fs/nilfs2/btree.c

   1 /*
   2  * btree.c - NILFS B-tree.
   3  *
   4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  * Written by Koji Sato <koji@osrg.net>.
  21  */
  22
  23 #include <linux/slab.h>
  24 #include <linux/string.h>
  25 #include <linux/errno.h>
  26 #include <linux/pagevec.h>
  27 #include "nilfs.h"
  28 #include "page.h"
  29 #include "btnode.h"
  30 #include "btree.h"
  31 #include "alloc.h"
  32 #include "dat.h"
  33
  34 static void __nilfs_btree_init(struct nilfs_bmap *bmap);
  35
  36 static struct nilfs_btree_path *nilfs_btree_alloc_path(void)
  37 {
  38         struct nilfs_btree_path *path;
  39         int level = NILFS_BTREE_LEVEL_DATA;
  40
  41         path = kmem_cache_alloc(nilfs_btree_path_cache, GFP_NOFS);
  42         if (path == NULL)
  43                 goto out;
  44
  45         for (; level < NILFS_BTREE_LEVEL_MAX; level++) {
  46                 path[level].bp_bh = NULL;
  47                 path[level].bp_sib_bh = NULL;
  48                 path[level].bp_index = 0;
  49                 path[level].bp_oldreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
  50                 path[level].bp_newreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
  51                 path[level].bp_op = NULL;
  52         }
  53
  54 out:
  55         return path;
  56 }
  57
  58 static void nilfs_btree_free_path(struct nilfs_btree_path *path)
  59 {
  60         int level = NILFS_BTREE_LEVEL_DATA;
  61
  62         for (; level < NILFS_BTREE_LEVEL_MAX; level++)
  63                 brelse(path[level].bp_bh);
  64
  65         kmem_cache_free(nilfs_btree_path_cache, path);
  66 }
  67
  68 /*
  69  * B-tree node operations
  70  */
  71 static int nilfs_btree_get_new_block(const struct nilfs_bmap *btree,
  72                                      __u64 ptr, struct buffer_head **bhp)
  73 {
  74         struct address_space *btnc = &NILFS_BMAP_I(btree)->i_btnode_cache;
  75         struct buffer_head *bh;
  76
  77         bh = nilfs_btnode_create_block(btnc, ptr);
  78         if (!bh)
  79                 return -ENOMEM;
  80
  81         set_buffer_nilfs_volatile(bh);
  82         *bhp = bh;
  83         return 0;
  84 }
  85
  86 static int nilfs_btree_node_get_flags(const struct nilfs_btree_node *node)
  87 {
  88         return node->bn_flags;
  89 }
  90
  91 static void
  92 nilfs_btree_node_set_flags(struct nilfs_btree_node *node, int flags)
  93 {
  94         node->bn_flags = flags;
  95 }
  96
  97 static int nilfs_btree_node_root(const struct nilfs_btree_node *node)
  98 {
  99         return nilfs_btree_node_get_flags(node) & NILFS_BTREE_NODE_ROOT;
 100 }
 101
 102 static int nilfs_btree_node_get_level(const struct nilfs_btree_node *node)
 103 {
 104         return node->bn_level;
 105 }
 106
 107 static void
 108 nilfs_btree_node_set_level(struct nilfs_btree_node *node, int level)
 109 {
 110         node->bn_level = level;
 111 }
 112
 113 static int nilfs_btree_node_get_nchildren(const struct nilfs_btree_node *node)
 114 {
 115         return le16_to_cpu(node->bn_nchildren);
 116 }
 117
 118 static void
 119 nilfs_btree_node_set_nchildren(struct nilfs_btree_node *node, int nchildren)
 120 {
 121         node->bn_nchildren = cpu_to_le16(nchildren);
 122 }
 123
 124 static int nilfs_btree_node_size(const struct nilfs_bmap *btree)
 125 {
 126         return 1 << btree->b_inode->i_blkbits;
 127 }
 128
 129 static int nilfs_btree_nchildren_per_block(const struct nilfs_bmap *btree)
 130 {
 131         return btree->b_nchildren_per_block;
 132 }
 133
 134 static __le64 *
 135 nilfs_btree_node_dkeys(const struct nilfs_btree_node *node)
 136 {
 137         return (__le64 *)((char *)(node + 1) +
 138                           (nilfs_btree_node_root(node) ?
 139                            0 : NILFS_BTREE_NODE_EXTRA_PAD_SIZE));
 140 }
 141
 142 static __le64 *
 143 nilfs_btree_node_dptrs(const struct nilfs_btree_node *node, int ncmax)
 144 {
 145         return (__le64 *)(nilfs_btree_node_dkeys(node) + ncmax);
 146 }
 147
 148 static __u64
 149 nilfs_btree_node_get_key(const struct nilfs_btree_node *node, int index)
 150 {
 151         return le64_to_cpu(*(nilfs_btree_node_dkeys(node) + index));
 152 }
 153
 154 static void
 155 nilfs_btree_node_set_key(struct nilfs_btree_node *node, int index, __u64 key)
 156 {
 157         *(nilfs_btree_node_dkeys(node) + index) = cpu_to_le64(key);
 158 }
 159
 160 static __u64
 161 nilfs_btree_node_get_ptr(const struct nilfs_btree_node *node, int index,
 162                          int ncmax)
 163 {
 164         return le64_to_cpu(*(nilfs_btree_node_dptrs(node, ncmax) + index));
 165 }
 166
 167 static void
 168 nilfs_btree_node_set_ptr(struct nilfs_btree_node *node, int index, __u64 ptr,
 169                          int ncmax)
 170 {
 171         *(nilfs_btree_node_dptrs(node, ncmax) + index) = cpu_to_le64(ptr);
 172 }
 173
 174 static void nilfs_btree_node_init(struct nilfs_btree_node *node, int flags,
 175                                   int level, int nchildren, int ncmax,
 176                                   const __u64 *keys, const __u64 *ptrs)
 177 {
 178         __le64 *dkeys;
 179         __le64 *dptrs;
 180         int i;
 181
 182         nilfs_btree_node_set_flags(node, flags);
 183         nilfs_btree_node_set_level(node, level);
 184         nilfs_btree_node_set_nchildren(node, nchildren);
 185
 186         dkeys = nilfs_btree_node_dkeys(node);
 187         dptrs = nilfs_btree_node_dptrs(node, ncmax);
 188         for (i = 0; i < nchildren; i++) {
 189                 dkeys[i] = cpu_to_le64(keys[i]);
 190                 dptrs[i] = cpu_to_le64(ptrs[i]);
 191         }
 192 }
 193
 194 /* Assume the buffer heads corresponding to left and right are locked. */
 195 static void nilfs_btree_node_move_left(struct nilfs_btree_node *left,
 196                                        struct nilfs_btree_node *right,
 197                                        int n, int lncmax, int rncmax)
 198 {
 199         __le64 *ldkeys, *rdkeys;
 200         __le64 *ldptrs, *rdptrs;
 201         int lnchildren, rnchildren;
 202
 203         ldkeys = nilfs_btree_node_dkeys(left);
 204         ldptrs = nilfs_btree_node_dptrs(left, lncmax);
 205         lnchildren = nilfs_btree_node_get_nchildren(left);
 206
 207         rdkeys = nilfs_btree_node_dkeys(right);
 208         rdptrs = nilfs_btree_node_dptrs(right, rncmax);
 209         rnchildren = nilfs_btree_node_get_nchildren(right);
 210
 211         memcpy(ldkeys + lnchildren, rdkeys, n * sizeof(*rdkeys));
 212         memcpy(ldptrs + lnchildren, rdptrs, n * sizeof(*rdptrs));
 213         memmove(rdkeys, rdkeys + n, (rnchildren - n) * sizeof(*rdkeys));
 214         memmove(rdptrs, rdptrs + n, (rnchildren - n) * sizeof(*rdptrs));
 215
 216         lnchildren += n;
 217         rnchildren -= n;
 218         nilfs_btree_node_set_nchildren(left, lnchildren);
 219         nilfs_btree_node_set_nchildren(right, rnchildren);
 220 }
 221
 222 /* Assume that the buffer heads corresponding to left and right are locked. */
 223 static void nilfs_btree_node_move_right(struct nilfs_btree_node *left,
 224                                         struct nilfs_btree_node *right,
 225                                         int n, int lncmax, int rncmax)
 226 {
 227         __le64 *ldkeys, *rdkeys;
 228         __le64 *ldptrs, *rdptrs;
 229         int lnchildren, rnchildren;
 230
 231         ldkeys = nilfs_btree_node_dkeys(left);
 232         ldptrs = nilfs_btree_node_dptrs(left, lncmax);
 233         lnchildren = nilfs_btree_node_get_nchildren(left);
 234
 235         rdkeys = nilfs_btree_node_dkeys(right);
 236         rdptrs = nilfs_btree_node_dptrs(right, rncmax);
 237         rnchildren = nilfs_btree_node_get_nchildren(right);
 238
 239         memmove(rdkeys + n, rdkeys, rnchildren * sizeof(*rdkeys));
 240         memmove(rdptrs + n, rdptrs, rnchildren * sizeof(*rdptrs));
 241         memcpy(rdkeys, ldkeys + lnchildren - n, n * sizeof(*rdkeys));
 242         memcpy(rdptrs, ldptrs + lnchildren - n, n * sizeof(*rdptrs));
 243
 244         lnchildren -= n;
 245         rnchildren += n;
 246         nilfs_btree_node_set_nchildren(left, lnchildren);
 247         nilfs_btree_node_set_nchildren(right, rnchildren);
 248 }
 249
 250 /* Assume that the buffer head corresponding to node is locked. */
 251 static void nilfs_btree_node_insert(struct nilfs_btree_node *node, int index,
 252                                     __u64 key, __u64 ptr, int ncmax)
 253 {
 254         __le64 *dkeys;
 255         __le64 *dptrs;
 256         int nchildren;
 257
 258         dkeys = nilfs_btree_node_dkeys(node);
 259         dptrs = nilfs_btree_node_dptrs(node, ncmax);
 260         nchildren = nilfs_btree_node_get_nchildren(node);
 261         if (index < nchildren) {
 262                 memmove(dkeys + index + 1, dkeys + index,
 263                         (nchildren - index) * sizeof(*dkeys));
 264                 memmove(dptrs + index + 1, dptrs + index,
 265                         (nchildren - index) * sizeof(*dptrs));
 266         }
 267         dkeys[index] = cpu_to_le64(key);
 268         dptrs[index] = cpu_to_le64(ptr);
 269         nchildren++;
 270         nilfs_btree_node_set_nchildren(node, nchildren);
 271 }
 272
 273 /* Assume that the buffer head corresponding to node is locked. */
 274 static void nilfs_btree_node_delete(struct nilfs_btree_node *node, int index,
 275                                     __u64 *keyp, __u64 *ptrp, int ncmax)
 276 {
 277         __u64 key;
 278         __u64 ptr;
 279         __le64 *dkeys;
 280         __le64 *dptrs;
 281         int nchildren;
 282
 283         dkeys = nilfs_btree_node_dkeys(node);
 284         dptrs = nilfs_btree_node_dptrs(node, ncmax);
 285         key = le64_to_cpu(dkeys[index]);
 286         ptr = le64_to_cpu(dptrs[index]);
 287         nchildren = nilfs_btree_node_get_nchildren(node);
 288         if (keyp != NULL)
 289                 *keyp = key;
 290         if (ptrp != NULL)
 291                 *ptrp = ptr;
 292
 293         if (index < nchildren - 1) {
 294                 memmove(dkeys + index, dkeys + index + 1,
 295                         (nchildren - index - 1) * sizeof(*dkeys));
 296                 memmove(dptrs + index, dptrs + index + 1,
 297                         (nchildren - index - 1) * sizeof(*dptrs));
 298         }
 299         nchildren--;
 300         nilfs_btree_node_set_nchildren(node, nchildren);
 301 }
 302
 303 static int nilfs_btree_node_lookup(const struct nilfs_btree_node *node,
 304                                    __u64 key, int *indexp)
 305 {
 306         __u64 nkey;
 307         int index, low, high, s;
 308
 309         /* binary search */
 310         low = 0;
 311         high = nilfs_btree_node_get_nchildren(node) - 1;
 312         index = 0;
 313         s = 0;
 314         while (low <= high) {
 315                 index = (low + high) / 2;
 316                 nkey = nilfs_btree_node_get_key(node, index);
 317                 if (nkey == key) {
 318                         s = 0;
 319                         goto out;
 320                 } else if (nkey < key) {
 321                         low = index + 1;
 322                         s = -1;
 323                 } else {
 324                         high = index - 1;
 325                         s = 1;
 326                 }
 327         }
 328
 329         /* adjust index */
 330         if (nilfs_btree_node_get_level(node) > NILFS_BTREE_LEVEL_NODE_MIN) {
 331                 if (s > 0 && index > 0)
 332                         index--;
 333         } else if (s < 0)
 334                 index++;
 335
 336  out:
 337         *indexp = index;
 338
 339         return s == 0;
 340 }
 341
 342 /**
 343  * nilfs_btree_node_broken - verify consistency of btree node
 344  * @node: btree node block to be examined
 345  * @size: node size (in bytes)
 346  * @blocknr: block number
 347  *
 348  * Return Value: If node is broken, 1 is returned. Otherwise, 0 is returned.
 349  */
 350 static int nilfs_btree_node_broken(const struct nilfs_btree_node *node,
 351                                    size_t size, sector_t blocknr)
 352 {
 353         int level, flags, nchildren;
 354         int ret = 0;
 355
 356         level = nilfs_btree_node_get_level(node);
 357         flags = nilfs_btree_node_get_flags(node);
 358         nchildren = nilfs_btree_node_get_nchildren(node);
 359
 360         if (unlikely(level < NILFS_BTREE_LEVEL_NODE_MIN ||
 361                      level >= NILFS_BTREE_LEVEL_MAX ||
 362                      (flags & NILFS_BTREE_NODE_ROOT) ||
 363                      nchildren < 0 ||
 364                      nchildren > NILFS_BTREE_NODE_NCHILDREN_MAX(size))) {
 365                 printk(KERN_CRIT "NILFS: bad btree node (blocknr=%llu): "
 366                        "level = %d, flags = 0x%x, nchildren = %d\n",
 367                        (unsigned long long)blocknr, level, flags, nchildren);
 368                 ret = 1;
 369         }
 370         return ret;
 371 }
 372
 373 /**
 374  * nilfs_btree_root_broken - verify consistency of btree root node
 375  * @node: btree root node to be examined
 376  * @ino: inode number
 377  *
 378  * Return Value: If node is broken, 1 is returned. Otherwise, 0 is returned.
 379  */
 380 static int nilfs_btree_root_broken(const struct nilfs_btree_node *node,
 381                                    unsigned long ino)
 382 {
 383         int level, flags, nchildren;
 384         int ret = 0;
 385
 386         level = nilfs_btree_node_get_level(node);
 387         flags = nilfs_btree_node_get_flags(node);
 388         nchildren = nilfs_btree_node_get_nchildren(node);
 389
 390         if (unlikely(level < NILFS_BTREE_LEVEL_NODE_MIN ||
 391                      level >= NILFS_BTREE_LEVEL_MAX ||
 392                      nchildren < 0 ||
 393                      nchildren > NILFS_BTREE_ROOT_NCHILDREN_MAX)) {
 394                 pr_crit("NILFS: bad btree root (inode number=%lu): level = %d, flags = 0x%x, nchildren = %d\n",
 395                         ino, level, flags, nchildren);
 396                 ret = 1;
 397         }
 398         return ret;
 399 }
 400
 401 int nilfs_btree_broken_node_block(struct buffer_head *bh)
 402 {
 403         int ret;
 404
 405         if (buffer_nilfs_checked(bh))
 406                 return 0;
 407
 408         ret = nilfs_btree_node_broken((struct nilfs_btree_node *)bh->b_data,
 409                                        bh->b_size, bh->b_blocknr);
 410         if (likely(!ret))
 411                 set_buffer_nilfs_checked(bh);
 412         return ret;
 413 }
 414
 415 static struct nilfs_btree_node *
 416 nilfs_btree_get_root(const struct nilfs_bmap *btree)
 417 {
 418         return (struct nilfs_btree_node *)btree->b_u.u_data;
 419 }
 420
 421 static struct nilfs_btree_node *
 422 nilfs_btree_get_nonroot_node(const struct nilfs_btree_path *path, int level)
 423 {
 424         return (struct nilfs_btree_node *)path[level].bp_bh->b_data;
 425 }
 426
 427 static struct nilfs_btree_node *
 428 nilfs_btree_get_sib_node(const struct nilfs_btree_path *path, int level)
 429 {
 430         return (struct nilfs_btree_node *)path[level].bp_sib_bh->b_data;
 431 }
 432
 433 static int nilfs_btree_height(const struct nilfs_bmap *btree)
 434 {
 435         return nilfs_btree_node_get_level(nilfs_btree_get_root(btree)) + 1;
 436 }
 437
 438 static struct nilfs_btree_node *
 439 nilfs_btree_get_node(const struct nilfs_bmap *btree,
 440                      const struct nilfs_btree_path *path,
 441                      int level, int *ncmaxp)
 442 {
 443         struct nilfs_btree_node *node;
 444
 445         if (level == nilfs_btree_height(btree) - 1) {
 446                 node = nilfs_btree_get_root(btree);
 447                 *ncmaxp = NILFS_BTREE_ROOT_NCHILDREN_MAX;
 448         } else {
 449                 node = nilfs_btree_get_nonroot_node(path, level);
 450                 *ncmaxp = nilfs_btree_nchildren_per_block(btree);
 451         }
 452         return node;
 453 }
 454
 455 static int
 456 nilfs_btree_bad_node(struct nilfs_btree_node *node, int level)
 457 {
 458         if (unlikely(nilfs_btree_node_get_level(node) != level)) {
 459                 dump_stack();
 460                 printk(KERN_CRIT "NILFS: btree level mismatch: %d != %d\n",
 461                        nilfs_btree_node_get_level(node), level);
 462                 return 1;
 463         }
 464         return 0;
 465 }
 466
 467 struct nilfs_btree_readahead_info {
 468         struct nilfs_btree_node *node;  /* parent node */
 469         int max_ra_blocks;              /* max nof blocks to read ahead */
 470         int index;                      /* current index on the parent node */
 471         int ncmax;                      /* nof children in the parent node */
 472 };
 473
 474 static int __nilfs_btree_get_block(const struct nilfs_bmap *btree, __u64 ptr,
 475                                    struct buffer_head **bhp,
 476                                    const struct nilfs_btree_readahead_info *ra)
 477 {
 478         struct address_space *btnc = &NILFS_BMAP_I(btree)->i_btnode_cache;
 479         struct buffer_head *bh, *ra_bh;
 480         sector_t submit_ptr = 0;
 481         int ret;
 482
 483         ret = nilfs_btnode_submit_block(btnc, ptr, 0, READ, &bh, &submit_ptr);
 484         if (ret) {
 485                 if (ret != -EEXIST)
 486                         return ret;
 487                 goto out_check;
 488         }
 489
 490         if (ra) {
 491                 int i, n;
 492                 __u64 ptr2;
 493
 494                 /* read ahead sibling nodes */
 495                 for (n = ra->max_ra_blocks, i = ra->index + 1;
 496                      n > 0 && i < ra->ncmax; n--, i++) {
 497                         ptr2 = nilfs_btree_node_get_ptr(ra->node, i, ra->ncmax);
 498
 499                         ret = nilfs_btnode_submit_block(btnc, ptr2, 0, READA,
 500                                                         &ra_bh, &submit_ptr);
 501                         if (likely(!ret || ret == -EEXIST))
 502                                 brelse(ra_bh);
 503                         else if (ret != -EBUSY)
 504                                 break;
 505                         if (!buffer_locked(bh))
 506                                 goto out_no_wait;
 507                 }
 508         }
 509
 510         wait_on_buffer(bh);
 511
 512  out_no_wait:
 513         if (!buffer_uptodate(bh)) {
 514                 brelse(bh);
 515                 return -EIO;
 516         }
 517
 518  out_check:
 519         if (nilfs_btree_broken_node_block(bh)) {
 520                 clear_buffer_uptodate(bh);
 521                 brelse(bh);
 522                 return -EINVAL;
 523         }
 524
 525         *bhp = bh;
 526         return 0;
 527 }
 528
 529 static int nilfs_btree_get_block(const struct nilfs_bmap *btree, __u64 ptr,
 530                                    struct buffer_head **bhp)
 531 {
 532         return __nilfs_btree_get_block(btree, ptr, bhp, NULL);
 533 }
 534
 535 static int nilfs_btree_do_lookup(const struct nilfs_bmap *btree,
 536                                  struct nilfs_btree_path *path,
 537                                  __u64 key, __u64 *ptrp, int minlevel,
 538                                  int readahead)
 539 {
 540         struct nilfs_btree_node *node;
 541         struct nilfs_btree_readahead_info p, *ra;
 542         __u64 ptr;
 543         int level, index, found, ncmax, ret;
 544
 545         node = nilfs_btree_get_root(btree);
 546         level = nilfs_btree_node_get_level(node);
 547         if (level < minlevel || nilfs_btree_node_get_nchildren(node) <= 0)
 548                 return -ENOENT;
 549
 550         found = nilfs_btree_node_lookup(node, key, &index);
 551         ptr = nilfs_btree_node_get_ptr(node, index,
 552                                        NILFS_BTREE_ROOT_NCHILDREN_MAX);
 553         path[level].bp_bh = NULL;
 554         path[level].bp_index = index;
 555
 556         ncmax = nilfs_btree_nchildren_per_block(btree);
 557
 558         while (--level >= minlevel) {
 559                 ra = NULL;
 560                 if (level == NILFS_BTREE_LEVEL_NODE_MIN && readahead) {
 561                         p.node = nilfs_btree_get_node(btree, path, level + 1,
 562                                                       &p.ncmax);
 563                         p.index = index;
 564                         p.max_ra_blocks = 7;
 565                         ra = &p;
 566                 }
 567                 ret = __nilfs_btree_get_block(btree, ptr, &path[level].bp_bh,
 568                                               ra);
 569                 if (ret < 0)
 570                         return ret;
 571
 572                 node = nilfs_btree_get_nonroot_node(path, level);
 573                 if (nilfs_btree_bad_node(node, level))
 574                         return -EINVAL;
 575                 if (!found)
 576                         found = nilfs_btree_node_lookup(node, key, &index);
 577                 else
 578                         index = 0;
 579                 if (index < ncmax) {
 580                         ptr = nilfs_btree_node_get_ptr(node, index, ncmax);
 581                 } else {
 582                         WARN_ON(found || level != NILFS_BTREE_LEVEL_NODE_MIN);
 583                         /* insert */
 584                         ptr = NILFS_BMAP_INVALID_PTR;
 585                 }
 586                 path[level].bp_index = index;
 587         }
 588         if (!found)
 589                 return -ENOENT;
 590
 591         if (ptrp != NULL)
 592                 *ptrp = ptr;
 593
 594         return 0;
 595 }
 596
 597 static int nilfs_btree_do_lookup_last(const struct nilfs_bmap *btree,
 598                                       struct nilfs_btree_path *path,
 599                                       __u64 *keyp, __u64 *ptrp)
 600 {
 601         struct nilfs_btree_node *node;
 602         __u64 ptr;
 603         int index, level, ncmax, ret;
 604
 605         node = nilfs_btree_get_root(btree);
 606         index = nilfs_btree_node_get_nchildren(node) - 1;
 607         if (index < 0)
 608                 return -ENOENT;
 609         level = nilfs_btree_node_get_level(node);
 610         ptr = nilfs_btree_node_get_ptr(node, index,
 611                                        NILFS_BTREE_ROOT_NCHILDREN_MAX);
 612         path[level].bp_bh = NULL;
 613         path[level].bp_index = index;
 614         ncmax = nilfs_btree_nchildren_per_block(btree);
 615
 616         for (level--; level > 0; level--) {
 617                 ret = nilfs_btree_get_block(btree, ptr, &path[level].bp_bh);
 618                 if (ret < 0)
 619                         return ret;
 620                 node = nilfs_btree_get_nonroot_node(path, level);
 621                 if (nilfs_btree_bad_node(node, level))
 622                         return -EINVAL;
 623                 index = nilfs_btree_node_get_nchildren(node) - 1;
 624                 ptr = nilfs_btree_node_get_ptr(node, index, ncmax);
 625                 path[level].bp_index = index;
 626         }
 627
 628         if (keyp != NULL)
 629                 *keyp = nilfs_btree_node_get_key(node, index);
 630         if (ptrp != NULL)
 631                 *ptrp = ptr;
 632
 633         return 0;
 634 }
 635
 636 /**
 637  * nilfs_btree_get_next_key - get next valid key from btree path array
 638  * @btree: bmap struct of btree
 639  * @path: array of nilfs_btree_path struct
 640  * @minlevel: start level
 641  * @nextkey: place to store the next valid key
 642  *
 643  * Return Value: If a next key was found, 0 is returned. Otherwise,
 644  * -ENOENT is returned.
 645  */
 646 static int nilfs_btree_get_next_key(const struct nilfs_bmap *btree,
 647                                     const struct nilfs_btree_path *path,
 648                                     int minlevel, __u64 *nextkey)
 649 {
 650         struct nilfs_btree_node *node;
 651         int maxlevel = nilfs_btree_height(btree) - 1;
 652         int index, next_adj, level;
 653
 654         /* Next index is already set to bp_index for leaf nodes. */
 655         next_adj = 0;
 656         for (level = minlevel; level <= maxlevel; level++) {
 657                 if (level == maxlevel)
 658                         node = nilfs_btree_get_root(btree);
 659                 else
 660                         node = nilfs_btree_get_nonroot_node(path, level);
 661
 662                 index = path[level].bp_index + next_adj;
 663                 if (index < nilfs_btree_node_get_nchildren(node)) {
 664                         /* Next key is in this node */
 665                         *nextkey = nilfs_btree_node_get_key(node, index);
 666                         return 0;
 667                 }
 668                 /* For non-leaf nodes, next index is stored at bp_index + 1. */
 669                 next_adj = 1;
 670         }
 671         return -ENOENT;
 672 }
 673
 674 static int nilfs_btree_lookup(const struct nilfs_bmap *btree,
 675                               __u64 key, int level, __u64 *ptrp)
 676 {
 677         struct nilfs_btree_path *path;
 678         int ret;
 679
 680         path = nilfs_btree_alloc_path();
 681         if (path == NULL)
 682                 return -ENOMEM;
 683
 684         ret = nilfs_btree_do_lookup(btree, path, key, ptrp, level, 0);
 685
 686         nilfs_btree_free_path(path);
 687
 688         return ret;
 689 }
 690
 691 static int nilfs_btree_lookup_contig(const struct nilfs_bmap *btree,
 692                                      __u64 key, __u64 *ptrp, unsigned maxblocks)
 693 {
 694         struct nilfs_btree_path *path;
 695         struct nilfs_btree_node *node;
 696         struct inode *dat = NULL;
 697         __u64 ptr, ptr2;
 698         sector_t blocknr;
 699         int level = NILFS_BTREE_LEVEL_NODE_MIN;
 700         int ret, cnt, index, maxlevel, ncmax;
 701         struct nilfs_btree_readahead_info p;
 702
 703         path = nilfs_btree_alloc_path();
 704         if (path == NULL)
 705                 return -ENOMEM;
 706
 707         ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level, 1);
 708         if (ret < 0)
 709                 goto out;
 710
 711         if (NILFS_BMAP_USE_VBN(btree)) {
 712                 dat = nilfs_bmap_get_dat(btree);
 713                 ret = nilfs_dat_translate(dat, ptr, &blocknr);
 714                 if (ret < 0)
 715                         goto out;
 716                 ptr = blocknr;
 717         }
 718         cnt = 1;
 719         if (cnt == maxblocks)
 720                 goto end;
 721
 722         maxlevel = nilfs_btree_height(btree) - 1;
 723         node = nilfs_btree_get_node(btree, path, level, &ncmax);
 724         index = path[level].bp_index + 1;
 725         for (;;) {
 726                 while (index < nilfs_btree_node_get_nchildren(node)) {
 727                         if (nilfs_btree_node_get_key(node, index) !=
 728                             key + cnt)
 729                                 goto end;
 730                         ptr2 = nilfs_btree_node_get_ptr(node, index, ncmax);
 731                         if (dat) {
 732                                 ret = nilfs_dat_translate(dat, ptr2, &blocknr);
 733                                 if (ret < 0)
 734                                         goto out;
 735                                 ptr2 = blocknr;
 736                         }
 737                         if (ptr2 != ptr + cnt || ++cnt == maxblocks)
 738                                 goto end;
 739                         index++;
 740                         continue;
 741                 }
 742                 if (level == maxlevel)
 743                         break;
 744
 745                 /* look-up right sibling node */
 746                 p.node = nilfs_btree_get_node(btree, path, level + 1, &p.ncmax);
 747                 p.index = path[level + 1].bp_index + 1;
 748                 p.max_ra_blocks = 7;
 749                 if (p.index >= nilfs_btree_node_get_nchildren(p.node) ||
 750                     nilfs_btree_node_get_key(p.node, p.index) != key + cnt)
 751                         break;
 752                 ptr2 = nilfs_btree_node_get_ptr(p.node, p.index, p.ncmax);
 753                 path[level + 1].bp_index = p.index;
 754
 755                 brelse(path[level].bp_bh);
 756                 path[level].bp_bh = NULL;
 757
 758                 ret = __nilfs_btree_get_block(btree, ptr2, &path[level].bp_bh,
 759                                               &p);
 760                 if (ret < 0)
 761                         goto out;
 762                 node = nilfs_btree_get_nonroot_node(path, level);
 763                 ncmax = nilfs_btree_nchildren_per_block(btree);
 764                 index = 0;
 765                 path[level].bp_index = index;
 766         }
 767  end:
 768         *ptrp = ptr;
 769         ret = cnt;
 770  out:
 771         nilfs_btree_free_path(path);
 772         return ret;
 773 }
 774
 775 static void nilfs_btree_promote_key(struct nilfs_bmap *btree,
 776                                     struct nilfs_btree_path *path,
 777                                     int level, __u64 key)
 778 {
 779         if (level < nilfs_btree_height(btree) - 1) {
 780                 do {
 781                         nilfs_btree_node_set_key(
 782                                 nilfs_btree_get_nonroot_node(path, level),
 783                                 path[level].bp_index, key);
 784                         if (!buffer_dirty(path[level].bp_bh))
 785                                 mark_buffer_dirty(path[level].bp_bh);
 786                 } while ((path[level].bp_index == 0) &&
 787                          (++level < nilfs_btree_height(btree) - 1));
 788         }
 789
 790         /* root */
 791         if (level == nilfs_btree_height(btree) - 1) {
 792                 nilfs_btree_node_set_key(nilfs_btree_get_root(btree),
 793                                          path[level].bp_index, key);
 794         }
 795 }
 796
 797 static void nilfs_btree_do_insert(struct nilfs_bmap *btree,
 798                                   struct nilfs_btree_path *path,
 799                                   int level, __u64 *keyp, __u64 *ptrp)
 800 {
 801         struct nilfs_btree_node *node;
 802         int ncblk;
 803
 804         if (level < nilfs_btree_height(btree) - 1) {
 805                 node = nilfs_btree_get_nonroot_node(path, level);
 806                 ncblk = nilfs_btree_nchildren_per_block(btree);
 807                 nilfs_btree_node_insert(node, path[level].bp_index,
 808                                         *keyp, *ptrp, ncblk);
 809                 if (!buffer_dirty(path[level].bp_bh))
 810                         mark_buffer_dirty(path[level].bp_bh);
 811
 812                 if (path[level].bp_index == 0)
 813                         nilfs_btree_promote_key(btree, path, level + 1,
 814                                                 nilfs_btree_node_get_key(node,
 815                                                                          0));
 816         } else {
 817                 node = nilfs_btree_get_root(btree);
 818                 nilfs_btree_node_insert(node, path[level].bp_index,
 819                                         *keyp, *ptrp,
 820                                         NILFS_BTREE_ROOT_NCHILDREN_MAX);
 821         }
 822 }
 823
 824 static void nilfs_btree_carry_left(struct nilfs_bmap *btree,
 825                                    struct nilfs_btree_path *path,
 826                                    int level, __u64 *keyp, __u64 *ptrp)
 827 {
 828         struct nilfs_btree_node *node, *left;
 829         int nchildren, lnchildren, n, move, ncblk;
 830
 831         node = nilfs_btree_get_nonroot_node(path, level);
 832         left = nilfs_btree_get_sib_node(path, level);
 833         nchildren = nilfs_btree_node_get_nchildren(node);
 834         lnchildren = nilfs_btree_node_get_nchildren(left);
 835         ncblk = nilfs_btree_nchildren_per_block(btree);
 836         move = 0;
 837
 838         n = (nchildren + lnchildren + 1) / 2 - lnchildren;
 839         if (n > path[level].bp_index) {
 840                 /* move insert point */
 841                 n--;
 842                 move = 1;
 843         }
 844
 845         nilfs_btree_node_move_left(left, node, n, ncblk, ncblk);
 846
 847         if (!buffer_dirty(path[level].bp_bh))
 848                 mark_buffer_dirty(path[level].bp_bh);
 849         if (!buffer_dirty(path[level].bp_sib_bh))
 850                 mark_buffer_dirty(path[level].bp_sib_bh);
 851
 852         nilfs_btree_promote_key(btree, path, level + 1,
 853                                 nilfs_btree_node_get_key(node, 0));
 854
 855         if (move) {
 856                 brelse(path[level].bp_bh);
 857                 path[level].bp_bh = path[level].bp_sib_bh;
 858                 path[level].bp_sib_bh = NULL;
 859                 path[level].bp_index += lnchildren;
 860                 path[level + 1].bp_index--;
 861         } else {
 862                 brelse(path[level].bp_sib_bh);
 863                 path[level].bp_sib_bh = NULL;
 864                 path[level].bp_index -= n;
 865         }
 866
 867         nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
 868 }
 869
 870 static void nilfs_btree_carry_right(struct nilfs_bmap *btree,
 871                                     struct nilfs_btree_path *path,
 872                                     int level, __u64 *keyp, __u64 *ptrp)
 873 {
 874         struct nilfs_btree_node *node, *right;
 875         int nchildren, rnchildren, n, move, ncblk;
 876
 877         node = nilfs_btree_get_nonroot_node(path, level);
 878         right = nilfs_btree_get_sib_node(path, level);
 879         nchildren = nilfs_btree_node_get_nchildren(node);
 880         rnchildren = nilfs_btree_node_get_nchildren(right);
 881         ncblk = nilfs_btree_nchildren_per_block(btree);
 882         move = 0;
 883
 884         n = (nchildren + rnchildren + 1) / 2 - rnchildren;
 885         if (n > nchildren - path[level].bp_index) {
 886                 /* move insert point */
 887                 n--;
 888                 move = 1;
 889         }
 890
 891         nilfs_btree_node_move_right(node, right, n, ncblk, ncblk);
 892
 893         if (!buffer_dirty(path[level].bp_bh))
 894                 mark_buffer_dirty(path[level].bp_bh);
 895         if (!buffer_dirty(path[level].bp_sib_bh))
 896                 mark_buffer_dirty(path[level].bp_sib_bh);
 897
 898         path[level + 1].bp_index++;
 899         nilfs_btree_promote_key(btree, path, level + 1,
 900                                 nilfs_btree_node_get_key(right, 0));
 901         path[level + 1].bp_index--;
 902
 903         if (move) {
 904                 brelse(path[level].bp_bh);
 905                 path[level].bp_bh = path[level].bp_sib_bh;
 906                 path[level].bp_sib_bh = NULL;
 907                 path[level].bp_index -= nilfs_btree_node_get_nchildren(node);
 908                 path[level + 1].bp_index++;
 909         } else {
 910                 brelse(path[level].bp_sib_bh);
 911                 path[level].bp_sib_bh = NULL;
 912         }
 913
 914         nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
 915 }
 916
 917 static void nilfs_btree_split(struct nilfs_bmap *btree,
 918                               struct nilfs_btree_path *path,
 919                               int level, __u64 *keyp, __u64 *ptrp)
 920 {
 921         struct nilfs_btree_node *node, *right;
 922         int nchildren, n, move, ncblk;
 923
 924         node = nilfs_btree_get_nonroot_node(path, level);
 925         right = nilfs_btree_get_sib_node(path, level);
 926         nchildren = nilfs_btree_node_get_nchildren(node);
 927         ncblk = nilfs_btree_nchildren_per_block(btree);
 928         move = 0;
 929
 930         n = (nchildren + 1) / 2;
 931         if (n > nchildren - path[level].bp_index) {
 932                 n--;
 933                 move = 1;
 934         }
 935
 936         nilfs_btree_node_move_right(node, right, n, ncblk, ncblk);
 937
 938         if (!buffer_dirty(path[level].bp_bh))
 939                 mark_buffer_dirty(path[level].bp_bh);
 940         if (!buffer_dirty(path[level].bp_sib_bh))
 941                 mark_buffer_dirty(path[level].bp_sib_bh);
 942
 943         if (move) {
 944                 path[level].bp_index -= nilfs_btree_node_get_nchildren(node);
 945                 nilfs_btree_node_insert(right, path[level].bp_index,
 946                                         *keyp, *ptrp, ncblk);
 947
 948                 *keyp = nilfs_btree_node_get_key(right, 0);
 949                 *ptrp = path[level].bp_newreq.bpr_ptr;
 950
 951                 brelse(path[level].bp_bh);
 952                 path[level].bp_bh = path[level].bp_sib_bh;
 953                 path[level].bp_sib_bh = NULL;
 954         } else {
 955                 nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
 956
 957                 *keyp = nilfs_btree_node_get_key(right, 0);
 958                 *ptrp = path[level].bp_newreq.bpr_ptr;
 959
 960                 brelse(path[level].bp_sib_bh);
 961                 path[level].bp_sib_bh = NULL;
 962         }
 963
 964         path[level + 1].bp_index++;
 965 }
 966
 967 static void nilfs_btree_grow(struct nilfs_bmap *btree,
 968                              struct nilfs_btree_path *path,
 969                              int level, __u64 *keyp, __u64 *ptrp)
 970 {
 971         struct nilfs_btree_node *root, *child;
 972         int n, ncblk;
 973
 974         root = nilfs_btree_get_root(btree);
 975         child = nilfs_btree_get_sib_node(path, level);
 976         ncblk = nilfs_btree_nchildren_per_block(btree);
 977
 978         n = nilfs_btree_node_get_nchildren(root);
 979
 980         nilfs_btree_node_move_right(root, child, n,
 981                                     NILFS_BTREE_ROOT_NCHILDREN_MAX, ncblk);
 982         nilfs_btree_node_set_level(root, level + 1);
 983
 984         if (!buffer_dirty(path[level].bp_sib_bh))
 985                 mark_buffer_dirty(path[level].bp_sib_bh);
 986
 987         path[level].bp_bh = path[level].bp_sib_bh;
 988         path[level].bp_sib_bh = NULL;
 989
 990         nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
 991
 992         *keyp = nilfs_btree_node_get_key(child, 0);
 993         *ptrp = path[level].bp_newreq.bpr_ptr;
 994 }
 995
 996 static __u64 nilfs_btree_find_near(const struct nilfs_bmap *btree,
 997                                    const struct nilfs_btree_path *path)
 998 {
 999         struct nilfs_btree_node *node;
1000         int level, ncmax;
1001
1002         if (path == NULL)
1003                 return NILFS_BMAP_INVALID_PTR;
1004
1005         /* left sibling */
1006         level = NILFS_BTREE_LEVEL_NODE_MIN;
1007         if (path[level].bp_index > 0) {
1008                 node = nilfs_btree_get_node(btree, path, level, &ncmax);
1009                 return nilfs_btree_node_get_ptr(node,
1010                                                 path[level].bp_index - 1,
1011                                                 ncmax);
1012         }
1013
1014         /* parent */
1015         level = NILFS_BTREE_LEVEL_NODE_MIN + 1;
1016         if (level <= nilfs_btree_height(btree) - 1) {
1017                 node = nilfs_btree_get_node(btree, path, level, &ncmax);
1018                 return nilfs_btree_node_get_ptr(node, path[level].bp_index,
1019                                                 ncmax);
1020         }
1021
1022         return NILFS_BMAP_INVALID_PTR;
1023 }
1024
1025 static __u64 nilfs_btree_find_target_v(const struct nilfs_bmap *btree,
1026                                        const struct nilfs_btree_path *path,
1027                                        __u64 key)
1028 {
1029         __u64 ptr;
1030
1031         ptr = nilfs_bmap_find_target_seq(btree, key);
1032         if (ptr != NILFS_BMAP_INVALID_PTR)
1033                 /* sequential access */
1034                 return ptr;
1035         else {
1036                 ptr = nilfs_btree_find_near(btree, path);
1037                 if (ptr != NILFS_BMAP_INVALID_PTR)
1038                         /* near */
1039                         return ptr;
1040         }
1041         /* block group */
1042         return nilfs_bmap_find_target_in_group(btree);
1043 }
1044
1045 static int nilfs_btree_prepare_insert(struct nilfs_bmap *btree,
1046                                       struct nilfs_btree_path *path,
1047                                       int *levelp, __u64 key, __u64 ptr,
1048                                       struct nilfs_bmap_stats *stats)
1049 {
1050         struct buffer_head *bh;
1051         struct nilfs_btree_node *node, *parent, *sib;
1052         __u64 sibptr;
1053         int pindex, level, ncmax, ncblk, ret;
1054         struct inode *dat = NULL;
1055
1056         stats->bs_nblocks = 0;
1057         level = NILFS_BTREE_LEVEL_DATA;
1058
1059         /* allocate a new ptr for data block */
1060         if (NILFS_BMAP_USE_VBN(btree)) {
1061                 path[level].bp_newreq.bpr_ptr =
1062                         nilfs_btree_find_target_v(btree, path, key);
1063                 dat = nilfs_bmap_get_dat(btree);
1064         }
1065
1066         ret = nilfs_bmap_prepare_alloc_ptr(btree, &path[level].bp_newreq, dat);
1067         if (ret < 0)
1068                 goto err_out_data;
1069
1070         ncblk = nilfs_btree_nchildren_per_block(btree);
1071
1072         for (level = NILFS_BTREE_LEVEL_NODE_MIN;
1073              level < nilfs_btree_height(btree) - 1;
1074              level++) {
1075                 node = nilfs_btree_get_nonroot_node(path, level);
1076                 if (nilfs_btree_node_get_nchildren(node) < ncblk) {
1077                         path[level].bp_op = nilfs_btree_do_insert;
1078                         stats->bs_nblocks++;
1079                         goto out;
1080                 }
1081
1082                 parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
1083                 pindex = path[level + 1].bp_index;
1084
1085                 /* left sibling */
1086                 if (pindex > 0) {
1087                         sibptr = nilfs_btree_node_get_ptr(parent, pindex - 1,
1088                                                           ncmax);
1089                         ret = nilfs_btree_get_block(btree, sibptr, &bh);
1090                         if (ret < 0)
1091                                 goto err_out_child_node;
1092                         sib = (struct nilfs_btree_node *)bh->b_data;
1093                         if (nilfs_btree_node_get_nchildren(sib) < ncblk) {
1094                                 path[level].bp_sib_bh = bh;
1095                                 path[level].bp_op = nilfs_btree_carry_left;
1096                                 stats->bs_nblocks++;
1097                                 goto out;
1098                         } else {
1099                                 brelse(bh);
1100                         }
1101                 }
1102
1103                 /* right sibling */
1104                 if (pindex < nilfs_btree_node_get_nchildren(parent) - 1) {
1105                         sibptr = nilfs_btree_node_get_ptr(parent, pindex + 1,
1106                                                           ncmax);
1107                         ret = nilfs_btree_get_block(btree, sibptr, &bh);
1108                         if (ret < 0)
1109                                 goto err_out_child_node;
1110                         sib = (struct nilfs_btree_node *)bh->b_data;
1111                         if (nilfs_btree_node_get_nchildren(sib) < ncblk) {
1112                                 path[level].bp_sib_bh = bh;
1113                                 path[level].bp_op = nilfs_btree_carry_right;
1114                                 stats->bs_nblocks++;
1115                                 goto out;
1116                         } else {
1117                                 brelse(bh);
1118                         }
1119                 }
1120
1121                 /* split */
1122                 path[level].bp_newreq.bpr_ptr =
1123                         path[level - 1].bp_newreq.bpr_ptr + 1;
1124                 ret = nilfs_bmap_prepare_alloc_ptr(btree,
1125                                                    &path[level].bp_newreq, dat);
1126                 if (ret < 0)
1127                         goto err_out_child_node;
1128                 ret = nilfs_btree_get_new_block(btree,
1129                                                 path[level].bp_newreq.bpr_ptr,
1130                                                 &bh);
1131                 if (ret < 0)
1132                         goto err_out_curr_node;
1133
1134                 stats->bs_nblocks++;
1135
1136                 sib = (struct nilfs_btree_node *)bh->b_data;
1137                 nilfs_btree_node_init(sib, 0, level, 0, ncblk, NULL, NULL);
1138                 path[level].bp_sib_bh = bh;
1139                 path[level].bp_op = nilfs_btree_split;
1140         }
1141
1142         /* root */
1143         node = nilfs_btree_get_root(btree);
1144         if (nilfs_btree_node_get_nchildren(node) <
1145             NILFS_BTREE_ROOT_NCHILDREN_MAX) {
1146                 path[level].bp_op = nilfs_btree_do_insert;
1147                 stats->bs_nblocks++;
1148                 goto out;
1149         }
1150
1151         /* grow */
1152         path[level].bp_newreq.bpr_ptr = path[level - 1].bp_newreq.bpr_ptr + 1;
1153         ret = nilfs_bmap_prepare_alloc_ptr(btree, &path[level].bp_newreq, dat);
1154         if (ret < 0)
1155                 goto err_out_child_node;
1156         ret = nilfs_btree_get_new_block(btree, path[level].bp_newreq.bpr_ptr,
1157                                         &bh);
1158         if (ret < 0)
1159                 goto err_out_curr_node;
1160
1161         nilfs_btree_node_init((struct nilfs_btree_node *)bh->b_data,
1162                               0, level, 0, ncblk, NULL, NULL);
1163         path[level].bp_sib_bh = bh;
1164         path[level].bp_op = nilfs_btree_grow;
1165
1166         level++;
1167         path[level].bp_op = nilfs_btree_do_insert;
1168
1169         /* a newly-created node block and a data block are added */
1170         stats->bs_nblocks += 2;
1171
1172         /* success */
1173  out:
1174         *levelp = level;
1175         return ret;
1176
1177         /* error */
1178  err_out_curr_node:
1179         nilfs_bmap_abort_alloc_ptr(btree, &path[level].bp_newreq, dat);
1180  err_out_child_node:
1181         for (level--; level > NILFS_BTREE_LEVEL_DATA; level--) {
1182                 nilfs_btnode_delete(path[level].bp_sib_bh);
1183                 nilfs_bmap_abort_alloc_ptr(btree, &path[level].bp_newreq, dat);
1184
1185         }
1186
1187         nilfs_bmap_abort_alloc_ptr(btree, &path[level].bp_newreq, dat);
1188  err_out_data:
1189         *levelp = level;
1190         stats->bs_nblocks = 0;
1191         return ret;
1192 }
1193
1194 static void nilfs_btree_commit_insert(struct nilfs_bmap *btree,
1195                                       struct nilfs_btree_path *path,
1196                                       int maxlevel, __u64 key, __u64 ptr)
1197 {
1198         struct inode *dat = NULL;
1199         int level;
1200
1201         set_buffer_nilfs_volatile((struct buffer_head *)((unsigned long)ptr));
1202         ptr = path[NILFS_BTREE_LEVEL_DATA].bp_newreq.bpr_ptr;
1203         if (NILFS_BMAP_USE_VBN(btree)) {
1204                 nilfs_bmap_set_target_v(btree, key, ptr);
1205                 dat = nilfs_bmap_get_dat(btree);
1206         }
1207
1208         for (level = NILFS_BTREE_LEVEL_NODE_MIN; level <= maxlevel; level++) {
1209                 nilfs_bmap_commit_alloc_ptr(btree,
1210                                             &path[level - 1].bp_newreq, dat);
1211                 path[level].bp_op(btree, path, level, &key, &ptr);
1212         }
1213
1214         if (!nilfs_bmap_dirty(btree))
1215                 nilfs_bmap_set_dirty(btree);
1216 }
1217
1218 static int nilfs_btree_insert(struct nilfs_bmap *btree, __u64 key, __u64 ptr)
1219 {
1220         struct nilfs_btree_path *path;
1221         struct nilfs_bmap_stats stats;
1222         int level, ret;
1223
1224         path = nilfs_btree_alloc_path();
1225         if (path == NULL)
1226                 return -ENOMEM;
1227
1228         ret = nilfs_btree_do_lookup(btree, path, key, NULL,
1229                                     NILFS_BTREE_LEVEL_NODE_MIN, 0);
1230         if (ret != -ENOENT) {
1231                 if (ret == 0)
1232                         ret = -EEXIST;
1233                 goto out;
1234         }
1235
1236         ret = nilfs_btree_prepare_insert(btree, path, &level, key, ptr, &stats);
1237         if (ret < 0)
1238                 goto out;
1239         nilfs_btree_commit_insert(btree, path, level, key, ptr);
1240         nilfs_inode_add_blocks(btree->b_inode, stats.bs_nblocks);
1241
1242  out:
1243         nilfs_btree_free_path(path);
1244         return ret;
1245 }
1246
1247 static void nilfs_btree_do_delete(struct nilfs_bmap *btree,
1248                                   struct nilfs_btree_path *path,
1249                                   int level, __u64 *keyp, __u64 *ptrp)
1250 {
1251         struct nilfs_btree_node *node;
1252         int ncblk;
1253
1254         if (level < nilfs_btree_height(btree) - 1) {
1255                 node = nilfs_btree_get_nonroot_node(path, level);
1256                 ncblk = nilfs_btree_nchildren_per_block(btree);
1257                 nilfs_btree_node_delete(node, path[level].bp_index,
1258                                         keyp, ptrp, ncblk);
1259                 if (!buffer_dirty(path[level].bp_bh))
1260                         mark_buffer_dirty(path[level].bp_bh);
1261                 if (path[level].bp_index == 0)
1262                         nilfs_btree_promote_key(btree, path, level + 1,
1263                                 nilfs_btree_node_get_key(node, 0));
1264         } else {
1265                 node = nilfs_btree_get_root(btree);
1266                 nilfs_btree_node_delete(node, path[level].bp_index,
1267                                         keyp, ptrp,
1268                                         NILFS_BTREE_ROOT_NCHILDREN_MAX);
1269         }
1270 }
1271
1272 static void nilfs_btree_borrow_left(struct nilfs_bmap *btree,
1273                                     struct nilfs_btree_path *path,
1274                                     int level, __u64 *keyp, __u64 *ptrp)
1275 {
1276         struct nilfs_btree_node *node, *left;
1277         int nchildren, lnchildren, n, ncblk;
1278
1279         nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1280
1281         node = nilfs_btree_get_nonroot_node(path, level);
1282         left = nilfs_btree_get_sib_node(path, level);
1283         nchildren = nilfs_btree_node_get_nchildren(node);
1284         lnchildren = nilfs_btree_node_get_nchildren(left);
1285         ncblk = nilfs_btree_nchildren_per_block(btree);
1286
1287         n = (nchildren + lnchildren) / 2 - nchildren;
1288
1289         nilfs_btree_node_move_right(left, node, n, ncblk, ncblk);
1290
1291         if (!buffer_dirty(path[level].bp_bh))
1292                 mark_buffer_dirty(path[level].bp_bh);
1293         if (!buffer_dirty(path[level].bp_sib_bh))
1294                 mark_buffer_dirty(path[level].bp_sib_bh);
1295
1296         nilfs_btree_promote_key(btree, path, level + 1,
1297                                 nilfs_btree_node_get_key(node, 0));
1298
1299         brelse(path[level].bp_sib_bh);
1300         path[level].bp_sib_bh = NULL;
1301         path[level].bp_index += n;
1302 }
1303
1304 static void nilfs_btree_borrow_right(struct nilfs_bmap *btree,
1305                                      struct nilfs_btree_path *path,
1306                                      int level, __u64 *keyp, __u64 *ptrp)
1307 {
1308         struct nilfs_btree_node *node, *right;
1309         int nchildren, rnchildren, n, ncblk;
1310
1311         nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1312
1313         node = nilfs_btree_get_nonroot_node(path, level);
1314         right = nilfs_btree_get_sib_node(path, level);
1315         nchildren = nilfs_btree_node_get_nchildren(node);
1316         rnchildren = nilfs_btree_node_get_nchildren(right);
1317         ncblk = nilfs_btree_nchildren_per_block(btree);
1318
1319         n = (nchildren + rnchildren) / 2 - nchildren;
1320
1321         nilfs_btree_node_move_left(node, right, n, ncblk, ncblk);
1322
1323         if (!buffer_dirty(path[level].bp_bh))
1324                 mark_buffer_dirty(path[level].bp_bh);
1325         if (!buffer_dirty(path[level].bp_sib_bh))
1326                 mark_buffer_dirty(path[level].bp_sib_bh);
1327
1328         path[level + 1].bp_index++;
1329         nilfs_btree_promote_key(btree, path, level + 1,
1330                                 nilfs_btree_node_get_key(right, 0));
1331         path[level + 1].bp_index--;
1332
1333         brelse(path[level].bp_sib_bh);
1334         path[level].bp_sib_bh = NULL;
1335 }
1336
1337 static void nilfs_btree_concat_left(struct nilfs_bmap *btree,
1338                                     struct nilfs_btree_path *path,
1339                                     int level, __u64 *keyp, __u64 *ptrp)
1340 {
1341         struct nilfs_btree_node *node, *left;
1342         int n, ncblk;
1343
1344         nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1345
1346         node = nilfs_btree_get_nonroot_node(path, level);
1347         left = nilfs_btree_get_sib_node(path, level);
1348         ncblk = nilfs_btree_nchildren_per_block(btree);
1349
1350         n = nilfs_btree_node_get_nchildren(node);
1351
1352         nilfs_btree_node_move_left(left, node, n, ncblk, ncblk);
1353
1354         if (!buffer_dirty(path[level].bp_sib_bh))
1355                 mark_buffer_dirty(path[level].bp_sib_bh);
1356
1357         nilfs_btnode_delete(path[level].bp_bh);
1358         path[level].bp_bh = path[level].bp_sib_bh;
1359         path[level].bp_sib_bh = NULL;
1360         path[level].bp_index += nilfs_btree_node_get_nchildren(left);
1361 }
1362
1363 static void nilfs_btree_concat_right(struct nilfs_bmap *btree,
1364                                      struct nilfs_btree_path *path,
1365                                      int level, __u64 *keyp, __u64 *ptrp)
1366 {
1367         struct nilfs_btree_node *node, *right;
1368         int n, ncblk;
1369
1370         nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1371
1372         node = nilfs_btree_get_nonroot_node(path, level);
1373         right = nilfs_btree_get_sib_node(path, level);
1374         ncblk = nilfs_btree_nchildren_per_block(btree);
1375
1376         n = nilfs_btree_node_get_nchildren(right);
1377
1378         nilfs_btree_node_move_left(node, right, n, ncblk, ncblk);
1379
1380         if (!buffer_dirty(path[level].bp_bh))
1381                 mark_buffer_dirty(path[level].bp_bh);
1382
1383         nilfs_btnode_delete(path[level].bp_sib_bh);
1384         path[level].bp_sib_bh = NULL;
1385         path[level + 1].bp_index++;
1386 }
1387
1388 static void nilfs_btree_shrink(struct nilfs_bmap *btree,
1389                                struct nilfs_btree_path *path,
1390                                int level, __u64 *keyp, __u64 *ptrp)
1391 {
1392         struct nilfs_btree_node *root, *child;
1393         int n, ncblk;
1394
1395         nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1396
1397         root = nilfs_btree_get_root(btree);
1398         child = nilfs_btree_get_nonroot_node(path, level);
1399         ncblk = nilfs_btree_nchildren_per_block(btree);
1400
1401         nilfs_btree_node_delete(root, 0, NULL, NULL,
1402                                 NILFS_BTREE_ROOT_NCHILDREN_MAX);
1403         nilfs_btree_node_set_level(root, level);
1404         n = nilfs_btree_node_get_nchildren(child);
1405         nilfs_btree_node_move_left(root, child, n,
1406                                    NILFS_BTREE_ROOT_NCHILDREN_MAX, ncblk);
1407
1408         nilfs_btnode_delete(path[level].bp_bh);
1409         path[level].bp_bh = NULL;
1410 }
1411
1412 static void nilfs_btree_nop(struct nilfs_bmap *btree,
1413                             struct nilfs_btree_path *path,
1414                             int level, __u64 *keyp, __u64 *ptrp)
1415 {
1416 }
1417
1418 static int nilfs_btree_prepare_delete(struct nilfs_bmap *btree,
1419                                       struct nilfs_btree_path *path,
1420                                       int *levelp,
1421                                       struct nilfs_bmap_stats *stats,
1422                                       struct inode *dat)
1423 {
1424         struct buffer_head *bh;
1425         struct nilfs_btree_node *node, *parent, *sib;
1426         __u64 sibptr;
1427         int pindex, dindex, level, ncmin, ncmax, ncblk, ret;
1428
1429         ret = 0;
1430         stats->bs_nblocks = 0;
1431         ncmin = NILFS_BTREE_NODE_NCHILDREN_MIN(nilfs_btree_node_size(btree));
1432         ncblk = nilfs_btree_nchildren_per_block(btree);
1433
1434         for (level = NILFS_BTREE_LEVEL_NODE_MIN, dindex = path[level].bp_index;
1435              level < nilfs_btree_height(btree) - 1;
1436              level++) {
1437                 node = nilfs_btree_get_nonroot_node(path, level);
1438                 path[level].bp_oldreq.bpr_ptr =
1439                         nilfs_btree_node_get_ptr(node, dindex, ncblk);
1440                 ret = nilfs_bmap_prepare_end_ptr(btree,
1441                                                  &path[level].bp_oldreq, dat);
1442                 if (ret < 0)
1443                         goto err_out_child_node;
1444
1445                 if (nilfs_btree_node_get_nchildren(node) > ncmin) {
1446                         path[level].bp_op = nilfs_btree_do_delete;
1447                         stats->bs_nblocks++;
1448                         goto out;
1449                 }
1450
1451                 parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
1452                 pindex = path[level + 1].bp_index;
1453                 dindex = pindex;
1454
1455                 if (pindex > 0) {
1456                         /* left sibling */
1457                         sibptr = nilfs_btree_node_get_ptr(parent, pindex - 1,
1458                                                           ncmax);
1459                         ret = nilfs_btree_get_block(btree, sibptr, &bh);
1460                         if (ret < 0)
1461                                 goto err_out_curr_node;
1462                         sib = (struct nilfs_btree_node *)bh->b_data;
1463                         if (nilfs_btree_node_get_nchildren(sib) > ncmin) {
1464                                 path[level].bp_sib_bh = bh;
1465                                 path[level].bp_op = nilfs_btree_borrow_left;
1466                                 stats->bs_nblocks++;
1467                                 goto out;
1468                         } else {
1469                                 path[level].bp_sib_bh = bh;
1470                                 path[level].bp_op = nilfs_btree_concat_left;
1471                                 stats->bs_nblocks++;
1472                                 /* continue; */
1473                         }
1474                 } else if (pindex <
1475                            nilfs_btree_node_get_nchildren(parent) - 1) {
1476                         /* right sibling */
1477                         sibptr = nilfs_btree_node_get_ptr(parent, pindex + 1,
1478                                                           ncmax);
1479                         ret = nilfs_btree_get_block(btree, sibptr, &bh);
1480                         if (ret < 0)
1481                                 goto err_out_curr_node;
1482                         sib = (struct nilfs_btree_node *)bh->b_data;
1483                         if (nilfs_btree_node_get_nchildren(sib) > ncmin) {
1484                                 path[level].bp_sib_bh = bh;
1485                                 path[level].bp_op = nilfs_btree_borrow_right;
1486                                 stats->bs_nblocks++;
1487                                 goto out;
1488                         } else {
1489                                 path[level].bp_sib_bh = bh;
1490                                 path[level].bp_op = nilfs_btree_concat_right;
1491                                 stats->bs_nblocks++;
1492                                 /*
1493                                  * When merging right sibling node
1494                                  * into the current node, pointer to
1495                                  * the right sibling node must be
1496                                  * terminated instead.  The adjustment
1497                                  * below is required for that.
1498                                  */
1499                                 dindex = pindex + 1;
1500                                 /* continue; */
1501                         }
1502                 } else {
1503                         /* no siblings */
1504                         /* the only child of the root node */
1505                         WARN_ON(level != nilfs_btree_height(btree) - 2);
1506                         if (nilfs_btree_node_get_nchildren(node) - 1 <=
1507                             NILFS_BTREE_ROOT_NCHILDREN_MAX) {
1508                                 path[level].bp_op = nilfs_btree_shrink;
1509                                 stats->bs_nblocks += 2;
1510                                 level++;
1511                                 path[level].bp_op = nilfs_btree_nop;
1512                                 goto shrink_root_child;
1513                         } else {
1514                                 path[level].bp_op = nilfs_btree_do_delete;
1515                                 stats->bs_nblocks++;
1516                                 goto out;
1517                         }
1518                 }
1519         }
1520
1521         /* child of the root node is deleted */
1522         path[level].bp_op = nilfs_btree_do_delete;
1523         stats->bs_nblocks++;
1524
1525 shrink_root_child:
1526         node = nilfs_btree_get_root(btree);
1527         path[level].bp_oldreq.bpr_ptr =
1528                 nilfs_btree_node_get_ptr(node, dindex,
1529                                          NILFS_BTREE_ROOT_NCHILDREN_MAX);
1530
1531         ret = nilfs_bmap_prepare_end_ptr(btree, &path[level].bp_oldreq, dat);
1532         if (ret < 0)
1533                 goto err_out_child_node;
1534
1535         /* success */
1536  out:
1537         *levelp = level;
1538         return ret;
1539
1540         /* error */
1541  err_out_curr_node:
1542         nilfs_bmap_abort_end_ptr(btree, &path[level].bp_oldreq, dat);
1543  err_out_child_node:
1544         for (level--; level >= NILFS_BTREE_LEVEL_NODE_MIN; level--) {
1545                 brelse(path[level].bp_sib_bh);
1546                 nilfs_bmap_abort_end_ptr(btree, &path[level].bp_oldreq, dat);
1547         }
1548         *levelp = level;
1549         stats->bs_nblocks = 0;
1550         return ret;
1551 }
1552
1553 static void nilfs_btree_commit_delete(struct nilfs_bmap *btree,
1554                                       struct nilfs_btree_path *path,
1555                                       int maxlevel, struct inode *dat)
1556 {
1557         int level;
1558
1559         for (level = NILFS_BTREE_LEVEL_NODE_MIN; level <= maxlevel; level++) {
1560                 nilfs_bmap_commit_end_ptr(btree, &path[level].bp_oldreq, dat);
1561                 path[level].bp_op(btree, path, level, NULL, NULL);
1562         }
1563
1564         if (!nilfs_bmap_dirty(btree))
1565                 nilfs_bmap_set_dirty(btree);
1566 }
1567
1568 static int nilfs_btree_delete(struct nilfs_bmap *btree, __u64 key)
1569
1570 {
1571         struct nilfs_btree_path *path;
1572         struct nilfs_bmap_stats stats;
1573         struct inode *dat;
1574         int level, ret;
1575
1576         path = nilfs_btree_alloc_path();
1577         if (path == NULL)
1578                 return -ENOMEM;
1579
1580         ret = nilfs_btree_do_lookup(btree, path, key, NULL,
1581                                     NILFS_BTREE_LEVEL_NODE_MIN, 0);
1582         if (ret < 0)
1583                 goto out;
1584
1585
1586         dat = NILFS_BMAP_USE_VBN(btree) ? nilfs_bmap_get_dat(btree) : NULL;
1587
1588         ret = nilfs_btree_prepare_delete(btree, path, &level, &stats, dat);
1589         if (ret < 0)
1590                 goto out;
1591         nilfs_btree_commit_delete(btree, path, level, dat);
1592         nilfs_inode_sub_blocks(btree->b_inode, stats.bs_nblocks);
1593
1594 out:
1595         nilfs_btree_free_path(path);
1596         return ret;
1597 }
1598
1599 static int nilfs_btree_seek_key(const struct nilfs_bmap *btree, __u64 start,
1600                                 __u64 *keyp)
1601 {
1602         struct nilfs_btree_path *path;
1603         const int minlevel = NILFS_BTREE_LEVEL_NODE_MIN;
1604         int ret;
1605
1606         path = nilfs_btree_alloc_path();
1607         if (!path)
1608                 return -ENOMEM;
1609
1610         ret = nilfs_btree_do_lookup(btree, path, start, NULL, minlevel, 0);
1611         if (!ret)
1612                 *keyp = start;
1613         else if (ret == -ENOENT)
1614                 ret = nilfs_btree_get_next_key(btree, path, minlevel, keyp);
1615
1616         nilfs_btree_free_path(path);
1617         return ret;
1618 }
1619
1620 static int nilfs_btree_last_key(const struct nilfs_bmap *btree, __u64 *keyp)
1621 {
1622         struct nilfs_btree_path *path;
1623         int ret;
1624
1625         path = nilfs_btree_alloc_path();
1626         if (path == NULL)
1627                 return -ENOMEM;
1628
1629         ret = nilfs_btree_do_lookup_last(btree, path, keyp, NULL);
1630
1631         nilfs_btree_free_path(path);
1632
1633         return ret;
1634 }
1635
1636 static int nilfs_btree_check_delete(struct nilfs_bmap *btree, __u64 key)
1637 {
1638         struct buffer_head *bh;
1639         struct nilfs_btree_node *root, *node;
1640         __u64 maxkey, nextmaxkey;
1641         __u64 ptr;
1642         int nchildren, ret;
1643
1644         root = nilfs_btree_get_root(btree);
1645         switch (nilfs_btree_height(btree)) {
1646         case 2:
1647                 bh = NULL;
1648                 node = root;
1649                 break;
1650         case 3:
1651                 nchildren = nilfs_btree_node_get_nchildren(root);
1652                 if (nchildren > 1)
1653                         return 0;
1654                 ptr = nilfs_btree_node_get_ptr(root, nchildren - 1,
1655                                                NILFS_BTREE_ROOT_NCHILDREN_MAX);
1656                 ret = nilfs_btree_get_block(btree, ptr, &bh);
1657                 if (ret < 0)
1658                         return ret;
1659                 node = (struct nilfs_btree_node *)bh->b_data;
1660                 break;
1661         default:
1662                 return 0;
1663         }
1664
1665         nchildren = nilfs_btree_node_get_nchildren(node);
1666         maxkey = nilfs_btree_node_get_key(node, nchildren - 1);
1667         nextmaxkey = (nchildren > 1) ?
1668                 nilfs_btree_node_get_key(node, nchildren - 2) : 0;
1669         if (bh != NULL)
1670                 brelse(bh);
1671
1672         return (maxkey == key) && (nextmaxkey < NILFS_BMAP_LARGE_LOW);
1673 }
1674
1675 static int nilfs_btree_gather_data(struct nilfs_bmap *btree,
1676                                    __u64 *keys, __u64 *ptrs, int nitems)
1677 {
1678         struct buffer_head *bh;
1679         struct nilfs_btree_node *node, *root;
1680         __le64 *dkeys;
1681         __le64 *dptrs;
1682         __u64 ptr;
1683         int nchildren, ncmax, i, ret;
1684
1685         root = nilfs_btree_get_root(btree);
1686         switch (nilfs_btree_height(btree)) {
1687         case 2:
1688                 bh = NULL;
1689                 node = root;
1690                 ncmax = NILFS_BTREE_ROOT_NCHILDREN_MAX;
1691                 break;
1692         case 3:
1693                 nchildren = nilfs_btree_node_get_nchildren(root);
1694                 WARN_ON(nchildren > 1);
1695                 ptr = nilfs_btree_node_get_ptr(root, nchildren - 1,
1696                                                NILFS_BTREE_ROOT_NCHILDREN_MAX);
1697                 ret = nilfs_btree_get_block(btree, ptr, &bh);
1698                 if (ret < 0)
1699                         return ret;
1700                 node = (struct nilfs_btree_node *)bh->b_data;
1701                 ncmax = nilfs_btree_nchildren_per_block(btree);
1702                 break;
1703         default:
1704                 node = NULL;
1705                 return -EINVAL;
1706         }
1707
1708         nchildren = nilfs_btree_node_get_nchildren(node);
1709         if (nchildren < nitems)
1710                 nitems = nchildren;
1711         dkeys = nilfs_btree_node_dkeys(node);
1712         dptrs = nilfs_btree_node_dptrs(node, ncmax);
1713         for (i = 0; i < nitems; i++) {
1714                 keys[i] = le64_to_cpu(dkeys[i]);
1715                 ptrs[i] = le64_to_cpu(dptrs[i]);
1716         }
1717
1718         if (bh != NULL)
1719                 brelse(bh);
1720
1721         return nitems;
1722 }
1723
1724 static int
1725 nilfs_btree_prepare_convert_and_insert(struct nilfs_bmap *btree, __u64 key,
1726                                        union nilfs_bmap_ptr_req *dreq,
1727                                        union nilfs_bmap_ptr_req *nreq,
1728                                        struct buffer_head **bhp,
1729                                        struct nilfs_bmap_stats *stats)
1730 {
1731         struct buffer_head *bh;
1732         struct inode *dat = NULL;
1733         int ret;
1734
1735         stats->bs_nblocks = 0;
1736
1737         /* for data */
1738         /* cannot find near ptr */
1739         if (NILFS_BMAP_USE_VBN(btree)) {
1740                 dreq->bpr_ptr = nilfs_btree_find_target_v(btree, NULL, key);
1741                 dat = nilfs_bmap_get_dat(btree);
1742         }
1743
1744         ret = nilfs_bmap_prepare_alloc_ptr(btree, dreq, dat);
1745         if (ret < 0)
1746                 return ret;
1747
1748         *bhp = NULL;
1749         stats->bs_nblocks++;
1750         if (nreq != NULL) {
1751                 nreq->bpr_ptr = dreq->bpr_ptr + 1;
1752                 ret = nilfs_bmap_prepare_alloc_ptr(btree, nreq, dat);
1753                 if (ret < 0)
1754                         goto err_out_dreq;
1755
1756                 ret = nilfs_btree_get_new_block(btree, nreq->bpr_ptr, &bh);
1757                 if (ret < 0)
1758                         goto err_out_nreq;
1759
1760                 *bhp = bh;
1761                 stats->bs_nblocks++;
1762         }
1763
1764         /* success */
1765         return 0;
1766
1767         /* error */
1768  err_out_nreq:
1769         nilfs_bmap_abort_alloc_ptr(btree, nreq, dat);
1770  err_out_dreq:
1771         nilfs_bmap_abort_alloc_ptr(btree, dreq, dat);
1772         stats->bs_nblocks = 0;
1773         return ret;
1774
1775 }
1776
1777 static void
1778 nilfs_btree_commit_convert_and_insert(struct nilfs_bmap *btree,
1779                                       __u64 key, __u64 ptr,
1780                                       const __u64 *keys, const __u64 *ptrs,
1781                                       int n,
1782                                       union nilfs_bmap_ptr_req *dreq,
1783                                       union nilfs_bmap_ptr_req *nreq,
1784                                       struct buffer_head *bh)
1785 {
1786         struct nilfs_btree_node *node;
1787         struct inode *dat;
1788         __u64 tmpptr;
1789         int ncblk;
1790
1791         /* free resources */
1792         if (btree->b_ops->bop_clear != NULL)
1793                 btree->b_ops->bop_clear(btree);
1794
1795         /* ptr must be a pointer to a buffer head. */
1796         set_buffer_nilfs_volatile((struct buffer_head *)((unsigned long)ptr));
1797
1798         /* convert and insert */
1799         dat = NILFS_BMAP_USE_VBN(btree) ? nilfs_bmap_get_dat(btree) : NULL;
1800         __nilfs_btree_init(btree);
1801         if (nreq != NULL) {
1802                 nilfs_bmap_commit_alloc_ptr(btree, dreq, dat);
1803                 nilfs_bmap_commit_alloc_ptr(btree, nreq, dat);
1804
1805                 /* create child node at level 1 */
1806                 node = (struct nilfs_btree_node *)bh->b_data;
1807                 ncblk = nilfs_btree_nchildren_per_block(btree);
1808                 nilfs_btree_node_init(node, 0, 1, n, ncblk, keys, ptrs);
1809                 nilfs_btree_node_insert(node, n, key, dreq->bpr_ptr, ncblk);
1810                 if (!buffer_dirty(bh))
1811                         mark_buffer_dirty(bh);
1812                 if (!nilfs_bmap_dirty(btree))
1813                         nilfs_bmap_set_dirty(btree);
1814
1815                 brelse(bh);
1816
1817                 /* create root node at level 2 */
1818                 node = nilfs_btree_get_root(btree);
1819                 tmpptr = nreq->bpr_ptr;
1820                 nilfs_btree_node_init(node, NILFS_BTREE_NODE_ROOT, 2, 1,
1821                                       NILFS_BTREE_ROOT_NCHILDREN_MAX,
1822                                       &keys[0], &tmpptr);
1823         } else {
1824                 nilfs_bmap_commit_alloc_ptr(btree, dreq, dat);
1825
1826                 /* create root node at level 1 */
1827                 node = nilfs_btree_get_root(btree);
1828                 nilfs_btree_node_init(node, NILFS_BTREE_NODE_ROOT, 1, n,
1829                                       NILFS_BTREE_ROOT_NCHILDREN_MAX,
1830                                       keys, ptrs);
1831                 nilfs_btree_node_insert(node, n, key, dreq->bpr_ptr,
1832                                         NILFS_BTREE_ROOT_NCHILDREN_MAX);
1833                 if (!nilfs_bmap_dirty(btree))
1834                         nilfs_bmap_set_dirty(btree);
1835         }
1836
1837         if (NILFS_BMAP_USE_VBN(btree))
1838                 nilfs_bmap_set_target_v(btree, key, dreq->bpr_ptr);
1839 }
1840
1841 /**
1842  * nilfs_btree_convert_and_insert -
1843  * @bmap:
1844  * @key:
1845  * @ptr:
1846  * @keys:
1847  * @ptrs:
1848  * @n:
1849  */
1850 int nilfs_btree_convert_and_insert(struct nilfs_bmap *btree,
1851                                    __u64 key, __u64 ptr,
1852                                    const __u64 *keys, const __u64 *ptrs, int n)
1853 {
1854         struct buffer_head *bh = NULL;
1855         union nilfs_bmap_ptr_req dreq, nreq, *di, *ni;
1856         struct nilfs_bmap_stats stats;
1857         int ret;
1858
1859         if (n + 1 <= NILFS_BTREE_ROOT_NCHILDREN_MAX) {
1860                 di = &dreq;
1861                 ni = NULL;
1862         } else if ((n + 1) <= NILFS_BTREE_NODE_NCHILDREN_MAX(
1863                            1 << btree->b_inode->i_blkbits)) {
1864                 di = &dreq;
1865                 ni = &nreq;
1866         } else {
1867                 di = NULL;
1868                 ni = NULL;
1869                 BUG();
1870         }
1871
1872         ret = nilfs_btree_prepare_convert_and_insert(btree, key, di, ni, &bh,
1873                                                      &stats);
1874         if (ret < 0)
1875                 return ret;
1876         nilfs_btree_commit_convert_and_insert(btree, key, ptr, keys, ptrs, n,
1877                                               di, ni, bh);
1878         nilfs_inode_add_blocks(btree->b_inode, stats.bs_nblocks);
1879         return 0;
1880 }
1881
1882 static int nilfs_btree_propagate_p(struct nilfs_bmap *btree,
1883                                    struct nilfs_btree_path *path,
1884                                    int level,
1885                                    struct buffer_head *bh)
1886 {
1887         while ((++level < nilfs_btree_height(btree) - 1) &&
1888                !buffer_dirty(path[level].bp_bh))
1889                 mark_buffer_dirty(path[level].bp_bh);
1890
1891         return 0;
1892 }
1893
1894 static int nilfs_btree_prepare_update_v(struct nilfs_bmap *btree,
1895                                         struct nilfs_btree_path *path,
1896                                         int level, struct inode *dat)
1897 {
1898         struct nilfs_btree_node *parent;
1899         int ncmax, ret;
1900
1901         parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
1902         path[level].bp_oldreq.bpr_ptr =
1903                 nilfs_btree_node_get_ptr(parent, path[level + 1].bp_index,
1904                                          ncmax);
1905         path[level].bp_newreq.bpr_ptr = path[level].bp_oldreq.bpr_ptr + 1;
1906         ret = nilfs_dat_prepare_update(dat, &path[level].bp_oldreq.bpr_req,
1907                                        &path[level].bp_newreq.bpr_req);
1908         if (ret < 0)
1909                 return ret;
1910
1911         if (buffer_nilfs_node(path[level].bp_bh)) {
1912                 path[level].bp_ctxt.oldkey = path[level].bp_oldreq.bpr_ptr;
1913                 path[level].bp_ctxt.newkey = path[level].bp_newreq.bpr_ptr;
1914                 path[level].bp_ctxt.bh = path[level].bp_bh;
1915                 ret = nilfs_btnode_prepare_change_key(
1916                         &NILFS_BMAP_I(btree)->i_btnode_cache,
1917                         &path[level].bp_ctxt);
1918                 if (ret < 0) {
1919                         nilfs_dat_abort_update(dat,
1920                                                &path[level].bp_oldreq.bpr_req,
1921                                                &path[level].bp_newreq.bpr_req);
1922                         return ret;
1923                 }
1924         }
1925
1926         return 0;
1927 }
1928
1929 static void nilfs_btree_commit_update_v(struct nilfs_bmap *btree,
1930                                         struct nilfs_btree_path *path,
1931                                         int level, struct inode *dat)
1932 {
1933         struct nilfs_btree_node *parent;
1934         int ncmax;
1935
1936         nilfs_dat_commit_update(dat, &path[level].bp_oldreq.bpr_req,
1937                                 &path[level].bp_newreq.bpr_req,
1938                                 btree->b_ptr_type == NILFS_BMAP_PTR_VS);
1939
1940         if (buffer_nilfs_node(path[level].bp_bh)) {
1941                 nilfs_btnode_commit_change_key(
1942                         &NILFS_BMAP_I(btree)->i_btnode_cache,
1943                         &path[level].bp_ctxt);
1944                 path[level].bp_bh = path[level].bp_ctxt.bh;
1945         }
1946         set_buffer_nilfs_volatile(path[level].bp_bh);
1947
1948         parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
1949         nilfs_btree_node_set_ptr(parent, path[level + 1].bp_index,
1950                                  path[level].bp_newreq.bpr_ptr, ncmax);
1951 }
1952
1953 static void nilfs_btree_abort_update_v(struct nilfs_bmap *btree,
1954                                        struct nilfs_btree_path *path,
1955                                        int level, struct inode *dat)
1956 {
1957         nilfs_dat_abort_update(dat, &path[level].bp_oldreq.bpr_req,
1958                                &path[level].bp_newreq.bpr_req);
1959         if (buffer_nilfs_node(path[level].bp_bh))
1960                 nilfs_btnode_abort_change_key(
1961                         &NILFS_BMAP_I(btree)->i_btnode_cache,
1962                         &path[level].bp_ctxt);
1963 }
1964
1965 static int nilfs_btree_prepare_propagate_v(struct nilfs_bmap *btree,
1966                                            struct nilfs_btree_path *path,
1967                                            int minlevel, int *maxlevelp,
1968                                            struct inode *dat)
1969 {
1970         int level, ret;
1971
1972         level = minlevel;
1973         if (!buffer_nilfs_volatile(path[level].bp_bh)) {
1974                 ret = nilfs_btree_prepare_update_v(btree, path, level, dat);
1975                 if (ret < 0)
1976                         return ret;
1977         }
1978         while ((++level < nilfs_btree_height(btree) - 1) &&
1979                !buffer_dirty(path[level].bp_bh)) {
1980
1981                 WARN_ON(buffer_nilfs_volatile(path[level].bp_bh));
1982                 ret = nilfs_btree_prepare_update_v(btree, path, level, dat);
1983                 if (ret < 0)
1984                         goto out;
1985         }
1986
1987         /* success */
1988         *maxlevelp = level - 1;
1989         return 0;
1990
1991         /* error */
1992  out:
1993         while (--level > minlevel)
1994                 nilfs_btree_abort_update_v(btree, path, level, dat);
1995         if (!buffer_nilfs_volatile(path[level].bp_bh))
1996                 nilfs_btree_abort_update_v(btree, path, level, dat);
1997         return ret;
1998 }
1999
2000 static void nilfs_btree_commit_propagate_v(struct nilfs_bmap *btree,
2001                                            struct nilfs_btree_path *path,
2002                                            int minlevel, int maxlevel,
2003                                            struct buffer_head *bh,
2004                                            struct inode *dat)
2005 {
2006         int level;
2007
2008         if (!buffer_nilfs_volatile(path[minlevel].bp_bh))
2009                 nilfs_btree_commit_update_v(btree, path, minlevel, dat);
2010
2011         for (level = minlevel + 1; level <= maxlevel; level++)
2012                 nilfs_btree_commit_update_v(btree, path, level, dat);
2013 }
2014
2015 static int nilfs_btree_propagate_v(struct nilfs_bmap *btree,
2016                                    struct nilfs_btree_path *path,
2017                                    int level, struct buffer_head *bh)
2018 {
2019         int maxlevel = 0, ret;
2020         struct nilfs_btree_node *parent;
2021         struct inode *dat = nilfs_bmap_get_dat(btree);
2022         __u64 ptr;
2023         int ncmax;
2024
2025         get_bh(bh);
2026         path[level].bp_bh = bh;
2027         ret = nilfs_btree_prepare_propagate_v(btree, path, level, &maxlevel,
2028                                               dat);
2029         if (ret < 0)
2030                 goto out;
2031
2032         if (buffer_nilfs_volatile(path[level].bp_bh)) {
2033                 parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
2034                 ptr = nilfs_btree_node_get_ptr(parent,
2035                                                path[level + 1].bp_index,
2036                                                ncmax);
2037                 ret = nilfs_dat_mark_dirty(dat, ptr);
2038                 if (ret < 0)
2039                         goto out;
2040         }
2041
2042         nilfs_btree_commit_propagate_v(btree, path, level, maxlevel, bh, dat);
2043
2044  out:
2045         brelse(path[level].bp_bh);
2046         path[level].bp_bh = NULL;
2047         return ret;
2048 }
2049
2050 static int nilfs_btree_propagate(struct nilfs_bmap *btree,
2051                                  struct buffer_head *bh)
2052 {
2053         struct nilfs_btree_path *path;
2054         struct nilfs_btree_node *node;
2055         __u64 key;
2056         int level, ret;
2057
2058         WARN_ON(!buffer_dirty(bh));
2059
2060         path = nilfs_btree_alloc_path();
2061         if (path == NULL)
2062                 return -ENOMEM;
2063
2064         if (buffer_nilfs_node(bh)) {
2065                 node = (struct nilfs_btree_node *)bh->b_data;
2066                 key = nilfs_btree_node_get_key(node, 0);
2067                 level = nilfs_btree_node_get_level(node);
2068         } else {
2069                 key = nilfs_bmap_data_get_key(btree, bh);
2070                 level = NILFS_BTREE_LEVEL_DATA;
2071         }
2072
2073         ret = nilfs_btree_do_lookup(btree, path, key, NULL, level + 1, 0);
2074         if (ret < 0) {
2075                 if (unlikely(ret == -ENOENT))
2076                         printk(KERN_CRIT "%s: key = %llu, level == %d\n",
2077                                __func__, (unsigned long long)key, level);
2078                 goto out;
2079         }
2080
2081         ret = NILFS_BMAP_USE_VBN(btree) ?
2082                 nilfs_btree_propagate_v(btree, path, level, bh) :
2083                 nilfs_btree_propagate_p(btree, path, level, bh);
2084
2085  out:
2086         nilfs_btree_free_path(path);
2087
2088         return ret;
2089 }
2090
2091 static int nilfs_btree_propagate_gc(struct nilfs_bmap *btree,
2092                                     struct buffer_head *bh)
2093 {
2094         return nilfs_dat_mark_dirty(nilfs_bmap_get_dat(btree), bh->b_blocknr);
2095 }
2096
2097 static void nilfs_btree_add_dirty_buffer(struct nilfs_bmap *btree,
2098                                          struct list_head *lists,
2099                                          struct buffer_head *bh)
2100 {
2101         struct list_head *head;
2102         struct buffer_head *cbh;
2103         struct nilfs_btree_node *node, *cnode;
2104         __u64 key, ckey;
2105         int level;
2106
2107         get_bh(bh);
2108         node = (struct nilfs_btree_node *)bh->b_data;
2109         key = nilfs_btree_node_get_key(node, 0);
2110         level = nilfs_btree_node_get_level(node);
2111         if (level < NILFS_BTREE_LEVEL_NODE_MIN ||
2112             level >= NILFS_BTREE_LEVEL_MAX) {
2113                 dump_stack();
2114                 printk(KERN_WARNING
2115                        "%s: invalid btree level: %d (key=%llu, ino=%lu, "
2116                        "blocknr=%llu)\n",
2117                        __func__, level, (unsigned long long)key,
2118                        NILFS_BMAP_I(btree)->vfs_inode.i_ino,
2119                        (unsigned long long)bh->b_blocknr);
2120                 return;
2121         }
2122
2123         list_for_each(head, &lists[level]) {
2124                 cbh = list_entry(head, struct buffer_head, b_assoc_buffers);
2125                 cnode = (struct nilfs_btree_node *)cbh->b_data;
2126                 ckey = nilfs_btree_node_get_key(cnode, 0);
2127                 if (key < ckey)
2128                         break;
2129         }
2130         list_add_tail(&bh->b_assoc_buffers, head);
2131 }
2132
2133 static void nilfs_btree_lookup_dirty_buffers(struct nilfs_bmap *btree,
2134                                              struct list_head *listp)
2135 {
2136         struct address_space *btcache = &NILFS_BMAP_I(btree)->i_btnode_cache;
2137         struct list_head lists[NILFS_BTREE_LEVEL_MAX];
2138         struct pagevec pvec;
2139         struct buffer_head *bh, *head;
2140         pgoff_t index = 0;
2141         int level, i;
2142
2143         for (level = NILFS_BTREE_LEVEL_NODE_MIN;
2144              level < NILFS_BTREE_LEVEL_MAX;
2145              level++)
2146                 INIT_LIST_HEAD(&lists[level]);
2147
2148         pagevec_init(&pvec, 0);
2149
2150         while (pagevec_lookup_tag(&pvec, btcache, &index, PAGECACHE_TAG_DIRTY,
2151                                   PAGEVEC_SIZE)) {
2152                 for (i = 0; i < pagevec_count(&pvec); i++) {
2153                         bh = head = page_buffers(pvec.pages[i]);
2154                         do {
2155                                 if (buffer_dirty(bh))
2156                                         nilfs_btree_add_dirty_buffer(btree,
2157                                                                      lists, bh);
2158                         } while ((bh = bh->b_this_page) != head);
2159                 }
2160                 pagevec_release(&pvec);
2161                 cond_resched();
2162         }
2163
2164         for (level = NILFS_BTREE_LEVEL_NODE_MIN;
2165              level < NILFS_BTREE_LEVEL_MAX;
2166              level++)
2167                 list_splice_tail(&lists[level], listp);
2168 }
2169
2170 static int nilfs_btree_assign_p(struct nilfs_bmap *btree,
2171                                 struct nilfs_btree_path *path,
2172                                 int level,
2173                                 struct buffer_head **bh,
2174                                 sector_t blocknr,
2175                                 union nilfs_binfo *binfo)
2176 {
2177         struct nilfs_btree_node *parent;
2178         __u64 key;
2179         __u64 ptr;
2180         int ncmax, ret;
2181
2182         parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
2183         ptr = nilfs_btree_node_get_ptr(parent, path[level + 1].bp_index,
2184                                        ncmax);
2185         if (buffer_nilfs_node(*bh)) {
2186                 path[level].bp_ctxt.oldkey = ptr;
2187                 path[level].bp_ctxt.newkey = blocknr;
2188                 path[level].bp_ctxt.bh = *bh;
2189                 ret = nilfs_btnode_prepare_change_key(
2190                         &NILFS_BMAP_I(btree)->i_btnode_cache,
2191                         &path[level].bp_ctxt);
2192                 if (ret < 0)
2193                         return ret;
2194                 nilfs_btnode_commit_change_key(
2195                         &NILFS_BMAP_I(btree)->i_btnode_cache,
2196                         &path[level].bp_ctxt);
2197                 *bh = path[level].bp_ctxt.bh;
2198         }
2199
2200         nilfs_btree_node_set_ptr(parent, path[level + 1].bp_index, blocknr,
2201                                  ncmax);
2202
2203         key = nilfs_btree_node_get_key(parent, path[level + 1].bp_index);
2204         /* on-disk format */
2205         binfo->bi_dat.bi_blkoff = cpu_to_le64(key);
2206         binfo->bi_dat.bi_level = level;
2207
2208         return 0;
2209 }
2210
2211 static int nilfs_btree_assign_v(struct nilfs_bmap *btree,
2212                                 struct nilfs_btree_path *path,
2213                                 int level,
2214                                 struct buffer_head **bh,
2215                                 sector_t blocknr,
2216                                 union nilfs_binfo *binfo)
2217 {
2218         struct nilfs_btree_node *parent;
2219         struct inode *dat = nilfs_bmap_get_dat(btree);
2220         __u64 key;
2221         __u64 ptr;
2222         union nilfs_bmap_ptr_req req;
2223         int ncmax, ret;
2224
2225         parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
2226         ptr = nilfs_btree_node_get_ptr(parent, path[level + 1].bp_index,
2227                                        ncmax);
2228         req.bpr_ptr = ptr;
2229         ret = nilfs_dat_prepare_start(dat, &req.bpr_req);
2230         if (ret < 0)
2231                 return ret;
2232         nilfs_dat_commit_start(dat, &req.bpr_req, blocknr);
2233
2234         key = nilfs_btree_node_get_key(parent, path[level + 1].bp_index);
2235         /* on-disk format */
2236         binfo->bi_v.bi_vblocknr = cpu_to_le64(ptr);
2237         binfo->bi_v.bi_blkoff = cpu_to_le64(key);
2238
2239         return 0;
2240 }
2241
2242 static int nilfs_btree_assign(struct nilfs_bmap *btree,
2243                               struct buffer_head **bh,
2244                               sector_t blocknr,
2245                               union nilfs_binfo *binfo)
2246 {
2247         struct nilfs_btree_path *path;
2248         struct nilfs_btree_node *node;
2249         __u64 key;
2250         int level, ret;
2251
2252         path = nilfs_btree_alloc_path();
2253         if (path == NULL)
2254                 return -ENOMEM;
2255
2256         if (buffer_nilfs_node(*bh)) {
2257                 node = (struct nilfs_btree_node *)(*bh)->b_data;
2258                 key = nilfs_btree_node_get_key(node, 0);
2259                 level = nilfs_btree_node_get_level(node);
2260         } else {
2261                 key = nilfs_bmap_data_get_key(btree, *bh);
2262                 level = NILFS_BTREE_LEVEL_DATA;
2263         }
2264
2265         ret = nilfs_btree_do_lookup(btree, path, key, NULL, level + 1, 0);
2266         if (ret < 0) {
2267                 WARN_ON(ret == -ENOENT);
2268                 goto out;
2269         }
2270
2271         ret = NILFS_BMAP_USE_VBN(btree) ?
2272                 nilfs_btree_assign_v(btree, path, level, bh, blocknr, binfo) :
2273                 nilfs_btree_assign_p(btree, path, level, bh, blocknr, binfo);
2274
2275  out:
2276         nilfs_btree_free_path(path);
2277
2278         return ret;
2279 }
2280
2281 static int nilfs_btree_assign_gc(struct nilfs_bmap *btree,
2282                                  struct buffer_head **bh,
2283                                  sector_t blocknr,
2284                                  union nilfs_binfo *binfo)
2285 {
2286         struct nilfs_btree_node *node;
2287         __u64 key;
2288         int ret;
2289
2290         ret = nilfs_dat_move(nilfs_bmap_get_dat(btree), (*bh)->b_blocknr,
2291                              blocknr);
2292         if (ret < 0)
2293                 return ret;
2294
2295         if (buffer_nilfs_node(*bh)) {
2296                 node = (struct nilfs_btree_node *)(*bh)->b_data;
2297                 key = nilfs_btree_node_get_key(node, 0);
2298         } else
2299                 key = nilfs_bmap_data_get_key(btree, *bh);
2300
2301         /* on-disk format */
2302         binfo->bi_v.bi_vblocknr = cpu_to_le64((*bh)->b_blocknr);
2303         binfo->bi_v.bi_blkoff = cpu_to_le64(key);
2304
2305         return 0;
2306 }
2307
2308 static int nilfs_btree_mark(struct nilfs_bmap *btree, __u64 key, int level)
2309 {
2310         struct buffer_head *bh;
2311         struct nilfs_btree_path *path;
2312         __u64 ptr;
2313         int ret;
2314
2315         path = nilfs_btree_alloc_path();
2316         if (path == NULL)
2317                 return -ENOMEM;
2318
2319         ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level + 1, 0);
2320         if (ret < 0) {
2321                 WARN_ON(ret == -ENOENT);
2322                 goto out;
2323         }
2324         ret = nilfs_btree_get_block(btree, ptr, &bh);
2325         if (ret < 0) {
2326                 WARN_ON(ret == -ENOENT);
2327                 goto out;
2328         }
2329
2330         if (!buffer_dirty(bh))
2331                 mark_buffer_dirty(bh);
2332         brelse(bh);
2333         if (!nilfs_bmap_dirty(btree))
2334                 nilfs_bmap_set_dirty(btree);
2335
2336  out:
2337         nilfs_btree_free_path(path);
2338         return ret;
2339 }
2340
2341 static const struct nilfs_bmap_operations nilfs_btree_ops = {
2342         .bop_lookup             =       nilfs_btree_lookup,
2343         .bop_lookup_contig      =       nilfs_btree_lookup_contig,
2344         .bop_insert             =       nilfs_btree_insert,
2345         .bop_delete             =       nilfs_btree_delete,
2346         .bop_clear              =       NULL,
2347
2348         .bop_propagate          =       nilfs_btree_propagate,
2349
2350         .bop_lookup_dirty_buffers =     nilfs_btree_lookup_dirty_buffers,
2351
2352         .bop_assign             =       nilfs_btree_assign,
2353         .bop_mark               =       nilfs_btree_mark,
2354
2355         .bop_seek_key           =       nilfs_btree_seek_key,
2356         .bop_last_key           =       nilfs_btree_last_key,
2357
2358         .bop_check_insert       =       NULL,
2359         .bop_check_delete       =       nilfs_btree_check_delete,
2360         .bop_gather_data        =       nilfs_btree_gather_data,
2361 };
2362
2363 static const struct nilfs_bmap_operations nilfs_btree_ops_gc = {
2364         .bop_lookup             =       NULL,
2365         .bop_lookup_contig      =       NULL,
2366         .bop_insert             =       NULL,
2367         .bop_delete             =       NULL,
2368         .bop_clear              =       NULL,
2369
2370         .bop_propagate          =       nilfs_btree_propagate_gc,
2371
2372         .bop_lookup_dirty_buffers =     nilfs_btree_lookup_dirty_buffers,
2373
2374         .bop_assign             =       nilfs_btree_assign_gc,
2375         .bop_mark               =       NULL,
2376
2377         .bop_seek_key           =       NULL,
2378         .bop_last_key           =       NULL,
2379
2380         .bop_check_insert       =       NULL,
2381         .bop_check_delete       =       NULL,
2382         .bop_gather_data        =       NULL,
2383 };
2384
2385 static void __nilfs_btree_init(struct nilfs_bmap *bmap)
2386 {
2387         bmap->b_ops = &nilfs_btree_ops;
2388         bmap->b_nchildren_per_block =
2389                 NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(bmap));
2390 }
2391
2392 int nilfs_btree_init(struct nilfs_bmap *bmap)
2393 {
2394         int ret = 0;
2395
2396         __nilfs_btree_init(bmap);
2397
2398         if (nilfs_btree_root_broken(nilfs_btree_get_root(bmap),
2399                                     bmap->b_inode->i_ino))
2400                 ret = -EIO;
2401         return ret;
2402 }
2403
2404 void nilfs_btree_init_gc(struct nilfs_bmap *bmap)
2405 {
2406         bmap->b_ops = &nilfs_btree_ops_gc;
2407         bmap->b_nchildren_per_block =
2408                 NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(bmap));
2409 }