fs/ubifs/scan.c

   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  */
  40 static 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  */
  69 int 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(c, "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(c, "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 the scanned information on success and a negative error
 135  * code on failure.
 136  */
 137 struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
 138                                         int offs, void *sbuf)
 139 {
 140         struct ubifs_scan_leb *sleb;
 141         int err;
 142
 143         dbg_scan("scan LEB %d:%d", lnum, offs);
 144
 145         sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
 146         if (!sleb)
 147                 return ERR_PTR(-ENOMEM);
 148
 149         sleb->lnum = lnum;
 150         INIT_LIST_HEAD(&sleb->nodes);
 151         sleb->buf = sbuf;
 152
 153         err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
 154         if (err && err != -EBADMSG) {
 155                 ubifs_err(c, "cannot read %d bytes from LEB %d:%d, error %d",
 156                           c->leb_size - offs, lnum, offs, err);
 157                 kfree(sleb);
 158                 return ERR_PTR(err);
 159         }
 160
 161         /*
 162          * Note, we ignore integrity errors (EBASMSG) because all the nodes are
 163          * protected by CRC checksums.
 164          */
 165         return sleb;
 166 }
 167
 168 /**
 169  * ubifs_end_scan - update LEB scanning information at end of scan.
 170  * @c: UBIFS file-system description object
 171  * @sleb: scanning information
 172  * @lnum: logical eraseblock number
 173  * @offs: offset to start at (usually zero)
 174  */
 175 void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 176                     int lnum, int offs)
 177 {
 178         dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
 179         ubifs_assert(c, 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  */
 193 int 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  */
 237 void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
 238                               void *buf)
 239 {
 240         int len;
 241
 242         ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
 243         len = c->leb_size - offs;
 244         if (len > 8192)
 245                 len = 8192;
 246         ubifs_err(c, "first %d bytes from LEB %d:%d", len, lnum, offs);
 247         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
 248 }
 249
 250 /**
 251  * ubifs_scan - scan a logical eraseblock.
 252  * @c: UBIFS file-system description object
 253  * @lnum: logical eraseblock number
 254  * @offs: offset to start at (usually zero)
 255  * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
 256  * @quiet: print no messages
 257  *
 258  * This function scans LEB number @lnum and returns complete information about
 259  * its contents. Returns the scanned information in case of success and,
 260  * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
 261  * of failure.
 262  *
 263  * If @quiet is non-zero, this function does not print large and scary
 264  * error messages and flash dumps in case of errors.
 265  */
 266 struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 267                                   int offs, void *sbuf, int quiet)
 268 {
 269         void *buf = sbuf + offs;
 270         int err, len = c->leb_size - offs;
 271         struct ubifs_scan_leb *sleb;
 272
 273         sleb = ubifs_start_scan(c, lnum, offs, sbuf);
 274         if (IS_ERR(sleb))
 275                 return sleb;
 276
 277         while (len >= 8) {
 278                 struct ubifs_ch *ch = buf;
 279                 int node_len, ret;
 280
 281                 dbg_scan("look at LEB %d:%d (%d bytes left)",
 282                          lnum, offs, len);
 283
 284                 cond_resched();
 285
 286                 ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
 287                 if (ret > 0) {
 288                         /* Padding bytes or a valid padding node */
 289                         offs += ret;
 290                         buf += ret;
 291                         len -= ret;
 292                         continue;
 293                 }
 294
 295                 if (ret == SCANNED_EMPTY_SPACE)
 296                         /* Empty space is checked later */
 297                         break;
 298
 299                 switch (ret) {
 300                 case SCANNED_GARBAGE:
 301                         ubifs_err(c, "garbage");
 302                         goto corrupted;
 303                 case SCANNED_A_NODE:
 304                         break;
 305                 case SCANNED_A_CORRUPT_NODE:
 306                 case SCANNED_A_BAD_PAD_NODE:
 307                         ubifs_err(c, "bad node");
 308                         goto corrupted;
 309                 default:
 310                         ubifs_err(c, "unknown");
 311                         err = -EINVAL;
 312                         goto error;
 313                 }
 314
 315                 err = ubifs_add_snod(c, sleb, buf, offs);
 316                 if (err)
 317                         goto error;
 318
 319                 node_len = ALIGN(le32_to_cpu(ch->len), 8);
 320                 offs += node_len;
 321                 buf += node_len;
 322                 len -= node_len;
 323         }
 324
 325         if (offs % c->min_io_size) {
 326                 if (!quiet)
 327                         ubifs_err(c, "empty space starts at non-aligned offset %d",
 328                                   offs);
 329                 goto corrupted;
 330         }
 331
 332         ubifs_end_scan(c, sleb, lnum, offs);
 333
 334         for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
 335                 if (*(uint32_t *)buf != 0xffffffff)
 336                         break;
 337         for (; len; offs++, buf++, len--)
 338                 if (*(uint8_t *)buf != 0xff) {
 339                         if (!quiet)
 340                                 ubifs_err(c, "corrupt empty space at LEB %d:%d",
 341                                           lnum, offs);
 342                         goto corrupted;
 343                 }
 344
 345         return sleb;
 346
 347 corrupted:
 348         if (!quiet) {
 349                 ubifs_scanned_corruption(c, lnum, offs, buf);
 350                 ubifs_err(c, "LEB %d scanning failed", lnum);
 351         }
 352         err = -EUCLEAN;
 353         ubifs_scan_destroy(sleb);
 354         return ERR_PTR(err);
 355
 356 error:
 357         ubifs_err(c, "LEB %d scanning failed, error %d", lnum, err);
 358         ubifs_scan_destroy(sleb);
 359         return ERR_PTR(err);
 360 }
 361
 362 /**
 363  * ubifs_scan_destroy - destroy LEB scanning information.
 364  * @sleb: scanning information to free
 365  */
 366 void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
 367 {
 368         struct ubifs_scan_node *node;
 369         struct list_head *head;
 370
 371         head = &sleb->nodes;
 372         while (!list_empty(head)) {
 373                 node = list_entry(head->next, struct ubifs_scan_node, list);
 374                 list_del(&node->list);
 375                 kfree(node);
 376         }
 377         kfree(sleb);
 378 }