lustre/osd-ldiskfs/osd_iam_lfix.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   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 version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see [sun.com URL with a
  18  * copy of GPLv2].
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2012 Whamcloud, Inc.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * iam_lfix.c
  37  * implementation of iam format for fixed size records.
  38  *
  39  * Author: Wang Di <wangdi@clusterfs.com>
  40  * Author: Nikita Danilov <nikita@clusterfs.com>
  41  */
  42
  43 #include <linux/types.h>
  44 #include "osd_internal.h"
  45
  46 /*
  47  * Leaf operations.
  48  */
  49
  50 enum {
  51         IAM_LEAF_HEADER_MAGIC = 0x1976 /* This is duplicated in
  52                                         * lustre/utils/create_iam.c */
  53 };
  54
  55 /* This is duplicated in lustre/utils/create_iam.c */
  56 struct iam_leaf_head {
  57         __le16 ill_magic;
  58         __le16 ill_count;
  59 };
  60
  61 static inline int iam_lfix_entry_size(const struct iam_leaf *l)
  62 {
  63         return iam_leaf_descr(l)->id_key_size + iam_leaf_descr(l)->id_rec_size;
  64 }
  65
  66 static inline struct iam_lentry *
  67 iam_lfix_shift(const struct iam_leaf *l, struct iam_lentry *entry, int shift)
  68 {
  69         return (void *)entry + shift * iam_lfix_entry_size(l);
  70 }
  71
  72 static inline struct iam_key *iam_leaf_key_at(struct iam_lentry *entry)
  73 {
  74         return (struct iam_key *)entry;
  75 }
  76
  77 static inline int lfix_keycmp(const struct iam_container *c,
  78                               const struct iam_key *k1,
  79                               const struct iam_key *k2)
  80 {
  81         return memcmp(k1, k2, c->ic_descr->id_key_size);
  82 }
  83
  84 static struct iam_leaf_head *iam_get_head(const struct iam_leaf *l)
  85 {
  86         return (struct iam_leaf_head *)l->il_bh->b_data;
  87 }
  88
  89 static struct iam_lentry *iam_entries(const struct buffer_head *bh)
  90 {
  91         return (void *)bh->b_data + sizeof(struct iam_leaf_head);
  92 }
  93
  94 static struct iam_lentry *iam_get_lentries(const struct iam_leaf *l)
  95 {
  96         return iam_entries(l->il_bh);
  97 }
  98
  99 static int leaf_count_limit(const struct iam_leaf *leaf)
 100 {
 101         int free_space;
 102
 103         free_space = iam_leaf_container(leaf)->ic_object->i_sb->s_blocksize;
 104         free_space -= sizeof(struct iam_leaf_head);
 105         return free_space / iam_lfix_entry_size(leaf);
 106 }
 107
 108 static int lentry_count_get(const struct iam_leaf *leaf)
 109 {
 110         return le16_to_cpu(iam_get_head(leaf)->ill_count);
 111 }
 112
 113 static void lentry_count_set(struct iam_leaf *leaf, unsigned count)
 114 {
 115         assert_corr(0 <= count && count <= leaf_count_limit(leaf));
 116         iam_get_head(leaf)->ill_count = cpu_to_le16(count);
 117 }
 118
 119 static struct iam_lentry *iam_lfix_get_end(const struct iam_leaf *l);
 120
 121 #if LDISKFS_CORRECTNESS_ON || LDISKFS_INVARIANT_ON
 122 static int iam_leaf_at_rec(const struct iam_leaf *folio)
 123 {
 124         return
 125                 iam_get_lentries(folio) <= folio->il_at &&
 126                 folio->il_at < iam_lfix_get_end(folio);
 127 }
 128 #endif
 129
 130 static struct iam_ikey *iam_lfix_ikey(const struct iam_leaf *l,
 131                                       struct iam_ikey *key)
 132 {
 133         void *ie = l->il_at;
 134         assert_corr(iam_leaf_at_rec(l));
 135         return (struct iam_ikey*)ie;
 136 }
 137
 138 static struct iam_key *iam_lfix_key(const struct iam_leaf *l)
 139 {
 140         void *ie = l->il_at;
 141         assert_corr(iam_leaf_at_rec(l));
 142         return (struct iam_key*)ie;
 143 }
 144
 145 static int iam_lfix_key_size(const struct iam_leaf *l)
 146 {
 147         return iam_leaf_descr(l)->id_key_size;
 148 }
 149
 150 static void iam_lfix_start(struct iam_leaf *l)
 151 {
 152         l->il_at = iam_get_lentries(l);
 153 }
 154
 155 static inline ptrdiff_t iam_lfix_diff(const struct iam_leaf *l,
 156                                       const struct iam_lentry *e1,
 157                                       const struct iam_lentry *e2)
 158 {
 159         ptrdiff_t diff;
 160         int esize;
 161
 162         esize = iam_lfix_entry_size(l);
 163         diff = (void *)e1 - (void *)e2;
 164         assert_corr(diff / esize * esize == diff);
 165         return diff / esize;
 166 }
 167
 168 static int iam_lfix_init(struct iam_leaf *l)
 169 {
 170         int result;
 171         struct iam_leaf_head *ill;
 172         int count;
 173
 174         assert_corr(l->il_bh != NULL);
 175
 176         ill = iam_get_head(l);
 177         count = le16_to_cpu(ill->ill_count);
 178         if (ill->ill_magic == le16_to_cpu(IAM_LEAF_HEADER_MAGIC) &&
 179             0 <= count && count <= leaf_count_limit(l)) {
 180                 l->il_at = l->il_entries = iam_get_lentries(l);
 181                 result = 0;
 182         } else {
 183                 struct inode *obj;
 184
 185                 obj = iam_leaf_container(l)->ic_object;
 186                 CERROR("Wrong magic in node %llu (#%lu): %#x != %#x or "
 187                        "wrong count: %d (%d)\n",
 188                        (unsigned long long)l->il_bh->b_blocknr, obj->i_ino,
 189                        ill->ill_magic, le16_to_cpu(IAM_LEAF_HEADER_MAGIC),
 190                        count, leaf_count_limit(l));
 191                 result = -EIO;
 192         }
 193         return result;
 194 }
 195
 196 static void iam_lfix_fini(struct iam_leaf *l)
 197 {
 198         l->il_entries = l->il_at = NULL;
 199 }
 200
 201 static struct iam_lentry *iam_lfix_get_end(const struct iam_leaf *l)
 202 {
 203         int count = lentry_count_get(l);
 204         struct iam_lentry *ile = iam_lfix_shift(l, l->il_entries, count);
 205
 206         return ile;
 207 }
 208
 209 struct iam_rec *iam_lfix_rec(const struct iam_leaf *l)
 210 {
 211         void *e = l->il_at;
 212         assert_corr(iam_leaf_at_rec(l));
 213         return e + iam_leaf_descr(l)->id_key_size;
 214 }
 215
 216 static void iam_lfix_next(struct iam_leaf *l)
 217 {
 218         assert_corr(iam_leaf_at_rec(l));
 219         l->il_at = iam_lfix_shift(l, l->il_at, 1);
 220 }
 221
 222 /*
 223  * Bug chasing.
 224  */
 225 int lfix_dump = 0;
 226 EXPORT_SYMBOL(lfix_dump);
 227
 228 static char hdigit(char ch)
 229 {
 230         static char d[] = "0123456789abcdef";
 231         return d[ch & 0xf];
 232 }
 233
 234 static char *hex(char ch, char *area)
 235 {
 236         area[0] = hdigit(ch >> 4);
 237         area[1] = hdigit(ch);
 238         area[2] = 0;
 239         return area;
 240 }
 241
 242 static void l_print(struct iam_leaf *leaf, struct iam_lentry *entry)
 243 {
 244         int i;
 245         char *area;
 246         char h[3];
 247
 248         area = (char *)entry;
 249         printk(CFS_KERN_EMERG "[");
 250         for (i = iam_lfix_key_size(leaf); i > 0; --i, ++area)
 251                 printk("%s", hex(*area, h));
 252         printk("]-(");
 253         for (i = iam_leaf_descr(leaf)->id_rec_size; i > 0; --i, ++area)
 254                 printk("%s", hex(*area, h));
 255         printk(")\n");
 256 }
 257
 258 static void lfix_print(struct iam_leaf *leaf)
 259 {
 260         struct iam_lentry *entry;
 261         int count;
 262         int i;
 263
 264         entry = leaf->il_entries;
 265         count = lentry_count_get(leaf);
 266         printk(CFS_KERN_EMERG "lfix: %p %p %d\n", leaf, leaf->il_at, count);
 267         for (i = 0; i < count; ++i, entry = iam_lfix_shift(leaf, entry, 1))
 268                 l_print(leaf, entry);
 269 }
 270
 271 static int iam_lfix_lookup(struct iam_leaf *l, const struct iam_key *k)
 272 {
 273         struct iam_lentry *p, *q, *m, *t;
 274         struct iam_container *c;
 275         int count;
 276         int result;
 277
 278         count = lentry_count_get(l);
 279         if (count == 0)
 280                 return IAM_LOOKUP_EMPTY;
 281
 282         result = IAM_LOOKUP_OK;
 283         c = iam_leaf_container(l);
 284
 285         p = l->il_entries;
 286         q = iam_lfix_shift(l, p, count - 1);
 287         if (lfix_keycmp(c, k, iam_leaf_key_at(p)) < 0) {
 288                 /*
 289                  * @k is less than the least key in the leaf
 290                  */
 291                 l->il_at = p;
 292                 result = IAM_LOOKUP_BEFORE;
 293         } else if (lfix_keycmp(c, iam_leaf_key_at(q), k) <= 0) {
 294                 l->il_at = q;
 295         } else {
 296                 /*
 297                  * EWD1293
 298                  */
 299                 while (iam_lfix_shift(l, p, 1) != q) {
 300                         m = iam_lfix_shift(l, p, iam_lfix_diff(l, q, p) / 2);
 301                         assert_corr(p < m && m < q);
 302                         if (lfix_keycmp(c, iam_leaf_key_at(m), k) <= 0)
 303                                 p = m;
 304                         else
 305                                 q = m;
 306                 }
 307                 assert_corr(lfix_keycmp(c, iam_leaf_key_at(p), k) <= 0 &&
 308                             lfix_keycmp(c, k, iam_leaf_key_at(q)) < 0);
 309                 /*
 310                  * skip over records with duplicate keys.
 311                  */
 312                 while (p > l->il_entries) {
 313                         t = iam_lfix_shift(l, p, -1);
 314                         if (lfix_keycmp(c, iam_leaf_key_at(t), k) == 0)
 315                                 p = t;
 316                         else
 317                                 break;
 318                 }
 319                 l->il_at = p;
 320         }
 321         assert_corr(iam_leaf_at_rec(l));
 322
 323         if (lfix_keycmp(c, iam_leaf_key_at(l->il_at), k) == 0)
 324                 result = IAM_LOOKUP_EXACT;
 325
 326         if (lfix_dump)
 327                 lfix_print(l);
 328
 329         return result;
 330 }
 331
 332 static int iam_lfix_ilookup(struct iam_leaf *l, const struct iam_ikey *ik)
 333 {
 334         assert(0);
 335         return IAM_LOOKUP_OK;
 336 }
 337
 338 static void iam_lfix_key_set(struct iam_leaf *l, const struct iam_key *k)
 339 {
 340         assert_corr(iam_leaf_at_rec(l));
 341         memcpy(iam_leaf_key_at(l->il_at), k, iam_leaf_descr(l)->id_key_size);
 342 }
 343
 344 static int iam_lfix_key_cmp(const struct iam_leaf *l, const struct iam_key *k)
 345 {
 346         return lfix_keycmp(iam_leaf_container(l), iam_leaf_key_at(l->il_at), k);
 347 }
 348
 349 static int iam_lfix_key_eq(const struct iam_leaf *l, const struct iam_key *k)
 350 {
 351         return !lfix_keycmp(iam_leaf_container(l),
 352                             iam_leaf_key_at(l->il_at), k);
 353 }
 354
 355 static void iam_lfix_rec_set(struct iam_leaf *l, const struct iam_rec *r)
 356 {
 357         assert_corr(iam_leaf_at_rec(l));
 358         memcpy(iam_lfix_rec(l), r, iam_leaf_descr(l)->id_rec_size);
 359 }
 360
 361 static inline int lfix_reccmp(const struct iam_container *c,
 362                               const struct iam_rec *r1,
 363                               const struct iam_rec *r2)
 364 {
 365         return memcmp(r1, r2, c->ic_descr->id_rec_size);
 366 }
 367
 368 static int iam_lfix_rec_eq(const struct iam_leaf *l, const struct iam_rec *r)
 369 {
 370         return !lfix_reccmp(iam_leaf_container(l), iam_lfix_rec(l), r);
 371 }
 372
 373 static void iam_lfix_rec_get(const struct iam_leaf *l, struct iam_rec *r)
 374 {
 375         assert_corr(iam_leaf_at_rec(l));
 376         memcpy(r, iam_lfix_rec(l), iam_leaf_descr(l)->id_rec_size);
 377 }
 378
 379 static void iam_lfix_rec_add(struct iam_leaf *leaf,
 380                              const struct iam_key *k, const struct iam_rec *r)
 381 {
 382         struct iam_lentry *end;
 383         struct iam_lentry *cur;
 384         struct iam_lentry *start;
 385         ptrdiff_t diff;
 386         int count;
 387
 388         assert_corr(iam_leaf_can_add(leaf, k, r));
 389
 390         count = lentry_count_get(leaf);
 391         /*
 392          * This branch handles two exceptional cases:
 393          *
 394          *   - leaf positioned beyond last record, and
 395          *
 396          *   - empty leaf.
 397          */
 398         if (!iam_leaf_at_end(leaf)) {
 399                 end   = iam_lfix_get_end(leaf);
 400                 cur   = leaf->il_at;
 401                 if (lfix_keycmp(iam_leaf_container(leaf),
 402                                k, iam_leaf_key_at(cur)) >= 0)
 403                         iam_lfix_next(leaf);
 404                 else
 405                         /*
 406                          * Another exceptional case: insertion with the key
 407                          * less than least key in the leaf.
 408                          */
 409                         assert_corr(cur == leaf->il_entries);
 410
 411                 start = leaf->il_at;
 412                 diff  = (void *)end - (void *)start;
 413                 assert_corr(diff >= 0);
 414                 memmove(iam_lfix_shift(leaf, start, 1), start, diff);
 415         }
 416         lentry_count_set(leaf, count + 1);
 417         iam_lfix_key_set(leaf, k);
 418         iam_lfix_rec_set(leaf, r);
 419         assert_corr(iam_leaf_at_rec(leaf));
 420 }
 421
 422 static void iam_lfix_rec_del(struct iam_leaf *leaf, int shift)
 423 {
 424         struct iam_lentry *next, *end;
 425         int count;
 426         ptrdiff_t diff;
 427
 428         assert_corr(iam_leaf_at_rec(leaf));
 429
 430         count = lentry_count_get(leaf);
 431         end = iam_lfix_get_end(leaf);
 432         next = iam_lfix_shift(leaf, leaf->il_at, 1);
 433         diff = (void *)end - (void *)next;
 434         memmove(leaf->il_at, next, diff);
 435
 436         lentry_count_set(leaf, count - 1);
 437 }
 438
 439 static int iam_lfix_can_add(const struct iam_leaf *l,
 440                             const struct iam_key *k, const struct iam_rec *r)
 441 {
 442         return lentry_count_get(l) < leaf_count_limit(l);
 443 }
 444
 445 static int iam_lfix_at_end(const struct iam_leaf *folio)
 446 {
 447         return folio->il_at == iam_lfix_get_end(folio);
 448 }
 449
 450 static void iam_lfix_init_new(struct iam_container *c, struct buffer_head *bh)
 451 {
 452         struct iam_leaf_head *hdr;
 453
 454         hdr = (struct iam_leaf_head*)bh->b_data;
 455         hdr->ill_magic = cpu_to_le16(IAM_LEAF_HEADER_MAGIC);
 456         hdr->ill_count = cpu_to_le16(0);
 457 }
 458
 459 static void iam_lfix_split(struct iam_leaf *l, struct buffer_head **bh,
 460                            iam_ptr_t new_blknr)
 461 {
 462         struct iam_path       *path;
 463         struct iam_leaf_head  *hdr;
 464         const struct iam_ikey *pivot;
 465         struct buffer_head    *new_leaf;
 466
 467         unsigned count;
 468         unsigned split;
 469
 470         void *start;
 471         void *finis;
 472
 473         new_leaf = *bh;
 474         path = iam_leaf_path(l);
 475
 476         hdr = (void *)new_leaf->b_data;
 477
 478         count = lentry_count_get(l);
 479         split = count / 2;
 480
 481         start = iam_lfix_shift(l, iam_get_lentries(l), split);
 482         finis = iam_lfix_shift(l, iam_get_lentries(l), count);
 483
 484         pivot = (const struct iam_ikey *)iam_leaf_key_at(start);
 485
 486         memmove(iam_entries(new_leaf), start, finis - start);
 487         hdr->ill_count = count - split;
 488         lentry_count_set(l, split);
 489         if ((void *)l->il_at >= start) {
 490                 /*
 491                  * insertion point moves into new leaf.
 492                  */
 493                 int shift;
 494                 int result;
 495
 496                 shift = iam_lfix_diff(l, l->il_at, start);
 497                 *bh = l->il_bh;
 498                 l->il_bh = new_leaf;
 499                 l->il_curidx = new_blknr;
 500                 result = iam_lfix_init(l);
 501                 /*
 502                  * init cannot fail, as node was just initialized.
 503                  */
 504                 assert_corr(result == 0);
 505                 l->il_at = iam_lfix_shift(l, iam_get_lentries(l), shift);
 506         }
 507         /*
 508          * Insert pointer to the new node (together with the least key in
 509          * the node) into index node.
 510          */
 511         iam_insert_key_lock(path, path->ip_frame, pivot, new_blknr);
 512 }
 513
 514 static struct iam_leaf_operations iam_lfix_leaf_ops = {
 515         .init           = iam_lfix_init,
 516         .init_new       = iam_lfix_init_new,
 517         .fini           = iam_lfix_fini,
 518         .start          = iam_lfix_start,
 519         .next           = iam_lfix_next,
 520         .key            = iam_lfix_key,
 521         .ikey           = iam_lfix_ikey,
 522         .rec            = iam_lfix_rec,
 523         .key_set        = iam_lfix_key_set,
 524         .key_cmp        = iam_lfix_key_cmp,
 525         .key_eq         = iam_lfix_key_eq,
 526         .key_size       = iam_lfix_key_size,
 527         .rec_set        = iam_lfix_rec_set,
 528         .rec_eq         = iam_lfix_rec_eq,
 529         .rec_get        = iam_lfix_rec_get,
 530         .lookup         = iam_lfix_lookup,
 531         .ilookup        = iam_lfix_ilookup,
 532         .at_end         = iam_lfix_at_end,
 533         .rec_add        = iam_lfix_rec_add,
 534         .rec_del        = iam_lfix_rec_del,
 535         .can_add        = iam_lfix_can_add,
 536         .split          = iam_lfix_split
 537 };
 538
 539 /*
 540  * Index operations.
 541  */
 542
 543 enum {
 544         /* This is duplicated in lustre/utils/create_iam.c */
 545         /*
 546          * Then shalt thou see the dew-BEDABBLED wretch
 547          * Turn, and return, indenting with the way;
 548          * Each envious brier his weary legs doth scratch,
 549          * Each shadow makes him stop, each murmur stay:
 550          * For misery is trodden on by many,
 551          * And being low never relieved by any.
 552          */
 553         IAM_LFIX_ROOT_MAGIC = 0xbedabb1edULL // d01efull
 554 };
 555
 556 /* This is duplicated in lustre/utils/create_iam.c */
 557 struct iam_lfix_root {
 558         __le64  ilr_magic;
 559         __le16  ilr_keysize;
 560         __le16  ilr_recsize;
 561         __le16  ilr_ptrsize;
 562         u8      ilr_indirect_levels;
 563         u8      ilr_padding;
 564 };
 565
 566 static __u32 iam_lfix_root_ptr(struct iam_container *c)
 567 {
 568         return 0;
 569 }
 570
 571 static int iam_lfix_node_init(struct iam_container *c, struct buffer_head *bh,
 572                               int root)
 573 {
 574         return 0;
 575 }
 576
 577 static struct iam_entry *iam_lfix_root_inc(struct iam_container *c,
 578                                            struct iam_path *path,
 579                                            struct iam_frame *frame)
 580 {
 581         struct iam_lfix_root *root;
 582         struct iam_entry     *entries;
 583
 584         entries = frame->entries;
 585
 586         dx_set_count(entries, 2);
 587         assert_corr(dx_get_limit(entries) == dx_root_limit(path));
 588
 589         root = (void *)frame->bh->b_data;
 590         assert_corr(le64_to_cpu(root->ilr_magic) == IAM_LFIX_ROOT_MAGIC);
 591         root->ilr_indirect_levels ++;
 592         frame->at = entries = iam_entry_shift(path, entries, 1);
 593         memset(iam_ikey_at(path, entries), 0,
 594                iam_path_descr(path)->id_ikey_size);
 595         return entries;
 596 }
 597
 598 static int iam_lfix_node_check(struct iam_path *path, struct iam_frame *frame)
 599 {
 600         unsigned count;
 601         unsigned limit;
 602         unsigned limit_correct;
 603         struct iam_entry *entries;
 604
 605         entries = dx_node_get_entries(path, frame);
 606
 607         if (frame == path->ip_frames) {
 608                 struct iam_lfix_root *root;
 609
 610                 root = (void *)frame->bh->b_data;
 611                 if (le64_to_cpu(root->ilr_magic) != IAM_LFIX_ROOT_MAGIC) {
 612                         return -EIO;
 613                 }
 614                 limit_correct = dx_root_limit(path);
 615         } else
 616                 limit_correct = dx_node_limit(path);
 617         count = dx_get_count(entries);
 618         limit = dx_get_limit(entries);
 619         if (count > limit) {
 620                 return -EIO;
 621         }
 622         if (limit != limit_correct) {
 623                 return -EIO;
 624         }
 625         return 0;
 626 }
 627
 628 static int iam_lfix_node_load(struct iam_path *path, struct iam_frame *frame)
 629 {
 630         struct iam_entry *entries;
 631         void *data;
 632         entries = dx_node_get_entries(path, frame);
 633
 634         data = frame->bh->b_data;
 635
 636         if (frame == path->ip_frames) {
 637                 struct iam_lfix_root *root;
 638
 639                 root = data;
 640                 path->ip_indirect = root->ilr_indirect_levels;
 641                 if (path->ip_ikey_target == NULL)
 642                         path->ip_ikey_target =
 643                                 (struct iam_ikey *)path->ip_key_target;
 644         }
 645         frame->entries = frame->at = entries;
 646         return 0;
 647 }
 648
 649 static int iam_lfix_ikeycmp(const struct iam_container *c,
 650                             const struct iam_ikey *k1,
 651                             const struct iam_ikey *k2)
 652 {
 653         return memcmp(k1, k2, c->ic_descr->id_ikey_size);
 654 }
 655
 656 static struct iam_path_descr *iam_lfix_ipd_alloc(const struct iam_container *c,
 657                                                  void *area)
 658 {
 659         return iam_ipd_alloc(area, c->ic_descr->id_ikey_size);
 660 }
 661
 662 static struct iam_operations iam_lfix_ops = {
 663         .id_root_ptr    = iam_lfix_root_ptr,
 664         .id_node_read   = iam_node_read,
 665         .id_node_init   = iam_lfix_node_init,
 666         .id_node_check  = iam_lfix_node_check,
 667         .id_node_load   = iam_lfix_node_load,
 668         .id_ikeycmp     = iam_lfix_ikeycmp,
 669         .id_root_inc    = iam_lfix_root_inc,
 670         .id_ipd_alloc   = iam_lfix_ipd_alloc,
 671         .id_ipd_free    = iam_ipd_free,
 672         .id_name        = "lfix"
 673 };
 674
 675 static int iam_lfix_guess(struct iam_container *c)
 676 {
 677         int result;
 678         struct buffer_head *bh;
 679         const struct iam_lfix_root *root;
 680
 681         assert_corr(c->ic_object != NULL);
 682
 683         result = iam_node_read(c, iam_lfix_root_ptr(c), NULL, &bh);
 684         if (result == 0) {
 685                 root = (void *)bh->b_data;
 686                 if (le64_to_cpu(root->ilr_magic) == IAM_LFIX_ROOT_MAGIC) {
 687                         struct iam_descr *descr;
 688
 689                         descr = c->ic_descr;
 690                         descr->id_key_size  = le16_to_cpu(root->ilr_keysize);
 691                         descr->id_ikey_size = le16_to_cpu(root->ilr_keysize);
 692                         descr->id_rec_size  = le16_to_cpu(root->ilr_recsize);
 693                         descr->id_ptr_size  = le16_to_cpu(root->ilr_ptrsize);
 694                         descr->id_root_gap  = sizeof(struct iam_lfix_root);
 695                         descr->id_node_gap  = 0;
 696                         descr->id_ops       = &iam_lfix_ops;
 697                         descr->id_leaf_ops  = &iam_lfix_leaf_ops;
 698                 } else
 699                         result = -EBADF;
 700                 brelse(bh);
 701         }
 702         return result;
 703 }
 704
 705 static struct iam_format iam_lfix_format = {
 706         .if_guess = iam_lfix_guess
 707 };
 708
 709 void iam_lfix_format_init(void)
 710 {
 711         iam_format_register(&iam_lfix_format);
 712 }
 713
 714 /*
 715  * Debugging aid.
 716  */
 717
 718 #define KEYSIZE (8)
 719 #define RECSIZE (8)
 720 #define PTRSIZE (4)
 721
 722 #define LFIX_ROOT_RECNO \
 723         ((4096 - sizeof(struct iam_lfix_root)) / (KEYSIZE + PTRSIZE))
 724
 725 #define LFIX_INDEX_RECNO (4096 / (KEYSIZE + PTRSIZE))
 726
 727 #define LFIX_LEAF_RECNO \
 728         ((4096 - sizeof(struct iam_leaf_head)) / (KEYSIZE + RECSIZE))
 729
 730 struct lfix_root {
 731         struct iam_lfix_root lr_root;
 732         struct {
 733                 char key[KEYSIZE];
 734                 char ptr[PTRSIZE];
 735         } lr_entry[LFIX_ROOT_RECNO];
 736 };
 737
 738 struct lfix_index {
 739         struct dx_countlimit li_cl;
 740         char   li_padding[KEYSIZE + PTRSIZE - sizeof(struct dx_countlimit)];
 741         struct {
 742                 char key[KEYSIZE];
 743                 char ptr[PTRSIZE];
 744         } li_entry[LFIX_INDEX_RECNO - 1];
 745 };
 746
 747 struct lfix_leaf {
 748         struct iam_leaf_head ll_head;
 749         struct {
 750                 char key[KEYSIZE];
 751                 char rec[RECSIZE];
 752         } ll_entry[LFIX_LEAF_RECNO];
 753 };
 754
 755 #define STORE_UNALIGNED(val, dst)                       \
 756 ({                                                      \
 757         typeof(val) __val = (val);                      \
 758         CLASSERT(sizeof(val) == sizeof(*(dst)));        \
 759         memcpy(dst, &__val, sizeof(*(dst)));            \
 760 })
 761
 762 static void lfix_root(void *buf,
 763                       int blocksize, int keysize, int ptrsize, int recsize)
 764 {
 765         struct iam_lfix_root *root;
 766         struct dx_countlimit *limit;
 767         void                 *entry;
 768
 769         root = buf;
 770         *root = (typeof(*root)) {
 771                 .ilr_magic           = cpu_to_le64(IAM_LFIX_ROOT_MAGIC),
 772                 .ilr_keysize         = cpu_to_le16(keysize),
 773                 .ilr_recsize         = cpu_to_le16(recsize),
 774                 .ilr_ptrsize         = cpu_to_le16(ptrsize),
 775                 .ilr_indirect_levels = 0
 776         };
 777
 778         limit = (void *)(root + 1);
 779         *limit = (typeof(*limit)){
 780                 /*
 781                  * limit itself + one pointer to the leaf.
 782                  */
 783                 .count = cpu_to_le16(2),
 784                 .limit = iam_root_limit(sizeof(struct iam_lfix_root),
 785                                         blocksize, keysize + ptrsize)
 786         };
 787
 788         entry = root + 1;
 789         /*
 790          * Skip over @limit.
 791          */
 792         entry += keysize + ptrsize;
 793
 794         /*
 795          * Entry format is <key> followed by <ptr>. In the minimal tree
 796          * consisting of a root and single node, <key> is a minimal possible
 797          * key.
 798          *
 799          * XXX: this key is hard-coded to be a sequence of 0's.
 800          */
 801
 802         entry += keysize;
 803         /* now @entry points to <ptr> */
 804         if (ptrsize == 4)
 805                 STORE_UNALIGNED(cpu_to_le32(1), (u_int32_t *)entry);
 806         else
 807                 STORE_UNALIGNED(cpu_to_le64(1), (u_int64_t *)entry);
 808 }
 809
 810 static void lfix_leaf(void *buf,
 811                       int blocksize, int keysize, int ptrsize, int recsize)
 812 {
 813         struct iam_leaf_head *head;
 814
 815         /* form leaf */
 816         head = buf;
 817         *head = (struct iam_leaf_head) {
 818                 .ill_magic = cpu_to_le16(IAM_LEAF_HEADER_MAGIC),
 819                 /*
 820                  * Leaf contains an entry with the smallest possible key
 821                  * (created by zeroing).
 822                  */
 823                 .ill_count = cpu_to_le16(1),
 824         };
 825 }
 826
 827 int iam_lfix_create(struct inode *obj,
 828                     int keysize, int ptrsize, int recsize, handle_t *handle)
 829 {
 830         struct buffer_head *root_node;
 831         struct buffer_head *leaf_node;
 832         struct super_block *sb;
 833
 834         u32 blknr;
 835         int result;
 836         unsigned long bsize;
 837
 838         assert_corr(obj->i_size == 0);
 839
 840         sb = obj->i_sb;
 841         bsize = sb->s_blocksize;
 842         root_node = ldiskfs_append(handle, obj, &blknr, &result);
 843         leaf_node = ldiskfs_append(handle, obj, &blknr, &result);
 844         if (root_node != NULL && leaf_node != NULL) {
 845                 lfix_root(root_node->b_data, bsize, keysize, ptrsize, recsize);
 846                 lfix_leaf(leaf_node->b_data, bsize, keysize, ptrsize, recsize);
 847                 ldiskfs_mark_inode_dirty(handle, obj);
 848                 result = ldiskfs_journal_dirty_metadata(handle, root_node);
 849                 if (result == 0)
 850                         result = ldiskfs_journal_dirty_metadata(handle, leaf_node);
 851                 if (result != 0)
 852                         ldiskfs_std_error(sb, result);
 853         }
 854         brelse(leaf_node);
 855         brelse(root_node);
 856         return result;
 857 }
 858 EXPORT_SYMBOL(iam_lfix_create);