lib/ext2fs/openfs.c

   1 /*
   2  * openfs.c --- open an ext2 filesystem
   3  *
   4  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Library
   8  * General Public License, version 2.
   9  * %End-Header%
  10  */
  11
  12 #include "config.h"
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18 #include <fcntl.h>
  19 #include <time.h>
  20 #if HAVE_SYS_STAT_H
  21 #include <sys/stat.h>
  22 #endif
  23 #if HAVE_SYS_TYPES_H
  24 #include <sys/types.h>
  25 #endif
  26 #ifdef HAVE_ERRNO_H
  27 #include <errno.h>
  28 #endif
  29
  30 #include "ext2_fs.h"
  31
  32 #include "ext2fs.h"
  33 #include "e2image.h"
  34
  35 blk64_t ext2fs_descriptor_block_loc2(ext2_filsys fs, blk64_t group_block,
  36                                      dgrp_t i)
  37 {
  38         int     bg;
  39         int     has_super = 0, group_zero_adjust = 0;
  40         blk64_t ret_blk;
  41
  42         /*
  43          * On a bigalloc FS with 1K blocks, block 0 is reserved for non-ext4
  44          * stuff, so adjust for that if we're being asked for group 0.
  45          */
  46         if (i == 0 && fs->blocksize == 1024 && EXT2FS_CLUSTER_RATIO(fs) > 1)
  47                 group_zero_adjust = 1;
  48
  49         if (!ext2fs_has_feature_meta_bg(fs->super) ||
  50             (i < fs->super->s_first_meta_bg))
  51                 return group_block + i + 1 + group_zero_adjust;
  52
  53         bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
  54         if (ext2fs_bg_has_super(fs, bg))
  55                 has_super = 1;
  56         ret_blk = ext2fs_group_first_block2(fs, bg);
  57         /*
  58          * If group_block is not the normal value, we're trying to use
  59          * the backup group descriptors and superblock --- so use the
  60          * alternate location of the second block group in the
  61          * metablock group.  Ideally we should be testing each bg
  62          * descriptor block individually for correctness, but we don't
  63          * have the infrastructure in place to do that.
  64          */
  65         if (group_block != fs->super->s_first_data_block &&
  66             ((ret_blk + has_super + fs->super->s_blocks_per_group) <
  67              ext2fs_blocks_count(fs->super))) {
  68                 ret_blk += fs->super->s_blocks_per_group;
  69
  70                 /*
  71                  * If we're going to jump forward a block group, make sure
  72                  * that we adjust has_super to account for the next group's
  73                  * backup superblock (or lack thereof).
  74                  */
  75                 if (ext2fs_bg_has_super(fs, bg + 1))
  76                         has_super = 1;
  77                 else
  78                         has_super = 0;
  79         }
  80         return ret_blk + has_super + group_zero_adjust;
  81 }
  82
  83 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
  84 {
  85         return ext2fs_descriptor_block_loc2(fs, group_block, i);
  86 }
  87
  88 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  89                       unsigned int block_size, io_manager manager,
  90                       ext2_filsys *ret_fs)
  91 {
  92         return ext2fs_open2(name, 0, flags, superblock, block_size,
  93                             manager, ret_fs);
  94 }
  95
  96 static void block_sha_map_free_entry(void *data)
  97 {
  98         free(data);
  99         return;
 100 }
 101
 102 /*
 103  *  Note: if superblock is non-zero, block-size must also be non-zero.
 104  *      Superblock and block_size can be zero to use the default size.
 105  *
 106  * Valid flags for ext2fs_open()
 107  *
 108  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
 109  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
 110  *                              features aren't supported.
 111  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
 112  *      EXT2_FLAG_SKIP_MMP - Open without multi-mount protection check.
 113  *      EXT2_FLAG_64BITS - Allow 64-bit bitfields (needed for large
 114  *                              filesystems)
 115  */
 116 errcode_t ext2fs_open2(const char *name, const char *io_options,
 117                        int flags, int superblock,
 118                        unsigned int block_size, io_manager manager,
 119                        ext2_filsys *ret_fs)
 120 {
 121         ext2_filsys     fs;
 122         errcode_t       retval;
 123         unsigned long   i, first_meta_bg;
 124         __u32           features;
 125         unsigned int    blocks_per_group, io_flags;
 126         blk64_t         group_block, blk;
 127         char            *dest, *cp;
 128         int             group_zero_adjust = 0;
 129         unsigned int    inode_size;
 130         __u64           groups_cnt;
 131 #ifdef WORDS_BIGENDIAN
 132         unsigned int    groups_per_block;
 133         struct ext2_group_desc *gdp;
 134         int             j;
 135 #endif
 136         char            *time_env;
 137         int             csum_retries = 0;
 138
 139         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 140
 141         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 142         if (retval)
 143                 return retval;
 144
 145         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 146         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 147         fs->flags = flags;
 148         /* don't overwrite sb backups unless flag is explicitly cleared */
 149         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 150         fs->umask = 022;
 151
 152         time_env = getenv("E2FSPROGS_FAKE_TIME");
 153         if (time_env)
 154                 fs->now = strtoul(time_env, NULL, 0);
 155
 156         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 157         if (retval)
 158                 goto cleanup;
 159         strcpy(fs->device_name, name);
 160         cp = strchr(fs->device_name, '?');
 161         if (!io_options && cp) {
 162                 *cp++ = 0;
 163                 io_options = cp;
 164         }
 165
 166         io_flags = 0;
 167         if (flags & EXT2_FLAG_RW)
 168                 io_flags |= IO_FLAG_RW;
 169         if (flags & EXT2_FLAG_EXCLUSIVE)
 170                 io_flags |= IO_FLAG_EXCLUSIVE;
 171         if (flags & EXT2_FLAG_DIRECT_IO)
 172                 io_flags |= IO_FLAG_DIRECT_IO;
 173         retval = manager->open(fs->device_name, io_flags, &fs->io);
 174         if (retval)
 175                 goto cleanup;
 176         if (io_options &&
 177             (retval = io_channel_set_options(fs->io, io_options)))
 178                 goto cleanup;
 179         fs->image_io = fs->io;
 180         fs->io->app_data = fs;
 181         retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super);
 182         if (retval)
 183                 goto cleanup;
 184         if (flags & EXT2_FLAG_IMAGE_FILE) {
 185                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 186                                         &fs->image_header);
 187                 if (retval)
 188                         goto cleanup;
 189                 retval = io_channel_read_blk(fs->io, 0,
 190                                              -(int)sizeof(struct ext2_image_hdr),
 191                                              fs->image_header);
 192                 if (retval)
 193                         goto cleanup;
 194                 if (ext2fs_le32_to_cpu(fs->image_header->magic_number) != EXT2_ET_MAGIC_E2IMAGE)
 195                         return EXT2_ET_MAGIC_E2IMAGE;
 196                 superblock = 1;
 197                 block_size = ext2fs_le32_to_cpu(fs->image_header->fs_blocksize);
 198         }
 199
 200         /*
 201          * If the user specifies a specific block # for the
 202          * superblock, then he/she must also specify the block size!
 203          * Otherwise, read the master superblock located at offset
 204          * SUPERBLOCK_OFFSET from the start of the partition.
 205          *
 206          * Note: we only save a backup copy of the superblock if we
 207          * are reading the superblock from the primary superblock location.
 208          */
 209         if (superblock) {
 210                 if (!block_size) {
 211                         retval = EXT2_ET_INVALID_ARGUMENT;
 212                         goto cleanup;
 213                 }
 214                 io_channel_set_blksize(fs->io, block_size);
 215                 group_block = superblock;
 216                 fs->orig_super = 0;
 217         } else {
 218                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 219                 superblock = 1;
 220                 group_block = 0;
 221                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 222                 if (retval)
 223                         goto cleanup;
 224         }
 225 retry:
 226         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 227                                      fs->super);
 228         if (retval)
 229                 goto cleanup;
 230         if (fs->orig_super)
 231                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 232
 233         if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
 234                 retval = 0;
 235                 if (!ext2fs_verify_csum_type(fs, fs->super))
 236                         retval = EXT2_ET_UNKNOWN_CSUM;
 237                 if (!ext2fs_superblock_csum_verify(fs, fs->super)) {
 238                         if (csum_retries++ < 3)
 239                                 goto retry;
 240                         retval = EXT2_ET_SB_CSUM_INVALID;
 241                 }
 242         }
 243
 244 #ifdef WORDS_BIGENDIAN
 245         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 246         ext2fs_swap_super(fs->super);
 247 #else
 248         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 249                 retval = EXT2_ET_UNIMPLEMENTED;
 250                 goto cleanup;
 251         }
 252 #endif
 253
 254         if (fs->super->s_magic != EXT2_SUPER_MAGIC)
 255                 retval = EXT2_ET_BAD_MAGIC;
 256         if (retval)
 257                 goto cleanup;
 258
 259         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 260                 retval = EXT2_ET_REV_TOO_HIGH;
 261                 goto cleanup;
 262         }
 263
 264         /*
 265          * Check for feature set incompatibility
 266          */
 267         if (!(flags & EXT2_FLAG_FORCE)) {
 268                 features = fs->super->s_feature_incompat;
 269 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 270                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 271                         features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
 272 #endif
 273                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 274                         retval = EXT2_ET_UNSUPP_FEATURE;
 275                         goto cleanup;
 276                 }
 277
 278                 features = fs->super->s_feature_ro_compat;
 279 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 280                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 281                         features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
 282 #endif
 283                 if ((flags & EXT2_FLAG_RW) &&
 284                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 285                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 286                         goto cleanup;
 287                 }
 288
 289                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 290                     ext2fs_has_feature_journal_dev(fs->super)) {
 291                         retval = EXT2_ET_UNSUPP_FEATURE;
 292                         goto cleanup;
 293                 }
 294         }
 295
 296         if (fs->super->s_log_block_size >
 297             (unsigned) (EXT2_MAX_BLOCK_LOG_SIZE - EXT2_MIN_BLOCK_LOG_SIZE)) {
 298                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 299                 goto cleanup;
 300         }
 301
 302         /*
 303          * bigalloc requires cluster-aware bitfield operations, which at the
 304          * moment means we need EXT2_FLAG_64BITS.
 305          */
 306         if (ext2fs_has_feature_bigalloc(fs->super) &&
 307             !(flags & EXT2_FLAG_64BITS)) {
 308                 retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS;
 309                 goto cleanup;
 310         }
 311
 312         if (!ext2fs_has_feature_bigalloc(fs->super) &&
 313             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 314                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 315                 goto cleanup;
 316         }
 317         fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 318         inode_size = EXT2_INODE_SIZE(fs->super);
 319         if ((inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 320             (inode_size > fs->blocksize) ||
 321             (inode_size & (inode_size - 1))) {
 322                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 323                 goto cleanup;
 324         }
 325
 326         /* Enforce the block group descriptor size */
 327         if (ext2fs_has_feature_64bit(fs->super)) {
 328                 if (fs->super->s_desc_size < EXT2_MIN_DESC_SIZE_64BIT) {
 329                         retval = EXT2_ET_BAD_DESC_SIZE;
 330                         goto cleanup;
 331                 }
 332         }
 333
 334         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 335                 fs->super->s_log_block_size;
 336         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 337             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 338                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 339                 goto cleanup;
 340         }
 341         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 342                                        EXT2_INODE_SIZE(fs->super) +
 343                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 344                                       EXT2_BLOCK_SIZE(fs->super));
 345         if (block_size) {
 346                 if (block_size != fs->blocksize) {
 347                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 348                         goto cleanup;
 349                 }
 350         }
 351         /*
 352          * Set the blocksize to the filesystem's blocksize.
 353          */
 354         io_channel_set_blksize(fs->io, fs->blocksize);
 355
 356         /*
 357          * If this is an external journal device, don't try to read
 358          * the group descriptors, because they're not there.
 359          */
 360         if (ext2fs_has_feature_journal_dev(fs->super)) {
 361                 fs->group_desc_count = 0;
 362                 *ret_fs = fs;
 363                 return 0;
 364         }
 365
 366         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 367                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 368                 goto cleanup;
 369         }
 370         /* Precompute the FS UUID to seed other checksums */
 371         ext2fs_init_csum_seed(fs);
 372
 373         /*
 374          * Read group descriptors
 375          */
 376         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 377         if (blocks_per_group == 0 ||
 378             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 379             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 380            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 381            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 382                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 383                 goto cleanup;
 384         }
 385         groups_cnt = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 386                                        fs->super->s_first_data_block,
 387                                        blocks_per_group);
 388         if (groups_cnt >> 32) {
 389                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 390                 goto cleanup;
 391         }
 392         fs->group_desc_count =  groups_cnt;
 393         if (!(flags & EXT2_FLAG_IGNORE_SB_ERRORS) &&
 394             (__u64)fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 395             fs->super->s_inodes_count) {
 396                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 397                 goto cleanup;
 398         }
 399         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 400                                           EXT2_DESC_PER_BLOCK(fs->super));
 401         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 402                                 &fs->group_desc);
 403         if (retval)
 404                 goto cleanup;
 405         if (!group_block)
 406                 group_block = fs->super->s_first_data_block;
 407         /*
 408          * On a FS with a 1K blocksize, block 0 is reserved for bootloaders
 409          * so we must increment block numbers to any group 0 items.
 410          *
 411          * However, we cannot touch group_block directly because in the meta_bg
 412          * case, the ext2fs_descriptor_block_loc2() function will interpret
 413          * group_block != s_first_data_block to mean that we want to access the
 414          * backup group descriptors.  This is not what we want if the caller
 415          * set superblock == 0 (i.e. auto-detect the superblock), which is
 416          * what's going on here.
 417          */
 418         if (group_block == 0 && fs->blocksize == 1024)
 419                 group_zero_adjust = 1;
 420         dest = (char *) fs->group_desc;
 421 #ifdef WORDS_BIGENDIAN
 422         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 423 #endif
 424         if (ext2fs_has_feature_meta_bg(fs->super) &&
 425             !(flags & EXT2_FLAG_IMAGE_FILE)) {
 426                 first_meta_bg = fs->super->s_first_meta_bg;
 427                 if (first_meta_bg > fs->desc_blocks)
 428                         first_meta_bg = fs->desc_blocks;
 429         } else
 430                 first_meta_bg = fs->desc_blocks;
 431         if (first_meta_bg) {
 432                 retval = io_channel_read_blk(fs->io, group_block +
 433                                              group_zero_adjust + 1,
 434                                              first_meta_bg, dest);
 435                 if (retval)
 436                         goto cleanup;
 437 #ifdef WORDS_BIGENDIAN
 438                 gdp = (struct ext2_group_desc *) dest;
 439                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 440                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 441                         ext2fs_swap_group_desc2(fs, gdp);
 442                 }
 443 #endif
 444                 dest += fs->blocksize*first_meta_bg;
 445         }
 446
 447         for (i = first_meta_bg ; i < fs->desc_blocks; i++) {
 448                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 449                 io_channel_cache_readahead(fs->io, blk, 1);
 450         }
 451
 452         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 453                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 454                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 455                 if (retval)
 456                         goto cleanup;
 457 #ifdef WORDS_BIGENDIAN
 458                 for (j=0; j < groups_per_block; j++) {
 459                         gdp = ext2fs_group_desc(fs, fs->group_desc,
 460                                                 i * groups_per_block + j);
 461                         ext2fs_swap_group_desc2(fs, gdp);
 462                 }
 463 #endif
 464                 dest += fs->blocksize;
 465         }
 466
 467         fs->stride = fs->super->s_raid_stride;
 468
 469         /*
 470          * If recovery is from backup superblock, Clear _UNININT flags &
 471          * reset bg_itable_unused to zero
 472          */
 473         if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
 474                 dgrp_t group;
 475
 476                 for (group = 0; group < fs->group_desc_count; group++) {
 477                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 478                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 479                         ext2fs_bg_itable_unused_set(fs, group, 0);
 480                         /* The checksum will be reset later, but fix it here
 481                          * anyway to avoid printing a lot of spurious errors. */
 482                         ext2fs_group_desc_csum_set(fs, group);
 483                 }
 484                 if (fs->flags & EXT2_FLAG_RW)
 485                         ext2fs_mark_super_dirty(fs);
 486         }
 487
 488         if (ext2fs_has_feature_mmp(fs->super) &&
 489             !(flags & EXT2_FLAG_SKIP_MMP) &&
 490             (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
 491                 retval = ext2fs_mmp_start(fs);
 492                 if (retval) {
 493                         fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
 494                         ext2fs_mmp_stop(fs);
 495                         goto cleanup;
 496                 }
 497         }
 498
 499         if (fs->flags & EXT2_FLAG_SHARE_DUP) {
 500                 fs->block_sha_map = ext2fs_hashmap_create(ext2fs_djb2_hash,
 501                                         block_sha_map_free_entry, 4096);
 502                 if (!fs->block_sha_map) {
 503                         retval = EXT2_ET_NO_MEMORY;
 504                         goto cleanup;
 505                 }
 506                 ext2fs_set_feature_shared_blocks(fs->super);
 507         }
 508
 509         if (ext2fs_has_feature_casefold(fs->super))
 510                 fs->encoding = ext2fs_load_nls_table(fs->super->s_encoding);
 511
 512         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 513         *ret_fs = fs;
 514
 515         return 0;
 516 cleanup:
 517         if (!(flags & EXT2_FLAG_NOFREE_ON_ERROR)) {
 518                 ext2fs_free(fs);
 519                 fs = NULL;
 520         }
 521         *ret_fs = fs;
 522         return retval;
 523 }
 524
 525 /*
 526  * Set/get the filesystem data I/O channel.
 527  *
 528  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 529  */
 530 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 531 {
 532         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 533                 return EXT2_ET_NOT_IMAGE_FILE;
 534         if (old_io) {
 535                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 536         }
 537         return 0;
 538 }
 539
 540 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 541 {
 542         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 543                 return EXT2_ET_NOT_IMAGE_FILE;
 544         fs->io = new_io ? new_io : fs->image_io;
 545         return 0;
 546 }
 547
 548 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 549 {
 550         errcode_t err;
 551
 552         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 553                 return EXT2_ET_NOT_IMAGE_FILE;
 554         err = io_channel_set_blksize(new_io, fs->blocksize);
 555         if (err)
 556                 return err;
 557         if ((new_io == fs->image_io) || (new_io == fs->io))
 558                 return 0;
 559         if ((fs->image_io != fs->io) &&
 560             fs->image_io)
 561                 io_channel_close(fs->image_io);
 562         if (fs->io)
 563                 io_channel_close(fs->io);
 564         fs->io = fs->image_io = new_io;
 565         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 566                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 567         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 568         return 0;
 569 }