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 #define __UBOOT__
  20 #ifdef __UBOOT__
  21 #include <linux/err.h>
  22 #endif
  23 #include "ubifs.h"
  24
  25 /**
  26  * scan_padding_bytes - scan for padding bytes.
  27  * @buf: buffer to scan
  28  * @len: length of buffer
  29  *
  30  * This function returns the number of padding bytes on success and
  31  * %SCANNED_GARBAGE on failure.
  32  */
  33 static int scan_padding_bytes(void *buf, int len)
  34 {
  35         int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
  36         uint8_t *p = buf;
  37
  38         dbg_scan("not a node");
  39
  40         while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
  41                 pad_len += 1;
  42
  43         if (!pad_len || (pad_len & 7))
  44                 return SCANNED_GARBAGE;
  45
  46         dbg_scan("%d padding bytes", pad_len);
  47
  48         return pad_len;
  49 }
  50
  51 /**
  52  * ubifs_scan_a_node - scan for a node or padding.
  53  * @c: UBIFS file-system description object
  54  * @buf: buffer to scan
  55  * @len: length of buffer
  56  * @lnum: logical eraseblock number
  57  * @offs: offset within the logical eraseblock
  58  * @quiet: print no messages
  59  *
  60  * This function returns a scanning code to indicate what was scanned.
  61  */
  62 int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
  63                       int offs, int quiet)
  64 {
  65         struct ubifs_ch *ch = buf;
  66         uint32_t magic;
  67
  68         magic = le32_to_cpu(ch->magic);
  69
  70         if (magic == 0xFFFFFFFF) {
  71                 dbg_scan("hit empty space at LEB %d:%d", lnum, offs);
  72                 return SCANNED_EMPTY_SPACE;
  73         }
  74
  75         if (magic != UBIFS_NODE_MAGIC)
  76                 return scan_padding_bytes(buf, len);
  77
  78         if (len < UBIFS_CH_SZ)
  79                 return SCANNED_GARBAGE;
  80
  81         dbg_scan("scanning %s at LEB %d:%d",
  82                  dbg_ntype(ch->node_type), lnum, offs);
  83
  84         if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
  85                 return SCANNED_A_CORRUPT_NODE;
  86
  87         if (ch->node_type == UBIFS_PAD_NODE) {
  88                 struct ubifs_pad_node *pad = buf;
  89                 int pad_len = le32_to_cpu(pad->pad_len);
  90                 int node_len = le32_to_cpu(ch->len);
  91
  92                 /* Validate the padding node */
  93                 if (pad_len < 0 ||
  94                     offs + node_len + pad_len > c->leb_size) {
  95                         if (!quiet) {
  96                                 ubifs_err("bad pad node at LEB %d:%d",
  97                                           lnum, offs);
  98                                 ubifs_dump_node(c, pad);
  99                         }
 100                         return SCANNED_A_BAD_PAD_NODE;
 101                 }
 102
 103                 /* Make the node pads to 8-byte boundary */
 104                 if ((node_len + pad_len) & 7) {
 105                         if (!quiet)
 106                                 ubifs_err("bad padding length %d - %d",
 107                                           offs, offs + node_len + pad_len);
 108                         return SCANNED_A_BAD_PAD_NODE;
 109                 }
 110
 111                 dbg_scan("%d bytes padded at LEB %d:%d, offset now %d", pad_len,
 112                          lnum, offs, ALIGN(offs + node_len + pad_len, 8));
 113
 114                 return node_len + pad_len;
 115         }
 116
 117         return SCANNED_A_NODE;
 118 }
 119
 120 /**
 121  * ubifs_start_scan - create LEB scanning information at start of scan.
 122  * @c: UBIFS file-system description object
 123  * @lnum: logical eraseblock number
 124  * @offs: offset to start at (usually zero)
 125  * @sbuf: scan buffer (must be c->leb_size)
 126  *
 127  * This function returns %0 on success and a negative error 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("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         if (err == -EBADMSG)
 154                 sleb->ecc = 1;
 155
 156         return sleb;
 157 }
 158
 159 /**
 160  * ubifs_end_scan - update LEB scanning information at end of scan.
 161  * @c: UBIFS file-system description object
 162  * @sleb: scanning information
 163  * @lnum: logical eraseblock number
 164  * @offs: offset to start at (usually zero)
 165  *
 166  * This function returns %0 on success and a negative error code on failure.
 167  */
 168 void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 169                     int lnum, int offs)
 170 {
 171         lnum = lnum;
 172         dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
 173         ubifs_assert(offs % c->min_io_size == 0);
 174
 175         sleb->endpt = ALIGN(offs, c->min_io_size);
 176 }
 177
 178 /**
 179  * ubifs_add_snod - add a scanned node to LEB scanning information.
 180  * @c: UBIFS file-system description object
 181  * @sleb: scanning information
 182  * @buf: buffer containing node
 183  * @offs: offset of node on flash
 184  *
 185  * This function returns %0 on success and a negative error code on failure.
 186  */
 187 int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 188                    void *buf, int offs)
 189 {
 190         struct ubifs_ch *ch = buf;
 191         struct ubifs_ino_node *ino = buf;
 192         struct ubifs_scan_node *snod;
 193
 194         snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
 195         if (!snod)
 196                 return -ENOMEM;
 197
 198         snod->sqnum = le64_to_cpu(ch->sqnum);
 199         snod->type = ch->node_type;
 200         snod->offs = offs;
 201         snod->len = le32_to_cpu(ch->len);
 202         snod->node = buf;
 203
 204         switch (ch->node_type) {
 205         case UBIFS_INO_NODE:
 206         case UBIFS_DENT_NODE:
 207         case UBIFS_XENT_NODE:
 208         case UBIFS_DATA_NODE:
 209                 /*
 210                  * The key is in the same place in all keyed
 211                  * nodes.
 212                  */
 213                 key_read(c, &ino->key, &snod->key);
 214                 break;
 215         default:
 216                 invalid_key_init(c, &snod->key);
 217                 break;
 218         }
 219         list_add_tail(&snod->list, &sleb->nodes);
 220         sleb->nodes_cnt += 1;
 221         return 0;
 222 }
 223
 224 /**
 225  * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
 226  * @c: UBIFS file-system description object
 227  * @lnum: LEB number of corruption
 228  * @offs: offset of corruption
 229  * @buf: buffer containing corruption
 230  */
 231 void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
 232                               void *buf)
 233 {
 234         int len;
 235
 236         ubifs_err("corruption at LEB %d:%d", lnum, offs);
 237         len = c->leb_size - offs;
 238         if (len > 8192)
 239                 len = 8192;
 240         ubifs_err("first %d bytes from LEB %d:%d", len, lnum, offs);
 241         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
 242 }
 243
 244 /**
 245  * ubifs_scan - scan a logical eraseblock.
 246  * @c: UBIFS file-system description object
 247  * @lnum: logical eraseblock number
 248  * @offs: offset to start at (usually zero)
 249  * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
 250  * @quiet: print no messages
 251  *
 252  * This function scans LEB number @lnum and returns complete information about
 253  * its contents. Returns the scaned information in case of success and,
 254  * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
 255  * of failure.
 256  *
 257  * If @quiet is non-zero, this function does not print large and scary
 258  * error messages and flash dumps in case of errors.
 259  */
 260 struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 261                                   int offs, void *sbuf, int quiet)
 262 {
 263         void *buf = sbuf + offs;
 264         int err, len = c->leb_size - offs;
 265         struct ubifs_scan_leb *sleb;
 266
 267         sleb = ubifs_start_scan(c, lnum, offs, sbuf);
 268         if (IS_ERR(sleb))
 269                 return sleb;
 270
 271         while (len >= 8) {
 272                 struct ubifs_ch *ch = buf;
 273                 int node_len, ret;
 274
 275                 dbg_scan("look at LEB %d:%d (%d bytes left)",
 276                          lnum, offs, len);
 277
 278                 cond_resched();
 279
 280                 ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
 281                 if (ret > 0) {
 282                         /* Padding bytes or a valid padding node */
 283                         offs += ret;
 284                         buf += ret;
 285                         len -= ret;
 286                         continue;
 287                 }
 288
 289                 if (ret == SCANNED_EMPTY_SPACE)
 290                         /* Empty space is checked later */
 291                         break;
 292
 293                 switch (ret) {
 294                 case SCANNED_GARBAGE:
 295                         ubifs_err("garbage");
 296                         goto corrupted;
 297                 case SCANNED_A_NODE:
 298                         break;
 299                 case SCANNED_A_CORRUPT_NODE:
 300                 case SCANNED_A_BAD_PAD_NODE:
 301                         ubifs_err("bad node");
 302                         goto corrupted;
 303                 default:
 304                         ubifs_err("unknown");
 305                         err = -EINVAL;
 306                         goto error;
 307                 }
 308
 309                 err = ubifs_add_snod(c, sleb, buf, offs);
 310                 if (err)
 311                         goto error;
 312
 313                 node_len = ALIGN(le32_to_cpu(ch->len), 8);
 314                 offs += node_len;
 315                 buf += node_len;
 316                 len -= node_len;
 317         }
 318
 319         if (offs % c->min_io_size) {
 320                 if (!quiet)
 321                         ubifs_err("empty space starts at non-aligned offset %d",
 322                                   offs);
 323                 goto corrupted;
 324         }
 325
 326         ubifs_end_scan(c, sleb, lnum, offs);
 327
 328         for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
 329                 if (*(uint32_t *)buf != 0xffffffff)
 330                         break;
 331         for (; len; offs++, buf++, len--)
 332                 if (*(uint8_t *)buf != 0xff) {
 333                         if (!quiet)
 334                                 ubifs_err("corrupt empty space at LEB %d:%d",
 335                                           lnum, offs);
 336                         goto corrupted;
 337                 }
 338
 339         return sleb;
 340
 341 corrupted:
 342         if (!quiet) {
 343                 ubifs_scanned_corruption(c, lnum, offs, buf);
 344                 ubifs_err("LEB %d scanning failed", lnum);
 345         }
 346         err = -EUCLEAN;
 347         ubifs_scan_destroy(sleb);
 348         return ERR_PTR(err);
 349
 350 error:
 351         ubifs_err("LEB %d scanning failed, error %d", lnum, err);
 352         ubifs_scan_destroy(sleb);
 353         return ERR_PTR(err);
 354 }
 355
 356 /**
 357  * ubifs_scan_destroy - destroy LEB scanning information.
 358  * @sleb: scanning information to free
 359  */
 360 void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
 361 {
 362         struct ubifs_scan_node *node;
 363         struct list_head *head;
 364
 365         head = &sleb->nodes;
 366         while (!list_empty(head)) {
 367                 node = list_entry(head->next, struct ubifs_scan_node, list);
 368                 list_del(&node->list);
 369                 kfree(node);
 370         }
 371         kfree(sleb);
 372 }