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))
  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                         }
 115                         return SCANNED_A_BAD_PAD_NODE;
 116                 }
 117
 118                 dbg_scan("%d bytes padded, offset now %d",
 119                          pad_len, 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  */
 136 struct 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 = ubi_read(c->ubi, lnum, sbuf + offs, offs, c->leb_size - offs);
 153         if (err && err != -EBADMSG) {
 154                 ubifs_err("cannot read %d bytes from LEB %d:%d,"
 155                           " error %d", 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  */
 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 = kzalloc(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         case UBIFS_TRUN_NODE:
 217                 /*
 218                  * The key is in the same place in all keyed
 219                  * nodes.
 220                  */
 221                 key_read(c, &ino->key, &snod->key);
 222                 break;
 223         }
 224         list_add_tail(&snod->list, &sleb->nodes);
 225         sleb->nodes_cnt += 1;
 226         return 0;
 227 }
 228
 229 /**
 230  * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
 231  * @c: UBIFS file-system description object
 232  * @lnum: LEB number of corruption
 233  * @offs: offset of corruption
 234  * @buf: buffer containing corruption
 235  */
 236 void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
 237                               void *buf)
 238 {
 239         int len;
 240
 241         ubifs_err("corrupted data at LEB %d:%d", lnum, offs);
 242         if (dbg_failure_mode)
 243                 return;
 244         len = c->leb_size - offs;
 245         if (len > 4096)
 246                 len = 4096;
 247         dbg_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 c->leb_size)
 257  *
 258  * This function scans LEB number @lnum and returns complete information about
 259  * its contents. Returns an error code in case of failure.
 260  */
 261 struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 262                                   int offs, void *sbuf)
 263 {
 264         void *buf = sbuf + offs;
 265         int err, len = c->leb_size - offs;
 266         struct ubifs_scan_leb *sleb;
 267
 268         sleb = ubifs_start_scan(c, lnum, offs, sbuf);
 269         if (IS_ERR(sleb))
 270                 return sleb;
 271
 272         while (len >= 8) {
 273                 struct ubifs_ch *ch = buf;
 274                 int node_len, ret;
 275
 276                 dbg_scan("look at LEB %d:%d (%d bytes left)",
 277                          lnum, offs, len);
 278
 279                 cond_resched();
 280
 281                 ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 0);
 282
 283                 if (ret > 0) {
 284                         /* Padding bytes or a valid padding node */
 285                         offs += ret;
 286                         buf += ret;
 287                         len -= ret;
 288                         continue;
 289                 }
 290
 291                 if (ret == SCANNED_EMPTY_SPACE)
 292                         /* Empty space is checked later */
 293                         break;
 294
 295                 switch (ret) {
 296                 case SCANNED_GARBAGE:
 297                         dbg_err("garbage");
 298                         goto corrupted;
 299                 case SCANNED_A_NODE:
 300                         break;
 301                 case SCANNED_A_CORRUPT_NODE:
 302                 case SCANNED_A_BAD_PAD_NODE:
 303                         dbg_err("bad node");
 304                         goto corrupted;
 305                 default:
 306                         dbg_err("unknown");
 307                         goto corrupted;
 308                 }
 309
 310                 err = ubifs_add_snod(c, sleb, buf, offs);
 311                 if (err)
 312                         goto error;
 313
 314                 node_len = ALIGN(le32_to_cpu(ch->len), 8);
 315                 offs += node_len;
 316                 buf += node_len;
 317                 len -= node_len;
 318         }
 319
 320         if (offs % c->min_io_size)
 321                 goto corrupted;
 322
 323         ubifs_end_scan(c, sleb, lnum, offs);
 324
 325         for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
 326                 if (*(uint32_t *)buf != 0xffffffff)
 327                         break;
 328         for (; len; offs++, buf++, len--)
 329                 if (*(uint8_t *)buf != 0xff) {
 330                         ubifs_err("corrupt empty space at LEB %d:%d",
 331                                   lnum, offs);
 332                         goto corrupted;
 333                 }
 334
 335         return sleb;
 336
 337 corrupted:
 338         ubifs_scanned_corruption(c, lnum, offs, buf);
 339         err = -EUCLEAN;
 340 error:
 341         ubifs_err("LEB %d scanning failed", lnum);
 342         ubifs_scan_destroy(sleb);
 343         return ERR_PTR(err);
 344 }
 345
 346 /**
 347  * ubifs_scan_destroy - destroy LEB scanning information.
 348  * @sleb: scanning information to free
 349  */
 350 void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
 351 {
 352         struct ubifs_scan_node *node;
 353         struct list_head *head;
 354
 355         head = &sleb->nodes;
 356         while (!list_empty(head)) {
 357                 node = list_entry(head->next, struct ubifs_scan_node, list);
 358                 list_del(&node->list);
 359                 kfree(node);
 360         }
 361         kfree(sleb);
 362 }