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
 120         /*
 121          * This flag allows the btree scan code to return internal nodes,
 122          * so we can reblock them in addition to the leafs.  Only specify it
 123          * if we intend to reblock B-Tree nodes.
 124          */
 125         if (reblock->head.flags & HAMMER_IOC_DO_BTREE)
 126                 cursor.flags |= HAMMER_CURSOR_REBLOCKING;
 127
 128         error = hammer_btree_first(&cursor);
 129         while (error == 0) {
 130                 /*
 131                  * Internal or Leaf node
 132                  */
 133                 KKASSERT(cursor.index < cursor.node->ondisk->count);
 134                 elm = &cursor.node->ondisk->elms[cursor.index];
 135                 reblock->key_cur.obj_id = elm->base.obj_id;
 136                 reblock->key_cur.localization = elm->base.localization;
 137
 138                 /*
 139                  * Yield to more important tasks
 140                  */
 141                 if ((error = hammer_signal_check(trans->hmp)) != 0)
 142                         break;
 143
 144                 /*
 145                  * If there is insufficient free space it may be due to
 146                  * reserved bigblocks, which flushing might fix.
 147                  *
 148                  * We must force a retest in case the unlocked cursor is
 149                  * moved to the end of the leaf, or moved to an internal
 150                  * node.
 151                  *
 152                  * WARNING: See warnings in hammer_unlock_cursor() function.
 153                  */
 154                 if (hammer_checkspace(trans->hmp, slop)) {
 155                         if (++checkspace_count == 10) {
 156                                 error = ENOSPC;
 157                                 break;
 158                         }
 159                         hammer_unlock_cursor(&cursor);
 160                         cursor.flags |= HAMMER_CURSOR_RETEST;
 161                         hammer_flusher_wait(trans->hmp, seq);
 162                         hammer_lock_cursor(&cursor);
 163                         seq = hammer_flusher_async(trans->hmp, NULL);
 164                         goto skip;
 165                 }
 166
 167                 /*
 168                  * Acquiring the sync_lock prevents the operation from
 169                  * crossing a synchronization boundary.
 170                  *
 171                  * NOTE: cursor.node may have changed on return.
 172                  *
 173                  * WARNING: See warnings in hammer_unlock_cursor() function.
 174                  */
 175                 hammer_sync_lock_sh(trans);
 176                 error = hammer_reblock_helper(reblock, &cursor, elm);
 177                 hammer_sync_unlock(trans);
 178
 179                 while (hammer_flusher_meta_halflimit(trans->hmp) ||
 180                        hammer_flusher_undo_exhausted(trans, 2)) {
 181                         hammer_unlock_cursor(&cursor);
 182                         hammer_flusher_wait(trans->hmp, seq);
 183                         hammer_lock_cursor(&cursor);
 184                         seq = hammer_flusher_async_one(trans->hmp);
 185                 }
 186
 187                 /*
 188                  * Setup for iteration, our cursor flags may be modified by
 189                  * other threads while we are unlocked.
 190                  */
 191                 cursor.flags |= HAMMER_CURSOR_ATEDISK;
 192
 193                 /*
 194                  * We allocate data buffers, which atm we don't track
 195                  * dirty levels for because we allow the kernel to write
 196                  * them.  But if we allocate too many we can still deadlock
 197                  * the buffer cache.
 198                  *
 199                  * WARNING: See warnings in hammer_unlock_cursor() function.
 200                  *          (The cursor's node and element may change!)
 201                  */
 202                 if (bd_heatup()) {
 203                         hammer_unlock_cursor(&cursor);
 204                         bwillwrite(HAMMER_XBUFSIZE);
 205                         hammer_lock_cursor(&cursor);
 206                 }
 207 skip:
 208                 if (error == 0) {
 209                         error = hammer_btree_iterate(&cursor);
 210                 }
 211         }
 212         if (error == ENOENT)
 213                 error = 0;
 214         hammer_done_cursor(&cursor);
 215         if (error == EWOULDBLOCK) {
 216                 hammer_flusher_sync(trans->hmp);
 217                 goto retry;
 218         }
 219         if (error == EDEADLK)
 220                 goto retry;
 221         if (error == EINTR) {
 222                 reblock->head.flags |= HAMMER_IOC_HEAD_INTR;
 223                 error = 0;
 224         }
 225 failed:
 226         reblock->key_cur.localization &= HAMMER_LOCALIZE_MASK;
 227         return(error);
 228 }
 229
 230 /*
 231  * Reblock the B-Tree (leaf) node, record, and/or data if necessary.
 232  *
 233  * XXX We have no visibility into internal B-Tree nodes at the moment,
 234  * only leaf nodes.
 235  */
 236 static int
 237 hammer_reblock_helper(struct hammer_ioc_reblock *reblock,
 238                       hammer_cursor_t cursor, hammer_btree_elm_t elm)
 239 {
 240         hammer_mount_t hmp;
 241         hammer_off_t tmp_offset;
 242         hammer_node_ondisk_t ondisk;
 243         struct hammer_btree_leaf_elm leaf;
 244         int error;
 245         int bytes;
 246         int cur;
 247         int iocflags;
 248
 249         error = 0;
 250         hmp = cursor->trans->hmp;
 251
 252         /*
 253          * Reblock data.  Note that data embedded in a record is reblocked
 254          * by the record reblock code.  Data processing only occurs at leaf
 255          * nodes and for RECORD element types.
 256          */
 257         if (cursor->node->ondisk->type != HAMMER_BTREE_TYPE_LEAF)
 258                 goto skip;
 259         if (elm->leaf.base.btype != HAMMER_BTREE_TYPE_RECORD)
 260                 return(0);
 261         tmp_offset = elm->leaf.data_offset;
 262         if (tmp_offset == 0)
 263                 goto skip;
 264         if (error)
 265                 goto skip;
 266
 267         /*
 268          * NOTE: Localization restrictions may also have been set-up, we can't
 269          *       just set the match flags willy-nilly here.
 270          */
 271         switch(elm->leaf.base.rec_type) {
 272         case HAMMER_RECTYPE_INODE:
 273         case HAMMER_RECTYPE_SNAPSHOT:
 274         case HAMMER_RECTYPE_CONFIG:
 275                 iocflags = HAMMER_IOC_DO_INODES;
 276                 break;
 277         case HAMMER_RECTYPE_EXT:
 278         case HAMMER_RECTYPE_FIX:
 279         case HAMMER_RECTYPE_PFS:
 280         case HAMMER_RECTYPE_DIRENTRY:
 281                 iocflags = HAMMER_IOC_DO_DIRS;
 282                 break;
 283         case HAMMER_RECTYPE_DATA:
 284         case HAMMER_RECTYPE_DB:
 285                 iocflags = HAMMER_IOC_DO_DATA;
 286                 break;
 287         default:
 288                 iocflags = 0;
 289                 break;
 290         }
 291         if (reblock->head.flags & iocflags) {
 292                 ++reblock->data_count;
 293                 reblock->data_byte_count += elm->leaf.data_len;
 294                 bytes = hammer_blockmap_getfree(hmp, tmp_offset, &cur, &error);
 295                 if (hammer_debug_general & 0x4000)
 296                         kprintf("D %6d/%d\n", bytes, reblock->free_level);
 297                 if (error == 0 && (cur == 0 || reblock->free_level == 0) &&
 298                     bytes >= reblock->free_level) {
 299                         /*
 300                          * This is nasty, the uncache code may have to get
 301                          * vnode locks and because of that we can't hold
 302                          * the cursor locked.
 303                          *
 304                          * WARNING: See warnings in hammer_unlock_cursor()
 305                          *          function.
 306                          */
 307                         leaf = elm->leaf;
 308                         hammer_unlock_cursor(cursor);
 309                         hammer_io_direct_uncache(hmp, &leaf);
 310                         hammer_lock_cursor(cursor);
 311
 312                         /*
 313                          * elm may have become stale or invalid, reload it.
 314                          * ondisk variable is temporary only.  Note that
 315                          * cursor->node and thus cursor->node->ondisk may
 316                          * also changed.
 317                          */
 318                         ondisk = cursor->node->ondisk;
 319                         elm = &ondisk->elms[cursor->index];
 320                         if (cursor->flags & HAMMER_CURSOR_RETEST) {
 321                                 kprintf("hammer: debug: retest on "
 322                                         "reblocker uncache\n");
 323                                 error = EDEADLK;
 324                         } else if (ondisk->type != HAMMER_BTREE_TYPE_LEAF ||
 325                                    cursor->index >= ondisk->count) {
 326                                 kprintf("hammer: debug: shifted on "
 327                                         "reblocker uncache\n");
 328                                 error = EDEADLK;
 329                         } else if (bcmp(&elm->leaf, &leaf, sizeof(leaf))) {
 330                                 kprintf("hammer: debug: changed on "
 331                                         "reblocker uncache\n");
 332                                 error = EDEADLK;
 333                         }
 334                         if (error == 0)
 335                                 error = hammer_cursor_upgrade(cursor);
 336                         if (error == 0) {
 337                                 KKASSERT(cursor->index < ondisk->count);
 338                                 error = hammer_reblock_data(reblock,
 339                                                             cursor, elm);
 340                         }
 341                         if (error == 0) {
 342                                 ++reblock->data_moves;
 343                                 reblock->data_byte_moves += elm->leaf.data_len;
 344                         }
 345                 }
 346         }
 347
 348 skip:
 349         /*
 350          * Reblock a B-Tree internal or leaf node.  A leaf node is reblocked
 351          * on initial entry only (element 0).  An internal node is reblocked
 352          * when entered upward from its first leaf node only (also element 0).
 353          * Further revisits of the internal node (index > 0) are ignored.
 354          */
 355         tmp_offset = cursor->node->node_offset;
 356         if (cursor->index == 0 &&
 357             error == 0 && (reblock->head.flags & HAMMER_IOC_DO_BTREE)) {
 358                 ++reblock->btree_count;
 359                 bytes = hammer_blockmap_getfree(hmp, tmp_offset, &cur, &error);
 360                 if (hammer_debug_general & 0x4000)
 361                         kprintf("B %6d/%d\n", bytes, reblock->free_level);
 362                 if (error == 0 && (cur == 0 || reblock->free_level == 0) &&
 363                     bytes >= reblock->free_level) {
 364                         error = hammer_cursor_upgrade(cursor);
 365                         if (error == 0) {
 366                                 if (cursor->parent) {
 367                                         KKASSERT(cursor->parent_index <
 368                                                  cursor->parent->ondisk->count);
 369                                         elm = &cursor->parent->ondisk->elms[cursor->parent_index];
 370                                 } else {
 371                                         elm = NULL;
 372                                 }
 373                                 switch(cursor->node->ondisk->type) {
 374                                 case HAMMER_BTREE_TYPE_LEAF:
 375                                         error = hammer_reblock_leaf_node(
 376                                                         reblock, cursor, elm);
 377                                         break;
 378                                 case HAMMER_BTREE_TYPE_INTERNAL:
 379                                         error = hammer_reblock_int_node(
 380                                                         reblock, cursor, elm);
 381                                         break;
 382                                 default:
 383                                         panic("Illegal B-Tree node type");
 384                                 }
 385                         }
 386                         if (error == 0) {
 387                                 ++reblock->btree_moves;
 388                         }
 389                 }
 390         }
 391
 392         hammer_cursor_downgrade(cursor);
 393         return(error);
 394 }
 395
 396 /*
 397  * Reblock a record's data.  Both the B-Tree element and record pointers
 398  * to the data must be adjusted.
 399  */
 400 static int
 401 hammer_reblock_data(struct hammer_ioc_reblock *reblock,
 402                     hammer_cursor_t cursor, hammer_btree_elm_t elm)
 403 {
 404         struct hammer_buffer *data_buffer = NULL;
 405         hammer_off_t ndata_offset;
 406         int error;
 407         void *ndata;
 408
 409         error = hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA |
 410                                              HAMMER_CURSOR_GET_LEAF);
 411         if (error)
 412                 return (error);
 413         ndata = hammer_alloc_data(cursor->trans, elm->leaf.data_len,
 414                                   elm->leaf.base.rec_type,
 415                                   &ndata_offset, &data_buffer,
 416                                   0, &error);
 417         if (error)
 418                 goto done;
 419         hammer_io_notmeta(data_buffer);
 420
 421         /*
 422          * Move the data.  Note that we must invalidate any cached
 423          * data buffer in the cursor before calling blockmap_free.
 424          * The blockmap_free may free up the entire large-block and
 425          * will not be able to invalidate it if the cursor is holding
 426          * a data buffer cached in that large block.
 427          */
 428         hammer_modify_buffer(cursor->trans, data_buffer, NULL, 0);
 429         bcopy(cursor->data, ndata, elm->leaf.data_len);
 430         hammer_modify_buffer_done(data_buffer);
 431         hammer_cursor_invalidate_cache(cursor);
 432
 433         hammer_blockmap_free(cursor->trans,
 434                              elm->leaf.data_offset, elm->leaf.data_len);
 435
 436         hammer_modify_node(cursor->trans, cursor->node,
 437                            &elm->leaf.data_offset, sizeof(hammer_off_t));
 438         elm->leaf.data_offset = ndata_offset;
 439         hammer_modify_node_done(cursor->node);
 440
 441 done:
 442         if (data_buffer)
 443                 hammer_rel_buffer(data_buffer, 0);
 444         return (error);
 445 }
 446
 447 /*
 448  * Reblock a B-Tree leaf node.  The parent must be adjusted to point to
 449  * the new copy of the leaf node.
 450  *
 451  * elm is a pointer to the parent element pointing at cursor.node.
 452  */
 453 static int
 454 hammer_reblock_leaf_node(struct hammer_ioc_reblock *reblock,
 455                          hammer_cursor_t cursor, hammer_btree_elm_t elm)
 456 {
 457         hammer_node_t onode;
 458         hammer_node_t nnode;
 459         int error;
 460
 461         /*
 462          * Don't supply a hint when allocating the leaf.  Fills are done
 463          * from the leaf upwards.
 464          */
 465         onode = cursor->node;
 466         nnode = hammer_alloc_btree(cursor->trans, 0, &error);
 467
 468         if (nnode == NULL)
 469                 return (error);
 470
 471         /*
 472          * Move the node
 473          */
 474         hammer_lock_ex(&nnode->lock);
 475         hammer_modify_node_noundo(cursor->trans, nnode);
 476         bcopy(onode->ondisk, nnode->ondisk, sizeof(*nnode->ondisk));
 477
 478         if (elm) {
 479                 /*
 480                  * We are not the root of the B-Tree
 481                  */
 482                 hammer_modify_node(cursor->trans, cursor->parent,
 483                                    &elm->internal.subtree_offset,
 484                                    sizeof(elm->internal.subtree_offset));
 485                 elm->internal.subtree_offset = nnode->node_offset;
 486                 hammer_modify_node_done(cursor->parent);
 487         } else {
 488                 /*
 489                  * We are the root of the B-Tree
 490                  */
 491                 hammer_volume_t volume;
 492
 493                 volume = hammer_get_root_volume(cursor->trans->hmp, &error);
 494                 KKASSERT(error == 0);
 495
 496                 hammer_modify_volume_field(cursor->trans, volume,
 497                                            vol0_btree_root);
 498                 volume->ondisk->vol0_btree_root = nnode->node_offset;
 499                 hammer_modify_volume_done(volume);
 500                 hammer_rel_volume(volume, 0);
 501         }
 502
 503         hammer_cursor_replaced_node(onode, nnode);
 504         hammer_delete_node(cursor->trans, onode);
 505
 506         if (hammer_debug_general & 0x4000) {
 507                 kprintf("REBLOCK LNODE %016llx -> %016llx\n",
 508                         (long long)onode->node_offset,
 509                         (long long)nnode->node_offset);
 510         }
 511         hammer_modify_node_done(nnode);
 512         cursor->node = nnode;
 513
 514         hammer_unlock(&onode->lock);
 515         hammer_rel_node(onode);
 516
 517         return (error);
 518 }
 519
 520 /*
 521  * Reblock a B-Tree internal node.  The parent must be adjusted to point to
 522  * the new copy of the internal node, and the node's children's parent
 523  * pointers must also be adjusted to point to the new copy.
 524  *
 525  * elm is a pointer to the parent element pointing at cursor.node.
 526  */
 527 static int
 528 hammer_reblock_int_node(struct hammer_ioc_reblock *reblock,
 529                          hammer_cursor_t cursor, hammer_btree_elm_t elm)
 530 {
 531         struct hammer_node_lock lockroot;
 532         hammer_node_t onode;
 533         hammer_node_t nnode;
 534         hammer_off_t hint;
 535         int error;
 536         int i;
 537
 538         hammer_node_lock_init(&lockroot, cursor->node);
 539         error = hammer_btree_lock_children(cursor, 1, &lockroot, NULL);
 540         if (error)
 541                 goto done;
 542
 543         /*
 544          * The internal node is visited after recursing through its
 545          * first element.  Use the subtree offset allocated for that
 546          * element as a hint for allocating the internal node.
 547          */
 548         onode = cursor->node;
 549         if (onode->ondisk->count)
 550                 hint = onode->ondisk->elms[0].internal.subtree_offset;
 551         else
 552                 hint = 0;
 553         nnode = hammer_alloc_btree(cursor->trans, 0, &error);
 554
 555         if (nnode == NULL)
 556                 goto done;
 557
 558         /*
 559          * Move the node.  Adjust the parent's pointer to us first.
 560          */
 561         hammer_lock_ex(&nnode->lock);
 562         hammer_modify_node_noundo(cursor->trans, nnode);
 563         bcopy(onode->ondisk, nnode->ondisk, sizeof(*nnode->ondisk));
 564
 565         if (elm) {
 566                 /*
 567                  * We are not the root of the B-Tree
 568                  */
 569                 hammer_modify_node(cursor->trans, cursor->parent,
 570                                    &elm->internal.subtree_offset,
 571                                    sizeof(elm->internal.subtree_offset));
 572                 elm->internal.subtree_offset = nnode->node_offset;
 573                 hammer_modify_node_done(cursor->parent);
 574         } else {
 575                 /*
 576                  * We are the root of the B-Tree
 577                  */
 578                 hammer_volume_t volume;
 579
 580                 volume = hammer_get_root_volume(cursor->trans->hmp, &error);
 581                 KKASSERT(error == 0);
 582
 583                 hammer_modify_volume_field(cursor->trans, volume,
 584                                            vol0_btree_root);
 585                 volume->ondisk->vol0_btree_root = nnode->node_offset;
 586                 hammer_modify_volume_done(volume);
 587                 hammer_rel_volume(volume, 0);
 588         }
 589
 590         /*
 591          * Now adjust our children's pointers to us.
 592          */
 593         for (i = 0; i < nnode->ondisk->count; ++i) {
 594                 elm = &nnode->ondisk->elms[i];
 595                 error = btree_set_parent(cursor->trans, nnode, elm);
 596                 if (error)
 597                         panic("reblock internal node: fixup problem");
 598         }
 599
 600         /*
 601          * Clean up.
 602          *
 603          * The new node replaces the current node in the cursor.  The cursor
 604          * expects it to be locked so leave it locked.  Discard onode.
 605          */
 606         hammer_cursor_replaced_node(onode, nnode);
 607         hammer_delete_node(cursor->trans, onode);
 608
 609         if (hammer_debug_general & 0x4000) {
 610                 kprintf("REBLOCK INODE %016llx -> %016llx\n",
 611                         (long long)onode->node_offset,
 612                         (long long)nnode->node_offset);
 613         }
 614         hammer_modify_node_done(nnode);
 615         cursor->node = nnode;
 616
 617         hammer_unlock(&onode->lock);
 618         hammer_rel_node(onode);
 619
 620 done:
 621         hammer_btree_unlock_children(cursor->trans->hmp, &lockroot, NULL);
 622         return (error);
 623 }
 624