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