sys/vfs/hammer/hammer_reblock.c

   1 /*
   2  * Copyright (c) 2008 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>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  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
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/vfs/hammer/hammer_reblock.c,v 1.34 2008/11/13 02:18:43 dillon Exp $
  35  */
  36 /*
  37  * HAMMER reblocker - This code frees up fragmented physical space
  38  *
  39  * HAMMER only keeps track of free space on a big-block basis.  A big-block
  40  * containing holes can only be freed by migrating the remaining data in
  41  * that big-block into a new big-block, then freeing the big-block.
  42  *
  43  * This function is called from an ioctl or via the hammer support thread.
  44  */
  45
  46 #include "hammer.h"
  47
  48 static int hammer_reblock_helper(struct hammer_ioc_reblock *reblock,
  49                                  hammer_cursor_t cursor,
  50                                  hammer_btree_elm_t elm);
  51 static int hammer_reblock_data(struct hammer_ioc_reblock *reblock,
  52                                 hammer_cursor_t cursor, hammer_btree_elm_t elm);
  53 static int hammer_reblock_leaf_node(struct hammer_ioc_reblock *reblock,
  54                                 hammer_cursor_t cursor, hammer_btree_elm_t elm);
  55 static int hammer_reblock_int_node(struct hammer_ioc_reblock *reblock,
  56                                 hammer_cursor_t cursor, hammer_btree_elm_t elm);
  57
  58 int
  59 hammer_ioc_reblock(hammer_transaction_t trans, hammer_inode_t ip,
  60                struct hammer_ioc_reblock *reblock)
  61 {
  62         struct hammer_cursor cursor;
  63         hammer_btree_elm_t elm;
  64         int checkspace_count;
  65         int error;
  66         int seq;
  67         int slop;
  68
  69         /*
  70          * A fill level <= 20% is considered an emergency.  free_level is
  71          * inverted from fill_level.
  72          */
  73         if (reblock->free_level >= HAMMER_LARGEBLOCK_SIZE * 8 / 10)
  74                 slop = HAMMER_CHKSPC_EMERGENCY;
  75         else
  76                 slop = HAMMER_CHKSPC_REBLOCK;
  77
  78         if ((reblock->key_beg.localization | reblock->key_end.localization) &
  79             HAMMER_LOCALIZE_PSEUDOFS_MASK) {
  80                 return(EINVAL);
  81         }
  82         if (reblock->key_beg.obj_id >= reblock->key_end.obj_id)
  83                 return(EINVAL);
  84         if (reblock->free_level < 0)
  85                 return(EINVAL);
  86
  87         reblock->key_cur = reblock->key_beg;
  88         reblock->key_cur.localization &= HAMMER_LOCALIZE_MASK;
  89         reblock->key_cur.localization += ip->obj_localization;
  90
  91         checkspace_count = 0;
  92         seq = trans->hmp->flusher.act;
  93 retry:
  94         error = hammer_init_cursor(trans, &cursor, NULL, NULL);
  95         if (error) {
  96                 hammer_done_cursor(&cursor);
  97                 goto failed;
  98         }
  99         cursor.key_beg.localization = reblock->key_cur.localization;
 100         cursor.key_beg.obj_id = reblock->key_cur.obj_id;
 101         cursor.key_beg.key = HAMMER_MIN_KEY;
 102         cursor.key_beg.create_tid = 1;
 103         cursor.key_beg.delete_tid = 0;
 104         cursor.key_beg.rec_type = HAMMER_MIN_RECTYPE;
 105         cursor.key_beg.obj_type = 0;
 106
 107         cursor.key_end.localization = (reblock->key_end.localization &
 108                                         HAMMER_LOCALIZE_MASK) +
 109                                       ip->obj_localization;
 110         cursor.key_end.obj_id = reblock->key_end.obj_id;
 111         cursor.key_end.key = HAMMER_MAX_KEY;
 112         cursor.key_end.create_tid = HAMMER_MAX_TID - 1;
 113         cursor.key_end.delete_tid = 0;
 114         cursor.key_end.rec_type = HAMMER_MAX_RECTYPE;
 115         cursor.key_end.obj_type = 0;
 116
 117         cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;
 118         cursor.flags |= HAMMER_CURSOR_BACKEND;
 119         cursor.flags |= HAMMER_CURSOR_NOSWAPCACHE;
 120
 121         /*
 122          * This flag allows the btree scan code to return internal nodes,
 123          * so we can reblock them in addition to the leafs.  Only specify it
 124          * if we intend to reblock B-Tree nodes.
 125          */
 126         if (reblock->head.flags & HAMMER_IOC_DO_BTREE)
 127                 cursor.flags |= HAMMER_CURSOR_REBLOCKING;
 128
 129         error = hammer_btree_first(&cursor);
 130         while (error == 0) {
 131                 /*
 132                  * Internal or Leaf node
 133                  */
 134                 KKASSERT(cursor.index < cursor.node->ondisk->count);
 135                 elm = &cursor.node->ondisk->elms[cursor.index];
 136                 reblock->key_cur.obj_id = elm->base.obj_id;
 137                 reblock->key_cur.localization = elm->base.localization;
 138
 139                 /*
 140                  * Yield to more important tasks
 141                  */
 142                 if ((error = hammer_signal_check(trans->hmp)) != 0)
 143                         break;
 144
 145                 /*
 146                  * If there is insufficient free space it may be due to
 147                  * reserved bigblocks, which flushing might fix.
 148                  *
 149                  * We must force a retest in case the unlocked cursor is
 150                  * moved to the end of the leaf, or moved to an internal
 151                  * node.
 152                  *
 153                  * WARNING: See warnings in hammer_unlock_cursor() function.
 154                  */
 155                 if (hammer_checkspace(trans->hmp, slop)) {
 156                         if (++checkspace_count == 10) {
 157                                 error = ENOSPC;
 158                                 break;
 159                         }
 160                         hammer_unlock_cursor(&cursor);
 161                         cursor.flags |= HAMMER_CURSOR_RETEST;
 162                         hammer_flusher_wait(trans->hmp, seq);
 163                         hammer_lock_cursor(&cursor);
 164                         seq = hammer_flusher_async(trans->hmp, NULL);
 165                         goto skip;
 166                 }
 167
 168                 /*
 169                  * Acquiring the sync_lock prevents the operation from
 170                  * crossing a synchronization boundary.
 171                  *
 172                  * NOTE: cursor.node may have changed on return.
 173                  *
 174                  * WARNING: See warnings in hammer_unlock_cursor() function.
 175                  */
 176                 hammer_sync_lock_sh(trans);
 177                 error = hammer_reblock_helper(reblock, &cursor, elm);
 178                 hammer_sync_unlock(trans);
 179
 180                 while (hammer_flusher_meta_halflimit(trans->hmp) ||
 181                        hammer_flusher_undo_exhausted(trans, 2)) {
 182                         hammer_unlock_cursor(&cursor);
 183                         hammer_flusher_wait(trans->hmp, seq);
 184                         hammer_lock_cursor(&cursor);
 185                         seq = hammer_flusher_async_one(trans->hmp);
 186                 }
 187
 188                 /*
 189                  * Setup for iteration, our cursor flags may be modified by
 190                  * other threads while we are unlocked.
 191                  */
 192                 cursor.flags |= HAMMER_CURSOR_ATEDISK;
 193
 194                 /*
 195                  * We allocate data buffers, which atm we don't track
 196                  * dirty levels for because we allow the kernel to write
 197                  * them.  But if we allocate too many we can still deadlock
 198                  * the buffer cache.
 199                  *
 200                  * WARNING: See warnings in hammer_unlock_cursor() function.
 201                  *          (The cursor's node and element may change!)
 202                  */
 203                 if (bd_heatup()) {
 204                         hammer_unlock_cursor(&cursor);
 205                         bwillwrite(HAMMER_XBUFSIZE);
 206                         hammer_lock_cursor(&cursor);
 207                 }
 208 skip:
 209                 if (error == 0) {
 210                         error = hammer_btree_iterate(&cursor);
 211                 }
 212         }
 213         if (error == ENOENT)
 214                 error = 0;
 215         hammer_done_cursor(&cursor);
 216         if (error == EWOULDBLOCK) {
 217                 hammer_flusher_sync(trans->hmp);
 218                 goto retry;
 219         }
 220         if (error == EDEADLK)
 221                 goto retry;
 222         if (error == EINTR) {
 223                 reblock->head.flags |= HAMMER_IOC_HEAD_INTR;
 224                 error = 0;
 225         }
 226 failed:
 227         reblock->key_cur.localization &= HAMMER_LOCALIZE_MASK;
 228         return(error);
 229 }
 230
 231 /*
 232  * Reblock the B-Tree (leaf) node, record, and/or data if necessary.
 233  *
 234  * XXX We have no visibility into internal B-Tree nodes at the moment,
 235  * only leaf nodes.
 236  */
 237 static int
 238 hammer_reblock_helper(struct hammer_ioc_reblock *reblock,
 239                       hammer_cursor_t cursor, hammer_btree_elm_t elm)
 240 {
 241         hammer_mount_t hmp;
 242         hammer_off_t tmp_offset;
 243         hammer_node_ondisk_t ondisk;
 244         struct hammer_btree_leaf_elm leaf;
 245         int error;
 246         int bytes;
 247         int cur;
 248         int iocflags;
 249
 250         error = 0;
 251         hmp = cursor->trans->hmp;
 252
 253         /*
 254          * Reblock data.  Note that data embedded in a record is reblocked
 255          * by the record reblock code.  Data processing only occurs at leaf
 256          * nodes and for RECORD element types.
 257          */
 258         if (cursor->node->ondisk->type != HAMMER_BTREE_TYPE_LEAF)
 259                 goto skip;
 260         if (elm->leaf.base.btype != HAMMER_BTREE_TYPE_RECORD)
 261                 return(0);
 262         tmp_offset = elm->leaf.data_offset;
 263         if (tmp_offset == 0)
 264                 goto skip;
 265         if (error)
 266                 goto skip;
 267
 268         /*
 269          * NOTE: Localization restrictions may also have been set-up, we can't
 270          *       just set the match flags willy-nilly here.
 271          */
 272         switch(elm->leaf.base.rec_type) {
 273         case HAMMER_RECTYPE_INODE:
 274         case HAMMER_RECTYPE_SNAPSHOT:
 275         case HAMMER_RECTYPE_CONFIG:
 276                 iocflags = HAMMER_IOC_DO_INODES;
 277                 break;
 278         case HAMMER_RECTYPE_EXT:
 279         case HAMMER_RECTYPE_FIX:
 280         case HAMMER_RECTYPE_PFS:
 281         case HAMMER_RECTYPE_DIRENTRY:
 282                 iocflags = HAMMER_IOC_DO_DIRS;
 283                 break;
 284         case HAMMER_RECTYPE_DATA:
 285         case HAMMER_RECTYPE_DB:
 286                 iocflags = HAMMER_IOC_DO_DATA;
 287                 break;
 288         default:
 289                 iocflags = 0;
 290                 break;
 291         }
 292         if (reblock->head.flags & iocflags) {
 293                 ++reblock->data_count;
 294                 reblock->data_byte_count += elm->leaf.data_len;
 295                 bytes = hammer_blockmap_getfree(hmp, tmp_offset, &cur, &error);
 296                 if (hammer_debug_general & 0x4000)
 297                         kprintf("D %6d/%d\n", bytes, reblock->free_level);
 298                 if (error == 0 && (cur == 0 || reblock->free_level == 0) &&
 299                     bytes >= reblock->free_level) {
 300                         /*
 301                          * This is nasty, the uncache code may have to get
 302                          * vnode locks and because of that we can't hold
 303                          * the cursor locked.
 304                          *
 305                          * WARNING: See warnings in hammer_unlock_cursor()
 306                          *          function.
 307                          */
 308                         leaf = elm->leaf;
 309                         hammer_unlock_cursor(cursor);
 310                         hammer_io_direct_uncache(hmp, &leaf);
 311                         hammer_lock_cursor(cursor);
 312
 313                         /*
 314                          * elm may have become stale or invalid, reload it.
 315                          * ondisk variable is temporary only.  Note that
 316                          * cursor->node and thus cursor->node->ondisk may
 317                          * also changed.
 318                          */
 319                         ondisk = cursor->node->ondisk;
 320                         elm = &ondisk->elms[cursor->index];
 321                         if (cursor->flags & HAMMER_CURSOR_RETEST) {
 322                                 kprintf("hammer: debug: retest on "
 323                                         "reblocker uncache\n");
 324                                 error = EDEADLK;
 325                         } else if (ondisk->type != HAMMER_BTREE_TYPE_LEAF ||
 326                                    cursor->index >= ondisk->count) {
 327                                 kprintf("hammer: debug: shifted on "
 328                                         "reblocker uncache\n");
 329                                 error = EDEADLK;
 330                         } else if (bcmp(&elm->leaf, &leaf, sizeof(leaf))) {
 331                                 kprintf("hammer: debug: changed on "
 332                                         "reblocker uncache\n");
 333                                 error = EDEADLK;
 334                         }
 335                         if (error == 0)
 336                                 error = hammer_cursor_upgrade(cursor);
 337                         if (error == 0) {
 338                                 KKASSERT(cursor->index < ondisk->count);
 339                                 error = hammer_reblock_data(reblock,
 340                                                             cursor, elm);
 341                         }
 342                         if (error == 0) {
 343                                 ++reblock->data_moves;
 344                                 reblock->data_byte_moves += elm->leaf.data_len;
 345                         }
 346                 }
 347         }
 348
 349 skip:
 350         /*
 351          * Reblock a B-Tree internal or leaf node.  A leaf node is reblocked
 352          * on initial entry only (element 0).  An internal node is reblocked
 353          * when entered upward from its first leaf node only (also element 0).
 354          * Further revisits of the internal node (index > 0) are ignored.
 355          */
 356         tmp_offset = cursor->node->node_offset;
 357         if (cursor->index == 0 &&
 358             error == 0 && (reblock->head.flags & HAMMER_IOC_DO_BTREE)) {
 359                 ++reblock->btree_count;
 360                 bytes = hammer_blockmap_getfree(hmp, tmp_offset, &cur, &error);
 361                 if (hammer_debug_general & 0x4000)
 362                         kprintf("B %6d/%d\n", bytes, reblock->free_level);
 363                 if (error == 0 && (cur == 0 || reblock->free_level == 0) &&
 364                     bytes >= reblock->free_level) {
 365                         error = hammer_cursor_upgrade(cursor);
 366                         if (error == 0) {
 367                                 if (cursor->parent) {
 368                                         KKASSERT(cursor->parent_index <
 369                                                  cursor->parent->ondisk->count);
 370                                         elm = &cursor->parent->ondisk->elms[cursor->parent_index];
 371                                 } else {
 372                                         elm = NULL;
 373                                 }
 374                                 switch(cursor->node->ondisk->type) {
 375                                 case HAMMER_BTREE_TYPE_LEAF:
 376                                         error = hammer_reblock_leaf_node(
 377                                                         reblock, cursor, elm);
 378                                         break;
 379                                 case HAMMER_BTREE_TYPE_INTERNAL:
 380                                         error = hammer_reblock_int_node(
 381                                                         reblock, cursor, elm);
 382                                         break;
 383                                 default:
 384                                         panic("Illegal B-Tree node type");
 385                                 }
 386                         }
 387                         if (error == 0) {
 388                                 ++reblock->btree_moves;
 389                         }
 390                 }
 391         }
 392
 393         hammer_cursor_downgrade(cursor);
 394         return(error);
 395 }
 396
 397 /*
 398  * Reblock a record's data.  Both the B-Tree element and record pointers
 399  * to the data must be adjusted.
 400  */
 401 static int
 402 hammer_reblock_data(struct hammer_ioc_reblock *reblock,
 403                     hammer_cursor_t cursor, hammer_btree_elm_t elm)
 404 {
 405         struct hammer_buffer *data_buffer = NULL;
 406         hammer_off_t ndata_offset;
 407         int error;
 408         void *ndata;
 409
 410         error = hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA |
 411                                              HAMMER_CURSOR_GET_LEAF);
 412         if (error)
 413                 return (error);
 414         ndata = hammer_alloc_data(cursor->trans, elm->leaf.data_len,
 415                                   elm->leaf.base.rec_type,
 416                                   &ndata_offset, &data_buffer,
 417                                   0, &error);
 418         if (error)
 419                 goto done;
 420         hammer_io_notmeta(data_buffer);
 421
 422         /*
 423          * Move the data.  Note that we must invalidate any cached
 424          * data buffer in the cursor before calling blockmap_free.
 425          * The blockmap_free may free up the entire large-block and
 426          * will not be able to invalidate it if the cursor is holding
 427          * a data buffer cached in that large block.
 428          */
 429         hammer_modify_buffer(cursor->trans, data_buffer, NULL, 0);
 430         bcopy(cursor->data, ndata, elm->leaf.data_len);
 431         hammer_modify_buffer_done(data_buffer);
 432         hammer_cursor_invalidate_cache(cursor);
 433
 434         hammer_blockmap_free(cursor->trans,
 435                              elm->leaf.data_offset, elm->leaf.data_len);
 436
 437         hammer_modify_node(cursor->trans, cursor->node,
 438                            &elm->leaf.data_offset, sizeof(hammer_off_t));
 439         elm->leaf.data_offset = ndata_offset;
 440         hammer_modify_node_done(cursor->node);
 441
 442 done:
 443         if (data_buffer)
 444                 hammer_rel_buffer(data_buffer, 0);
 445         return (error);
 446 }
 447
 448 /*
 449  * Reblock a B-Tree leaf node.  The parent must be adjusted to point to
 450  * the new copy of the leaf node.
 451  *
 452  * elm is a pointer to the parent element pointing at cursor.node.
 453  */
 454 static int
 455 hammer_reblock_leaf_node(struct hammer_ioc_reblock *reblock,
 456                          hammer_cursor_t cursor, hammer_btree_elm_t elm)
 457 {
 458         hammer_node_t onode;
 459         hammer_node_t nnode;
 460         int error;
 461
 462         /*
 463          * Don't supply a hint when allocating the leaf.  Fills are done
 464          * from the leaf upwards.
 465          */
 466         onode = cursor->node;
 467         nnode = hammer_alloc_btree(cursor->trans, 0, &error);
 468
 469         if (nnode == NULL)
 470                 return (error);
 471
 472         /*
 473          * Move the node
 474          */
 475         hammer_lock_ex(&nnode->lock);
 476         hammer_modify_node_noundo(cursor->trans, nnode);
 477         bcopy(onode->ondisk, nnode->ondisk, sizeof(*nnode->ondisk));
 478
 479         if (elm) {
 480                 /*
 481                  * We are not the root of the B-Tree
 482                  */
 483                 hammer_modify_node(cursor->trans, cursor->parent,
 484                                    &elm->internal.subtree_offset,
 485                                    sizeof(elm->internal.subtree_offset));
 486                 elm->internal.subtree_offset = nnode->node_offset;
 487                 hammer_modify_node_done(cursor->parent);
 488         } else {
 489                 /*
 490                  * We are the root of the B-Tree
 491                  */
 492                 hammer_volume_t volume;
 493
 494                 volume = hammer_get_root_volume(cursor->trans->hmp, &error);
 495                 KKASSERT(error == 0);
 496
 497                 hammer_modify_volume_field(cursor->trans, volume,
 498                                            vol0_btree_root);
 499                 volume->ondisk->vol0_btree_root = nnode->node_offset;
 500                 hammer_modify_volume_done(volume);
 501                 hammer_rel_volume(volume, 0);
 502         }
 503
 504         hammer_cursor_replaced_node(onode, nnode);
 505         hammer_delete_node(cursor->trans, onode);
 506
 507         if (hammer_debug_general & 0x4000) {
 508                 kprintf("REBLOCK LNODE %016llx -> %016llx\n",
 509                         (long long)onode->node_offset,
 510                         (long long)nnode->node_offset);
 511         }
 512         hammer_modify_node_done(nnode);
 513         cursor->node = nnode;
 514
 515         hammer_unlock(&onode->lock);
 516         hammer_rel_node(onode);
 517
 518         return (error);
 519 }
 520
 521 /*
 522  * Reblock a B-Tree internal node.  The parent must be adjusted to point to
 523  * the new copy of the internal node, and the node's children's parent
 524  * pointers must also be adjusted to point to the new copy.
 525  *
 526  * elm is a pointer to the parent element pointing at cursor.node.
 527  */
 528 static int
 529 hammer_reblock_int_node(struct hammer_ioc_reblock *reblock,
 530                          hammer_cursor_t cursor, hammer_btree_elm_t elm)
 531 {
 532         struct hammer_node_lock lockroot;
 533         hammer_node_t onode;
 534         hammer_node_t nnode;
 535         hammer_off_t hint;
 536         int error;
 537         int i;
 538
 539         hammer_node_lock_init(&lockroot, cursor->node);
 540         error = hammer_btree_lock_children(cursor, 1, &lockroot, NULL);
 541         if (error)
 542                 goto done;
 543
 544         /*
 545          * The internal node is visited after recursing through its
 546          * first element.  Use the subtree offset allocated for that
 547          * element as a hint for allocating the internal node.
 548          */
 549         onode = cursor->node;
 550         if (onode->ondisk->count)
 551                 hint = onode->ondisk->elms[0].internal.subtree_offset;
 552         else
 553                 hint = 0;
 554         nnode = hammer_alloc_btree(cursor->trans, 0, &error);
 555
 556         if (nnode == NULL)
 557                 goto done;
 558
 559         /*
 560          * Move the node.  Adjust the parent's pointer to us first.
 561          */
 562         hammer_lock_ex(&nnode->lock);
 563         hammer_modify_node_noundo(cursor->trans, nnode);
 564         bcopy(onode->ondisk, nnode->ondisk, sizeof(*nnode->ondisk));
 565
 566         if (elm) {
 567                 /*
 568                  * We are not the root of the B-Tree
 569                  */
 570                 hammer_modify_node(cursor->trans, cursor->parent,
 571                                    &elm->internal.subtree_offset,
 572                                    sizeof(elm->internal.subtree_offset));
 573                 elm->internal.subtree_offset = nnode->node_offset;
 574                 hammer_modify_node_done(cursor->parent);
 575         } else {
 576                 /*
 577                  * We are the root of the B-Tree
 578                  */
 579                 hammer_volume_t volume;
 580
 581                 volume = hammer_get_root_volume(cursor->trans->hmp, &error);
 582                 KKASSERT(error == 0);
 583
 584                 hammer_modify_volume_field(cursor->trans, volume,
 585                                            vol0_btree_root);
 586                 volume->ondisk->vol0_btree_root = nnode->node_offset;
 587                 hammer_modify_volume_done(volume);
 588                 hammer_rel_volume(volume, 0);
 589         }
 590
 591         /*
 592          * Now adjust our children's pointers to us.
 593          */
 594         for (i = 0; i < nnode->ondisk->count; ++i) {
 595                 elm = &nnode->ondisk->elms[i];
 596                 error = btree_set_parent(cursor->trans, nnode, elm);
 597                 if (error)
 598                         panic("reblock internal node: fixup problem");
 599         }
 600
 601         /*
 602          * Clean up.
 603          *
 604          * The new node replaces the current node in the cursor.  The cursor
 605          * expects it to be locked so leave it locked.  Discard onode.
 606          */
 607         hammer_cursor_replaced_node(onode, nnode);
 608         hammer_delete_node(cursor->trans, onode);
 609
 610         if (hammer_debug_general & 0x4000) {
 611                 kprintf("REBLOCK INODE %016llx -> %016llx\n",
 612                         (long long)onode->node_offset,
 613                         (long long)nnode->node_offset);
 614         }
 615         hammer_modify_node_done(nnode);
 616         cursor->node = nnode;
 617
 618         hammer_unlock(&onode->lock);
 619         hammer_rel_node(onode);
 620
 621 done:
 622         hammer_btree_unlock_children(cursor->trans->hmp, &lockroot, NULL);
 623         return (error);
 624 }
 625