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");
  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                                 dbg_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                                 dbg_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  */
 135 struct 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 = ubi_read(c->ubi, lnum, sbuf + offs, offs, c->leb_size - offs);
 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  */
 174 void 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  */
 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("corruption at LEB %d:%d", lnum, offs);
 243         if (dbg_failure_mode)
 244                 return;
 245         len = c->leb_size - offs;
 246         if (len > 8192)
 247                 len = 8192;
 248         dbg_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  */
 268 struct 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                         dbg_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                         dbg_err("bad node");
 310                         goto corrupted;
 311                 default:
 312                         dbg_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
 349 corrupted:
 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
 358 error:
 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  */
 368 void 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 }