closefs.c revision 4a568505ab904d39d9553e9c1d1c565615a5c6ca
1/* 2 * closefs.c --- close 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 Public 8 * License. 9 * %End-Header% 10 */ 11 12#include <stdio.h> 13#if HAVE_UNISTD_H 14#include <unistd.h> 15#endif 16#include <time.h> 17#include <string.h> 18 19#include "ext2_fs.h" 20#include "ext2fsP.h" 21 22static int test_root(int a, int b) 23{ 24 if (a == 0) 25 return 1; 26 while (1) { 27 if (a == 1) 28 return 1; 29 if (a % b) 30 return 0; 31 a = a / b; 32 } 33} 34 35int ext2fs_bg_has_super(ext2_filsys fs, int group_block) 36{ 37 if (!(fs->super->s_feature_ro_compat & 38 EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)) 39 return 1; 40 41 if (test_root(group_block, 3) || (test_root(group_block, 5)) || 42 test_root(group_block, 7)) 43 return 1; 44 45 return 0; 46} 47 48/* 49 * This function returns the location of the superblock, block group 50 * descriptors for a given block group. It currently returns the 51 * number of free blocks assuming that inode table and allocation 52 * bitmaps will be in the group. This is not necessarily the case 53 * when the flex_bg feature is enabled, so callers should take care! 54 * It was only really intended for use by mke2fs, and even there it's 55 * not that useful. In the future, when we redo this function for 56 * 64-bit block numbers, we should probably return the number of 57 * blocks used by the super block and group descriptors instead. 58 * 59 * See also the comment for ext2fs_reserve_super_and_bgd() 60 */ 61int ext2fs_super_and_bgd_loc(ext2_filsys fs, 62 dgrp_t group, 63 blk_t *ret_super_blk, 64 blk_t *ret_old_desc_blk, 65 blk_t *ret_new_desc_blk, 66 int *ret_meta_bg) 67{ 68 blk_t group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0; 69 unsigned int meta_bg, meta_bg_size; 70 blk_t numblocks, old_desc_blocks; 71 int has_super; 72 73 group_block = ext2fs_group_first_block(fs, group); 74 75 if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) 76 old_desc_blocks = fs->super->s_first_meta_bg; 77 else 78 old_desc_blocks = 79 fs->desc_blocks + fs->super->s_reserved_gdt_blocks; 80 81 if (group == fs->group_desc_count-1) { 82 numblocks = (fs->super->s_blocks_count - 83 fs->super->s_first_data_block) % 84 fs->super->s_blocks_per_group; 85 if (!numblocks) 86 numblocks = fs->super->s_blocks_per_group; 87 } else 88 numblocks = fs->super->s_blocks_per_group; 89 90 has_super = ext2fs_bg_has_super(fs, group); 91 92 if (has_super) { 93 super_blk = group_block; 94 numblocks--; 95 } 96 meta_bg_size = EXT2_DESC_PER_BLOCK(fs->super); 97 meta_bg = group / meta_bg_size; 98 99 if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) || 100 (meta_bg < fs->super->s_first_meta_bg)) { 101 if (has_super) { 102 old_desc_blk = group_block + 1; 103 numblocks -= old_desc_blocks; 104 } 105 } else { 106 if (((group % meta_bg_size) == 0) || 107 ((group % meta_bg_size) == 1) || 108 ((group % meta_bg_size) == (meta_bg_size-1))) { 109 if (has_super) 110 has_super = 1; 111 new_desc_blk = group_block + has_super; 112 numblocks--; 113 } 114 } 115 116 numblocks -= 2 + fs->inode_blocks_per_group; 117 118 if (ret_super_blk) 119 *ret_super_blk = super_blk; 120 if (ret_old_desc_blk) 121 *ret_old_desc_blk = old_desc_blk; 122 if (ret_new_desc_blk) 123 *ret_new_desc_blk = new_desc_blk; 124 if (ret_meta_bg) 125 *ret_meta_bg = meta_bg; 126 return (numblocks); 127} 128 129 130/* 131 * This function forces out the primary superblock. We need to only 132 * write out those fields which we have changed, since if the 133 * filesystem is mounted, it may have changed some of the other 134 * fields. 135 * 136 * It takes as input a superblock which has already been byte swapped 137 * (if necessary). 138 * 139 */ 140static errcode_t write_primary_superblock(ext2_filsys fs, 141 struct ext2_super_block *super) 142{ 143 __u16 *old_super, *new_super; 144 int check_idx, write_idx, size; 145 errcode_t retval; 146 147 if (!fs->io->manager->write_byte || !fs->orig_super) { 148 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET); 149 retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE, 150 super); 151 io_channel_set_blksize(fs->io, fs->blocksize); 152 return retval; 153 } 154 155 old_super = (__u16 *) fs->orig_super; 156 new_super = (__u16 *) super; 157 158 for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) { 159 if (old_super[check_idx] == new_super[check_idx]) 160 continue; 161 write_idx = check_idx; 162 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++) 163 if (old_super[check_idx] == new_super[check_idx]) 164 break; 165 size = 2 * (check_idx - write_idx); 166#if 0 167 printf("Writing %d bytes starting at %d\n", 168 size, write_idx*2); 169#endif 170 retval = io_channel_write_byte(fs->io, 171 SUPERBLOCK_OFFSET + (2 * write_idx), size, 172 new_super + write_idx); 173 if (retval) 174 return retval; 175 } 176 memcpy(fs->orig_super, super, SUPERBLOCK_SIZE); 177 return 0; 178} 179 180 181/* 182 * Updates the revision to EXT2_DYNAMIC_REV 183 */ 184void ext2fs_update_dynamic_rev(ext2_filsys fs) 185{ 186 struct ext2_super_block *sb = fs->super; 187 188 if (sb->s_rev_level > EXT2_GOOD_OLD_REV) 189 return; 190 191 sb->s_rev_level = EXT2_DYNAMIC_REV; 192 sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO; 193 sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE; 194 /* s_uuid is handled by e2fsck already */ 195 /* other fields should be left alone */ 196} 197 198static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group, 199 blk_t group_block, 200 struct ext2_super_block *super_shadow) 201{ 202 dgrp_t sgrp = group; 203 204 if (sgrp > ((1 << 16) - 1)) 205 sgrp = (1 << 16) - 1; 206#ifdef WORDS_BIGENDIAN 207 super_shadow->s_block_group_nr = ext2fs_swab16(sgrp); 208#else 209 fs->super->s_block_group_nr = sgrp; 210#endif 211 212 return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE, 213 super_shadow); 214} 215 216 217errcode_t ext2fs_flush(ext2_filsys fs) 218{ 219 dgrp_t i; 220 errcode_t retval; 221 unsigned long fs_state; 222 __u32 feature_incompat; 223 struct ext2_super_block *super_shadow = 0; 224 struct ext2_group_desc *group_shadow = 0; 225#ifdef WORDS_BIGENDIAN 226 struct ext2_group_desc *s, *t; 227 dgrp_t j; 228#endif 229 char *group_ptr; 230 int old_desc_blocks; 231 232 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 233 234 fs_state = fs->super->s_state; 235 feature_incompat = fs->super->s_feature_incompat; 236 237 fs->super->s_wtime = fs->now ? fs->now : time(NULL); 238 fs->super->s_block_group_nr = 0; 239#ifdef WORDS_BIGENDIAN 240 retval = EXT2_ET_NO_MEMORY; 241 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow); 242 if (retval) 243 goto errout; 244 retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize, 245 &group_shadow); 246 if (retval) 247 goto errout; 248 memset(group_shadow, 0, (size_t) fs->blocksize * 249 fs->desc_blocks); 250 251 /* swap the group descriptors */ 252 for (j=0, s=fs->group_desc, t=group_shadow; 253 j < fs->group_desc_count; j++, t++, s++) { 254 *t = *s; 255 ext2fs_swap_group_desc(t); 256 } 257#else 258 super_shadow = fs->super; 259 group_shadow = fs->group_desc; 260#endif 261 262 /* 263 * Set the state of the FS to be non-valid. (The state has 264 * already been backed up earlier, and will be restored after 265 * we write out the backup superblocks.) 266 */ 267 fs->super->s_state &= ~EXT2_VALID_FS; 268 fs->super->s_feature_incompat &= ~EXT3_FEATURE_INCOMPAT_RECOVER; 269#ifdef WORDS_BIGENDIAN 270 *super_shadow = *fs->super; 271 ext2fs_swap_super(super_shadow); 272#endif 273 274 /* 275 * If this is an external journal device, don't write out the 276 * block group descriptors or any of the backup superblocks 277 */ 278 if (fs->super->s_feature_incompat & 279 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) 280 goto write_primary_superblock_only; 281 282 /* 283 * Write out the master group descriptors, and the backup 284 * superblocks and group descriptors. 285 */ 286 group_ptr = (char *) group_shadow; 287 if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) 288 old_desc_blocks = fs->super->s_first_meta_bg; 289 else 290 old_desc_blocks = fs->desc_blocks; 291 292 for (i = 0; i < fs->group_desc_count; i++) { 293 blk_t super_blk, old_desc_blk, new_desc_blk; 294 int meta_bg; 295 296 ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk, 297 &new_desc_blk, &meta_bg); 298 299 if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) { 300 retval = write_backup_super(fs, i, super_blk, 301 super_shadow); 302 if (retval) 303 goto errout; 304 } 305 if (fs->flags & EXT2_FLAG_SUPER_ONLY) 306 continue; 307 if ((old_desc_blk) && 308 (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) { 309 retval = io_channel_write_blk(fs->io, 310 old_desc_blk, old_desc_blocks, group_ptr); 311 if (retval) 312 goto errout; 313 } 314 if (new_desc_blk) { 315 retval = io_channel_write_blk(fs->io, new_desc_blk, 316 1, group_ptr + (meta_bg*fs->blocksize)); 317 if (retval) 318 goto errout; 319 } 320 } 321 322 /* 323 * If the write_bitmaps() function is present, call it to 324 * flush the bitmaps. This is done this way so that a simple 325 * program that doesn't mess with the bitmaps doesn't need to 326 * drag in the bitmaps.c code. 327 */ 328 if (fs->write_bitmaps) { 329 retval = fs->write_bitmaps(fs); 330 if (retval) 331 goto errout; 332 } 333 334write_primary_superblock_only: 335 /* 336 * Write out master superblock. This has to be done 337 * separately, since it is located at a fixed location 338 * (SUPERBLOCK_OFFSET). We flush all other pending changes 339 * out to disk first, just to avoid a race condition with an 340 * insy-tinsy window.... 341 */ 342 343 fs->super->s_block_group_nr = 0; 344 fs->super->s_state = fs_state; 345 fs->super->s_feature_incompat = feature_incompat; 346#ifdef WORDS_BIGENDIAN 347 *super_shadow = *fs->super; 348 ext2fs_swap_super(super_shadow); 349#endif 350 351 retval = io_channel_flush(fs->io); 352 retval = write_primary_superblock(fs, super_shadow); 353 if (retval) 354 goto errout; 355 356 fs->flags &= ~EXT2_FLAG_DIRTY; 357 358 retval = io_channel_flush(fs->io); 359errout: 360 fs->super->s_state = fs_state; 361#ifdef WORDS_BIGENDIAN 362 if (super_shadow) 363 ext2fs_free_mem(&super_shadow); 364 if (group_shadow) 365 ext2fs_free_mem(&group_shadow); 366#endif 367 return retval; 368} 369 370errcode_t ext2fs_close(ext2_filsys fs) 371{ 372 errcode_t retval; 373 374 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 375 376 if (fs->flags & EXT2_FLAG_DIRTY) { 377 retval = ext2fs_flush(fs); 378 if (retval) 379 return retval; 380 } 381 if (fs->write_bitmaps) { 382 retval = fs->write_bitmaps(fs); 383 if (retval) 384 return retval; 385 } 386 ext2fs_free(fs); 387 return 0; 388} 389 390