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
  18  * http://www.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2012, 2015, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * iam_lfix.c
  33  * implementation of iam format for fixed size records.
  34  *
  35  * Author: Wang Di <wangdi@clusterfs.com>
  36  * Author: Nikita Danilov <nikita@clusterfs.com>
  37  */
  38
  39 #include <linux/types.h>
  40 #include "osd_internal.h"
  41
  42 /*
  43  * Leaf operations.
  44  */
  45
  46 enum {
  47         IAM_LEAF_HEADER_MAGIC = 0x1976 /* This is duplicated in
  48                                         * lustre/utils/create_iam.c */
  49 };
  50
  51 /* This is duplicated in lustre/utils/create_iam.c */
  52 struct iam_leaf_head {
  53         __le16 ill_magic;
  54         __le16 ill_count;
  55 };
  56
  57 static inline int iam_lfix_entry_size(const struct iam_leaf *l)
  58 {
  59         return iam_leaf_descr(l)->id_key_size + iam_leaf_descr(l)->id_rec_size;
  60 }
  61
  62 static inline struct iam_lentry *
  63 iam_lfix_shift(const struct iam_leaf *l, struct iam_lentry *entry, int shift)
  64 {
  65         return (void *)entry + shift * iam_lfix_entry_size(l);
  66 }
  67
  68 static inline struct iam_key *iam_leaf_key_at(struct iam_lentry *entry)
  69 {
  70         return (struct iam_key *)entry;
  71 }
  72
  73 static inline int lfix_keycmp(const struct iam_container *c,
  74                               const struct iam_key *k1,
  75                               const struct iam_key *k2)
  76 {
  77         return memcmp(k1, k2, c->ic_descr->id_key_size);
  78 }
  79
  80 static struct iam_leaf_head *iam_get_head(const struct iam_leaf *l)
  81 {
  82         return (struct iam_leaf_head *)l->il_bh->b_data;
  83 }
  84
  85 static struct iam_lentry *iam_entries(const struct buffer_head *bh)
  86 {
  87         return (void *)bh->b_data + sizeof(struct iam_leaf_head);
  88 }
  89
  90 static struct iam_lentry *iam_get_lentries(const struct iam_leaf *l)
  91 {
  92         return iam_entries(l->il_bh);
  93 }
  94
  95 static int leaf_count_limit(const struct iam_leaf *leaf)
  96 {
  97         int free_space;
  98
  99         free_space = iam_leaf_container(leaf)->ic_object->i_sb->s_blocksize;
 100         free_space -= sizeof(struct iam_leaf_head);
 101         return free_space / iam_lfix_entry_size(leaf);
 102 }
 103
 104 static int lentry_count_get(const struct iam_leaf *leaf)
 105 {
 106         return le16_to_cpu(iam_get_head(leaf)->ill_count);
 107 }
 108
 109 static void lentry_count_set(struct iam_leaf *leaf, unsigned count)
 110 {
 111         assert_corr(0 <= count && count <= leaf_count_limit(leaf));
 112         iam_get_head(leaf)->ill_count = cpu_to_le16(count);
 113 }
 114
 115 static struct iam_lentry *iam_lfix_get_end(const struct iam_leaf *l);
 116
 117 #if LDISKFS_CORRECTNESS_ON || LDISKFS_INVARIANT_ON
 118 static int iam_leaf_at_rec(const struct iam_leaf *folio)
 119 {
 120         return
 121                 iam_get_lentries(folio) <= folio->il_at &&
 122                 folio->il_at < iam_lfix_get_end(folio);
 123 }
 124 #endif
 125
 126 static struct iam_ikey *iam_lfix_ikey(const struct iam_leaf *l,
 127                                       struct iam_ikey *key)
 128 {
 129         void *ie = l->il_at;
 130         assert_corr(iam_leaf_at_rec(l));
 131         return (struct iam_ikey*)ie;
 132 }
 133
 134 static struct iam_key *iam_lfix_key(const struct iam_leaf *l)
 135 {
 136         void *ie = l->il_at;
 137         assert_corr(iam_leaf_at_rec(l));
 138         return (struct iam_key*)ie;
 139 }
 140
 141 static int iam_lfix_key_size(const struct iam_leaf *l)
 142 {
 143         return iam_leaf_descr(l)->id_key_size;
 144 }
 145
 146 static void iam_lfix_start(struct iam_leaf *l)
 147 {
 148         l->il_at = iam_get_lentries(l);
 149 }
 150
 151 static inline ptrdiff_t iam_lfix_diff(const struct iam_leaf *l,
 152                                       const struct iam_lentry *e1,
 153                                       const struct iam_lentry *e2)
 154 {
 155         ptrdiff_t diff;
 156         int esize;
 157
 158         esize = iam_lfix_entry_size(l);
 159         diff = (void *)e1 - (void *)e2;
 160         assert_corr(diff / esize * esize == diff);
 161         return diff / esize;
 162 }
 163
 164 static int iam_lfix_init(struct iam_leaf *l)
 165 {
 166         int result;
 167         struct iam_leaf_head *ill;
 168         int count;
 169
 170         assert_corr(l->il_bh != NULL);
 171
 172         ill = iam_get_head(l);
 173         count = le16_to_cpu(ill->ill_count);
 174         if (le16_to_cpu(ill->ill_magic) == IAM_LEAF_HEADER_MAGIC &&
 175             0 <= count && count <= leaf_count_limit(l)) {
 176                 l->il_at = l->il_entries = iam_get_lentries(l);
 177                 result = 0;
 178         } else {
 179                 struct inode *obj;
 180
 181                 obj = iam_leaf_container(l)->ic_object;
 182                 CERROR("Wrong magic in node %llu (#%lu): %#x != %#x or "
 183                        "wrong count: %d (%d)\n",
 184                        (unsigned long long)l->il_bh->b_blocknr, obj->i_ino,
 185                        le16_to_cpu(ill->ill_magic), IAM_LEAF_HEADER_MAGIC,
 186                        count, leaf_count_limit(l));
 187                 result = -EIO;
 188         }
 189         return result;
 190 }
 191
 192 static void iam_lfix_fini(struct iam_leaf *l)
 193 {
 194         l->il_entries = l->il_at = NULL;
 195 }
 196
 197 static struct iam_lentry *iam_lfix_get_end(const struct iam_leaf *l)
 198 {
 199         int count = lentry_count_get(l);
 200         struct iam_lentry *ile = iam_lfix_shift(l, l->il_entries, count);
 201
 202         return ile;
 203 }
 204
 205 static struct iam_rec *iam_lfix_rec(const struct iam_leaf *l)
 206 {
 207         void *e = l->il_at;
 208         assert_corr(iam_leaf_at_rec(l));
 209         return e + iam_leaf_descr(l)->id_key_size;
 210 }
 211
 212 static void iam_lfix_next(struct iam_leaf *l)
 213 {
 214         assert_corr(iam_leaf_at_rec(l));
 215         l->il_at = iam_lfix_shift(l, l->il_at, 1);
 216 }
 217
 218 /*
 219  * Bug chasing.
 220  */
 221 int lfix_dump = 0;
 222
 223 static char hdigit(char ch)
 224 {
 225         static char d[] = "0123456789abcdef";
 226         return d[ch & 0xf];
 227 }
 228
 229 static char *hex(char ch, char *area)
 230 {
 231         area[0] = hdigit(ch >> 4);
 232         area[1] = hdigit(ch);
 233         area[2] = 0;
 234         return area;
 235 }
 236
 237 static void l_print(struct iam_leaf *leaf, struct iam_lentry *entry)
 238 {
 239         int i;
 240         char *area;
 241         char h[3];
 242
 243         area = (char *)entry;
 244         printk(KERN_EMERG "[");
 245         for (i = iam_lfix_key_size(leaf); i > 0; --i, ++area)
 246                 printk("%s", hex(*area, h));
 247         printk("]-(");
 248         for (i = iam_leaf_descr(leaf)->id_rec_size; i > 0; --i, ++area)
 249                 printk("%s", hex(*area, h));
 250         printk(")\n");
 251 }
 252
 253 static void lfix_print(struct iam_leaf *leaf)
 254 {
 255         struct iam_lentry *entry;
 256         int count;
 257         int i;
 258
 259         entry = leaf->il_entries;
 260         count = lentry_count_get(leaf);
 261         printk(KERN_EMERG "lfix: %p %p %d\n", leaf, leaf->il_at, count);
 262         for (i = 0; i < count; ++i, entry = iam_lfix_shift(leaf, entry, 1))
 263                 l_print(leaf, entry);
 264 }
 265
 266 static int iam_lfix_lookup(struct iam_leaf *l, const struct iam_key *k)
 267 {
 268         struct iam_lentry *p, *q, *m, *t;
 269         struct iam_container *c;
 270         int count;
 271         int result;
 272
 273         count = lentry_count_get(l);
 274         if (count == 0)
 275                 return IAM_LOOKUP_EMPTY;
 276
 277         result = IAM_LOOKUP_OK;
 278         c = iam_leaf_container(l);
 279
 280         p = l->il_entries;
 281         q = iam_lfix_shift(l, p, count - 1);
 282         if (lfix_keycmp(c, k, iam_leaf_key_at(p)) < 0) {
 283                 /*
 284                  * @k is less than the least key in the leaf
 285                  */
 286                 l->il_at = p;
 287                 result = IAM_LOOKUP_BEFORE;
 288         } else if (lfix_keycmp(c, iam_leaf_key_at(q), k) <= 0) {
 289                 l->il_at = q;
 290         } else {
 291                 /*
 292                  * EWD1293
 293                  */
 294                 while (iam_lfix_shift(l, p, 1) != q) {
 295                         m = iam_lfix_shift(l, p, iam_lfix_diff(l, q, p) / 2);
 296                         assert_corr(p < m && m < q);
 297                         if (lfix_keycmp(c, iam_leaf_key_at(m), k) <= 0)
 298                                 p = m;
 299                         else
 300                                 q = m;
 301                 }
 302                 assert_corr(lfix_keycmp(c, iam_leaf_key_at(p), k) <= 0 &&
 303                             lfix_keycmp(c, k, iam_leaf_key_at(q)) < 0);
 304                 /*
 305                  * skip over records with duplicate keys.
 306                  */
 307                 while (p > l->il_entries) {
 308                         t = iam_lfix_shift(l, p, -1);
 309                         if (lfix_keycmp(c, iam_leaf_key_at(t), k) == 0)
 310                                 p = t;
 311                         else
 312                                 break;
 313                 }
 314                 l->il_at = p;
 315         }
 316         assert_corr(iam_leaf_at_rec(l));
 317
 318         if (lfix_keycmp(c, iam_leaf_key_at(l->il_at), k) == 0)
 319                 result = IAM_LOOKUP_EXACT;
 320
 321         if (lfix_dump)
 322                 lfix_print(l);
 323
 324         return result;
 325 }
 326
 327 static int iam_lfix_ilookup(struct iam_leaf *l, const struct iam_ikey *ik)
 328 {
 329         return iam_lfix_lookup(l, (const struct iam_key *)ik);
 330 }
 331
 332 static void iam_lfix_key_set(struct iam_leaf *l, const struct iam_key *k)
 333 {
 334         assert_corr(iam_leaf_at_rec(l));
 335         memcpy(iam_leaf_key_at(l->il_at), k, iam_leaf_descr(l)->id_key_size);
 336 }
 337
 338 static int iam_lfix_key_cmp(const struct iam_leaf *l, const struct iam_key *k)
 339 {
 340         return lfix_keycmp(iam_leaf_container(l), iam_leaf_key_at(l->il_at), k);
 341 }
 342
 343 static int iam_lfix_key_eq(const struct iam_leaf *l, const struct iam_key *k)
 344 {
 345         return !lfix_keycmp(iam_leaf_container(l),
 346                             iam_leaf_key_at(l->il_at), k);
 347 }
 348
 349 static void iam_lfix_rec_set(struct iam_leaf *l, const struct iam_rec *r)
 350 {
 351         assert_corr(iam_leaf_at_rec(l));
 352         memcpy(iam_lfix_rec(l), r, iam_leaf_descr(l)->id_rec_size);
 353 }
 354
 355 static inline int lfix_reccmp(const struct iam_container *c,
 356                               const struct iam_rec *r1,
 357                               const struct iam_rec *r2)
 358 {
 359         return memcmp(r1, r2, c->ic_descr->id_rec_size);
 360 }
 361
 362 static int iam_lfix_rec_eq(const struct iam_leaf *l, const struct iam_rec *r)
 363 {
 364         return !lfix_reccmp(iam_leaf_container(l), iam_lfix_rec(l), r);
 365 }
 366
 367 static void iam_lfix_rec_get(const struct iam_leaf *l, struct iam_rec *r)
 368 {
 369         assert_corr(iam_leaf_at_rec(l));
 370         memcpy(r, iam_lfix_rec(l), iam_leaf_descr(l)->id_rec_size);
 371 }
 372
 373 static void iam_lfix_rec_add(struct iam_leaf *leaf,
 374                              const struct iam_key *k, const struct iam_rec *r)
 375 {
 376         struct iam_lentry *end;
 377         struct iam_lentry *cur;
 378         struct iam_lentry *start;
 379         ptrdiff_t diff;
 380         int count;
 381
 382         assert_corr(iam_leaf_can_add(leaf, k, r));
 383
 384         count = lentry_count_get(leaf);
 385         /*
 386          * This branch handles two exceptional cases:
 387          *
 388          *   - leaf positioned beyond last record, and
 389          *
 390          *   - empty leaf.
 391          */
 392         if (!iam_leaf_at_end(leaf)) {
 393                 end   = iam_lfix_get_end(leaf);
 394                 cur   = leaf->il_at;
 395                 if (lfix_keycmp(iam_leaf_container(leaf),
 396                                k, iam_leaf_key_at(cur)) >= 0)
 397                         iam_lfix_next(leaf);
 398                 else
 399                         /*
 400                          * Another exceptional case: insertion with the key
 401                          * less than least key in the leaf.
 402                          */
 403                         assert_corr(cur == leaf->il_entries);
 404
 405                 start = leaf->il_at;
 406                 diff  = (void *)end - (void *)start;
 407                 assert_corr(diff >= 0);
 408                 memmove(iam_lfix_shift(leaf, start, 1), start, diff);
 409         }
 410         lentry_count_set(leaf, count + 1);
 411         iam_lfix_key_set(leaf, k);
 412         iam_lfix_rec_set(leaf, r);
 413         assert_corr(iam_leaf_at_rec(leaf));
 414 }
 415
 416 static void iam_lfix_rec_del(struct iam_leaf *leaf, int shift)
 417 {
 418         struct iam_lentry *next, *end;
 419         int count;
 420         ptrdiff_t diff;
 421
 422         assert_corr(iam_leaf_at_rec(leaf));
 423
 424         count = lentry_count_get(leaf);
 425         end = iam_lfix_get_end(leaf);
 426         next = iam_lfix_shift(leaf, leaf->il_at, 1);
 427         diff = (void *)end - (void *)next;
 428         memmove(leaf->il_at, next, diff);
 429
 430         lentry_count_set(leaf, count - 1);
 431 }
 432
 433 static int iam_lfix_can_add(const struct iam_leaf *l,
 434                             const struct iam_key *k, const struct iam_rec *r)
 435 {
 436         return lentry_count_get(l) < leaf_count_limit(l);
 437 }
 438
 439 static int iam_lfix_at_end(const struct iam_leaf *folio)
 440 {
 441         return folio->il_at == iam_lfix_get_end(folio);
 442 }
 443
 444 static void iam_lfix_init_new(struct iam_container *c, struct buffer_head *bh)
 445 {
 446         struct iam_leaf_head *hdr;
 447
 448         hdr = (struct iam_leaf_head*)bh->b_data;
 449         hdr->ill_magic = cpu_to_le16(IAM_LEAF_HEADER_MAGIC);
 450         hdr->ill_count = cpu_to_le16(0);
 451 }
 452
 453 static void iam_lfix_split(struct iam_leaf *l, struct buffer_head **bh,
 454                            iam_ptr_t new_blknr)
 455 {
 456         struct iam_path       *path;
 457         struct iam_leaf_head  *hdr;
 458         const struct iam_ikey *pivot;
 459         struct buffer_head    *new_leaf;
 460
 461         unsigned count;
 462         unsigned split;
 463
 464         void *start;
 465         void *finis;
 466
 467         new_leaf = *bh;
 468         path = iam_leaf_path(l);
 469
 470         hdr = (void *)new_leaf->b_data;
 471
 472         count = lentry_count_get(l);
 473         split = count / 2;
 474
 475         start = iam_lfix_shift(l, iam_get_lentries(l), split);
 476         finis = iam_lfix_shift(l, iam_get_lentries(l), count);
 477
 478         pivot = (const struct iam_ikey *)iam_leaf_key_at(start);
 479
 480         memmove(iam_entries(new_leaf), start, finis - start);
 481         hdr->ill_count = cpu_to_le16(count - split);
 482         lentry_count_set(l, split);
 483         if ((void *)l->il_at >= start) {
 484                 /*
 485                  * insertion point moves into new leaf.
 486                  */
 487                 int shift;
 488                 int result;
 489
 490                 shift = iam_lfix_diff(l, l->il_at, start);
 491                 *bh = l->il_bh;
 492                 l->il_bh = new_leaf;
 493                 l->il_curidx = new_blknr;
 494                 result = iam_lfix_init(l);
 495                 /*
 496                  * init cannot fail, as node was just initialized.
 497                  */
 498                 assert_corr(result == 0);
 499                 l->il_at = iam_lfix_shift(l, iam_get_lentries(l), shift);
 500         }
 501         /*
 502          * Insert pointer to the new node (together with the least key in
 503          * the node) into index node.
 504          */
 505         iam_insert_key_lock(path, path->ip_frame, pivot, new_blknr);
 506 }
 507
 508 static int iam_lfix_leaf_empty(struct iam_leaf *leaf)
 509 {
 510         return lentry_count_get(leaf) == 0;
 511 }
 512
 513 static struct iam_leaf_operations iam_lfix_leaf_ops = {
 514         .init           = iam_lfix_init,
 515         .init_new       = iam_lfix_init_new,
 516         .fini           = iam_lfix_fini,
 517         .start          = iam_lfix_start,
 518         .next           = iam_lfix_next,
 519         .key            = iam_lfix_key,
 520         .ikey           = iam_lfix_ikey,
 521         .rec            = iam_lfix_rec,
 522         .key_set        = iam_lfix_key_set,
 523         .key_cmp        = iam_lfix_key_cmp,
 524         .key_eq         = iam_lfix_key_eq,
 525         .key_size       = iam_lfix_key_size,
 526         .rec_set        = iam_lfix_rec_set,
 527         .rec_eq         = iam_lfix_rec_eq,
 528         .rec_get        = iam_lfix_rec_get,
 529         .lookup         = iam_lfix_lookup,
 530         .ilookup        = iam_lfix_ilookup,
 531         .at_end         = iam_lfix_at_end,
 532         .rec_add        = iam_lfix_rec_add,
 533         .rec_del        = iam_lfix_rec_del,
 534         .can_add        = iam_lfix_can_add,
 535         .split          = iam_lfix_split,
 536         .leaf_empty     = iam_lfix_leaf_empty,
 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
 699                         c->ic_root_bh = bh;
 700                 } else {
 701                         result = -EBADF;
 702                         brelse(bh);
 703                 }
 704         }
 705         return result;
 706 }
 707
 708 static struct iam_format iam_lfix_format = {
 709         .if_guess = iam_lfix_guess
 710 };
 711
 712 void iam_lfix_format_init(void)
 713 {
 714         iam_format_register(&iam_lfix_format);
 715 }
 716
 717 /*
 718  * Debugging aid.
 719  */
 720
 721 #define KEYSIZE (8)
 722 #define RECSIZE (8)
 723 #define PTRSIZE (4)
 724
 725 #define LFIX_ROOT_RECNO \
 726         ((4096 - sizeof(struct iam_lfix_root)) / (KEYSIZE + PTRSIZE))
 727
 728 #define LFIX_INDEX_RECNO (4096 / (KEYSIZE + PTRSIZE))
 729
 730 #define LFIX_LEAF_RECNO \
 731         ((4096 - sizeof(struct iam_leaf_head)) / (KEYSIZE + RECSIZE))
 732
 733 struct lfix_root {
 734         struct iam_lfix_root lr_root;
 735         struct {
 736                 char key[KEYSIZE];
 737                 char ptr[PTRSIZE];
 738         } lr_entry[LFIX_ROOT_RECNO];
 739 };
 740
 741 struct lfix_index {
 742         struct dx_countlimit li_cl;
 743         char   li_padding[KEYSIZE + PTRSIZE - sizeof(struct dx_countlimit)];
 744         struct {
 745                 char key[KEYSIZE];
 746                 char ptr[PTRSIZE];
 747         } li_entry[LFIX_INDEX_RECNO - 1];
 748 };
 749
 750 struct lfix_leaf {
 751         struct iam_leaf_head ll_head;
 752         struct {
 753                 char key[KEYSIZE];
 754                 char rec[RECSIZE];
 755         } ll_entry[LFIX_LEAF_RECNO];
 756 };
 757
 758 #define STORE_UNALIGNED(val, dst)                       \
 759 ({                                                      \
 760         typeof(val) __val = (val);                      \
 761         CLASSERT(sizeof(val) == sizeof(*(dst)));        \
 762         memcpy(dst, &__val, sizeof(*(dst)));            \
 763 })
 764
 765 static void lfix_root(void *buf,
 766                       int blocksize, int keysize, int ptrsize, int recsize)
 767 {
 768         struct iam_lfix_root *root;
 769         struct dx_countlimit *limit;
 770         void                 *entry;
 771
 772         root = buf;
 773         *root = (typeof(*root)) {
 774                 .ilr_magic           = cpu_to_le64(IAM_LFIX_ROOT_MAGIC),
 775                 .ilr_keysize         = cpu_to_le16(keysize),
 776                 .ilr_recsize         = cpu_to_le16(recsize),
 777                 .ilr_ptrsize         = cpu_to_le16(ptrsize),
 778                 .ilr_indirect_levels = 0
 779         };
 780
 781         limit = (void *)(root + 1);
 782         *limit = (typeof(*limit)){
 783                 /*
 784                  * limit itself + one pointer to the leaf.
 785                  */
 786                 .count = cpu_to_le16(2),
 787                 .limit = iam_root_limit(sizeof(struct iam_lfix_root),
 788                                         blocksize, keysize + ptrsize)
 789         };
 790
 791         /* To guarantee that the padding "keysize + ptrsize"
 792          * covers the "dx_countlimit" and the "idle_blocks". */
 793         LASSERT((keysize + ptrsize) >=
 794                 (sizeof(struct dx_countlimit) + sizeof(__u32)));
 795
 796         entry = (void *)(limit + 1);
 797         /* Put "idle_blocks" just after the limit. There was padding after
 798          * the limit, the "idle_blocks" re-uses part of the padding, so no
 799          * compatibility issues with old layout.
 800          */
 801         *(__u32 *)entry = 0;
 802
 803         /*
 804          * Skip over @limit.
 805          */
 806         entry = (void *)(root + 1) + keysize + ptrsize;
 807
 808         /*
 809          * Entry format is <key> followed by <ptr>. In the minimal tree
 810          * consisting of a root and single node, <key> is a minimal possible
 811          * key.
 812          *
 813          * XXX: this key is hard-coded to be a sequence of 0's.
 814          */
 815
 816         memset(entry, 0, keysize);
 817         entry += keysize;
 818         /* now @entry points to <ptr> */
 819         if (ptrsize == 4)
 820                 STORE_UNALIGNED(cpu_to_le32(1), (u_int32_t *)entry);
 821         else
 822                 STORE_UNALIGNED(cpu_to_le64(1), (u_int64_t *)entry);
 823 }
 824
 825 static void lfix_leaf(void *buf,
 826                       int blocksize, int keysize, int ptrsize, int recsize)
 827 {
 828         struct iam_leaf_head *head;
 829         void *entry;
 830
 831         /* form leaf */
 832         head = buf;
 833         *head = (struct iam_leaf_head) {
 834                 .ill_magic = cpu_to_le16(IAM_LEAF_HEADER_MAGIC),
 835                 /*
 836                  * Leaf contains an entry with the smallest possible key
 837                  * (created by zeroing).
 838                  */
 839                 .ill_count = cpu_to_le16(1),
 840         };
 841
 842         entry = (void *)(head + 1);
 843         memset(entry, 0, keysize + recsize);
 844 }
 845
 846 int iam_lfix_create(struct inode *obj,
 847                     int keysize, int ptrsize, int recsize, handle_t *handle)
 848 {
 849         struct buffer_head *root_node;
 850         struct buffer_head *leaf_node;
 851         struct super_block *sb;
 852
 853         u32 blknr;
 854         int result = 0;
 855         unsigned long bsize;
 856
 857         assert_corr(obj->i_size == 0);
 858
 859         sb = obj->i_sb;
 860         bsize = sb->s_blocksize;
 861         root_node = osd_ldiskfs_append(handle, obj, &blknr);
 862         if (IS_ERR(root_node))
 863                 GOTO(out, result = PTR_ERR(root_node));
 864
 865         leaf_node = osd_ldiskfs_append(handle, obj, &blknr);
 866         if (IS_ERR(leaf_node))
 867                 GOTO(out_root, result = PTR_ERR(leaf_node));
 868
 869         lfix_root(root_node->b_data, bsize, keysize, ptrsize, recsize);
 870         lfix_leaf(leaf_node->b_data, bsize, keysize, ptrsize, recsize);
 871         ldiskfs_mark_inode_dirty(handle, obj);
 872         result = ldiskfs_handle_dirty_metadata(handle, NULL, root_node);
 873         if (result == 0)
 874                 result = ldiskfs_handle_dirty_metadata(handle, NULL, leaf_node);
 875         if (result != 0)
 876                 ldiskfs_std_error(sb, result);
 877
 878         brelse(leaf_node);
 879
 880         GOTO(out_root, result);
 881
 882 out_root:
 883         brelse(root_node);
 884 out:
 885         return result;
 886 }