openfs.c revision 585bca68f89aa2a99e39f9234a10f825eb243589
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 33#include "ext2fs.h" 34#include "e2image.h" 35 36blk64_t ext2fs_descriptor_block_loc2(ext2_filsys fs, blk64_t group_block, 37 dgrp_t i) 38{ 39 int bg; 40 int has_super = 0, group_zero_adjust = 0; 41 blk64_t ret_blk; 42 43 /* 44 * On a bigalloc FS with 1K blocks, block 0 is reserved for non-ext4 45 * stuff, so adjust for that if we're being asked for group 0. 46 */ 47 if (i == 0 && fs->blocksize == 1024 && EXT2FS_CLUSTER_RATIO(fs) > 1) 48 group_zero_adjust = 1; 49 50 if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) || 51 (i < fs->super->s_first_meta_bg)) 52 return group_block + i + 1 + group_zero_adjust; 53 54 bg = EXT2_DESC_PER_BLOCK(fs->super) * i; 55 if (ext2fs_bg_has_super(fs, bg)) 56 has_super = 1; 57 ret_blk = ext2fs_group_first_block2(fs, bg); 58 /* 59 * If group_block is not the normal value, we're trying to use 60 * the backup group descriptors and superblock --- so use the 61 * alternate location of the second block group in the 62 * metablock group. Ideally we should be testing each bg 63 * descriptor block individually for correctness, but we don't 64 * have the infrastructure in place to do that. 65 */ 66 if (group_block != fs->super->s_first_data_block && 67 ((ret_blk + has_super + fs->super->s_blocks_per_group) < 68 ext2fs_blocks_count(fs->super))) { 69 ret_blk += fs->super->s_blocks_per_group; 70 71 /* 72 * If we're going to jump forward a block group, make sure 73 * that we adjust has_super to account for the next group's 74 * backup superblock (or lack thereof). 75 */ 76 if (ext2fs_bg_has_super(fs, bg + 1)) 77 has_super = 1; 78 else 79 has_super = 0; 80 } 81 return ret_blk + has_super + group_zero_adjust; 82} 83 84blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i) 85{ 86 return ext2fs_descriptor_block_loc2(fs, group_block, i); 87} 88 89errcode_t ext2fs_open(const char *name, int flags, int superblock, 90 unsigned int block_size, io_manager manager, 91 ext2_filsys *ret_fs) 92{ 93 return ext2fs_open2(name, 0, flags, superblock, block_size, 94 manager, ret_fs); 95} 96 97/* 98 * Note: if superblock is non-zero, block-size must also be non-zero. 99 * Superblock and block_size can be zero to use the default size. 100 * 101 * Valid flags for ext2fs_open() 102 * 103 * EXT2_FLAG_RW - Open the filesystem for read/write. 104 * EXT2_FLAG_FORCE - Open the filesystem even if some of the 105 * features aren't supported. 106 * EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device 107 * EXT2_FLAG_SKIP_MMP - Open without multi-mount protection check. 108 * EXT2_FLAG_64BITS - Allow 64-bit bitfields (needed for large 109 * filesystems) 110 */ 111errcode_t ext2fs_open2(const char *name, const char *io_options, 112 int flags, int superblock, 113 unsigned int block_size, io_manager manager, 114 ext2_filsys *ret_fs) 115{ 116 ext2_filsys fs; 117 errcode_t retval; 118 unsigned long i, first_meta_bg; 119 __u32 features; 120 unsigned int blocks_per_group, io_flags; 121 blk64_t group_block, blk; 122 char *dest, *cp; 123 int group_zero_adjust = 0; 124#ifdef WORDS_BIGENDIAN 125 unsigned int groups_per_block; 126 struct ext2_group_desc *gdp; 127 int j; 128#endif 129 130 EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER); 131 132 retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs); 133 if (retval) 134 return retval; 135 136 memset(fs, 0, sizeof(struct struct_ext2_filsys)); 137 fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS; 138 fs->flags = flags; 139 /* don't overwrite sb backups unless flag is explicitly cleared */ 140 fs->flags |= EXT2_FLAG_MASTER_SB_ONLY; 141 fs->umask = 022; 142 retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name); 143 if (retval) 144 goto cleanup; 145 strcpy(fs->device_name, name); 146 cp = strchr(fs->device_name, '?'); 147 if (!io_options && cp) { 148 *cp++ = 0; 149 io_options = cp; 150 } 151 152 io_flags = 0; 153 if (flags & EXT2_FLAG_RW) 154 io_flags |= IO_FLAG_RW; 155 if (flags & EXT2_FLAG_EXCLUSIVE) 156 io_flags |= IO_FLAG_EXCLUSIVE; 157 if (flags & EXT2_FLAG_DIRECT_IO) 158 io_flags |= IO_FLAG_DIRECT_IO; 159 retval = manager->open(fs->device_name, io_flags, &fs->io); 160 if (retval) 161 goto cleanup; 162 if (io_options && 163 (retval = io_channel_set_options(fs->io, io_options))) 164 goto cleanup; 165 fs->image_io = fs->io; 166 fs->io->app_data = fs; 167 retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super); 168 if (retval) 169 goto cleanup; 170 if (flags & EXT2_FLAG_IMAGE_FILE) { 171 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr), 172 &fs->image_header); 173 if (retval) 174 goto cleanup; 175 retval = io_channel_read_blk(fs->io, 0, 176 -(int)sizeof(struct ext2_image_hdr), 177 fs->image_header); 178 if (retval) 179 goto cleanup; 180 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE) 181 return EXT2_ET_MAGIC_E2IMAGE; 182 superblock = 1; 183 block_size = fs->image_header->fs_blocksize; 184 } 185 186 /* 187 * If the user specifies a specific block # for the 188 * superblock, then he/she must also specify the block size! 189 * Otherwise, read the master superblock located at offset 190 * SUPERBLOCK_OFFSET from the start of the partition. 191 * 192 * Note: we only save a backup copy of the superblock if we 193 * are reading the superblock from the primary superblock location. 194 */ 195 if (superblock) { 196 if (!block_size) { 197 retval = EXT2_ET_INVALID_ARGUMENT; 198 goto cleanup; 199 } 200 io_channel_set_blksize(fs->io, block_size); 201 group_block = superblock; 202 fs->orig_super = 0; 203 } else { 204 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET); 205 superblock = 1; 206 group_block = 0; 207 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super); 208 if (retval) 209 goto cleanup; 210 } 211 retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE, 212 fs->super); 213 if (retval) 214 goto cleanup; 215 if (fs->orig_super) 216 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE); 217 218#ifdef WORDS_BIGENDIAN 219 fs->flags |= EXT2_FLAG_SWAP_BYTES; 220 ext2fs_swap_super(fs->super); 221#else 222 if (fs->flags & EXT2_FLAG_SWAP_BYTES) { 223 retval = EXT2_ET_UNIMPLEMENTED; 224 goto cleanup; 225 } 226#endif 227 228 if (fs->super->s_magic != EXT2_SUPER_MAGIC) { 229 retval = EXT2_ET_BAD_MAGIC; 230 goto cleanup; 231 } 232 if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) { 233 retval = EXT2_ET_REV_TOO_HIGH; 234 goto cleanup; 235 } 236 237 /* 238 * Check for feature set incompatibility 239 */ 240 if (!(flags & EXT2_FLAG_FORCE)) { 241 features = fs->super->s_feature_incompat; 242#ifdef EXT2_LIB_SOFTSUPP_INCOMPAT 243 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES) 244 features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT; 245#endif 246 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) { 247 retval = EXT2_ET_UNSUPP_FEATURE; 248 goto cleanup; 249 } 250 251 features = fs->super->s_feature_ro_compat; 252#ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT 253 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES) 254 features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT; 255#endif 256 if ((flags & EXT2_FLAG_RW) && 257 (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) { 258 retval = EXT2_ET_RO_UNSUPP_FEATURE; 259 goto cleanup; 260 } 261 262 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) && 263 (fs->super->s_feature_incompat & 264 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) { 265 retval = EXT2_ET_UNSUPP_FEATURE; 266 goto cleanup; 267 } 268 } 269 270 if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) > 271 EXT2_MAX_BLOCK_LOG_SIZE) { 272 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 273 goto cleanup; 274 } 275 276 /* 277 * bigalloc requires cluster-aware bitfield operations, which at the 278 * moment means we need EXT2_FLAG_64BITS. 279 */ 280 if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super, 281 EXT4_FEATURE_RO_COMPAT_BIGALLOC) && 282 !(flags & EXT2_FLAG_64BITS)) { 283 retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS; 284 goto cleanup; 285 } 286 287 if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, 288 EXT4_FEATURE_RO_COMPAT_BIGALLOC) && 289 (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) { 290 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 291 goto cleanup; 292 } 293 fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super); 294 if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) { 295 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 296 goto cleanup; 297 } 298 fs->cluster_ratio_bits = fs->super->s_log_cluster_size - 299 fs->super->s_log_block_size; 300 if (EXT2_BLOCKS_PER_GROUP(fs->super) != 301 EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) { 302 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 303 goto cleanup; 304 } 305 fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) * 306 EXT2_INODE_SIZE(fs->super) + 307 EXT2_BLOCK_SIZE(fs->super) - 1) / 308 EXT2_BLOCK_SIZE(fs->super)); 309 if (block_size) { 310 if (block_size != fs->blocksize) { 311 retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE; 312 goto cleanup; 313 } 314 } 315 /* 316 * Set the blocksize to the filesystem's blocksize. 317 */ 318 io_channel_set_blksize(fs->io, fs->blocksize); 319 320 /* 321 * If this is an external journal device, don't try to read 322 * the group descriptors, because they're not there. 323 */ 324 if (fs->super->s_feature_incompat & 325 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) { 326 fs->group_desc_count = 0; 327 *ret_fs = fs; 328 return 0; 329 } 330 331 if (EXT2_INODES_PER_GROUP(fs->super) == 0) { 332 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 333 goto cleanup; 334 } 335 336 /* 337 * Read group descriptors 338 */ 339 blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super); 340 if (blocks_per_group == 0 || 341 blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) || 342 fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) || 343 EXT2_DESC_PER_BLOCK(fs->super) == 0 || 344 fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) { 345 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 346 goto cleanup; 347 } 348 fs->group_desc_count = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) - 349 fs->super->s_first_data_block, 350 blocks_per_group); 351 if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) != 352 fs->super->s_inodes_count) { 353 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 354 goto cleanup; 355 } 356 fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count, 357 EXT2_DESC_PER_BLOCK(fs->super)); 358 retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize, 359 &fs->group_desc); 360 if (retval) 361 goto cleanup; 362 if (!group_block) 363 group_block = fs->super->s_first_data_block; 364 /* 365 * On a FS with a 1K blocksize, block 0 is reserved for bootloaders 366 * so we must increment block numbers to any group 0 items. 367 * 368 * However, we cannot touch group_block directly because in the meta_bg 369 * case, the ext2fs_descriptor_block_loc2() function will interpret 370 * group_block != s_first_data_block to mean that we want to access the 371 * backup group descriptors. This is not what we want if the caller 372 * set superblock == 0 (i.e. auto-detect the superblock), which is 373 * what's going on here. 374 */ 375 if (group_block == 0 && fs->blocksize == 1024) 376 group_zero_adjust = 1; 377 dest = (char *) fs->group_desc; 378#ifdef WORDS_BIGENDIAN 379 groups_per_block = EXT2_DESC_PER_BLOCK(fs->super); 380#endif 381 if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) 382 first_meta_bg = fs->super->s_first_meta_bg; 383 else 384 first_meta_bg = fs->desc_blocks; 385 if (first_meta_bg) { 386 retval = io_channel_read_blk(fs->io, group_block + 387 group_zero_adjust + 1, 388 first_meta_bg, dest); 389 if (retval) 390 goto cleanup; 391#ifdef WORDS_BIGENDIAN 392 gdp = (struct ext2_group_desc *) dest; 393 for (j=0; j < groups_per_block*first_meta_bg; j++) { 394 gdp = ext2fs_group_desc(fs, fs->group_desc, j); 395 ext2fs_swap_group_desc2(fs, gdp); 396 } 397#endif 398 dest += fs->blocksize*first_meta_bg; 399 } 400 for (i=first_meta_bg ; i < fs->desc_blocks; i++) { 401 blk = ext2fs_descriptor_block_loc2(fs, group_block, i); 402 retval = io_channel_read_blk64(fs->io, blk, 1, dest); 403 if (retval) 404 goto cleanup; 405#ifdef WORDS_BIGENDIAN 406 for (j=0; j < groups_per_block; j++) { 407 gdp = ext2fs_group_desc(fs, fs->group_desc, 408 i * groups_per_block + j); 409 ext2fs_swap_group_desc2(fs, gdp); 410 } 411#endif 412 dest += fs->blocksize; 413 } 414 415 fs->stride = fs->super->s_raid_stride; 416 417 /* 418 * If recovery is from backup superblock, Clear _UNININT flags & 419 * reset bg_itable_unused to zero 420 */ 421 if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super, 422 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) { 423 dgrp_t group; 424 425 for (group = 0; group < fs->group_desc_count; group++) { 426 ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT); 427 ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT); 428 ext2fs_bg_itable_unused_set(fs, group, 0); 429 /* The checksum will be reset later, but fix it here 430 * anyway to avoid printing a lot of spurious errors. */ 431 ext2fs_group_desc_csum_set(fs, group); 432 } 433 if (fs->flags & EXT2_FLAG_RW) 434 ext2fs_mark_super_dirty(fs); 435 } 436 437 if ((fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) && 438 !(flags & EXT2_FLAG_SKIP_MMP) && 439 (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) { 440 retval = ext2fs_mmp_start(fs); 441 if (retval) { 442 fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */ 443 ext2fs_mmp_stop(fs); 444 goto cleanup; 445 } 446 } 447 448 fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR; 449 *ret_fs = fs; 450 451 return 0; 452cleanup: 453 if (!(flags & EXT2_FLAG_NOFREE_ON_ERROR)) { 454 ext2fs_free(fs); 455 fs = NULL; 456 } 457 *ret_fs = fs; 458 return retval; 459} 460 461/* 462 * Set/get the filesystem data I/O channel. 463 * 464 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true. 465 */ 466errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io) 467{ 468 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0) 469 return EXT2_ET_NOT_IMAGE_FILE; 470 if (old_io) { 471 *old_io = (fs->image_io == fs->io) ? 0 : fs->io; 472 } 473 return 0; 474} 475 476errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io) 477{ 478 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0) 479 return EXT2_ET_NOT_IMAGE_FILE; 480 fs->io = new_io ? new_io : fs->image_io; 481 return 0; 482} 483 484errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io) 485{ 486 errcode_t err; 487 488 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0) 489 return EXT2_ET_NOT_IMAGE_FILE; 490 err = io_channel_set_blksize(new_io, fs->blocksize); 491 if (err) 492 return err; 493 if ((new_io == fs->image_io) || (new_io == fs->io)) 494 return 0; 495 if ((fs->image_io != fs->io) && 496 fs->image_io) 497 io_channel_close(fs->image_io); 498 if (fs->io) 499 io_channel_close(fs->io); 500 fs->io = fs->image_io = new_io; 501 fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW | 502 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY; 503 fs->flags &= ~EXT2_FLAG_IMAGE_FILE; 504 return 0; 505} 506