KKASSERT(volume != NULL && error == 0);
 342                 hammer_modify_volume_field(trans, volume, vol_count);
 343                 volume->ondisk->vol_count = hmp->nvolumes;
 344                 hammer_modify_volume_done(volume);
 345
 346                 /*
 347                  * Only changes to the header of the root volume
 348                  * are automatically flushed to disk. For all
 349                  * other volumes that we modify we do it here.
 350                  */
 351                 if (volume != trans->rootvol && volume->io.modified) {
 352                         hammer_crc_set_volume(volume->ondisk);
 353                         hammer_io_flush(&volume->io, 0);
 354                 }
 355
 356                 hammer_rel_volume(volume, 0);
 357         }
 358
 359         hammer_unlock(&hmp->blkmap_lock);
 360         hammer_sync_unlock(trans);
 361
 362         /*
 363          * Erase the volume header of the removed device.
 364          *
 365          * This is to not accidentally mount the volume again.
 366          */
 367         struct vnode *devvp = NULL;
 368         error = hammer_setup_device(&devvp, ioc->device_name, 0);
 369         if (error) {
 370                 kprintf("Failed to open device: %s\n", ioc->device_name);
 371                 return error;
 372         }
 373         KKASSERT(devvp);
 374         error = hammer_clear_volume_header(devvp);
 375         if (error) {
 376                 kprintf("Failed to clear volume header of device: %s\n",
 377                         ioc->device_name);
 378                 return error;
 379         }
 380         hammer_close_device(&devvp, 0);
 381
 382         return (0);
 383 }
 384
 385
 386 /*
 387  * Iterate over all usable L1 entries of the volume and
 388  * the corresponding L2 entries.
 389  */
 390 static int
 391 hammer_iterate_l1l2_entries(hammer_transaction_t trans, hammer_volume_t volume,
 392         int (*callback)(hammer_transaction_t, hammer_volume_t, hammer_buffer_t*,
 393                 struct hammer_blockmap_layer1*, struct hammer_blockmap_layer2*,
 394                 hammer_off_t, hammer_off_t, void*),
 395         void *data)
 396 {
 397         struct hammer_mount *hmp = trans->hmp;
 398         hammer_blockmap_t freemap = &hmp->blockmap[HAMMER_ZONE_FREEMAP_INDEX];
 399         hammer_buffer_t buffer = NULL;
 400         int error = 0;
 401
 402         hammer_off_t phys_off;
 403         hammer_off_t block_off;
 404         hammer_off_t layer1_off;
 405         hammer_off_t layer2_off;
 406         hammer_off_t aligned_buf_end_off;
 407         struct hammer_blockmap_layer1 *layer1;
 408         struct hammer_blockmap_layer2 *layer2;
 409
 410         /*
 411          * Calculate the usable size of the volume, which
 412          * must be aligned at a bigblock (8 MB) boundary.
 413          */
 414         aligned_buf_end_off = (HAMMER_ENCODE_RAW_BUFFER(volume->ondisk->vol_no,
 415                 (volume->ondisk->vol_buf_end - volume->ondisk->vol_buf_beg)
 416                 & ~HAMMER_LARGEBLOCK_MASK64));
 417
 418         /*
 419          * Iterate the volume's address space in chunks of 4 TB, where each
 420          * chunk consists of at least one physically available 8 MB bigblock.
 421          *
 422          * For each chunk we need one L1 entry and one L2 bigblock.
 423          * We use the first bigblock of each chunk as L2 block.
 424          */
 425         for (phys_off = HAMMER_ENCODE_RAW_BUFFER(volume->ondisk->vol_no, 0);
 426              phys_off < aligned_buf_end_off;
 427              phys_off += HAMMER_BLOCKMAP_LAYER2) {
 428                 for (block_off = 0;
 429                      block_off < HAMMER_BLOCKMAP_LAYER2;
 430                      block_off += HAMMER_LARGEBLOCK_SIZE) {
 431                         layer2_off = phys_off +
 432                                 HAMMER_BLOCKMAP_LAYER2_OFFSET(block_off);
 433                         layer2 = hammer_bread(hmp, layer2_off, &error, &buffer);
 434                         if (error)
 435                                 goto end;
 436
 437                         error = callback(trans, volume, &buffer, NULL,
 438                                          layer2, phys_off, block_off, data);
 439                         if (error)
 440                                 goto end;
 441                 }
 442
 443                 layer1_off = freemap->phys_offset +
 444                                 HAMMER_BLOCKMAP_LAYER1_OFFSET(phys_off);
 445                 layer1 = hammer_bread(hmp, layer1_off, &error, &buffer);
 446                 if (error)
 447                         goto end;
 448
 449                 error = callback(trans, volume, &buffer, layer1, NULL,
 450                                  phys_off, 0, data);
 451                 if (error)
 452                         goto end;
 453         }
 454
 455 end:
 456         if (buffer) {
 457                 hammer_rel_buffer(buffer, 0);
 458                 buffer = NULL;
 459         }
 460
 461         return error;
 462 }
 463
 464 struct format_bigblock_stat {
 465         uint64_t total_free_bigblocks;
 466         uint64_t free_bigblocks;
 467 };
 468
 469 static int
 470 format_callback(hammer_transaction_t trans, hammer_volume_t volume,
 471         hammer_buffer_t *bufferp,
 472         struct hammer_blockmap_layer1 *layer1,
 473         struct hammer_blockmap_layer2 *layer2,
 474         hammer_off_t phys_off,
 475         hammer_off_t block_off,
 476         void *data)
 477 {
 478         struct format_bigblock_stat *stat = (struct format_bigblock_stat*)data;
 479
 480         /*
 481          * Calculate the usable size of the volume, which must be aligned
 482          * at a bigblock (8 MB) boundary.
 483          */
 484         hammer_off_t aligned_buf_end_off;
 485         aligned_buf_end_off = (HAMMER_ENCODE_RAW_BUFFER(volume->ondisk->vol_no,
 486                 (volume->ondisk->vol_buf_end - volume->ondisk->vol_buf_beg)
 487                 & ~HAMMER_LARGEBLOCK_MASK64));
 488
 489         if (layer1) {
 490                 KKASSERT(layer1->phys_offset == HAMMER_BLOCKMAP_UNAVAIL);
 491
 492                 hammer_modify_buffer(trans, *bufferp, layer1, sizeof(*layer1));
 493                 bzero(layer1, sizeof(layer1));
 494                 layer1->phys_offset = phys_off;
 495                 layer1->blocks_free = stat->free_bigblocks;
 496                 layer1->layer1_crc = crc32(layer1, HAMMER_LAYER1_CRCSIZE);
 497                 hammer_modify_buffer_done(*bufferp);
 498
 499                 stat->total_free_bigblocks += stat->free_bigblocks;
 500                 stat->free_bigblocks = 0; /* reset */
 501         } else if (layer2) {
 502                 hammer_modify_buffer(trans, *bufferp, layer2, sizeof(*layer2));
 503                 bzero(layer2, sizeof(*layer2));
 504
 505                 if (block_off == 0) {
 506                         /*
 507                          * The first entry represents the L2 bigblock itself.
 508                          */
 509                         layer2->zone = HAMMER_ZONE_FREEMAP_INDEX;
 510                         layer2->append_off = HAMMER_LARGEBLOCK_SIZE;
 511                         layer2->bytes_free = 0;
 512                 } else if (phys_off + block_off < aligned_buf_end_off) {
 513                         /*
 514                          * Available bigblock
 515                          */
 516                         layer2->zone = 0;
 517                         layer2->append_off = 0;
 518                         layer2->bytes_free = HAMMER_LARGEBLOCK_SIZE;
 519                         ++stat->free_bigblocks;
 520                 } else {
 521                         /*
 522                          * Bigblock outside of physically available
 523                          * space
 524                          */
 525                         layer2->zone = HAMMER_ZONE_UNAVAIL_INDEX;
 526                         layer2->append_off = HAMMER_LARGEBLOCK_SIZE;
 527                         layer2->bytes_free = 0;
 528                 }
 529
 530                 layer2->entry_crc = crc32(layer2, HAMMER_LAYER2_CRCSIZE);
 531                 hammer_modify_buffer_done(*bufferp);
 532         } else {
 533                 KKASSERT(0);
 534         }
 535
 536         return 0;
 537 }
 538
 539 static uint64_t
 540 hammer_format_freemap(hammer_transaction_t trans, hammer_volume_t volume)
 541 {
 542         int error = 0;
 543
 544         struct format_bigblock_stat stat;
 545         stat.total_free_bigblocks = 0;
 546         stat.free_bigblocks = 0;
 547
 548         error = hammer_iterate_l1l2_entries(trans, volume, format_callback,
 549                                         (void*)&stat);
 550         KKASSERT(error == 0);
 551
 552         return stat.total_free_bigblocks;
 553 }
 554
 555 static int
 556 free_callback(hammer_transaction_t trans, hammer_volume_t volume __unused,
 557         hammer_buffer_t *bufferp,
 558         struct hammer_blockmap_layer1 *layer1,
 559         struct hammer_blockmap_layer2 *layer2,
 560         hammer_off_t phys_off,
 561         hammer_off_t block_off __unused,
 562         void *data)
 563 {
 564         /*
 565          * No modifications to ondisk structures
 566          */
 567         int testonly = (data != NULL);
 568
 569         if (layer1) {
 570                 if (layer1->phys_offset == HAMMER_BLOCKMAP_UNAVAIL) {
 571                         /*
 572                          * This layer1 entry is already free.
 573                          */
 574                         return 0;
 575                 }
 576
 577                 KKASSERT((int)HAMMER_VOL_DECODE(layer1->phys_offset) ==
 578                         trans->hmp->volume_to_remove);
 579
 580                 if (testonly)
 581                         return 0;
 582
 583                 /*
 584                  * Free the L1 entry
 585                  */
 586                 hammer_modify_buffer(trans, *bufferp, layer1, sizeof(*layer1));
 587                 bzero(layer1, sizeof(layer1));
 588                 layer1->phys_offset = HAMMER_BLOCKMAP_UNAVAIL;
 589                 layer1->layer1_crc = crc32(layer1, HAMMER_LAYER1_CRCSIZE);
 590                 hammer_modify_buffer_done(*bufferp);
 591
 592                 return 0;
 593         } else if (layer2) {
 594                 if (layer2->zone == HAMMER_ZONE_FREEMAP_INDEX ||
 595                     layer2->zone == HAMMER_ZONE_UNAVAIL_INDEX)
 596                         return 0;
 597
 598                 if (layer2->append_off == 0 &&
 599                     layer2->bytes_free == HAMMER_LARGEBLOCK_SIZE)
 600                         return 0;
 601                 /*
 602                  * We found a layer2 entry that is not empty!
 603                  */
 604                 return EBUSY;
 605         } else {
 606                 KKASSERT(0);
 607         }
 608
 609         return EINVAL;
 610 }
 611
 612 static int
 613 hammer_free_freemap(hammer_transaction_t trans, hammer_volume_t volume)
 614 {
 615         int error;
 616         error = hammer_iterate_l1l2_entries(trans, volume, free_callback,
 617                                             (void*)1);
 618         if (error)
 619                 return error;
 620
 621         error = hammer_iterate_l1l2_entries(trans, volume, free_callback, NULL);
 622         return error;
 623 }
 624
 625 /************************************************************************
 626  *                              MISC                                    *
 627  ************************************************************************
 628  */
 629
 630 static int
 631 hammer_setup_device(struct vnode **devvpp, const char *dev_path, int ronly)
 632 {
 633         int error;
 634         struct nlookupdata nd;
 635
 636         /*
 637          * Get the device vnode
 638          */
 639         if (*devvpp == NULL) {
 640                 error = nlookup_init(&nd, dev_path, UIO_SYSSPACE, NLC_FOLLOW);
 641                 if (error == 0)
 642                         error = nlookup(&nd);
 643                 if (error == 0)
 644                         error = cache_vref(&nd.nl_nch, nd.nl_cred, devvpp);
 645                 nlookup_done(&nd);
 646         } else {
 647                 error = 0;
 648         }
 649
 650         if (error == 0) {
 651                 if (vn_isdisk(*devvpp, &error)) {
 652                         error = vfs_mountedon(*devvpp);
 653                 }
 654         }
 655         if (error == 0 && vcount(*devvpp) > 0)
 656                 error = EBUSY;
 657         if (error == 0) {
 658                 vn_lock(*devvpp, LK_EXCLUSIVE | LK_RETRY);
 659                 error = vinvalbuf(*devvpp, V_SAVE, 0, 0);
 660                 if (error == 0) {
 661                         error = VOP_OPEN(*devvpp,
 662                                          (ronly ? FREAD : FREAD|FWRITE),
 663                                          FSCRED, NULL);
 664                 }
 665                 vn_unlock(*devvpp);
 666         }
 667         if (error && *devvpp) {
 668                 vrele(*devvpp);
 669                 *devvpp = NULL;
 670         }
 671         return (error);
 672 }
 673
 674 static void
 675 hammer_close_device(struct vnode **devvpp, int ronly)
 676 {
 677         VOP_CLOSE(*devvpp, (ronly ? FREAD : FREAD|FWRITE));
 678         if (*devvpp) {
 679                 vinvalbuf(*devvpp, ronly ? 0 : V_SAVE, 0, 0);
 680                 vrele(*devvpp);
 681                 *devvpp = NULL;
 682         }
 683 }
 684
 685 static int
 686 hammer_format_volume_header(struct hammer_mount *hmp, struct vnode *devvp,
 687         const char *vol_name, int vol_no, int vol_count,
 688         int64_t vol_size, int64_t boot_area_size, int64_t mem_area_size)
 689 {
 690         struct buf *bp = NULL;
 691         struct hammer_volume_ondisk *ondisk;
 692         int error;
 693
 694         /*
 695          * Extract the volume number from the volume header and do various
 696          * sanity checks.
 697          */
 698         KKASSERT(HAMMER_BUFSIZE >= sizeof(struct hammer_volume_ondisk));
 699         error = bread(devvp, 0LL, HAMMER_BUFSIZE, &bp);
 700         if (error || bp->b_bcount < sizeof(struct hammer_volume_ondisk))
 701                 goto late_failure;
 702
 703         ondisk = (struct hammer_volume_ondisk*) bp->b_data;
 704
 705         /*
 706          * Note that we do NOT allow to use a device that contains
 707          * a valid HAMMER signature. It has to be cleaned up with dd
 708          * before.
 709          */
 710         if (ondisk->vol_signature == HAMMER_FSBUF_VOLUME) {
 711                 kprintf("hammer_volume_add: Formatting of valid HAMMER volume "
 712                         "%s denied. Erase with dd!\n", vol_name);
 713                 error = EFTYPE;
 714                 goto late_failure;
 715         }
 716
 717         bzero(ondisk, sizeof(struct hammer_volume_ondisk));
 718         ksnprintf(ondisk->vol_name, sizeof(ondisk->vol_name), "%s", vol_name);
 719         ondisk->vol_fstype = hmp->rootvol->ondisk->vol_fstype;
 720         ondisk->vol_signature = HAMMER_FSBUF_VOLUME;
 721         ondisk->vol_fsid = hmp->fsid;
 722         ondisk->vol_rootvol = hmp->rootvol->vol_no;
 723         ondisk->vol_no = vol_no;
 724         ondisk->vol_count = vol_count;
 725         ondisk->vol_version = hmp->version;
 726
 727         /*
 728          * Reserve space for (future) header junk, setup our poor-man's
 729          * bigblock allocator.
 730          */
 731         int64_t vol_alloc = HAMMER_BUFSIZE * 16;
 732
 733         ondisk->vol_bot_beg = vol_alloc;
 734         vol_alloc += boot_area_size;
 735         ondisk->vol_mem_beg = vol_alloc;
 736         vol_alloc += mem_area_size;
 737
 738         /*
 739          * The remaining area is the zone 2 buffer allocation area.  These
 740          * buffers
 741          */
 742         ondisk->vol_buf_beg = vol_alloc;
 743         ondisk->vol_buf_end = vol_size & ~(int64_t)HAMMER_BUFMASK;
 744
 745         if (ondisk->vol_buf_end < ondisk->vol_buf_beg) {
 746                 kprintf("volume %d %s is too small to hold the volume header",
 747                      ondisk->vol_no, ondisk->vol_name);
 748                 error = EFTYPE;
 749                 goto late_failure;
 750         }
 751
 752         ondisk->vol_nblocks = (ondisk->vol_buf_end - ondisk->vol_buf_beg) /
 753                               HAMMER_BUFSIZE;
 754         ondisk->vol_blocksize = HAMMER_BUFSIZE;
 755
 756         /*
 757          * Write volume header to disk
 758          */
 759         error = bwrite(bp);
 760         bp = NULL;
 761
 762 late_failure:
 763         if (bp)
 764                 brelse(bp);
 765         return (error);
 766 }
 767
 768 /*
 769  * Invalidates the volume header. Used by volume-del.
 770  */
 771 static int
 772 hammer_clear_volume_header(struct vnode *devvp)
 773 {
 774         struct buf *bp = NULL;
 775         struct hammer_volume_ondisk *ondisk;
 776         int error;
 777
 778         /*
 779          * Extract the volume number from the volume header and do various
 780          * sanity checks.
 781          */
 782         KKASSERT(HAMMER_BUFSIZE >= sizeof(struct hammer_volume_ondisk));
 783         error = bread(devvp, 0LL, HAMMER_BUFSIZE, &bp);
 784         if (error || bp->b_bcount < sizeof(struct hammer_volume_ondisk))
 785                 goto late_failure;
 786
 787         ondisk = (struct hammer_volume_ondisk*) bp->b_data;
 788         bzero(ondisk, sizeof(struct hammer_volume_ondisk));
 789
 790         /*
 791          * Write volume header to disk
 792          */
 793         error = bwrite(bp);
 794         bp = NULL;
 795
 796 late_failure:
 797         if (bp)
 798                 brelse(bp);
 799         return (error);
 800 }