linux/fs/ubifs/scan.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 the scan which is a general-purpose function for
  25 * determining what nodes are in an eraseblock. The scan is used to replay the
  26 * journal, to do garbage collection. for the TNC in-the-gaps method, and by
  27 * debugging functions.
  28 */
  29
  30#include "ubifs.h"
  31
  32/**
  33 * scan_padding_bytes - scan for padding bytes.
  34 * @buf: buffer to scan
  35 * @len: length of buffer
  36 *
  37 * This function returns the number of padding bytes on success and
  38 * %SCANNED_GARBAGE on failure.
  39 */
  40static int scan_padding_bytes(void *buf, int len)
  41{
  42        int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
  43        uint8_t *p = buf;
  44
  45        dbg_scan("not a node");
  46
  47        while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
  48                pad_len += 1;
  49
  50        if (!pad_len || (pad_len & 7))
  51                return SCANNED_GARBAGE;
  52
  53        dbg_scan("%d padding bytes", pad_len);
  54
  55        return pad_len;
  56}
  57
  58/**
  59 * ubifs_scan_a_node - scan for a node or padding.
  60 * @c: UBIFS file-system description object
  61 * @buf: buffer to scan
  62 * @len: length of buffer
  63 * @lnum: logical eraseblock number
  64 * @offs: offset within the logical eraseblock
  65 * @quiet: print no messages
  66 *
  67 * This function returns a scanning code to indicate what was scanned.
  68 */
  69int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
  70                      int offs, int quiet)
  71{
  72        struct ubifs_ch *ch = buf;
  73        uint32_t magic;
  74
  75        magic = le32_to_cpu(ch->magic);
  76
  77        if (magic == 0xFFFFFFFF) {
  78                dbg_scan("hit empty space");
  79                return SCANNED_EMPTY_SPACE;
  80        }
  81
  82        if (magic != UBIFS_NODE_MAGIC)
  83                return scan_padding_bytes(buf, len);
  84
  85        if (len < UBIFS_CH_SZ)
  86                return SCANNED_GARBAGE;
  87
  88        dbg_scan("scanning %s", dbg_ntype(ch->node_type));
  89
  90        if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
  91                return SCANNED_A_CORRUPT_NODE;
  92
  93        if (ch->node_type == UBIFS_PAD_NODE) {
  94                struct ubifs_pad_node *pad = buf;
  95                int pad_len = le32_to_cpu(pad->pad_len);
  96                int node_len = le32_to_cpu(ch->len);
  97
  98                /* Validate the padding node */
  99                if (pad_len < 0 ||
 100                    offs + node_len + pad_len > c->leb_size) {
 101                        if (!quiet) {
 102                                ubifs_err("bad pad node at LEB %d:%d",
 103                                          lnum, offs);
 104                                ubifs_dump_node(c, pad);
 105                        }
 106                        return SCANNED_A_BAD_PAD_NODE;
 107                }
 108
 109                /* Make the node pads to 8-byte boundary */
 110                if ((node_len + pad_len) & 7) {
 111                        if (!quiet)
 112                                ubifs_err("bad padding length %d - %d",
 113                                          offs, offs + node_len + pad_len);
 114                        return SCANNED_A_BAD_PAD_NODE;
 115                }
 116
 117                dbg_scan("%d bytes padded, offset now %d",
 118                         pad_len, ALIGN(offs + node_len + pad_len, 8));
 119
 120                return node_len + pad_len;
 121        }
 122
 123        return SCANNED_A_NODE;
 124}
 125
 126/**
 127 * ubifs_start_scan - create LEB scanning information at start of scan.
 128 * @c: UBIFS file-system description object
 129 * @lnum: logical eraseblock number
 130 * @offs: offset to start at (usually zero)
 131 * @sbuf: scan buffer (must be c->leb_size)
 132 *
 133 * This function returns %0 on success and a negative error code on failure.
 134 */
 135struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
 136                                        int offs, void *sbuf)
 137{
 138        struct ubifs_scan_leb *sleb;
 139        int err;
 140
 141        dbg_scan("scan LEB %d:%d", lnum, offs);
 142
 143        sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
 144        if (!sleb)
 145                return ERR_PTR(-ENOMEM);
 146
 147        sleb->lnum = lnum;
 148        INIT_LIST_HEAD(&sleb->nodes);
 149        sleb->buf = sbuf;
 150
 151        err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
 152        if (err && err != -EBADMSG) {
 153                ubifs_err("cannot read %d bytes from LEB %d:%d,"
 154                          " error %d", c->leb_size - offs, lnum, offs, err);
 155                kfree(sleb);
 156                return ERR_PTR(err);
 157        }
 158
 159        if (err == -EBADMSG)
 160                sleb->ecc = 1;
 161
 162        return sleb;
 163}
 164
 165/**
 166 * ubifs_end_scan - update LEB scanning information at end of scan.
 167 * @c: UBIFS file-system description object
 168 * @sleb: scanning information
 169 * @lnum: logical eraseblock number
 170 * @offs: offset to start at (usually zero)
 171 *
 172 * This function returns %0 on success and a negative error code on failure.
 173 */
 174void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 175                    int lnum, int offs)
 176{
 177        lnum = lnum;
 178        dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
 179        ubifs_assert(offs % c->min_io_size == 0);
 180
 181        sleb->endpt = ALIGN(offs, c->min_io_size);
 182}
 183
 184/**
 185 * ubifs_add_snod - add a scanned node to LEB scanning information.
 186 * @c: UBIFS file-system description object
 187 * @sleb: scanning information
 188 * @buf: buffer containing node
 189 * @offs: offset of node on flash
 190 *
 191 * This function returns %0 on success and a negative error code on failure.
 192 */
 193int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 194                   void *buf, int offs)
 195{
 196        struct ubifs_ch *ch = buf;
 197        struct ubifs_ino_node *ino = buf;
 198        struct ubifs_scan_node *snod;
 199
 200        snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
 201        if (!snod)
 202                return -ENOMEM;
 203
 204        snod->sqnum = le64_to_cpu(ch->sqnum);
 205        snod->type = ch->node_type;
 206        snod->offs = offs;
 207        snod->len = le32_to_cpu(ch->len);
 208        snod->node = buf;
 209
 210        switch (ch->node_type) {
 211        case UBIFS_INO_NODE:
 212        case UBIFS_DENT_NODE:
 213        case UBIFS_XENT_NODE:
 214        case UBIFS_DATA_NODE:
 215                /*
 216                 * The key is in the same place in all keyed
 217                 * nodes.
 218                 */
 219                key_read(c, &ino->key, &snod->key);
 220                break;
 221        default:
 222                invalid_key_init(c, &snod->key);
 223                break;
 224        }
 225        list_add_tail(&snod->list, &sleb->nodes);
 226        sleb->nodes_cnt += 1;
 227        return 0;
 228}
 229
 230/**
 231 * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
 232 * @c: UBIFS file-system description object
 233 * @lnum: LEB number of corruption
 234 * @offs: offset of corruption
 235 * @buf: buffer containing corruption
 236 */
 237void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
 238                              void *buf)
 239{
 240        int len;
 241
 242        ubifs_err("corruption at LEB %d:%d", lnum, offs);
 243        if (dbg_is_tst_rcvry(c))
 244                return;
 245        len = c->leb_size - offs;
 246        if (len > 8192)
 247                len = 8192;
 248        ubifs_err("first %d bytes from LEB %d:%d", len, lnum, offs);
 249        print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
 250}
 251
 252/**
 253 * ubifs_scan - scan a logical eraseblock.
 254 * @c: UBIFS file-system description object
 255 * @lnum: logical eraseblock number
 256 * @offs: offset to start at (usually zero)
 257 * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
 258 * @quiet: print no messages
 259 *
 260 * This function scans LEB number @lnum and returns complete information about
 261 * its contents. Returns the scaned information in case of success and,
 262 * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
 263 * of failure.
 264 *
 265 * If @quiet is non-zero, this function does not print large and scary
 266 * error messages and flash dumps in case of errors.
 267 */
 268struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 269                                  int offs, void *sbuf, int quiet)
 270{
 271        void *buf = sbuf + offs;
 272        int err, len = c->leb_size - offs;
 273        struct ubifs_scan_leb *sleb;
 274
 275        sleb = ubifs_start_scan(c, lnum, offs, sbuf);
 276        if (IS_ERR(sleb))
 277                return sleb;
 278
 279        while (len >= 8) {
 280                struct ubifs_ch *ch = buf;
 281                int node_len, ret;
 282
 283                dbg_scan("look at LEB %d:%d (%d bytes left)",
 284                         lnum, offs, len);
 285
 286                cond_resched();
 287
 288                ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
 289                if (ret > 0) {
 290                        /* Padding bytes or a valid padding node */
 291                        offs += ret;
 292                        buf += ret;
 293                        len -= ret;
 294                        continue;
 295                }
 296
 297                if (ret == SCANNED_EMPTY_SPACE)
 298                        /* Empty space is checked later */
 299                        break;
 300
 301                switch (ret) {
 302                case SCANNED_GARBAGE:
 303                        ubifs_err("garbage");
 304                        goto corrupted;
 305                case SCANNED_A_NODE:
 306                        break;
 307                case SCANNED_A_CORRUPT_NODE:
 308                case SCANNED_A_BAD_PAD_NODE:
 309                        ubifs_err("bad node");
 310                        goto corrupted;
 311                default:
 312                        ubifs_err("unknown");
 313                        err = -EINVAL;
 314                        goto error;
 315                }
 316
 317                err = ubifs_add_snod(c, sleb, buf, offs);
 318                if (err)
 319                        goto error;
 320
 321                node_len = ALIGN(le32_to_cpu(ch->len), 8);
 322                offs += node_len;
 323                buf += node_len;
 324                len -= node_len;
 325        }
 326
 327        if (offs % c->min_io_size) {
 328                if (!quiet)
 329                        ubifs_err("empty space starts at non-aligned offset %d",
 330                                  offs);
 331                goto corrupted;
 332        }
 333
 334        ubifs_end_scan(c, sleb, lnum, offs);
 335
 336        for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
 337                if (*(uint32_t *)buf != 0xffffffff)
 338                        break;
 339        for (; len; offs++, buf++, len--)
 340                if (*(uint8_t *)buf != 0xff) {
 341                        if (!quiet)
 342                                ubifs_err("corrupt empty space at LEB %d:%d",
 343                                          lnum, offs);
 344                        goto corrupted;
 345                }
 346
 347        return sleb;
 348
 349corrupted:
 350        if (!quiet) {
 351                ubifs_scanned_corruption(c, lnum, offs, buf);
 352                ubifs_err("LEB %d scanning failed", lnum);
 353        }
 354        err = -EUCLEAN;
 355        ubifs_scan_destroy(sleb);
 356        return ERR_PTR(err);
 357
 358error:
 359        ubifs_err("LEB %d scanning failed, error %d", lnum, err);
 360        ubifs_scan_destroy(sleb);
 361        return ERR_PTR(err);
 362}
 363
 364/**
 365 * ubifs_scan_destroy - destroy LEB scanning information.
 366 * @sleb: scanning information to free
 367 */
 368void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
 369{
 370        struct ubifs_scan_node *node;
 371        struct list_head *head;
 372
 373        head = &sleb->nodes;
 374        while (!list_empty(head)) {
 375                node = list_entry(head->next, struct ubifs_scan_node, list);
 376                list_del(&node->list);
 377                kfree(node);
 378        }
 379        kfree(sleb);
 380}
 381
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