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         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  */
 194 int 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  */
 238 void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
 239                               void *buf)
 240 {
 241         int len;
 242
 243         ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
 244         len = c->leb_size - offs;
 245         if (len > 8192)
 246                 len = 8192;
 247         ubifs_err(c, "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 scanned 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  */
 267 struct 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(c, "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(c, "bad node");
 309                         goto corrupted;
 310                 default:
 311                         ubifs_err(c, "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(c, "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(c, "corrupt empty space at LEB %d:%d",
 342                                           lnum, offs);
 343                         goto corrupted;
 344                 }
 345
 346         return sleb;
 347
 348 corrupted:
 349         if (!quiet) {
 350                 ubifs_scanned_corruption(c, lnum, offs, buf);
 351                 ubifs_err(c, "LEB %d scanning failed", lnum);
 352         }
 353         err = -EUCLEAN;
 354         ubifs_scan_destroy(sleb);
 355         return ERR_PTR(err);
 356
 357 error:
 358         ubifs_err(c, "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  */
 367 void 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 }