fs/ubifs/scan.c

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  *
   8  * Authors: Adrian Hunter
   9  *          Artem Bityutskiy (Битюцкий Артём)
  10  */
  11
  12 /*
  13  * This file implements the scan which is a general-purpose function for
  14  * determining what nodes are in an eraseblock. The scan is used to replay the
  15  * journal, to do garbage collection. for the TNC in-the-gaps method, and by
  16  * debugging functions.
  17  */
  18
  19 #ifdef __UBOOT__
  20 #include <linux/err.h>
  21 #endif
  22 #include "ubifs.h"
  23
  24 /**
  25  * scan_padding_bytes - scan for padding bytes.
  26  * @buf: buffer to scan
  27  * @len: length of buffer
  28  *
  29  * This function returns the number of padding bytes on success and
  30  * %SCANNED_GARBAGE on failure.
  31  */
  32 static int scan_padding_bytes(void *buf, int len)
  33 {
  34         int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
  35         uint8_t *p = buf;
  36
  37         dbg_scan("not a node");
  38
  39         while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
  40                 pad_len += 1;
  41
  42         if (!pad_len || (pad_len & 7))
  43                 return SCANNED_GARBAGE;
  44
  45         dbg_scan("%d padding bytes", pad_len);
  46
  47         return pad_len;
  48 }
  49
  50 /**
  51  * ubifs_scan_a_node - scan for a node or padding.
  52  * @c: UBIFS file-system description object
  53  * @buf: buffer to scan
  54  * @len: length of buffer
  55  * @lnum: logical eraseblock number
  56  * @offs: offset within the logical eraseblock
  57  * @quiet: print no messages
  58  *
  59  * This function returns a scanning code to indicate what was scanned.
  60  */
  61 int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
  62                       int offs, int quiet)
  63 {
  64         struct ubifs_ch *ch = buf;
  65         uint32_t magic;
  66
  67         magic = le32_to_cpu(ch->magic);
  68
  69         if (magic == 0xFFFFFFFF) {
  70                 dbg_scan("hit empty space at LEB %d:%d", lnum, offs);
  71                 return SCANNED_EMPTY_SPACE;
  72         }
  73
  74         if (magic != UBIFS_NODE_MAGIC)
  75                 return scan_padding_bytes(buf, len);
  76
  77         if (len < UBIFS_CH_SZ)
  78                 return SCANNED_GARBAGE;
  79
  80         dbg_scan("scanning %s at LEB %d:%d",
  81                  dbg_ntype(ch->node_type), lnum, offs);
  82
  83         if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
  84                 return SCANNED_A_CORRUPT_NODE;
  85
  86         if (ch->node_type == UBIFS_PAD_NODE) {
  87                 struct ubifs_pad_node *pad = buf;
  88                 int pad_len = le32_to_cpu(pad->pad_len);
  89                 int node_len = le32_to_cpu(ch->len);
  90
  91                 /* Validate the padding node */
  92                 if (pad_len < 0 ||
  93                     offs + node_len + pad_len > c->leb_size) {
  94                         if (!quiet) {
  95                                 ubifs_err(c, "bad pad node at LEB %d:%d",
  96                                           lnum, offs);
  97                                 ubifs_dump_node(c, pad);
  98                         }
  99                         return SCANNED_A_BAD_PAD_NODE;
 100                 }
 101
 102                 /* Make the node pads to 8-byte boundary */
 103                 if ((node_len + pad_len) & 7) {
 104                         if (!quiet)
 105                                 ubifs_err(c, "bad padding length %d - %d",
 106                                           offs, offs + node_len + pad_len);
 107                         return SCANNED_A_BAD_PAD_NODE;
 108                 }
 109
 110                 dbg_scan("%d bytes padded at LEB %d:%d, offset now %d", pad_len,
 111                          lnum, offs, ALIGN(offs + node_len + pad_len, 8));
 112
 113                 return node_len + pad_len;
 114         }
 115
 116         return SCANNED_A_NODE;
 117 }
 118
 119 /**
 120  * ubifs_start_scan - create LEB scanning information at start of scan.
 121  * @c: UBIFS file-system description object
 122  * @lnum: logical eraseblock number
 123  * @offs: offset to start at (usually zero)
 124  * @sbuf: scan buffer (must be c->leb_size)
 125  *
 126  * This function returns the scanned information on success and a negative error
 127  * code on failure.
 128  */
 129 struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
 130                                         int offs, void *sbuf)
 131 {
 132         struct ubifs_scan_leb *sleb;
 133         int err;
 134
 135         dbg_scan("scan LEB %d:%d", lnum, offs);
 136
 137         sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
 138         if (!sleb)
 139                 return ERR_PTR(-ENOMEM);
 140
 141         sleb->lnum = lnum;
 142         INIT_LIST_HEAD(&sleb->nodes);
 143         sleb->buf = sbuf;
 144
 145         err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
 146         if (err && err != -EBADMSG) {
 147                 ubifs_err(c, "cannot read %d bytes from LEB %d:%d, error %d",
 148                           c->leb_size - offs, lnum, offs, err);
 149                 kfree(sleb);
 150                 return ERR_PTR(err);
 151         }
 152
 153         /*
 154          * Note, we ignore integrity errors (EBASMSG) because all the nodes are
 155          * protected by CRC checksums.
 156          */
 157         return sleb;
 158 }
 159
 160 /**
 161  * ubifs_end_scan - update LEB scanning information at end of scan.
 162  * @c: UBIFS file-system description object
 163  * @sleb: scanning information
 164  * @lnum: logical eraseblock number
 165  * @offs: offset to start at (usually zero)
 166  */
 167 void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 168                     int lnum, int offs)
 169 {
 170         lnum = lnum;
 171         dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
 172         ubifs_assert(offs % c->min_io_size == 0);
 173
 174         sleb->endpt = ALIGN(offs, c->min_io_size);
 175 }
 176
 177 /**
 178  * ubifs_add_snod - add a scanned node to LEB scanning information.
 179  * @c: UBIFS file-system description object
 180  * @sleb: scanning information
 181  * @buf: buffer containing node
 182  * @offs: offset of node on flash
 183  *
 184  * This function returns %0 on success and a negative error code on failure.
 185  */
 186 int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 187                    void *buf, int offs)
 188 {
 189         struct ubifs_ch *ch = buf;
 190         struct ubifs_ino_node *ino = buf;
 191         struct ubifs_scan_node *snod;
 192
 193         snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
 194         if (!snod)
 195                 return -ENOMEM;
 196
 197         snod->sqnum = le64_to_cpu(ch->sqnum);
 198         snod->type = ch->node_type;
 199         snod->offs = offs;
 200         snod->len = le32_to_cpu(ch->len);
 201         snod->node = buf;
 202
 203         switch (ch->node_type) {
 204         case UBIFS_INO_NODE:
 205         case UBIFS_DENT_NODE:
 206         case UBIFS_XENT_NODE:
 207         case UBIFS_DATA_NODE:
 208                 /*
 209                  * The key is in the same place in all keyed
 210                  * nodes.
 211                  */
 212                 key_read(c, &ino->key, &snod->key);
 213                 break;
 214         default:
 215                 invalid_key_init(c, &snod->key);
 216                 break;
 217         }
 218         list_add_tail(&snod->list, &sleb->nodes);
 219         sleb->nodes_cnt += 1;
 220         return 0;
 221 }
 222
 223 /**
 224  * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
 225  * @c: UBIFS file-system description object
 226  * @lnum: LEB number of corruption
 227  * @offs: offset of corruption
 228  * @buf: buffer containing corruption
 229  */
 230 void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
 231                               void *buf)
 232 {
 233         int len;
 234
 235         ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
 236         len = c->leb_size - offs;
 237         if (len > 8192)
 238                 len = 8192;
 239         ubifs_err(c, "first %d bytes from LEB %d:%d", len, lnum, offs);
 240         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
 241 }
 242
 243 /**
 244  * ubifs_scan - scan a logical eraseblock.
 245  * @c: UBIFS file-system description object
 246  * @lnum: logical eraseblock number
 247  * @offs: offset to start at (usually zero)
 248  * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
 249  * @quiet: print no messages
 250  *
 251  * This function scans LEB number @lnum and returns complete information about
 252  * its contents. Returns the scanned information in case of success and,
 253  * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
 254  * of failure.
 255  *
 256  * If @quiet is non-zero, this function does not print large and scary
 257  * error messages and flash dumps in case of errors.
 258  */
 259 struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 260                                   int offs, void *sbuf, int quiet)
 261 {
 262         void *buf = sbuf + offs;
 263         int err, len = c->leb_size - offs;
 264         struct ubifs_scan_leb *sleb;
 265
 266         sleb = ubifs_start_scan(c, lnum, offs, sbuf);
 267         if (IS_ERR(sleb))
 268                 return sleb;
 269
 270         while (len >= 8) {
 271                 struct ubifs_ch *ch = buf;
 272                 int node_len, ret;
 273
 274                 dbg_scan("look at LEB %d:%d (%d bytes left)",
 275                          lnum, offs, len);
 276
 277                 cond_resched();
 278
 279                 ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
 280                 if (ret > 0) {
 281                         /* Padding bytes or a valid padding node */
 282                         offs += ret;
 283                         buf += ret;
 284                         len -= ret;
 285                         continue;
 286                 }
 287
 288                 if (ret == SCANNED_EMPTY_SPACE)
 289                         /* Empty space is checked later */
 290                         break;
 291
 292                 switch (ret) {
 293                 case SCANNED_GARBAGE:
 294                         ubifs_err(c, "garbage");
 295                         goto corrupted;
 296                 case SCANNED_A_NODE:
 297                         break;
 298                 case SCANNED_A_CORRUPT_NODE:
 299                 case SCANNED_A_BAD_PAD_NODE:
 300                         ubifs_err(c, "bad node");
 301                         goto corrupted;
 302                 default:
 303                         ubifs_err(c, "unknown");
 304                         err = -EINVAL;
 305                         goto error;
 306                 }
 307
 308                 err = ubifs_add_snod(c, sleb, buf, offs);
 309                 if (err)
 310                         goto error;
 311
 312                 node_len = ALIGN(le32_to_cpu(ch->len), 8);
 313                 offs += node_len;
 314                 buf += node_len;
 315                 len -= node_len;
 316         }
 317
 318         if (offs % c->min_io_size) {
 319                 if (!quiet)
 320                         ubifs_err(c, "empty space starts at non-aligned offset %d",
 321                                   offs);
 322                 goto corrupted;
 323         }
 324
 325         ubifs_end_scan(c, sleb, lnum, offs);
 326
 327         for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
 328                 if (*(uint32_t *)buf != 0xffffffff)
 329                         break;
 330         for (; len; offs++, buf++, len--)
 331                 if (*(uint8_t *)buf != 0xff) {
 332                         if (!quiet)
 333                                 ubifs_err(c, "corrupt empty space at LEB %d:%d",
 334                                           lnum, offs);
 335                         goto corrupted;
 336                 }
 337
 338         return sleb;
 339
 340 corrupted:
 341         if (!quiet) {
 342                 ubifs_scanned_corruption(c, lnum, offs, buf);
 343                 ubifs_err(c, "LEB %d scanning failed", lnum);
 344         }
 345         err = -EUCLEAN;
 346         ubifs_scan_destroy(sleb);
 347         return ERR_PTR(err);
 348
 349 error:
 350         ubifs_err(c, "LEB %d scanning failed, error %d", lnum, err);
 351         ubifs_scan_destroy(sleb);
 352         return ERR_PTR(err);
 353 }
 354
 355 /**
 356  * ubifs_scan_destroy - destroy LEB scanning information.
 357  * @sleb: scanning information to free
 358  */
 359 void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
 360 {
 361         struct ubifs_scan_node *node;
 362         struct list_head *head;
 363
 364         head = &sleb->nodes;
 365         while (!list_empty(head)) {
 366                 node = list_entry(head->next, struct ubifs_scan_node, list);
 367                 list_del(&node->list);
 368                 kfree(node);
 369         }
 370         kfree(sleb);
 371 }