root/fs/ubifs/log.c

DEFINITIONS

1. ubifs_search_bud
2. ubifs_get_wbuf
3. empty_log_bytes
4. ubifs_add_bud
5. ubifs_add_bud_to_log
6. remove_buds
7. ubifs_log_start_commit
8. ubifs_log_end_commit
9. ubifs_log_post_commit
10. done_already
11. destroy_done_tree
12. add_node
13. ubifs_consolidate_log
14. dbg_check_bud_bytes

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * This file is part of UBIFS.
   4  *
   5  * Copyright (C) 2006-2008 Nokia Corporation.
   6  *
   7  * Authors: Artem Bityutskiy (Битюцкий Артём)
   8  *          Adrian Hunter
   9  */
  10 
  11 /*
  12  * This file is a part of UBIFS journal implementation and contains various
  13  * functions which manipulate the log. The log is a fixed area on the flash
  14  * which does not contain any data but refers to buds. The log is a part of the
  15  * journal.
  16  */
  17 
  18 #include "ubifs.h"
  19 
  20 static int dbg_check_bud_bytes(struct ubifs_info *c);
  21 
  22 /**
  23  * ubifs_search_bud - search bud LEB.
  24  * @c: UBIFS file-system description object
  25  * @lnum: logical eraseblock number to search
  26  *
  27  * This function searches bud LEB @lnum. Returns bud description object in case
  28  * of success and %NULL if there is no bud with this LEB number.
  29  */
  30 struct ubifs_bud *ubifs_search_bud(struct ubifs_info *c, int lnum)
  31 {
  32         struct rb_node *p;
  33         struct ubifs_bud *bud;
  34 
  35         spin_lock(&c->buds_lock);
  36         p = c->buds.rb_node;
  37         while (p) {
  38                 bud = rb_entry(p, struct ubifs_bud, rb);
  39                 if (lnum < bud->lnum)
  40                         p = p->rb_left;
  41                 else if (lnum > bud->lnum)
  42                         p = p->rb_right;
  43                 else {
  44                         spin_unlock(&c->buds_lock);
  45                         return bud;
  46                 }
  47         }
  48         spin_unlock(&c->buds_lock);
  49         return NULL;
  50 }
  51 
  52 /**
  53  * ubifs_get_wbuf - get the wbuf associated with a LEB, if there is one.
  54  * @c: UBIFS file-system description object
  55  * @lnum: logical eraseblock number to search
  56  *
  57  * This functions returns the wbuf for @lnum or %NULL if there is not one.
  58  */
  59 struct ubifs_wbuf *ubifs_get_wbuf(struct ubifs_info *c, int lnum)
  60 {
  61         struct rb_node *p;
  62         struct ubifs_bud *bud;
  63         int jhead;
  64 
  65         if (!c->jheads)
  66                 return NULL;
  67 
  68         spin_lock(&c->buds_lock);
  69         p = c->buds.rb_node;
  70         while (p) {
  71                 bud = rb_entry(p, struct ubifs_bud, rb);
  72                 if (lnum < bud->lnum)
  73                         p = p->rb_left;
  74                 else if (lnum > bud->lnum)
  75                         p = p->rb_right;
  76                 else {
  77                         jhead = bud->jhead;
  78                         spin_unlock(&c->buds_lock);
  79                         return &c->jheads[jhead].wbuf;
  80                 }
  81         }
  82         spin_unlock(&c->buds_lock);
  83         return NULL;
  84 }
  85 
  86 /**
  87  * empty_log_bytes - calculate amount of empty space in the log.
  88  * @c: UBIFS file-system description object
  89  */
  90 static inline long long empty_log_bytes(const struct ubifs_info *c)
  91 {
  92         long long h, t;
  93 
  94         h = (long long)c->lhead_lnum * c->leb_size + c->lhead_offs;
  95         t = (long long)c->ltail_lnum * c->leb_size;
  96 
  97         if (h > t)
  98                 return c->log_bytes - h + t;
  99         else if (h != t)
 100                 return t - h;
 101         else if (c->lhead_lnum != c->ltail_lnum)
 102                 return 0;
 103         else
 104                 return c->log_bytes;
 105 }
 106 
 107 /**
 108  * ubifs_add_bud - add bud LEB to the tree of buds and its journal head list.
 109  * @c: UBIFS file-system description object
 110  * @bud: the bud to add
 111  */
 112 void ubifs_add_bud(struct ubifs_info *c, struct ubifs_bud *bud)
 113 {
 114         struct rb_node **p, *parent = NULL;
 115         struct ubifs_bud *b;
 116         struct ubifs_jhead *jhead;
 117 
 118         spin_lock(&c->buds_lock);
 119         p = &c->buds.rb_node;
 120         while (*p) {
 121                 parent = *p;
 122                 b = rb_entry(parent, struct ubifs_bud, rb);
 123                 ubifs_assert(c, bud->lnum != b->lnum);
 124                 if (bud->lnum < b->lnum)
 125                         p = &(*p)->rb_left;
 126                 else
 127                         p = &(*p)->rb_right;
 128         }
 129 
 130         rb_link_node(&bud->rb, parent, p);
 131         rb_insert_color(&bud->rb, &c->buds);
 132         if (c->jheads) {
 133                 jhead = &c->jheads[bud->jhead];
 134                 list_add_tail(&bud->list, &jhead->buds_list);
 135         } else
 136                 ubifs_assert(c, c->replaying && c->ro_mount);
 137 
 138         /*
 139          * Note, although this is a new bud, we anyway account this space now,
 140          * before any data has been written to it, because this is about to
 141          * guarantee fixed mount time, and this bud will anyway be read and
 142          * scanned.
 143          */
 144         c->bud_bytes += c->leb_size - bud->start;
 145 
 146         dbg_log("LEB %d:%d, jhead %s, bud_bytes %lld", bud->lnum,
 147                 bud->start, dbg_jhead(bud->jhead), c->bud_bytes);
 148         spin_unlock(&c->buds_lock);
 149 }
 150 
 151 /**
 152  * ubifs_add_bud_to_log - add a new bud to the log.
 153  * @c: UBIFS file-system description object
 154  * @jhead: journal head the bud belongs to
 155  * @lnum: LEB number of the bud
 156  * @offs: starting offset of the bud
 157  *
 158  * This function writes a reference node for the new bud LEB @lnum to the log,
 159  * and adds it to the buds trees. It also makes sure that log size does not
 160  * exceed the 'c->max_bud_bytes' limit. Returns zero in case of success,
 161  * %-EAGAIN if commit is required, and a negative error code in case of
 162  * failure.
 163  */
 164 int ubifs_add_bud_to_log(struct ubifs_info *c, int jhead, int lnum, int offs)
 165 {
 166         int err;
 167         struct ubifs_bud *bud;
 168         struct ubifs_ref_node *ref;
 169 
 170         bud = kmalloc(sizeof(struct ubifs_bud), GFP_NOFS);
 171         if (!bud)
 172                 return -ENOMEM;
 173         ref = kzalloc(c->ref_node_alsz, GFP_NOFS);
 174         if (!ref) {
 175                 kfree(bud);
 176                 return -ENOMEM;
 177         }
 178 
 179         mutex_lock(&c->log_mutex);
 180         ubifs_assert(c, !c->ro_media && !c->ro_mount);
 181         if (c->ro_error) {
 182                 err = -EROFS;
 183                 goto out_unlock;
 184         }
 185 
 186         /* Make sure we have enough space in the log */
 187         if (empty_log_bytes(c) - c->ref_node_alsz < c->min_log_bytes) {
 188                 dbg_log("not enough log space - %lld, required %d",
 189                         empty_log_bytes(c), c->min_log_bytes);
 190                 ubifs_commit_required(c);
 191                 err = -EAGAIN;
 192                 goto out_unlock;
 193         }
 194 
 195         /*
 196          * Make sure the amount of space in buds will not exceed the
 197          * 'c->max_bud_bytes' limit, because we want to guarantee mount time
 198          * limits.
 199          *
 200          * It is not necessary to hold @c->buds_lock when reading @c->bud_bytes
 201          * because we are holding @c->log_mutex. All @c->bud_bytes take place
 202          * when both @c->log_mutex and @c->bud_bytes are locked.
 203          */
 204         if (c->bud_bytes + c->leb_size - offs > c->max_bud_bytes) {
 205                 dbg_log("bud bytes %lld (%lld max), require commit",
 206                         c->bud_bytes, c->max_bud_bytes);
 207                 ubifs_commit_required(c);
 208                 err = -EAGAIN;
 209                 goto out_unlock;
 210         }
 211 
 212         /*
 213          * If the journal is full enough - start background commit. Note, it is
 214          * OK to read 'c->cmt_state' without spinlock because integer reads
 215          * are atomic in the kernel.
 216          */
 217         if (c->bud_bytes >= c->bg_bud_bytes &&
 218             c->cmt_state == COMMIT_RESTING) {
 219                 dbg_log("bud bytes %lld (%lld max), initiate BG commit",
 220                         c->bud_bytes, c->max_bud_bytes);
 221                 ubifs_request_bg_commit(c);
 222         }
 223 
 224         bud->lnum = lnum;
 225         bud->start = offs;
 226         bud->jhead = jhead;
 227         bud->log_hash = NULL;
 228 
 229         ref->ch.node_type = UBIFS_REF_NODE;
 230         ref->lnum = cpu_to_le32(bud->lnum);
 231         ref->offs = cpu_to_le32(bud->start);
 232         ref->jhead = cpu_to_le32(jhead);
 233 
 234         if (c->lhead_offs > c->leb_size - c->ref_node_alsz) {
 235                 c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
 236                 ubifs_assert(c, c->lhead_lnum != c->ltail_lnum);
 237                 c->lhead_offs = 0;
 238         }
 239 
 240         if (c->lhead_offs == 0) {
 241                 /* Must ensure next log LEB has been unmapped */
 242                 err = ubifs_leb_unmap(c, c->lhead_lnum);
 243                 if (err)
 244                         goto out_unlock;
 245         }
 246 
 247         if (bud->start == 0) {
 248                 /*
 249                  * Before writing the LEB reference which refers an empty LEB
 250                  * to the log, we have to make sure it is mapped, because
 251                  * otherwise we'd risk to refer an LEB with garbage in case of
 252                  * an unclean reboot, because the target LEB might have been
 253                  * unmapped, but not yet physically erased.
 254                  */
 255                 err = ubifs_leb_map(c, bud->lnum);
 256                 if (err)
 257                         goto out_unlock;
 258         }
 259 
 260         dbg_log("write ref LEB %d:%d",
 261                 c->lhead_lnum, c->lhead_offs);
 262         err = ubifs_write_node(c, ref, UBIFS_REF_NODE_SZ, c->lhead_lnum,
 263                                c->lhead_offs);
 264         if (err)
 265                 goto out_unlock;
 266 
 267         err = ubifs_shash_update(c, c->log_hash, ref, UBIFS_REF_NODE_SZ);
 268         if (err)
 269                 goto out_unlock;
 270 
 271         err = ubifs_shash_copy_state(c, c->log_hash, c->jheads[jhead].log_hash);
 272         if (err)
 273                 goto out_unlock;
 274 
 275         c->lhead_offs += c->ref_node_alsz;
 276 
 277         ubifs_add_bud(c, bud);
 278 
 279         mutex_unlock(&c->log_mutex);
 280         kfree(ref);
 281         return 0;
 282 
 283 out_unlock:
 284         mutex_unlock(&c->log_mutex);
 285         kfree(ref);
 286         kfree(bud);
 287         return err;
 288 }
 289 
 290 /**
 291  * remove_buds - remove used buds.
 292  * @c: UBIFS file-system description object
 293  *
 294  * This function removes use buds from the buds tree. It does not remove the
 295  * buds which are pointed to by journal heads.
 296  */
 297 static void remove_buds(struct ubifs_info *c)
 298 {
 299         struct rb_node *p;
 300 
 301         ubifs_assert(c, list_empty(&c->old_buds));
 302         c->cmt_bud_bytes = 0;
 303         spin_lock(&c->buds_lock);
 304         p = rb_first(&c->buds);
 305         while (p) {
 306                 struct rb_node *p1 = p;
 307                 struct ubifs_bud *bud;
 308                 struct ubifs_wbuf *wbuf;
 309 
 310                 p = rb_next(p);
 311                 bud = rb_entry(p1, struct ubifs_bud, rb);
 312                 wbuf = &c->jheads[bud->jhead].wbuf;
 313 
 314                 if (wbuf->lnum == bud->lnum) {
 315                         /*
 316                          * Do not remove buds which are pointed to by journal
 317                          * heads (non-closed buds).
 318                          */
 319                         c->cmt_bud_bytes += wbuf->offs - bud->start;
 320                         dbg_log("preserve %d:%d, jhead %s, bud bytes %d, cmt_bud_bytes %lld",
 321                                 bud->lnum, bud->start, dbg_jhead(bud->jhead),
 322                                 wbuf->offs - bud->start, c->cmt_bud_bytes);
 323                         bud->start = wbuf->offs;
 324                 } else {
 325                         c->cmt_bud_bytes += c->leb_size - bud->start;
 326                         dbg_log("remove %d:%d, jhead %s, bud bytes %d, cmt_bud_bytes %lld",
 327                                 bud->lnum, bud->start, dbg_jhead(bud->jhead),
 328                                 c->leb_size - bud->start, c->cmt_bud_bytes);
 329                         rb_erase(p1, &c->buds);
 330                         /*
 331                          * If the commit does not finish, the recovery will need
 332                          * to replay the journal, in which case the old buds
 333                          * must be unchanged. Do not release them until post
 334                          * commit i.e. do not allow them to be garbage
 335                          * collected.
 336                          */
 337                         list_move(&bud->list, &c->old_buds);
 338                 }
 339         }
 340         spin_unlock(&c->buds_lock);
 341 }
 342 
 343 /**
 344  * ubifs_log_start_commit - start commit.
 345  * @c: UBIFS file-system description object
 346  * @ltail_lnum: return new log tail LEB number
 347  *
 348  * The commit operation starts with writing "commit start" node to the log and
 349  * reference nodes for all journal heads which will define new journal after
 350  * the commit has been finished. The commit start and reference nodes are
 351  * written in one go to the nearest empty log LEB (hence, when commit is
 352  * finished UBIFS may safely unmap all the previous log LEBs). This function
 353  * returns zero in case of success and a negative error code in case of
 354  * failure.
 355  */
 356 int ubifs_log_start_commit(struct ubifs_info *c, int *ltail_lnum)
 357 {
 358         void *buf;
 359         struct ubifs_cs_node *cs;
 360         struct ubifs_ref_node *ref;
 361         int err, i, max_len, len;
 362 
 363         err = dbg_check_bud_bytes(c);
 364         if (err)
 365                 return err;
 366 
 367         max_len = UBIFS_CS_NODE_SZ + c->jhead_cnt * UBIFS_REF_NODE_SZ;
 368         max_len = ALIGN(max_len, c->min_io_size);
 369         buf = cs = kmalloc(max_len, GFP_NOFS);
 370         if (!buf)
 371                 return -ENOMEM;
 372 
 373         cs->ch.node_type = UBIFS_CS_NODE;
 374         cs->cmt_no = cpu_to_le64(c->cmt_no);
 375         ubifs_prepare_node(c, cs, UBIFS_CS_NODE_SZ, 0);
 376 
 377         err = ubifs_shash_init(c, c->log_hash);
 378         if (err)
 379                 goto out;
 380 
 381         err = ubifs_shash_update(c, c->log_hash, cs, UBIFS_CS_NODE_SZ);
 382         if (err < 0)
 383                 goto out;
 384 
 385         /*
 386          * Note, we do not lock 'c->log_mutex' because this is the commit start
 387          * phase and we are exclusively using the log. And we do not lock
 388          * write-buffer because nobody can write to the file-system at this
 389          * phase.
 390          */
 391 
 392         len = UBIFS_CS_NODE_SZ;
 393         for (i = 0; i < c->jhead_cnt; i++) {
 394                 int lnum = c->jheads[i].wbuf.lnum;
 395                 int offs = c->jheads[i].wbuf.offs;
 396 
 397                 if (lnum == -1 || offs == c->leb_size)
 398                         continue;
 399 
 400                 dbg_log("add ref to LEB %d:%d for jhead %s",
 401                         lnum, offs, dbg_jhead(i));
 402                 ref = buf + len;
 403                 ref->ch.node_type = UBIFS_REF_NODE;
 404                 ref->lnum = cpu_to_le32(lnum);
 405                 ref->offs = cpu_to_le32(offs);
 406                 ref->jhead = cpu_to_le32(i);
 407 
 408                 ubifs_prepare_node(c, ref, UBIFS_REF_NODE_SZ, 0);
 409                 len += UBIFS_REF_NODE_SZ;
 410 
 411                 err = ubifs_shash_update(c, c->log_hash, ref,
 412                                          UBIFS_REF_NODE_SZ);
 413                 if (err)
 414                         goto out;
 415                 ubifs_shash_copy_state(c, c->log_hash, c->jheads[i].log_hash);
 416         }
 417 
 418         ubifs_pad(c, buf + len, ALIGN(len, c->min_io_size) - len);
 419 
 420         /* Switch to the next log LEB */
 421         if (c->lhead_offs) {
 422                 c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
 423                 ubifs_assert(c, c->lhead_lnum != c->ltail_lnum);
 424                 c->lhead_offs = 0;
 425         }
 426 
 427         /* Must ensure next LEB has been unmapped */
 428         err = ubifs_leb_unmap(c, c->lhead_lnum);
 429         if (err)
 430                 goto out;
 431 
 432         len = ALIGN(len, c->min_io_size);
 433         dbg_log("writing commit start at LEB %d:0, len %d", c->lhead_lnum, len);
 434         err = ubifs_leb_write(c, c->lhead_lnum, cs, 0, len);
 435         if (err)
 436                 goto out;
 437 
 438         *ltail_lnum = c->lhead_lnum;
 439 
 440         c->lhead_offs += len;
 441         ubifs_assert(c, c->lhead_offs < c->leb_size);
 442 
 443         remove_buds(c);
 444 
 445         /*
 446          * We have started the commit and now users may use the rest of the log
 447          * for new writes.
 448          */
 449         c->min_log_bytes = 0;
 450 
 451 out:
 452         kfree(buf);
 453         return err;
 454 }
 455 
 456 /**
 457  * ubifs_log_end_commit - end commit.
 458  * @c: UBIFS file-system description object
 459  * @ltail_lnum: new log tail LEB number
 460  *
 461  * This function is called on when the commit operation was finished. It
 462  * moves log tail to new position and updates the master node so that it stores
 463  * the new log tail LEB number. Returns zero in case of success and a negative
 464  * error code in case of failure.
 465  */
 466 int ubifs_log_end_commit(struct ubifs_info *c, int ltail_lnum)
 467 {
 468         int err;
 469 
 470         /*
 471          * At this phase we have to lock 'c->log_mutex' because UBIFS allows FS
 472          * writes during commit. Its only short "commit" start phase when
 473          * writers are blocked.
 474          */
 475         mutex_lock(&c->log_mutex);
 476 
 477         dbg_log("old tail was LEB %d:0, new tail is LEB %d:0",
 478                 c->ltail_lnum, ltail_lnum);
 479 
 480         c->ltail_lnum = ltail_lnum;
 481         /*
 482          * The commit is finished and from now on it must be guaranteed that
 483          * there is always enough space for the next commit.
 484          */
 485         c->min_log_bytes = c->leb_size;
 486 
 487         spin_lock(&c->buds_lock);
 488         c->bud_bytes -= c->cmt_bud_bytes;
 489         spin_unlock(&c->buds_lock);
 490 
 491         err = dbg_check_bud_bytes(c);
 492         if (err)
 493                 goto out;
 494 
 495         err = ubifs_write_master(c);
 496 
 497 out:
 498         mutex_unlock(&c->log_mutex);
 499         return err;
 500 }
 501 
 502 /**
 503  * ubifs_log_post_commit - things to do after commit is completed.
 504  * @c: UBIFS file-system description object
 505  * @old_ltail_lnum: old log tail LEB number
 506  *
 507  * Release buds only after commit is completed, because they must be unchanged
 508  * if recovery is needed.
 509  *
 510  * Unmap log LEBs only after commit is completed, because they may be needed for
 511  * recovery.
 512  *
 513  * This function returns %0 on success and a negative error code on failure.
 514  */
 515 int ubifs_log_post_commit(struct ubifs_info *c, int old_ltail_lnum)
 516 {
 517         int lnum, err = 0;
 518 
 519         while (!list_empty(&c->old_buds)) {
 520                 struct ubifs_bud *bud;
 521 
 522                 bud = list_entry(c->old_buds.next, struct ubifs_bud, list);
 523                 err = ubifs_return_leb(c, bud->lnum);
 524                 if (err)
 525                         return err;
 526                 list_del(&bud->list);
 527                 kfree(bud->log_hash);
 528                 kfree(bud);
 529         }
 530         mutex_lock(&c->log_mutex);
 531         for (lnum = old_ltail_lnum; lnum != c->ltail_lnum;
 532              lnum = ubifs_next_log_lnum(c, lnum)) {
 533                 dbg_log("unmap log LEB %d", lnum);
 534                 err = ubifs_leb_unmap(c, lnum);
 535                 if (err)
 536                         goto out;
 537         }
 538 out:
 539         mutex_unlock(&c->log_mutex);
 540         return err;
 541 }
 542 
 543 /**
 544  * struct done_ref - references that have been done.
 545  * @rb: rb-tree node
 546  * @lnum: LEB number
 547  */
 548 struct done_ref {
 549         struct rb_node rb;
 550         int lnum;
 551 };
 552 
 553 /**
 554  * done_already - determine if a reference has been done already.
 555  * @done_tree: rb-tree to store references that have been done
 556  * @lnum: LEB number of reference
 557  *
 558  * This function returns %1 if the reference has been done, %0 if not, otherwise
 559  * a negative error code is returned.
 560  */
 561 static int done_already(struct rb_root *done_tree, int lnum)
 562 {
 563         struct rb_node **p = &done_tree->rb_node, *parent = NULL;
 564         struct done_ref *dr;
 565 
 566         while (*p) {
 567                 parent = *p;
 568                 dr = rb_entry(parent, struct done_ref, rb);
 569                 if (lnum < dr->lnum)
 570                         p = &(*p)->rb_left;
 571                 else if (lnum > dr->lnum)
 572                         p = &(*p)->rb_right;
 573                 else
 574                         return 1;
 575         }
 576 
 577         dr = kzalloc(sizeof(struct done_ref), GFP_NOFS);
 578         if (!dr)
 579                 return -ENOMEM;
 580 
 581         dr->lnum = lnum;
 582 
 583         rb_link_node(&dr->rb, parent, p);
 584         rb_insert_color(&dr->rb, done_tree);
 585 
 586         return 0;
 587 }
 588 
 589 /**
 590  * destroy_done_tree - destroy the done tree.
 591  * @done_tree: done tree to destroy
 592  */
 593 static void destroy_done_tree(struct rb_root *done_tree)
 594 {
 595         struct done_ref *dr, *n;
 596 
 597         rbtree_postorder_for_each_entry_safe(dr, n, done_tree, rb)
 598                 kfree(dr);
 599 }
 600 
 601 /**
 602  * add_node - add a node to the consolidated log.
 603  * @c: UBIFS file-system description object
 604  * @buf: buffer to which to add
 605  * @lnum: LEB number to which to write is passed and returned here
 606  * @offs: offset to where to write is passed and returned here
 607  * @node: node to add
 608  *
 609  * This function returns %0 on success and a negative error code on failure.
 610  */
 611 static int add_node(struct ubifs_info *c, void *buf, int *lnum, int *offs,
 612                     void *node)
 613 {
 614         struct ubifs_ch *ch = node;
 615         int len = le32_to_cpu(ch->len), remains = c->leb_size - *offs;
 616 
 617         if (len > remains) {
 618                 int sz = ALIGN(*offs, c->min_io_size), err;
 619 
 620                 ubifs_pad(c, buf + *offs, sz - *offs);
 621                 err = ubifs_leb_change(c, *lnum, buf, sz);
 622                 if (err)
 623                         return err;
 624                 *lnum = ubifs_next_log_lnum(c, *lnum);
 625                 *offs = 0;
 626         }
 627         memcpy(buf + *offs, node, len);
 628         *offs += ALIGN(len, 8);
 629         return 0;
 630 }
 631 
 632 /**
 633  * ubifs_consolidate_log - consolidate the log.
 634  * @c: UBIFS file-system description object
 635  *
 636  * Repeated failed commits could cause the log to be full, but at least 1 LEB is
 637  * needed for commit. This function rewrites the reference nodes in the log
 638  * omitting duplicates, and failed CS nodes, and leaving no gaps.
 639  *
 640  * This function returns %0 on success and a negative error code on failure.
 641  */
 642 int ubifs_consolidate_log(struct ubifs_info *c)
 643 {
 644         struct ubifs_scan_leb *sleb;
 645         struct ubifs_scan_node *snod;
 646         struct rb_root done_tree = RB_ROOT;
 647         int lnum, err, first = 1, write_lnum, offs = 0;
 648         void *buf;
 649 
 650         dbg_rcvry("log tail LEB %d, log head LEB %d", c->ltail_lnum,
 651                   c->lhead_lnum);
 652         buf = vmalloc(c->leb_size);
 653         if (!buf)
 654                 return -ENOMEM;
 655         lnum = c->ltail_lnum;
 656         write_lnum = lnum;
 657         while (1) {
 658                 sleb = ubifs_scan(c, lnum, 0, c->sbuf, 0);
 659                 if (IS_ERR(sleb)) {
 660                         err = PTR_ERR(sleb);
 661                         goto out_free;
 662                 }
 663                 list_for_each_entry(snod, &sleb->nodes, list) {
 664                         switch (snod->type) {
 665                         case UBIFS_REF_NODE: {
 666                                 struct ubifs_ref_node *ref = snod->node;
 667                                 int ref_lnum = le32_to_cpu(ref->lnum);
 668 
 669                                 err = done_already(&done_tree, ref_lnum);
 670                                 if (err < 0)
 671                                         goto out_scan;
 672                                 if (err != 1) {
 673                                         err = add_node(c, buf, &write_lnum,
 674                                                        &offs, snod->node);
 675                                         if (err)
 676                                                 goto out_scan;
 677                                 }
 678                                 break;
 679                         }
 680                         case UBIFS_CS_NODE:
 681                                 if (!first)
 682                                         break;
 683                                 err = add_node(c, buf, &write_lnum, &offs,
 684                                                snod->node);
 685                                 if (err)
 686                                         goto out_scan;
 687                                 first = 0;
 688                                 break;
 689                         }
 690                 }
 691                 ubifs_scan_destroy(sleb);
 692                 if (lnum == c->lhead_lnum)
 693                         break;
 694                 lnum = ubifs_next_log_lnum(c, lnum);
 695         }
 696         if (offs) {
 697                 int sz = ALIGN(offs, c->min_io_size);
 698 
 699                 ubifs_pad(c, buf + offs, sz - offs);
 700                 err = ubifs_leb_change(c, write_lnum, buf, sz);
 701                 if (err)
 702                         goto out_free;
 703                 offs = ALIGN(offs, c->min_io_size);
 704         }
 705         destroy_done_tree(&done_tree);
 706         vfree(buf);
 707         if (write_lnum == c->lhead_lnum) {
 708                 ubifs_err(c, "log is too full");
 709                 return -EINVAL;
 710         }
 711         /* Unmap remaining LEBs */
 712         lnum = write_lnum;
 713         do {
 714                 lnum = ubifs_next_log_lnum(c, lnum);
 715                 err = ubifs_leb_unmap(c, lnum);
 716                 if (err)
 717                         return err;
 718         } while (lnum != c->lhead_lnum);
 719         c->lhead_lnum = write_lnum;
 720         c->lhead_offs = offs;
 721         dbg_rcvry("new log head at %d:%d", c->lhead_lnum, c->lhead_offs);
 722         return 0;
 723 
 724 out_scan:
 725         ubifs_scan_destroy(sleb);
 726 out_free:
 727         destroy_done_tree(&done_tree);
 728         vfree(buf);
 729         return err;
 730 }
 731 
 732 /**
 733  * dbg_check_bud_bytes - make sure bud bytes calculation are all right.
 734  * @c: UBIFS file-system description object
 735  *
 736  * This function makes sure the amount of flash space used by closed buds
 737  * ('c->bud_bytes' is correct). Returns zero in case of success and %-EINVAL in
 738  * case of failure.
 739  */
 740 static int dbg_check_bud_bytes(struct ubifs_info *c)
 741 {
 742         int i, err = 0;
 743         struct ubifs_bud *bud;
 744         long long bud_bytes = 0;
 745 
 746         if (!dbg_is_chk_gen(c))
 747                 return 0;
 748 
 749         spin_lock(&c->buds_lock);
 750         for (i = 0; i < c->jhead_cnt; i++)
 751                 list_for_each_entry(bud, &c->jheads[i].buds_list, list)
 752                         bud_bytes += c->leb_size - bud->start;
 753 
 754         if (c->bud_bytes != bud_bytes) {
 755                 ubifs_err(c, "bad bud_bytes %lld, calculated %lld",
 756                           c->bud_bytes, bud_bytes);
 757                 err = -EINVAL;
 758         }
 759         spin_unlock(&c->buds_lock);
 760 
 761         return err;
 762 }