linux/fs/ubifs/recovery.c
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   1/*
   2 * This file is part of UBIFS.
   3 *
   4 * Copyright (C) 2006-2008 Nokia Corporation
   5 *
   6 * This program is free software; you can redistribute it and/or modify it
   7 * under the terms of the GNU General Public License version 2 as published by
   8 * the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful, but WITHOUT
  11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13 * more details.
  14 *
  15 * You should have received a copy of the GNU General Public License along with
  16 * this program; if not, write to the Free Software Foundation, Inc., 51
  17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18 *
  19 * Authors: Adrian Hunter
  20 *          Artem Bityutskiy (Битюцкий Артём)
  21 */
  22
  23/*
  24 * This file implements functions needed to recover from unclean un-mounts.
  25 * When UBIFS is mounted, it checks a flag on the master node to determine if
  26 * an un-mount was completed successfully. If not, the process of mounting
  27 * incorporates additional checking and fixing of on-flash data structures.
  28 * UBIFS always cleans away all remnants of an unclean un-mount, so that
  29 * errors do not accumulate. However UBIFS defers recovery if it is mounted
  30 * read-only, and the flash is not modified in that case.
  31 *
  32 * The general UBIFS approach to the recovery is that it recovers from
  33 * corruptions which could be caused by power cuts, but it refuses to recover
  34 * from corruption caused by other reasons. And UBIFS tries to distinguish
  35 * between these 2 reasons of corruptions and silently recover in the former
  36 * case and loudly complain in the latter case.
  37 *
  38 * UBIFS writes only to erased LEBs, so it writes only to the flash space
  39 * containing only 0xFFs. UBIFS also always writes strictly from the beginning
  40 * of the LEB to the end. And UBIFS assumes that the underlying flash media
  41 * writes in @c->max_write_size bytes at a time.
  42 *
  43 * Hence, if UBIFS finds a corrupted node at offset X, it expects only the min.
  44 * I/O unit corresponding to offset X to contain corrupted data, all the
  45 * following min. I/O units have to contain empty space (all 0xFFs). If this is
  46 * not true, the corruption cannot be the result of a power cut, and UBIFS
  47 * refuses to mount.
  48 */
  49
  50#include <linux/crc32.h>
  51#include <linux/slab.h>
  52#include "ubifs.h"
  53
  54/**
  55 * is_empty - determine whether a buffer is empty (contains all 0xff).
  56 * @buf: buffer to clean
  57 * @len: length of buffer
  58 *
  59 * This function returns %1 if the buffer is empty (contains all 0xff) otherwise
  60 * %0 is returned.
  61 */
  62static int is_empty(void *buf, int len)
  63{
  64        uint8_t *p = buf;
  65        int i;
  66
  67        for (i = 0; i < len; i++)
  68                if (*p++ != 0xff)
  69                        return 0;
  70        return 1;
  71}
  72
  73/**
  74 * first_non_ff - find offset of the first non-0xff byte.
  75 * @buf: buffer to search in
  76 * @len: length of buffer
  77 *
  78 * This function returns offset of the first non-0xff byte in @buf or %-1 if
  79 * the buffer contains only 0xff bytes.
  80 */
  81static int first_non_ff(void *buf, int len)
  82{
  83        uint8_t *p = buf;
  84        int i;
  85
  86        for (i = 0; i < len; i++)
  87                if (*p++ != 0xff)
  88                        return i;
  89        return -1;
  90}
  91
  92/**
  93 * get_master_node - get the last valid master node allowing for corruption.
  94 * @c: UBIFS file-system description object
  95 * @lnum: LEB number
  96 * @pbuf: buffer containing the LEB read, is returned here
  97 * @mst: master node, if found, is returned here
  98 * @cor: corruption, if found, is returned here
  99 *
 100 * This function allocates a buffer, reads the LEB into it, and finds and
 101 * returns the last valid master node allowing for one area of corruption.
 102 * The corrupt area, if there is one, must be consistent with the assumption
 103 * that it is the result of an unclean unmount while the master node was being
 104 * written. Under those circumstances, it is valid to use the previously written
 105 * master node.
 106 *
 107 * This function returns %0 on success and a negative error code on failure.
 108 */
 109static int get_master_node(const struct ubifs_info *c, int lnum, void **pbuf,
 110                           struct ubifs_mst_node **mst, void **cor)
 111{
 112        const int sz = c->mst_node_alsz;
 113        int err, offs, len;
 114        void *sbuf, *buf;
 115
 116        sbuf = vmalloc(c->leb_size);
 117        if (!sbuf)
 118                return -ENOMEM;
 119
 120        err = ubifs_leb_read(c, lnum, sbuf, 0, c->leb_size, 0);
 121        if (err && err != -EBADMSG)
 122                goto out_free;
 123
 124        /* Find the first position that is definitely not a node */
 125        offs = 0;
 126        buf = sbuf;
 127        len = c->leb_size;
 128        while (offs + UBIFS_MST_NODE_SZ <= c->leb_size) {
 129                struct ubifs_ch *ch = buf;
 130
 131                if (le32_to_cpu(ch->magic) != UBIFS_NODE_MAGIC)
 132                        break;
 133                offs += sz;
 134                buf  += sz;
 135                len  -= sz;
 136        }
 137        /* See if there was a valid master node before that */
 138        if (offs) {
 139                int ret;
 140
 141                offs -= sz;
 142                buf  -= sz;
 143                len  += sz;
 144                ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
 145                if (ret != SCANNED_A_NODE && offs) {
 146                        /* Could have been corruption so check one place back */
 147                        offs -= sz;
 148                        buf  -= sz;
 149                        len  += sz;
 150                        ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
 151                        if (ret != SCANNED_A_NODE)
 152                                /*
 153                                 * We accept only one area of corruption because
 154                                 * we are assuming that it was caused while
 155                                 * trying to write a master node.
 156                                 */
 157                                goto out_err;
 158                }
 159                if (ret == SCANNED_A_NODE) {
 160                        struct ubifs_ch *ch = buf;
 161
 162                        if (ch->node_type != UBIFS_MST_NODE)
 163                                goto out_err;
 164                        dbg_rcvry("found a master node at %d:%d", lnum, offs);
 165                        *mst = buf;
 166                        offs += sz;
 167                        buf  += sz;
 168                        len  -= sz;
 169                }
 170        }
 171        /* Check for corruption */
 172        if (offs < c->leb_size) {
 173                if (!is_empty(buf, min_t(int, len, sz))) {
 174                        *cor = buf;
 175                        dbg_rcvry("found corruption at %d:%d", lnum, offs);
 176                }
 177                offs += sz;
 178                buf  += sz;
 179                len  -= sz;
 180        }
 181        /* Check remaining empty space */
 182        if (offs < c->leb_size)
 183                if (!is_empty(buf, len))
 184                        goto out_err;
 185        *pbuf = sbuf;
 186        return 0;
 187
 188out_err:
 189        err = -EINVAL;
 190out_free:
 191        vfree(sbuf);
 192        *mst = NULL;
 193        *cor = NULL;
 194        return err;
 195}
 196
 197/**
 198 * write_rcvrd_mst_node - write recovered master node.
 199 * @c: UBIFS file-system description object
 200 * @mst: master node
 201 *
 202 * This function returns %0 on success and a negative error code on failure.
 203 */
 204static int write_rcvrd_mst_node(struct ubifs_info *c,
 205                                struct ubifs_mst_node *mst)
 206{
 207        int err = 0, lnum = UBIFS_MST_LNUM, sz = c->mst_node_alsz;
 208        __le32 save_flags;
 209
 210        dbg_rcvry("recovery");
 211
 212        save_flags = mst->flags;
 213        mst->flags |= cpu_to_le32(UBIFS_MST_RCVRY);
 214
 215        ubifs_prepare_node(c, mst, UBIFS_MST_NODE_SZ, 1);
 216        err = ubifs_leb_change(c, lnum, mst, sz);
 217        if (err)
 218                goto out;
 219        err = ubifs_leb_change(c, lnum + 1, mst, sz);
 220        if (err)
 221                goto out;
 222out:
 223        mst->flags = save_flags;
 224        return err;
 225}
 226
 227/**
 228 * ubifs_recover_master_node - recover the master node.
 229 * @c: UBIFS file-system description object
 230 *
 231 * This function recovers the master node from corruption that may occur due to
 232 * an unclean unmount.
 233 *
 234 * This function returns %0 on success and a negative error code on failure.
 235 */
 236int ubifs_recover_master_node(struct ubifs_info *c)
 237{
 238        void *buf1 = NULL, *buf2 = NULL, *cor1 = NULL, *cor2 = NULL;
 239        struct ubifs_mst_node *mst1 = NULL, *mst2 = NULL, *mst;
 240        const int sz = c->mst_node_alsz;
 241        int err, offs1, offs2;
 242
 243        dbg_rcvry("recovery");
 244
 245        err = get_master_node(c, UBIFS_MST_LNUM, &buf1, &mst1, &cor1);
 246        if (err)
 247                goto out_free;
 248
 249        err = get_master_node(c, UBIFS_MST_LNUM + 1, &buf2, &mst2, &cor2);
 250        if (err)
 251                goto out_free;
 252
 253        if (mst1) {
 254                offs1 = (void *)mst1 - buf1;
 255                if ((le32_to_cpu(mst1->flags) & UBIFS_MST_RCVRY) &&
 256                    (offs1 == 0 && !cor1)) {
 257                        /*
 258                         * mst1 was written by recovery at offset 0 with no
 259                         * corruption.
 260                         */
 261                        dbg_rcvry("recovery recovery");
 262                        mst = mst1;
 263                } else if (mst2) {
 264                        offs2 = (void *)mst2 - buf2;
 265                        if (offs1 == offs2) {
 266                                /* Same offset, so must be the same */
 267                                if (memcmp((void *)mst1 + UBIFS_CH_SZ,
 268                                           (void *)mst2 + UBIFS_CH_SZ,
 269                                           UBIFS_MST_NODE_SZ - UBIFS_CH_SZ))
 270                                        goto out_err;
 271                                mst = mst1;
 272                        } else if (offs2 + sz == offs1) {
 273                                /* 1st LEB was written, 2nd was not */
 274                                if (cor1)
 275                                        goto out_err;
 276                                mst = mst1;
 277                        } else if (offs1 == 0 &&
 278                                   c->leb_size - offs2 - sz < sz) {
 279                                /* 1st LEB was unmapped and written, 2nd not */
 280                                if (cor1)
 281                                        goto out_err;
 282                                mst = mst1;
 283                        } else
 284                                goto out_err;
 285                } else {
 286                        /*
 287                         * 2nd LEB was unmapped and about to be written, so
 288                         * there must be only one master node in the first LEB
 289                         * and no corruption.
 290                         */
 291                        if (offs1 != 0 || cor1)
 292                                goto out_err;
 293                        mst = mst1;
 294                }
 295        } else {
 296                if (!mst2)
 297                        goto out_err;
 298                /*
 299                 * 1st LEB was unmapped and about to be written, so there must
 300                 * be no room left in 2nd LEB.
 301                 */
 302                offs2 = (void *)mst2 - buf2;
 303                if (offs2 + sz + sz <= c->leb_size)
 304                        goto out_err;
 305                mst = mst2;
 306        }
 307
 308        ubifs_msg("recovered master node from LEB %d",
 309                  (mst == mst1 ? UBIFS_MST_LNUM : UBIFS_MST_LNUM + 1));
 310
 311        memcpy(c->mst_node, mst, UBIFS_MST_NODE_SZ);
 312
 313        if (c->ro_mount) {
 314                /* Read-only mode. Keep a copy for switching to rw mode */
 315                c->rcvrd_mst_node = kmalloc(sz, GFP_KERNEL);
 316                if (!c->rcvrd_mst_node) {
 317                        err = -ENOMEM;
 318                        goto out_free;
 319                }
 320                memcpy(c->rcvrd_mst_node, c->mst_node, UBIFS_MST_NODE_SZ);
 321
 322                /*
 323                 * We had to recover the master node, which means there was an
 324                 * unclean reboot. However, it is possible that the master node
 325                 * is clean at this point, i.e., %UBIFS_MST_DIRTY is not set.
 326                 * E.g., consider the following chain of events:
 327                 *
 328                 * 1. UBIFS was cleanly unmounted, so the master node is clean
 329                 * 2. UBIFS is being mounted R/W and starts changing the master
 330                 *    node in the first (%UBIFS_MST_LNUM). A power cut happens,
 331                 *    so this LEB ends up with some amount of garbage at the
 332                 *    end.
 333                 * 3. UBIFS is being mounted R/O. We reach this place and
 334                 *    recover the master node from the second LEB
 335                 *    (%UBIFS_MST_LNUM + 1). But we cannot update the media
 336                 *    because we are being mounted R/O. We have to defer the
 337                 *    operation.
 338                 * 4. However, this master node (@c->mst_node) is marked as
 339                 *    clean (since the step 1). And if we just return, the
 340                 *    mount code will be confused and won't recover the master
 341                 *    node when it is re-mounter R/W later.
 342                 *
 343                 *    Thus, to force the recovery by marking the master node as
 344                 *    dirty.
 345                 */
 346                c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
 347        } else {
 348                /* Write the recovered master node */
 349                c->max_sqnum = le64_to_cpu(mst->ch.sqnum) - 1;
 350                err = write_rcvrd_mst_node(c, c->mst_node);
 351                if (err)
 352                        goto out_free;
 353        }
 354
 355        vfree(buf2);
 356        vfree(buf1);
 357
 358        return 0;
 359
 360out_err:
 361        err = -EINVAL;
 362out_free:
 363        ubifs_err("failed to recover master node");
 364        if (mst1) {
 365                ubifs_err("dumping first master node");
 366                ubifs_dump_node(c, mst1);
 367        }
 368        if (mst2) {
 369                ubifs_err("dumping second master node");
 370                ubifs_dump_node(c, mst2);
 371        }
 372        vfree(buf2);
 373        vfree(buf1);
 374        return err;
 375}
 376
 377/**
 378 * ubifs_write_rcvrd_mst_node - write the recovered master node.
 379 * @c: UBIFS file-system description object
 380 *
 381 * This function writes the master node that was recovered during mounting in
 382 * read-only mode and must now be written because we are remounting rw.
 383 *
 384 * This function returns %0 on success and a negative error code on failure.
 385 */
 386int ubifs_write_rcvrd_mst_node(struct ubifs_info *c)
 387{
 388        int err;
 389
 390        if (!c->rcvrd_mst_node)
 391                return 0;
 392        c->rcvrd_mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
 393        c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
 394        err = write_rcvrd_mst_node(c, c->rcvrd_mst_node);
 395        if (err)
 396                return err;
 397        kfree(c->rcvrd_mst_node);
 398        c->rcvrd_mst_node = NULL;
 399        return 0;
 400}
 401
 402/**
 403 * is_last_write - determine if an offset was in the last write to a LEB.
 404 * @c: UBIFS file-system description object
 405 * @buf: buffer to check
 406 * @offs: offset to check
 407 *
 408 * This function returns %1 if @offs was in the last write to the LEB whose data
 409 * is in @buf, otherwise %0 is returned. The determination is made by checking
 410 * for subsequent empty space starting from the next @c->max_write_size
 411 * boundary.
 412 */
 413static int is_last_write(const struct ubifs_info *c, void *buf, int offs)
 414{
 415        int empty_offs, check_len;
 416        uint8_t *p;
 417
 418        /*
 419         * Round up to the next @c->max_write_size boundary i.e. @offs is in
 420         * the last wbuf written. After that should be empty space.
 421         */
 422        empty_offs = ALIGN(offs + 1, c->max_write_size);
 423        check_len = c->leb_size - empty_offs;
 424        p = buf + empty_offs - offs;
 425        return is_empty(p, check_len);
 426}
 427
 428/**
 429 * clean_buf - clean the data from an LEB sitting in a buffer.
 430 * @c: UBIFS file-system description object
 431 * @buf: buffer to clean
 432 * @lnum: LEB number to clean
 433 * @offs: offset from which to clean
 434 * @len: length of buffer
 435 *
 436 * This function pads up to the next min_io_size boundary (if there is one) and
 437 * sets empty space to all 0xff. @buf, @offs and @len are updated to the next
 438 * @c->min_io_size boundary.
 439 */
 440static void clean_buf(const struct ubifs_info *c, void **buf, int lnum,
 441                      int *offs, int *len)
 442{
 443        int empty_offs, pad_len;
 444
 445        lnum = lnum;
 446        dbg_rcvry("cleaning corruption at %d:%d", lnum, *offs);
 447
 448        ubifs_assert(!(*offs & 7));
 449        empty_offs = ALIGN(*offs, c->min_io_size);
 450        pad_len = empty_offs - *offs;
 451        ubifs_pad(c, *buf, pad_len);
 452        *offs += pad_len;
 453        *buf += pad_len;
 454        *len -= pad_len;
 455        memset(*buf, 0xff, c->leb_size - empty_offs);
 456}
 457
 458/**
 459 * no_more_nodes - determine if there are no more nodes in a buffer.
 460 * @c: UBIFS file-system description object
 461 * @buf: buffer to check
 462 * @len: length of buffer
 463 * @lnum: LEB number of the LEB from which @buf was read
 464 * @offs: offset from which @buf was read
 465 *
 466 * This function ensures that the corrupted node at @offs is the last thing
 467 * written to a LEB. This function returns %1 if more data is not found and
 468 * %0 if more data is found.
 469 */
 470static int no_more_nodes(const struct ubifs_info *c, void *buf, int len,
 471                        int lnum, int offs)
 472{
 473        struct ubifs_ch *ch = buf;
 474        int skip, dlen = le32_to_cpu(ch->len);
 475
 476        /* Check for empty space after the corrupt node's common header */
 477        skip = ALIGN(offs + UBIFS_CH_SZ, c->max_write_size) - offs;
 478        if (is_empty(buf + skip, len - skip))
 479                return 1;
 480        /*
 481         * The area after the common header size is not empty, so the common
 482         * header must be intact. Check it.
 483         */
 484        if (ubifs_check_node(c, buf, lnum, offs, 1, 0) != -EUCLEAN) {
 485                dbg_rcvry("unexpected bad common header at %d:%d", lnum, offs);
 486                return 0;
 487        }
 488        /* Now we know the corrupt node's length we can skip over it */
 489        skip = ALIGN(offs + dlen, c->max_write_size) - offs;
 490        /* After which there should be empty space */
 491        if (is_empty(buf + skip, len - skip))
 492                return 1;
 493        dbg_rcvry("unexpected data at %d:%d", lnum, offs + skip);
 494        return 0;
 495}
 496
 497/**
 498 * fix_unclean_leb - fix an unclean LEB.
 499 * @c: UBIFS file-system description object
 500 * @sleb: scanned LEB information
 501 * @start: offset where scan started
 502 */
 503static int fix_unclean_leb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 504                           int start)
 505{
 506        int lnum = sleb->lnum, endpt = start;
 507
 508        /* Get the end offset of the last node we are keeping */
 509        if (!list_empty(&sleb->nodes)) {
 510                struct ubifs_scan_node *snod;
 511
 512                snod = list_entry(sleb->nodes.prev,
 513                                  struct ubifs_scan_node, list);
 514                endpt = snod->offs + snod->len;
 515        }
 516
 517        if (c->ro_mount && !c->remounting_rw) {
 518                /* Add to recovery list */
 519                struct ubifs_unclean_leb *ucleb;
 520
 521                dbg_rcvry("need to fix LEB %d start %d endpt %d",
 522                          lnum, start, sleb->endpt);
 523                ucleb = kzalloc(sizeof(struct ubifs_unclean_leb), GFP_NOFS);
 524                if (!ucleb)
 525                        return -ENOMEM;
 526                ucleb->lnum = lnum;
 527                ucleb->endpt = endpt;
 528                list_add_tail(&ucleb->list, &c->unclean_leb_list);
 529        } else {
 530                /* Write the fixed LEB back to flash */
 531                int err;
 532
 533                dbg_rcvry("fixing LEB %d start %d endpt %d",
 534                          lnum, start, sleb->endpt);
 535                if (endpt == 0) {
 536                        err = ubifs_leb_unmap(c, lnum);
 537                        if (err)
 538                                return err;
 539                } else {
 540                        int len = ALIGN(endpt, c->min_io_size);
 541
 542                        if (start) {
 543                                err = ubifs_leb_read(c, lnum, sleb->buf, 0,
 544                                                     start, 1);
 545                                if (err)
 546                                        return err;
 547                        }
 548                        /* Pad to min_io_size */
 549                        if (len > endpt) {
 550                                int pad_len = len - ALIGN(endpt, 8);
 551
 552                                if (pad_len > 0) {
 553                                        void *buf = sleb->buf + len - pad_len;
 554
 555                                        ubifs_pad(c, buf, pad_len);
 556                                }
 557                        }
 558                        err = ubifs_leb_change(c, lnum, sleb->buf, len);
 559                        if (err)
 560                                return err;
 561                }
 562        }
 563        return 0;
 564}
 565
 566/**
 567 * drop_last_group - drop the last group of nodes.
 568 * @sleb: scanned LEB information
 569 * @offs: offset of dropped nodes is returned here
 570 *
 571 * This is a helper function for 'ubifs_recover_leb()' which drops the last
 572 * group of nodes of the scanned LEB.
 573 */
 574static void drop_last_group(struct ubifs_scan_leb *sleb, int *offs)
 575{
 576        while (!list_empty(&sleb->nodes)) {
 577                struct ubifs_scan_node *snod;
 578                struct ubifs_ch *ch;
 579
 580                snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
 581                                  list);
 582                ch = snod->node;
 583                if (ch->group_type != UBIFS_IN_NODE_GROUP)
 584                        break;
 585
 586                dbg_rcvry("dropping grouped node at %d:%d",
 587                          sleb->lnum, snod->offs);
 588                *offs = snod->offs;
 589                list_del(&snod->list);
 590                kfree(snod);
 591                sleb->nodes_cnt -= 1;
 592        }
 593}
 594
 595/**
 596 * drop_last_node - drop the last node.
 597 * @sleb: scanned LEB information
 598 * @offs: offset of dropped nodes is returned here
 599 * @grouped: non-zero if whole group of nodes have to be dropped
 600 *
 601 * This is a helper function for 'ubifs_recover_leb()' which drops the last
 602 * node of the scanned LEB.
 603 */
 604static void drop_last_node(struct ubifs_scan_leb *sleb, int *offs)
 605{
 606        struct ubifs_scan_node *snod;
 607
 608        if (!list_empty(&sleb->nodes)) {
 609                snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
 610                                  list);
 611
 612                dbg_rcvry("dropping last node at %d:%d", sleb->lnum, snod->offs);
 613                *offs = snod->offs;
 614                list_del(&snod->list);
 615                kfree(snod);
 616                sleb->nodes_cnt -= 1;
 617        }
 618}
 619
 620/**
 621 * ubifs_recover_leb - scan and recover a LEB.
 622 * @c: UBIFS file-system description object
 623 * @lnum: LEB number
 624 * @offs: offset
 625 * @sbuf: LEB-sized buffer to use
 626 * @jhead: journal head number this LEB belongs to (%-1 if the LEB does not
 627 *         belong to any journal head)
 628 *
 629 * This function does a scan of a LEB, but caters for errors that might have
 630 * been caused by the unclean unmount from which we are attempting to recover.
 631 * Returns %0 in case of success, %-EUCLEAN if an unrecoverable corruption is
 632 * found, and a negative error code in case of failure.
 633 */
 634struct ubifs_scan_leb *ubifs_recover_leb(struct ubifs_info *c, int lnum,
 635                                         int offs, void *sbuf, int jhead)
 636{
 637        int ret = 0, err, len = c->leb_size - offs, start = offs, min_io_unit;
 638        int grouped = jhead == -1 ? 0 : c->jheads[jhead].grouped;
 639        struct ubifs_scan_leb *sleb;
 640        void *buf = sbuf + offs;
 641
 642        dbg_rcvry("%d:%d, jhead %d, grouped %d", lnum, offs, jhead, grouped);
 643
 644        sleb = ubifs_start_scan(c, lnum, offs, sbuf);
 645        if (IS_ERR(sleb))
 646                return sleb;
 647
 648        ubifs_assert(len >= 8);
 649        while (len >= 8) {
 650                dbg_scan("look at LEB %d:%d (%d bytes left)",
 651                         lnum, offs, len);
 652
 653                cond_resched();
 654
 655                /*
 656                 * Scan quietly until there is an error from which we cannot
 657                 * recover
 658                 */
 659                ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
 660                if (ret == SCANNED_A_NODE) {
 661                        /* A valid node, and not a padding node */
 662                        struct ubifs_ch *ch = buf;
 663                        int node_len;
 664
 665                        err = ubifs_add_snod(c, sleb, buf, offs);
 666                        if (err)
 667                                goto error;
 668                        node_len = ALIGN(le32_to_cpu(ch->len), 8);
 669                        offs += node_len;
 670                        buf += node_len;
 671                        len -= node_len;
 672                } else if (ret > 0) {
 673                        /* Padding bytes or a valid padding node */
 674                        offs += ret;
 675                        buf += ret;
 676                        len -= ret;
 677                } else if (ret == SCANNED_EMPTY_SPACE ||
 678                           ret == SCANNED_GARBAGE     ||
 679                           ret == SCANNED_A_BAD_PAD_NODE ||
 680                           ret == SCANNED_A_CORRUPT_NODE) {
 681                        dbg_rcvry("found corruption (%d) at %d:%d",
 682                                  ret, lnum, offs);
 683                        break;
 684                } else {
 685                        ubifs_err("unexpected return value %d", ret);
 686                        err = -EINVAL;
 687                        goto error;
 688                }
 689        }
 690
 691        if (ret == SCANNED_GARBAGE || ret == SCANNED_A_BAD_PAD_NODE) {
 692                if (!is_last_write(c, buf, offs))
 693                        goto corrupted_rescan;
 694        } else if (ret == SCANNED_A_CORRUPT_NODE) {
 695                if (!no_more_nodes(c, buf, len, lnum, offs))
 696                        goto corrupted_rescan;
 697        } else if (!is_empty(buf, len)) {
 698                if (!is_last_write(c, buf, offs)) {
 699                        int corruption = first_non_ff(buf, len);
 700
 701                        /*
 702                         * See header comment for this file for more
 703                         * explanations about the reasons we have this check.
 704                         */
 705                        ubifs_err("corrupt empty space LEB %d:%d, corruption "
 706                                  "starts at %d", lnum, offs, corruption);
 707                        /* Make sure we dump interesting non-0xFF data */
 708                        offs += corruption;
 709                        buf += corruption;
 710                        goto corrupted;
 711                }
 712        }
 713
 714        min_io_unit = round_down(offs, c->min_io_size);
 715        if (grouped)
 716                /*
 717                 * If nodes are grouped, always drop the incomplete group at
 718                 * the end.
 719                 */
 720                drop_last_group(sleb, &offs);
 721
 722        if (jhead == GCHD) {
 723                /*
 724                 * If this LEB belongs to the GC head then while we are in the
 725                 * middle of the same min. I/O unit keep dropping nodes. So
 726                 * basically, what we want is to make sure that the last min.
 727                 * I/O unit where we saw the corruption is dropped completely
 728                 * with all the uncorrupted nodes which may possibly sit there.
 729                 *
 730                 * In other words, let's name the min. I/O unit where the
 731                 * corruption starts B, and the previous min. I/O unit A. The
 732                 * below code tries to deal with a situation when half of B
 733                 * contains valid nodes or the end of a valid node, and the
 734                 * second half of B contains corrupted data or garbage. This
 735                 * means that UBIFS had been writing to B just before the power
 736                 * cut happened. I do not know how realistic is this scenario
 737                 * that half of the min. I/O unit had been written successfully
 738                 * and the other half not, but this is possible in our 'failure
 739                 * mode emulation' infrastructure at least.
 740                 *
 741                 * So what is the problem, why we need to drop those nodes? Why
 742                 * can't we just clean-up the second half of B by putting a
 743                 * padding node there? We can, and this works fine with one
 744                 * exception which was reproduced with power cut emulation
 745                 * testing and happens extremely rarely.
 746                 *
 747                 * Imagine the file-system is full, we run GC which starts
 748                 * moving valid nodes from LEB X to LEB Y (obviously, LEB Y is
 749                 * the current GC head LEB). The @c->gc_lnum is -1, which means
 750                 * that GC will retain LEB X and will try to continue. Imagine
 751                 * that LEB X is currently the dirtiest LEB, and the amount of
 752                 * used space in LEB Y is exactly the same as amount of free
 753                 * space in LEB X.
 754                 *
 755                 * And a power cut happens when nodes are moved from LEB X to
 756                 * LEB Y. We are here trying to recover LEB Y which is the GC
 757                 * head LEB. We find the min. I/O unit B as described above.
 758                 * Then we clean-up LEB Y by padding min. I/O unit. And later
 759                 * 'ubifs_rcvry_gc_commit()' function fails, because it cannot
 760                 * find a dirty LEB which could be GC'd into LEB Y! Even LEB X
 761                 * does not match because the amount of valid nodes there does
 762                 * not fit the free space in LEB Y any more! And this is
 763                 * because of the padding node which we added to LEB Y. The
 764                 * user-visible effect of this which I once observed and
 765                 * analysed is that we cannot mount the file-system with
 766                 * -ENOSPC error.
 767                 *
 768                 * So obviously, to make sure that situation does not happen we
 769                 * should free min. I/O unit B in LEB Y completely and the last
 770                 * used min. I/O unit in LEB Y should be A. This is basically
 771                 * what the below code tries to do.
 772                 */
 773                while (offs > min_io_unit)
 774                        drop_last_node(sleb, &offs);
 775        }
 776
 777        buf = sbuf + offs;
 778        len = c->leb_size - offs;
 779
 780        clean_buf(c, &buf, lnum, &offs, &len);
 781        ubifs_end_scan(c, sleb, lnum, offs);
 782
 783        err = fix_unclean_leb(c, sleb, start);
 784        if (err)
 785                goto error;
 786
 787        return sleb;
 788
 789corrupted_rescan:
 790        /* Re-scan the corrupted data with verbose messages */
 791        ubifs_err("corruption %d", ret);
 792        ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
 793corrupted:
 794        ubifs_scanned_corruption(c, lnum, offs, buf);
 795        err = -EUCLEAN;
 796error:
 797        ubifs_err("LEB %d scanning failed", lnum);
 798        ubifs_scan_destroy(sleb);
 799        return ERR_PTR(err);
 800}
 801
 802/**
 803 * get_cs_sqnum - get commit start sequence number.
 804 * @c: UBIFS file-system description object
 805 * @lnum: LEB number of commit start node
 806 * @offs: offset of commit start node
 807 * @cs_sqnum: commit start sequence number is returned here
 808 *
 809 * This function returns %0 on success and a negative error code on failure.
 810 */
 811static int get_cs_sqnum(struct ubifs_info *c, int lnum, int offs,
 812                        unsigned long long *cs_sqnum)
 813{
 814        struct ubifs_cs_node *cs_node = NULL;
 815        int err, ret;
 816
 817        dbg_rcvry("at %d:%d", lnum, offs);
 818        cs_node = kmalloc(UBIFS_CS_NODE_SZ, GFP_KERNEL);
 819        if (!cs_node)
 820                return -ENOMEM;
 821        if (c->leb_size - offs < UBIFS_CS_NODE_SZ)
 822                goto out_err;
 823        err = ubifs_leb_read(c, lnum, (void *)cs_node, offs,
 824                             UBIFS_CS_NODE_SZ, 0);
 825        if (err && err != -EBADMSG)
 826                goto out_free;
 827        ret = ubifs_scan_a_node(c, cs_node, UBIFS_CS_NODE_SZ, lnum, offs, 0);
 828        if (ret != SCANNED_A_NODE) {
 829                ubifs_err("Not a valid node");
 830                goto out_err;
 831        }
 832        if (cs_node->ch.node_type != UBIFS_CS_NODE) {
 833                ubifs_err("Node a CS node, type is %d", cs_node->ch.node_type);
 834                goto out_err;
 835        }
 836        if (le64_to_cpu(cs_node->cmt_no) != c->cmt_no) {
 837                ubifs_err("CS node cmt_no %llu != current cmt_no %llu",
 838                          (unsigned long long)le64_to_cpu(cs_node->cmt_no),
 839                          c->cmt_no);
 840                goto out_err;
 841        }
 842        *cs_sqnum = le64_to_cpu(cs_node->ch.sqnum);
 843        dbg_rcvry("commit start sqnum %llu", *cs_sqnum);
 844        kfree(cs_node);
 845        return 0;
 846
 847out_err:
 848        err = -EINVAL;
 849out_free:
 850        ubifs_err("failed to get CS sqnum");
 851        kfree(cs_node);
 852        return err;
 853}
 854
 855/**
 856 * ubifs_recover_log_leb - scan and recover a log LEB.
 857 * @c: UBIFS file-system description object
 858 * @lnum: LEB number
 859 * @offs: offset
 860 * @sbuf: LEB-sized buffer to use
 861 *
 862 * This function does a scan of a LEB, but caters for errors that might have
 863 * been caused by unclean reboots from which we are attempting to recover
 864 * (assume that only the last log LEB can be corrupted by an unclean reboot).
 865 *
 866 * This function returns %0 on success and a negative error code on failure.
 867 */
 868struct ubifs_scan_leb *ubifs_recover_log_leb(struct ubifs_info *c, int lnum,
 869                                             int offs, void *sbuf)
 870{
 871        struct ubifs_scan_leb *sleb;
 872        int next_lnum;
 873
 874        dbg_rcvry("LEB %d", lnum);
 875        next_lnum = lnum + 1;
 876        if (next_lnum >= UBIFS_LOG_LNUM + c->log_lebs)
 877                next_lnum = UBIFS_LOG_LNUM;
 878        if (next_lnum != c->ltail_lnum) {
 879                /*
 880                 * We can only recover at the end of the log, so check that the
 881                 * next log LEB is empty or out of date.
 882                 */
 883                sleb = ubifs_scan(c, next_lnum, 0, sbuf, 0);
 884                if (IS_ERR(sleb))
 885                        return sleb;
 886                if (sleb->nodes_cnt) {
 887                        struct ubifs_scan_node *snod;
 888                        unsigned long long cs_sqnum = c->cs_sqnum;
 889
 890                        snod = list_entry(sleb->nodes.next,
 891                                          struct ubifs_scan_node, list);
 892                        if (cs_sqnum == 0) {
 893                                int err;
 894
 895                                err = get_cs_sqnum(c, lnum, offs, &cs_sqnum);
 896                                if (err) {
 897                                        ubifs_scan_destroy(sleb);
 898                                        return ERR_PTR(err);
 899                                }
 900                        }
 901                        if (snod->sqnum > cs_sqnum) {
 902                                ubifs_err("unrecoverable log corruption "
 903                                          "in LEB %d", lnum);
 904                                ubifs_scan_destroy(sleb);
 905                                return ERR_PTR(-EUCLEAN);
 906                        }
 907                }
 908                ubifs_scan_destroy(sleb);
 909        }
 910        return ubifs_recover_leb(c, lnum, offs, sbuf, -1);
 911}
 912
 913/**
 914 * recover_head - recover a head.
 915 * @c: UBIFS file-system description object
 916 * @lnum: LEB number of head to recover
 917 * @offs: offset of head to recover
 918 * @sbuf: LEB-sized buffer to use
 919 *
 920 * This function ensures that there is no data on the flash at a head location.
 921 *
 922 * This function returns %0 on success and a negative error code on failure.
 923 */
 924static int recover_head(struct ubifs_info *c, int lnum, int offs, void *sbuf)
 925{
 926        int len = c->max_write_size, err;
 927
 928        if (offs + len > c->leb_size)
 929                len = c->leb_size - offs;
 930
 931        if (!len)
 932                return 0;
 933
 934        /* Read at the head location and check it is empty flash */
 935        err = ubifs_leb_read(c, lnum, sbuf, offs, len, 1);
 936        if (err || !is_empty(sbuf, len)) {
 937                dbg_rcvry("cleaning head at %d:%d", lnum, offs);
 938                if (offs == 0)
 939                        return ubifs_leb_unmap(c, lnum);
 940                err = ubifs_leb_read(c, lnum, sbuf, 0, offs, 1);
 941                if (err)
 942                        return err;
 943                return ubifs_leb_change(c, lnum, sbuf, offs);
 944        }
 945
 946        return 0;
 947}
 948
 949/**
 950 * ubifs_recover_inl_heads - recover index and LPT heads.
 951 * @c: UBIFS file-system description object
 952 * @sbuf: LEB-sized buffer to use
 953 *
 954 * This function ensures that there is no data on the flash at the index and
 955 * LPT head locations.
 956 *
 957 * This deals with the recovery of a half-completed journal commit. UBIFS is
 958 * careful never to overwrite the last version of the index or the LPT. Because
 959 * the index and LPT are wandering trees, data from a half-completed commit will
 960 * not be referenced anywhere in UBIFS. The data will be either in LEBs that are
 961 * assumed to be empty and will be unmapped anyway before use, or in the index
 962 * and LPT heads.
 963 *
 964 * This function returns %0 on success and a negative error code on failure.
 965 */
 966int ubifs_recover_inl_heads(struct ubifs_info *c, void *sbuf)
 967{
 968        int err;
 969
 970        ubifs_assert(!c->ro_mount || c->remounting_rw);
 971
 972        dbg_rcvry("checking index head at %d:%d", c->ihead_lnum, c->ihead_offs);
 973        err = recover_head(c, c->ihead_lnum, c->ihead_offs, sbuf);
 974        if (err)
 975                return err;
 976
 977        dbg_rcvry("checking LPT head at %d:%d", c->nhead_lnum, c->nhead_offs);
 978        err = recover_head(c, c->nhead_lnum, c->nhead_offs, sbuf);
 979        if (err)
 980                return err;
 981
 982        return 0;
 983}
 984
 985/**
 986 * clean_an_unclean_leb - read and write a LEB to remove corruption.
 987 * @c: UBIFS file-system description object
 988 * @ucleb: unclean LEB information
 989 * @sbuf: LEB-sized buffer to use
 990 *
 991 * This function reads a LEB up to a point pre-determined by the mount recovery,
 992 * checks the nodes, and writes the result back to the flash, thereby cleaning
 993 * off any following corruption, or non-fatal ECC errors.
 994 *
 995 * This function returns %0 on success and a negative error code on failure.
 996 */
 997static int clean_an_unclean_leb(struct ubifs_info *c,
 998                                struct ubifs_unclean_leb *ucleb, void *sbuf)
 999{
1000        int err, lnum = ucleb->lnum, offs = 0, len = ucleb->endpt, quiet = 1;
1001        void *buf = sbuf;
1002
1003        dbg_rcvry("LEB %d len %d", lnum, len);
1004
1005        if (len == 0) {
1006                /* Nothing to read, just unmap it */
1007                err = ubifs_leb_unmap(c, lnum);
1008                if (err)
1009                        return err;
1010                return 0;
1011        }
1012
1013        err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
1014        if (err && err != -EBADMSG)
1015                return err;
1016
1017        while (len >= 8) {
1018                int ret;
1019
1020                cond_resched();
1021
1022                /* Scan quietly until there is an error */
1023                ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
1024
1025                if (ret == SCANNED_A_NODE) {
1026                        /* A valid node, and not a padding node */
1027                        struct ubifs_ch *ch = buf;
1028                        int node_len;
1029
1030                        node_len = ALIGN(le32_to_cpu(ch->len), 8);
1031                        offs += node_len;
1032                        buf += node_len;
1033                        len -= node_len;
1034                        continue;
1035                }
1036
1037                if (ret > 0) {
1038                        /* Padding bytes or a valid padding node */
1039                        offs += ret;
1040                        buf += ret;
1041                        len -= ret;
1042                        continue;
1043                }
1044
1045                if (ret == SCANNED_EMPTY_SPACE) {
1046                        ubifs_err("unexpected empty space at %d:%d",
1047                                  lnum, offs);
1048                        return -EUCLEAN;
1049                }
1050
1051                if (quiet) {
1052                        /* Redo the last scan but noisily */
1053                        quiet = 0;
1054                        continue;
1055                }
1056
1057                ubifs_scanned_corruption(c, lnum, offs, buf);
1058                return -EUCLEAN;
1059        }
1060
1061        /* Pad to min_io_size */
1062        len = ALIGN(ucleb->endpt, c->min_io_size);
1063        if (len > ucleb->endpt) {
1064                int pad_len = len - ALIGN(ucleb->endpt, 8);
1065
1066                if (pad_len > 0) {
1067                        buf = c->sbuf + len - pad_len;
1068                        ubifs_pad(c, buf, pad_len);
1069                }
1070        }
1071
1072        /* Write back the LEB atomically */
1073        err = ubifs_leb_change(c, lnum, sbuf, len);
1074        if (err)
1075                return err;
1076
1077        dbg_rcvry("cleaned LEB %d", lnum);
1078
1079        return 0;
1080}
1081
1082/**
1083 * ubifs_clean_lebs - clean LEBs recovered during read-only mount.
1084 * @c: UBIFS file-system description object
1085 * @sbuf: LEB-sized buffer to use
1086 *
1087 * This function cleans a LEB identified during recovery that needs to be
1088 * written but was not because UBIFS was mounted read-only. This happens when
1089 * remounting to read-write mode.
1090 *
1091 * This function returns %0 on success and a negative error code on failure.
1092 */
1093int ubifs_clean_lebs(struct ubifs_info *c, void *sbuf)
1094{
1095        dbg_rcvry("recovery");
1096        while (!list_empty(&c->unclean_leb_list)) {
1097                struct ubifs_unclean_leb *ucleb;
1098                int err;
1099
1100                ucleb = list_entry(c->unclean_leb_list.next,
1101                                   struct ubifs_unclean_leb, list);
1102                err = clean_an_unclean_leb(c, ucleb, sbuf);
1103                if (err)
1104                        return err;
1105                list_del(&ucleb->list);
1106                kfree(ucleb);
1107        }
1108        return 0;
1109}
1110
1111/**
1112 * grab_empty_leb - grab an empty LEB to use as GC LEB and run commit.
1113 * @c: UBIFS file-system description object
1114 *
1115 * This is a helper function for 'ubifs_rcvry_gc_commit()' which grabs an empty
1116 * LEB to be used as GC LEB (@c->gc_lnum), and then runs the commit. Returns
1117 * zero in case of success and a negative error code in case of failure.
1118 */
1119static int grab_empty_leb(struct ubifs_info *c)
1120{
1121        int lnum, err;
1122
1123        /*
1124         * Note, it is very important to first search for an empty LEB and then
1125         * run the commit, not vice-versa. The reason is that there might be
1126         * only one empty LEB at the moment, the one which has been the
1127         * @c->gc_lnum just before the power cut happened. During the regular
1128         * UBIFS operation (not now) @c->gc_lnum is marked as "taken", so no
1129         * one but GC can grab it. But at this moment this single empty LEB is
1130         * not marked as taken, so if we run commit - what happens? Right, the
1131         * commit will grab it and write the index there. Remember that the
1132         * index always expands as long as there is free space, and it only
1133         * starts consolidating when we run out of space.
1134         *
1135         * IOW, if we run commit now, we might not be able to find a free LEB
1136         * after this.
1137         */
1138        lnum = ubifs_find_free_leb_for_idx(c);
1139        if (lnum < 0) {
1140                ubifs_err("could not find an empty LEB");
1141                ubifs_dump_lprops(c);
1142                ubifs_dump_budg(c, &c->bi);
1143                return lnum;
1144        }
1145
1146        /* Reset the index flag */
1147        err = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
1148                                  LPROPS_INDEX, 0);
1149        if (err)
1150                return err;
1151
1152        c->gc_lnum = lnum;
1153        dbg_rcvry("found empty LEB %d, run commit", lnum);
1154
1155        return ubifs_run_commit(c);
1156}
1157
1158/**
1159 * ubifs_rcvry_gc_commit - recover the GC LEB number and run the commit.
1160 * @c: UBIFS file-system description object
1161 *
1162 * Out-of-place garbage collection requires always one empty LEB with which to
1163 * start garbage collection. The LEB number is recorded in c->gc_lnum and is
1164 * written to the master node on unmounting. In the case of an unclean unmount
1165 * the value of gc_lnum recorded in the master node is out of date and cannot
1166 * be used. Instead, recovery must allocate an empty LEB for this purpose.
1167 * However, there may not be enough empty space, in which case it must be
1168 * possible to GC the dirtiest LEB into the GC head LEB.
1169 *
1170 * This function also runs the commit which causes the TNC updates from
1171 * size-recovery and orphans to be written to the flash. That is important to
1172 * ensure correct replay order for subsequent mounts.
1173 *
1174 * This function returns %0 on success and a negative error code on failure.
1175 */
1176int ubifs_rcvry_gc_commit(struct ubifs_info *c)
1177{
1178        struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
1179        struct ubifs_lprops lp;
1180        int err;
1181
1182        dbg_rcvry("GC head LEB %d, offs %d", wbuf->lnum, wbuf->offs);
1183
1184        c->gc_lnum = -1;
1185        if (wbuf->lnum == -1 || wbuf->offs == c->leb_size)
1186                return grab_empty_leb(c);
1187
1188        err = ubifs_find_dirty_leb(c, &lp, wbuf->offs, 2);
1189        if (err) {
1190                if (err != -ENOSPC)
1191                        return err;
1192
1193                dbg_rcvry("could not find a dirty LEB");
1194                return grab_empty_leb(c);
1195        }
1196
1197        ubifs_assert(!(lp.flags & LPROPS_INDEX));
1198        ubifs_assert(lp.free + lp.dirty >= wbuf->offs);
1199
1200        /*
1201         * We run the commit before garbage collection otherwise subsequent
1202         * mounts will see the GC and orphan deletion in a different order.
1203         */
1204        dbg_rcvry("committing");
1205        err = ubifs_run_commit(c);
1206        if (err)
1207                return err;
1208
1209        dbg_rcvry("GC'ing LEB %d", lp.lnum);
1210        mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
1211        err = ubifs_garbage_collect_leb(c, &lp);
1212        if (err >= 0) {
1213                int err2 = ubifs_wbuf_sync_nolock(wbuf);
1214
1215                if (err2)
1216                        err = err2;
1217        }
1218        mutex_unlock(&wbuf->io_mutex);
1219        if (err < 0) {
1220                ubifs_err("GC failed, error %d", err);
1221                if (err == -EAGAIN)
1222                        err = -EINVAL;
1223                return err;
1224        }
1225
1226        ubifs_assert(err == LEB_RETAINED);
1227        if (err != LEB_RETAINED)
1228                return -EINVAL;
1229
1230        err = ubifs_leb_unmap(c, c->gc_lnum);
1231        if (err)
1232                return err;
1233
1234        dbg_rcvry("allocated LEB %d for GC", lp.lnum);
1235        return 0;
1236}
1237
1238/**
1239 * struct size_entry - inode size information for recovery.
1240 * @rb: link in the RB-tree of sizes
1241 * @inum: inode number
1242 * @i_size: size on inode
1243 * @d_size: maximum size based on data nodes
1244 * @exists: indicates whether the inode exists
1245 * @inode: inode if pinned in memory awaiting rw mode to fix it
1246 */
1247struct size_entry {
1248        struct rb_node rb;
1249        ino_t inum;
1250        loff_t i_size;
1251        loff_t d_size;
1252        int exists;
1253        struct inode *inode;
1254};
1255
1256/**
1257 * add_ino - add an entry to the size tree.
1258 * @c: UBIFS file-system description object
1259 * @inum: inode number
1260 * @i_size: size on inode
1261 * @d_size: maximum size based on data nodes
1262 * @exists: indicates whether the inode exists
1263 */
1264static int add_ino(struct ubifs_info *c, ino_t inum, loff_t i_size,
1265                   loff_t d_size, int exists)
1266{
1267        struct rb_node **p = &c->size_tree.rb_node, *parent = NULL;
1268        struct size_entry *e;
1269
1270        while (*p) {
1271                parent = *p;
1272                e = rb_entry(parent, struct size_entry, rb);
1273                if (inum < e->inum)
1274                        p = &(*p)->rb_left;
1275                else
1276                        p = &(*p)->rb_right;
1277        }
1278
1279        e = kzalloc(sizeof(struct size_entry), GFP_KERNEL);
1280        if (!e)
1281                return -ENOMEM;
1282
1283        e->inum = inum;
1284        e->i_size = i_size;
1285        e->d_size = d_size;
1286        e->exists = exists;
1287
1288        rb_link_node(&e->rb, parent, p);
1289        rb_insert_color(&e->rb, &c->size_tree);
1290
1291        return 0;
1292}
1293
1294/**
1295 * find_ino - find an entry on the size tree.
1296 * @c: UBIFS file-system description object
1297 * @inum: inode number
1298 */
1299static struct size_entry *find_ino(struct ubifs_info *c, ino_t inum)
1300{
1301        struct rb_node *p = c->size_tree.rb_node;
1302        struct size_entry *e;
1303
1304        while (p) {
1305                e = rb_entry(p, struct size_entry, rb);
1306                if (inum < e->inum)
1307                        p = p->rb_left;
1308                else if (inum > e->inum)
1309                        p = p->rb_right;
1310                else
1311                        return e;
1312        }
1313        return NULL;
1314}
1315
1316/**
1317 * remove_ino - remove an entry from the size tree.
1318 * @c: UBIFS file-system description object
1319 * @inum: inode number
1320 */
1321static void remove_ino(struct ubifs_info *c, ino_t inum)
1322{
1323        struct size_entry *e = find_ino(c, inum);
1324
1325        if (!e)
1326                return;
1327        rb_erase(&e->rb, &c->size_tree);
1328        kfree(e);
1329}
1330
1331/**
1332 * ubifs_destroy_size_tree - free resources related to the size tree.
1333 * @c: UBIFS file-system description object
1334 */
1335void ubifs_destroy_size_tree(struct ubifs_info *c)
1336{
1337        struct rb_node *this = c->size_tree.rb_node;
1338        struct size_entry *e;
1339
1340        while (this) {
1341                if (this->rb_left) {
1342                        this = this->rb_left;
1343                        continue;
1344                } else if (this->rb_right) {
1345                        this = this->rb_right;
1346                        continue;
1347                }
1348                e = rb_entry(this, struct size_entry, rb);
1349                if (e->inode)
1350                        iput(e->inode);
1351                this = rb_parent(this);
1352                if (this) {
1353                        if (this->rb_left == &e->rb)
1354                                this->rb_left = NULL;
1355                        else
1356                                this->rb_right = NULL;
1357                }
1358                kfree(e);
1359        }
1360        c->size_tree = RB_ROOT;
1361}
1362
1363/**
1364 * ubifs_recover_size_accum - accumulate inode sizes for recovery.
1365 * @c: UBIFS file-system description object
1366 * @key: node key
1367 * @deletion: node is for a deletion
1368 * @new_size: inode size
1369 *
1370 * This function has two purposes:
1371 *     1) to ensure there are no data nodes that fall outside the inode size
1372 *     2) to ensure there are no data nodes for inodes that do not exist
1373 * To accomplish those purposes, a rb-tree is constructed containing an entry
1374 * for each inode number in the journal that has not been deleted, and recording
1375 * the size from the inode node, the maximum size of any data node (also altered
1376 * by truncations) and a flag indicating a inode number for which no inode node
1377 * was present in the journal.
1378 *
1379 * Note that there is still the possibility that there are data nodes that have
1380 * been committed that are beyond the inode size, however the only way to find
1381 * them would be to scan the entire index. Alternatively, some provision could
1382 * be made to record the size of inodes at the start of commit, which would seem
1383 * very cumbersome for a scenario that is quite unlikely and the only negative
1384 * consequence of which is wasted space.
1385 *
1386 * This functions returns %0 on success and a negative error code on failure.
1387 */
1388int ubifs_recover_size_accum(struct ubifs_info *c, union ubifs_key *key,
1389                             int deletion, loff_t new_size)
1390{
1391        ino_t inum = key_inum(c, key);
1392        struct size_entry *e;
1393        int err;
1394
1395        switch (key_type(c, key)) {
1396        case UBIFS_INO_KEY:
1397                if (deletion)
1398                        remove_ino(c, inum);
1399                else {
1400                        e = find_ino(c, inum);
1401                        if (e) {
1402                                e->i_size = new_size;
1403                                e->exists = 1;
1404                        } else {
1405                                err = add_ino(c, inum, new_size, 0, 1);
1406                                if (err)
1407                                        return err;
1408                        }
1409                }
1410                break;
1411        case UBIFS_DATA_KEY:
1412                e = find_ino(c, inum);
1413                if (e) {
1414                        if (new_size > e->d_size)
1415                                e->d_size = new_size;
1416                } else {
1417                        err = add_ino(c, inum, 0, new_size, 0);
1418                        if (err)
1419                                return err;
1420                }
1421                break;
1422        case UBIFS_TRUN_KEY:
1423                e = find_ino(c, inum);
1424                if (e)
1425                        e->d_size = new_size;
1426                break;
1427        }
1428        return 0;
1429}
1430
1431/**
1432 * fix_size_in_place - fix inode size in place on flash.
1433 * @c: UBIFS file-system description object
1434 * @e: inode size information for recovery
1435 */
1436static int fix_size_in_place(struct ubifs_info *c, struct size_entry *e)
1437{
1438        struct ubifs_ino_node *ino = c->sbuf;
1439        unsigned char *p;
1440        union ubifs_key key;
1441        int err, lnum, offs, len;
1442        loff_t i_size;
1443        uint32_t crc;
1444
1445        /* Locate the inode node LEB number and offset */
1446        ino_key_init(c, &key, e->inum);
1447        err = ubifs_tnc_locate(c, &key, ino, &lnum, &offs);
1448        if (err)
1449                goto out;
1450        /*
1451         * If the size recorded on the inode node is greater than the size that
1452         * was calculated from nodes in the journal then don't change the inode.
1453         */
1454        i_size = le64_to_cpu(ino->size);
1455        if (i_size >= e->d_size)
1456                return 0;
1457        /* Read the LEB */
1458        err = ubifs_leb_read(c, lnum, c->sbuf, 0, c->leb_size, 1);
1459        if (err)
1460                goto out;
1461        /* Change the size field and recalculate the CRC */
1462        ino = c->sbuf + offs;
1463        ino->size = cpu_to_le64(e->d_size);
1464        len = le32_to_cpu(ino->ch.len);
1465        crc = crc32(UBIFS_CRC32_INIT, (void *)ino + 8, len - 8);
1466        ino->ch.crc = cpu_to_le32(crc);
1467        /* Work out where data in the LEB ends and free space begins */
1468        p = c->sbuf;
1469        len = c->leb_size - 1;
1470        while (p[len] == 0xff)
1471                len -= 1;
1472        len = ALIGN(len + 1, c->min_io_size);
1473        /* Atomically write the fixed LEB back again */
1474        err = ubifs_leb_change(c, lnum, c->sbuf, len);
1475        if (err)
1476                goto out;
1477        dbg_rcvry("inode %lu at %d:%d size %lld -> %lld",
1478                  (unsigned long)e->inum, lnum, offs, i_size, e->d_size);
1479        return 0;
1480
1481out:
1482        ubifs_warn("inode %lu failed to fix size %lld -> %lld error %d",
1483                   (unsigned long)e->inum, e->i_size, e->d_size, err);
1484        return err;
1485}
1486
1487/**
1488 * ubifs_recover_size - recover inode size.
1489 * @c: UBIFS file-system description object
1490 *
1491 * This function attempts to fix inode size discrepancies identified by the
1492 * 'ubifs_recover_size_accum()' function.
1493 *
1494 * This functions returns %0 on success and a negative error code on failure.
1495 */
1496int ubifs_recover_size(struct ubifs_info *c)
1497{
1498        struct rb_node *this = rb_first(&c->size_tree);
1499
1500        while (this) {
1501                struct size_entry *e;
1502                int err;
1503
1504                e = rb_entry(this, struct size_entry, rb);
1505                if (!e->exists) {
1506                        union ubifs_key key;
1507
1508                        ino_key_init(c, &key, e->inum);
1509                        err = ubifs_tnc_lookup(c, &key, c->sbuf);
1510                        if (err && err != -ENOENT)
1511                                return err;
1512                        if (err == -ENOENT) {
1513                                /* Remove data nodes that have no inode */
1514                                dbg_rcvry("removing ino %lu",
1515                                          (unsigned long)e->inum);
1516                                err = ubifs_tnc_remove_ino(c, e->inum);
1517                                if (err)
1518                                        return err;
1519                        } else {
1520                                struct ubifs_ino_node *ino = c->sbuf;
1521
1522                                e->exists = 1;
1523                                e->i_size = le64_to_cpu(ino->size);
1524                        }
1525                }
1526
1527                if (e->exists && e->i_size < e->d_size) {
1528                        if (c->ro_mount) {
1529                                /* Fix the inode size and pin it in memory */
1530                                struct inode *inode;
1531                                struct ubifs_inode *ui;
1532
1533                                ubifs_assert(!e->inode);
1534
1535                                inode = ubifs_iget(c->vfs_sb, e->inum);
1536                                if (IS_ERR(inode))
1537                                        return PTR_ERR(inode);
1538
1539                                ui = ubifs_inode(inode);
1540                                if (inode->i_size < e->d_size) {
1541                                        dbg_rcvry("ino %lu size %lld -> %lld",
1542                                                  (unsigned long)e->inum,
1543                                                  inode->i_size, e->d_size);
1544                                        inode->i_size = e->d_size;
1545                                        ui->ui_size = e->d_size;
1546                                        ui->synced_i_size = e->d_size;
1547                                        e->inode = inode;
1548                                        this = rb_next(this);
1549                                        continue;
1550                                }
1551                                iput(inode);
1552                        } else {
1553                                /* Fix the size in place */
1554                                err = fix_size_in_place(c, e);
1555                                if (err)
1556                                        return err;
1557                                if (e->inode)
1558                                        iput(e->inode);
1559                        }
1560                }
1561
1562                this = rb_next(this);
1563                rb_erase(&e->rb, &c->size_tree);
1564                kfree(e);
1565        }
1566
1567        return 0;
1568}
1569
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