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
ext2fs_descriptor_block_loc2(ext2_filsys fs,blk64_t group_block,dgrp_t i)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
ext2fs_descriptor_block_loc(ext2_filsys fs,blk_t group_block,dgrp_t i)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
ext2fs_open(const char * name,int flags,int superblock,unsigned int block_size,io_manager manager,ext2_filsys * ret_fs)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
block_sha_map_free_entry(void * data)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 */
ext2fs_open2(const char * name,const char * io_options,int flags,int superblock,unsigned int block_size,io_manager manager,ext2_filsys * ret_fs)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 if (flags & EXT2_FLAG_THREADS)
174 io_flags |= IO_FLAG_THREADS;
175 retval = manager->open(fs->device_name, io_flags, &fs->io);
176 if (retval)
177 goto cleanup;
178 if (io_options &&
179 (retval = io_channel_set_options(fs->io, io_options)))
180 goto cleanup;
181 fs->image_io = fs->io;
182 fs->io->app_data = fs;
183 retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super);
184 if (retval)
185 goto cleanup;
186 if (flags & EXT2_FLAG_IMAGE_FILE) {
187 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
188 &fs->image_header);
189 if (retval)
190 goto cleanup;
191 retval = io_channel_read_blk(fs->io, 0,
192 -(int)sizeof(struct ext2_image_hdr),
193 fs->image_header);
194 if (retval)
195 goto cleanup;
196 if (ext2fs_le32_to_cpu(fs->image_header->magic_number) != EXT2_ET_MAGIC_E2IMAGE)
197 return EXT2_ET_MAGIC_E2IMAGE;
198 superblock = 1;
199 block_size = ext2fs_le32_to_cpu(fs->image_header->fs_blocksize);
200 }
201
202 /*
203 * If the user specifies a specific block # for the
204 * superblock, then he/she must also specify the block size!
205 * Otherwise, read the master superblock located at offset
206 * SUPERBLOCK_OFFSET from the start of the partition.
207 *
208 * Note: we only save a backup copy of the superblock if we
209 * are reading the superblock from the primary superblock location.
210 */
211 if (superblock) {
212 if (!block_size) {
213 retval = EXT2_ET_INVALID_ARGUMENT;
214 goto cleanup;
215 }
216 io_channel_set_blksize(fs->io, block_size);
217 group_block = superblock;
218 fs->orig_super = 0;
219 } else {
220 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
221 superblock = 1;
222 group_block = 0;
223 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
224 if (retval)
225 goto cleanup;
226 }
227 retry:
228 retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
229 fs->super);
230 if (retval)
231 goto cleanup;
232 if (fs->orig_super)
233 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
234
235 if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
236 retval = 0;
237 if (!ext2fs_verify_csum_type(fs, fs->super))
238 retval = EXT2_ET_UNKNOWN_CSUM;
239 if (!ext2fs_superblock_csum_verify(fs, fs->super)) {
240 if (csum_retries++ < 3)
241 goto retry;
242 retval = EXT2_ET_SB_CSUM_INVALID;
243 }
244 }
245
246 #ifdef WORDS_BIGENDIAN
247 fs->flags |= EXT2_FLAG_SWAP_BYTES;
248 ext2fs_swap_super(fs->super);
249 #else
250 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
251 retval = EXT2_ET_UNIMPLEMENTED;
252 goto cleanup;
253 }
254 #endif
255
256 if (fs->super->s_magic != EXT2_SUPER_MAGIC)
257 retval = EXT2_ET_BAD_MAGIC;
258 if (retval)
259 goto cleanup;
260
261 if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
262 retval = EXT2_ET_REV_TOO_HIGH;
263 goto cleanup;
264 }
265
266 /*
267 * Check for feature set incompatibility
268 */
269 if (!(flags & EXT2_FLAG_FORCE)) {
270 features = fs->super->s_feature_incompat;
271 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
272 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
273 features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
274 #endif
275 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
276 retval = EXT2_ET_UNSUPP_FEATURE;
277 goto cleanup;
278 }
279
280 features = fs->super->s_feature_ro_compat;
281 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
282 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
283 features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
284 #endif
285 if ((flags & EXT2_FLAG_RW) &&
286 (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
287 retval = EXT2_ET_RO_UNSUPP_FEATURE;
288 goto cleanup;
289 }
290
291 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
292 ext2fs_has_feature_journal_dev(fs->super)) {
293 retval = EXT2_ET_UNSUPP_FEATURE;
294 goto cleanup;
295 }
296 }
297
298 if ((fs->super->s_log_block_size >
299 (unsigned) (EXT2_MAX_BLOCK_LOG_SIZE - EXT2_MIN_BLOCK_LOG_SIZE)) ||
300 (fs->super->s_log_cluster_size >
301 (unsigned) (EXT2_MAX_CLUSTER_LOG_SIZE - EXT2_MIN_CLUSTER_LOG_SIZE)) ||
302 (fs->super->s_log_block_size > fs->super->s_log_cluster_size) ||
303 (fs->super->s_log_groups_per_flex > 31)) {
304 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
305 goto cleanup;
306 }
307
308 /*
309 * bigalloc requires cluster-aware bitfield operations, which at the
310 * moment means we need EXT2_FLAG_64BITS.
311 */
312 if (ext2fs_has_feature_bigalloc(fs->super) &&
313 !(flags & EXT2_FLAG_64BITS)) {
314 retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS;
315 goto cleanup;
316 }
317
318 if (!ext2fs_has_feature_bigalloc(fs->super) &&
319 (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
320 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
321 goto cleanup;
322 }
323 fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
324 inode_size = EXT2_INODE_SIZE(fs->super);
325 if ((inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
326 (inode_size > fs->blocksize) ||
327 (inode_size & (inode_size - 1))) {
328 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
329 goto cleanup;
330 }
331
332 /* Enforce the block group descriptor size */
333 if (!(flags & EXT2_FLAG_IGNORE_SB_ERRORS) &&
334 ext2fs_has_feature_64bit(fs->super)) {
335 unsigned desc_size = fs->super->s_desc_size;
336
337 if ((desc_size < EXT2_MIN_DESC_SIZE_64BIT) ||
338 (desc_size > EXT2_MAX_DESC_SIZE) ||
339 (desc_size & (desc_size - 1)) != 0) {
340 retval = EXT2_ET_BAD_DESC_SIZE;
341 goto cleanup;
342 }
343 }
344
345 fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
346 fs->super->s_log_block_size;
347 if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
348 EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
349 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
350 goto cleanup;
351 }
352 fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
353 EXT2_INODE_SIZE(fs->super) +
354 EXT2_BLOCK_SIZE(fs->super) - 1) /
355 EXT2_BLOCK_SIZE(fs->super));
356 if (block_size) {
357 if (block_size != fs->blocksize) {
358 retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
359 goto cleanup;
360 }
361 }
362 /*
363 * Set the blocksize to the filesystem's blocksize.
364 */
365 io_channel_set_blksize(fs->io, fs->blocksize);
366
367 /*
368 * If this is an external journal device, don't try to read
369 * the group descriptors, because they're not there.
370 */
371 if (ext2fs_has_feature_journal_dev(fs->super)) {
372 fs->group_desc_count = 0;
373 *ret_fs = fs;
374 return 0;
375 }
376
377 if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
378 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
379 goto cleanup;
380 }
381 /* Precompute the FS UUID to seed other checksums */
382 ext2fs_init_csum_seed(fs);
383
384 /*
385 * Read group descriptors
386 */
387 blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
388 if (blocks_per_group < 8 ||
389 blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
390 fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
391 EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
392 fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
393 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
394 goto cleanup;
395 }
396 groups_cnt = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
397 fs->super->s_first_data_block,
398 blocks_per_group);
399 if (groups_cnt >> 32) {
400 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
401 goto cleanup;
402 }
403 fs->group_desc_count = groups_cnt;
404 if (!(flags & EXT2_FLAG_IGNORE_SB_ERRORS) &&
405 (__u64)fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
406 fs->super->s_inodes_count) {
407 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
408 goto cleanup;
409 }
410 fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
411 EXT2_DESC_PER_BLOCK(fs->super));
412 if (ext2fs_has_feature_meta_bg(fs->super) &&
413 (fs->super->s_first_meta_bg > fs->desc_blocks) &&
414 !(flags & EXT2_FLAG_IGNORE_SB_ERRORS)) {
415 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
416 goto cleanup;
417 }
418 if (flags & EXT2_FLAG_SUPER_ONLY)
419 goto skip_read_bg;
420 retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
421 &fs->group_desc);
422 if (retval)
423 goto cleanup;
424 if (!group_block)
425 group_block = fs->super->s_first_data_block;
426 /*
427 * On a FS with a 1K blocksize, block 0 is reserved for bootloaders
428 * so we must increment block numbers to any group 0 items.
429 *
430 * However, we cannot touch group_block directly because in the meta_bg
431 * case, the ext2fs_descriptor_block_loc2() function will interpret
432 * group_block != s_first_data_block to mean that we want to access the
433 * backup group descriptors. This is not what we want if the caller
434 * set superblock == 0 (i.e. auto-detect the superblock), which is
435 * what's going on here.
436 */
437 if (group_block == 0 && fs->blocksize == 1024)
438 group_zero_adjust = 1;
439 dest = (char *) fs->group_desc;
440 #ifdef WORDS_BIGENDIAN
441 groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
442 #endif
443 if (ext2fs_has_feature_meta_bg(fs->super) &&
444 !(flags & EXT2_FLAG_IMAGE_FILE)) {
445 first_meta_bg = fs->super->s_first_meta_bg;
446 if (first_meta_bg > fs->desc_blocks)
447 first_meta_bg = fs->desc_blocks;
448 } else
449 first_meta_bg = fs->desc_blocks;
450 if (first_meta_bg) {
451 retval = io_channel_read_blk(fs->io, group_block +
452 group_zero_adjust + 1,
453 first_meta_bg, dest);
454 if (retval)
455 goto cleanup;
456 #ifdef WORDS_BIGENDIAN
457 gdp = (struct ext2_group_desc *) dest;
458 for (j=0; j < groups_per_block*first_meta_bg; j++) {
459 gdp = ext2fs_group_desc(fs, fs->group_desc, j);
460 if (gdp)
461 ext2fs_swap_group_desc2(fs, gdp);
462 }
463 #endif
464 dest += fs->blocksize*first_meta_bg;
465 }
466
467 for (i = first_meta_bg ; i < fs->desc_blocks; i++) {
468 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
469 io_channel_cache_readahead(fs->io, blk, 1);
470 }
471
472 for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
473 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
474 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
475 if (retval)
476 goto cleanup;
477 #ifdef WORDS_BIGENDIAN
478 for (j=0; j < groups_per_block; j++) {
479 gdp = ext2fs_group_desc(fs, fs->group_desc,
480 i * groups_per_block + j);
481 if (gdp)
482 ext2fs_swap_group_desc2(fs, gdp);
483 }
484 #endif
485 dest += fs->blocksize;
486 }
487
488 fs->stride = fs->super->s_raid_stride;
489
490 /*
491 * If recovery is from backup superblock, Clear _UNININT flags &
492 * reset bg_itable_unused to zero
493 */
494 if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
495 dgrp_t group;
496
497 for (group = 0; group < fs->group_desc_count; group++) {
498 ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
499 ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
500 ext2fs_bg_itable_unused_set(fs, group, 0);
501 /* The checksum will be reset later, but fix it here
502 * anyway to avoid printing a lot of spurious errors. */
503 ext2fs_group_desc_csum_set(fs, group);
504 }
505 if (fs->flags & EXT2_FLAG_RW)
506 ext2fs_mark_super_dirty(fs);
507 }
508 skip_read_bg:
509 if (ext2fs_has_feature_mmp(fs->super) &&
510 !(flags & EXT2_FLAG_SKIP_MMP) &&
511 (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
512 retval = ext2fs_mmp_start(fs);
513 if (retval) {
514 fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
515 ext2fs_mmp_stop(fs);
516 goto cleanup;
517 }
518 }
519
520 if (fs->flags & EXT2_FLAG_SHARE_DUP) {
521 fs->block_sha_map = ext2fs_hashmap_create(ext2fs_djb2_hash,
522 block_sha_map_free_entry, 4096);
523 if (!fs->block_sha_map) {
524 retval = EXT2_ET_NO_MEMORY;
525 goto cleanup;
526 }
527 ext2fs_set_feature_shared_blocks(fs->super);
528 }
529
530 if (ext2fs_has_feature_casefold(fs->super))
531 fs->encoding = ext2fs_load_nls_table(fs->super->s_encoding);
532
533 fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
534 *ret_fs = fs;
535
536 return 0;
537 cleanup:
538 if (!(flags & EXT2_FLAG_NOFREE_ON_ERROR)) {
539 ext2fs_free(fs);
540 fs = NULL;
541 }
542 *ret_fs = fs;
543 return retval;
544 }
545
546 /*
547 * Set/get the filesystem data I/O channel.
548 *
549 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
550 */
ext2fs_get_data_io(ext2_filsys fs,io_channel * old_io)551 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
552 {
553 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
554 return EXT2_ET_NOT_IMAGE_FILE;
555 if (old_io) {
556 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
557 }
558 return 0;
559 }
560
ext2fs_set_data_io(ext2_filsys fs,io_channel new_io)561 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
562 {
563 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
564 return EXT2_ET_NOT_IMAGE_FILE;
565 fs->io = new_io ? new_io : fs->image_io;
566 return 0;
567 }
568
ext2fs_rewrite_to_io(ext2_filsys fs,io_channel new_io)569 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
570 {
571 errcode_t err;
572
573 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
574 return EXT2_ET_NOT_IMAGE_FILE;
575 err = io_channel_set_blksize(new_io, fs->blocksize);
576 if (err)
577 return err;
578 if ((new_io == fs->image_io) || (new_io == fs->io))
579 return 0;
580 if ((fs->image_io != fs->io) &&
581 fs->image_io)
582 io_channel_close(fs->image_io);
583 if (fs->io)
584 io_channel_close(fs->io);
585 fs->io = fs->image_io = new_io;
586 fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
587 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
588 fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
589 return 0;
590 }
591