lib/ext2fs/closefs.c

   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
  22 static 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
  35 int 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  * ext2fs_super_and_bgd_loc2()
  50  * @fs:                 ext2 fs pointer
  51  * @group               given block group
  52  * @ret_super_blk:      if !NULL, returns super block location
  53  * @ret_old_desc_blk:   if !NULL, returns location of the old block
  54  *                      group descriptor
  55  * @ret_new_desc_blk:   if !NULL, returns location of meta_bg block
  56  *                      group descriptor
  57  * @ret_used_blks:      if !NULL, returns number of blocks used by
  58  *                      super block and group_descriptors.
  59  *
  60  * Returns errcode_t of 0
  61  */
  62 errcode_t ext2fs_super_and_bgd_loc2(ext2_filsys fs,
  63                                            dgrp_t group,
  64                                            blk64_t *ret_super_blk,
  65                                            blk64_t *ret_old_desc_blk,
  66                                            blk64_t *ret_new_desc_blk,
  67                                            blk_t *ret_used_blks)
  68 {
  69         blk64_t group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
  70         unsigned int meta_bg, meta_bg_size;
  71         blk_t   numblocks = 0;
  72         blk64_t old_desc_blocks;
  73         int     has_super;
  74
  75         group_block = ext2fs_group_first_block2(fs, group);
  76
  77         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
  78                 old_desc_blocks = fs->super->s_first_meta_bg;
  79         else
  80                 old_desc_blocks =
  81                         fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
  82
  83         has_super = ext2fs_bg_has_super(fs, group);
  84
  85         if (has_super) {
  86                 super_blk = group_block;
  87                 numblocks++;
  88         }
  89         meta_bg_size = EXT2_DESC_PER_BLOCK(fs->super);
  90         meta_bg = group / meta_bg_size;
  91
  92         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  93             (meta_bg < fs->super->s_first_meta_bg)) {
  94                 if (has_super) {
  95                         old_desc_blk = group_block + 1;
  96                         numblocks += old_desc_blocks;
  97                 }
  98         } else {
  99                 if (((group % meta_bg_size) == 0) ||
 100                     ((group % meta_bg_size) == 1) ||
 101                     ((group % meta_bg_size) == (meta_bg_size-1))) {
 102                         if (has_super)
 103                                 has_super = 1;
 104                         new_desc_blk = group_block + has_super;
 105                         numblocks++;
 106                 }
 107         }
 108
 109         if (ret_super_blk)
 110                 *ret_super_blk = super_blk;
 111         if (ret_old_desc_blk)
 112                 *ret_old_desc_blk = old_desc_blk;
 113         if (ret_new_desc_blk)
 114                 *ret_new_desc_blk = new_desc_blk;
 115         if (ret_used_blks)
 116                 *ret_used_blks = numblocks;
 117
 118         return 0;
 119 }
 120
 121 /*
 122  * This function returns the location of the superblock, block group
 123  * descriptors for a given block group.  It currently returns the
 124  * number of free blocks assuming that inode table and allocation
 125  * bitmaps will be in the group.  This is not necessarily the case
 126  * when the flex_bg feature is enabled, so callers should take care!
 127  * It was only really intended for use by mke2fs, and even there it's
 128  * not that useful.
 129  *
 130  * The ext2fs_super_and_bgd_loc2() function is 64-bit block number
 131  * capable and returns the number of blocks used by super block and
 132  * group descriptors.
 133  */
 134 int ext2fs_super_and_bgd_loc(ext2_filsys fs,
 135                              dgrp_t group,
 136                              blk_t *ret_super_blk,
 137                              blk_t *ret_old_desc_blk,
 138                              blk_t *ret_new_desc_blk,
 139                              int *ret_meta_bg)
 140 {
 141         blk64_t ret_super_blk2;
 142         blk64_t ret_old_desc_blk2;
 143         blk64_t ret_new_desc_blk2;
 144         blk_t ret_used_blks;
 145         blk_t numblocks;
 146         unsigned int meta_bg_size;
 147
 148         ext2fs_super_and_bgd_loc2(fs, group, &ret_super_blk2,
 149                                         &ret_old_desc_blk2,
 150                                         &ret_new_desc_blk2,
 151                                         &ret_used_blks);
 152
 153         if (group == fs->group_desc_count-1) {
 154                 numblocks = (fs->super->s_blocks_count -
 155                              fs->super->s_first_data_block) %
 156                         fs->super->s_blocks_per_group;
 157                 if (!numblocks)
 158                         numblocks = fs->super->s_blocks_per_group;
 159         } else
 160                 numblocks = fs->super->s_blocks_per_group;
 161
 162         if (ret_super_blk)
 163                 *ret_super_blk = (blk_t)ret_super_blk2;
 164         if (ret_old_desc_blk)
 165                 *ret_old_desc_blk = (blk_t)ret_old_desc_blk2;
 166         if (ret_new_desc_blk)
 167                 *ret_new_desc_blk = (blk_t)ret_new_desc_blk2;
 168         if (ret_meta_bg) {
 169                 meta_bg_size = EXT2_DESC_PER_BLOCK(fs->super);
 170                 *ret_meta_bg = group / meta_bg_size;
 171         }
 172
 173         numblocks -= 2 + fs->inode_blocks_per_group + ret_used_blks;
 174
 175         return numblocks;
 176 }
 177
 178 /*
 179  * This function forces out the primary superblock.  We need to only
 180  * write out those fields which we have changed, since if the
 181  * filesystem is mounted, it may have changed some of the other
 182  * fields.
 183  *
 184  * It takes as input a superblock which has already been byte swapped
 185  * (if necessary).
 186  *
 187  */
 188 static errcode_t write_primary_superblock(ext2_filsys fs,
 189                                           struct ext2_super_block *super)
 190 {
 191         __u16           *old_super, *new_super;
 192         int             check_idx, write_idx, size;
 193         errcode_t       retval;
 194
 195         if (!fs->io->manager->write_byte || !fs->orig_super) {
 196                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 197                 retval = io_channel_write_blk64(fs->io, 1, -SUPERBLOCK_SIZE,
 198                                               super);
 199                 io_channel_set_blksize(fs->io, fs->blocksize);
 200                 return retval;
 201         }
 202
 203         old_super = (__u16 *) fs->orig_super;
 204         new_super = (__u16 *) super;
 205
 206         for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
 207                 if (old_super[check_idx] == new_super[check_idx])
 208                         continue;
 209                 write_idx = check_idx;
 210                 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
 211                         if (old_super[check_idx] == new_super[check_idx])
 212                                 break;
 213                 size = 2 * (check_idx - write_idx);
 214 #if 0
 215                 printf("Writing %d bytes starting at %d\n",
 216                        size, write_idx*2);
 217 #endif
 218                 retval = io_channel_write_byte(fs->io,
 219                                SUPERBLOCK_OFFSET + (2 * write_idx), size,
 220                                                new_super + write_idx);
 221                 if (retval)
 222                         return retval;
 223         }
 224         memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
 225         return 0;
 226 }
 227
 228
 229 /*
 230  * Updates the revision to EXT2_DYNAMIC_REV
 231  */
 232 void ext2fs_update_dynamic_rev(ext2_filsys fs)
 233 {
 234         struct ext2_super_block *sb = fs->super;
 235
 236         if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
 237                 return;
 238
 239         sb->s_rev_level = EXT2_DYNAMIC_REV;
 240         sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 241         sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 242         /* s_uuid is handled by e2fsck already */
 243         /* other fields should be left alone */
 244 }
 245
 246 static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
 247                                     blk_t group_block,
 248                                     struct ext2_super_block *super_shadow)
 249 {
 250         dgrp_t  sgrp = group;
 251
 252         if (sgrp > ((1 << 16) - 1))
 253                 sgrp = (1 << 16) - 1;
 254 #ifdef WORDS_BIGENDIAN
 255         super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 256 #else
 257         fs->super->s_block_group_nr = sgrp;
 258 #endif
 259
 260         return io_channel_write_blk64(fs->io, group_block, -SUPERBLOCK_SIZE,
 261                                     super_shadow);
 262 }
 263
 264
 265 errcode_t ext2fs_flush(ext2_filsys fs)
 266 {
 267         dgrp_t          i;
 268         errcode_t       retval;
 269         unsigned long   fs_state;
 270         __u32           feature_incompat;
 271         struct ext2_super_block *super_shadow = 0;
 272         struct ext2_group_desc *group_shadow = 0;
 273 #ifdef WORDS_BIGENDIAN
 274         struct ext2_group_desc *s, *t;
 275         dgrp_t          j;
 276 #endif
 277         char    *group_ptr;
 278         int     old_desc_blocks;
 279
 280         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 281
 282         fs_state = fs->super->s_state;
 283         feature_incompat = fs->super->s_feature_incompat;
 284
 285         fs->super->s_wtime = fs->now ? fs->now : time(NULL);
 286         fs->super->s_block_group_nr = 0;
 287 #ifdef WORDS_BIGENDIAN
 288         retval = EXT2_ET_NO_MEMORY;
 289         retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
 290         if (retval)
 291                 goto errout;
 292         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 293                                   &group_shadow);
 294         if (retval)
 295                 goto errout;
 296         memset(group_shadow, 0, (size_t) fs->blocksize *
 297                fs->desc_blocks);
 298
 299         /* swap the group descriptors */
 300         for (j=0, s=fs->group_desc, t=group_shadow;
 301              j < fs->group_desc_count; j++, t++, s++) {
 302                 *t = *s;
 303                 ext2fs_swap_group_desc(t);
 304         }
 305 #else
 306         super_shadow = fs->super;
 307         group_shadow = fs->group_desc;
 308 #endif
 309
 310         /*
 311          * Set the state of the FS to be non-valid.  (The state has
 312          * already been backed up earlier, and will be restored after
 313          * we write out the backup superblocks.)
 314          */
 315         fs->super->s_state &= ~EXT2_VALID_FS;
 316         fs->super->s_feature_incompat &= ~EXT3_FEATURE_INCOMPAT_RECOVER;
 317 #ifdef WORDS_BIGENDIAN
 318         *super_shadow = *fs->super;
 319         ext2fs_swap_super(super_shadow);
 320 #endif
 321
 322         /*
 323          * If this is an external journal device, don't write out the
 324          * block group descriptors or any of the backup superblocks
 325          */
 326         if (fs->super->s_feature_incompat &
 327             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
 328                 goto write_primary_superblock_only;
 329
 330         /*
 331          * Write out the master group descriptors, and the backup
 332          * superblocks and group descriptors.
 333          */
 334         group_ptr = (char *) group_shadow;
 335         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 336                 old_desc_blocks = fs->super->s_first_meta_bg;
 337         else
 338                 old_desc_blocks = fs->desc_blocks;
 339
 340         for (i = 0; i < fs->group_desc_count; i++) {
 341                 blk64_t super_blk, old_desc_blk, new_desc_blk;
 342
 343                 ext2fs_super_and_bgd_loc2(fs, i, &super_blk, &old_desc_blk,
 344                                          &new_desc_blk, 0);
 345
 346                 if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
 347                         retval = write_backup_super(fs, i, super_blk,
 348                                                     super_shadow);
 349                         if (retval)
 350                                 goto errout;
 351                 }
 352                 if (fs->flags & EXT2_FLAG_SUPER_ONLY)
 353                         continue;
 354                 if ((old_desc_blk) &&
 355                     (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
 356                         retval = io_channel_write_blk64(fs->io,
 357                               old_desc_blk, old_desc_blocks, group_ptr);
 358                         if (retval)
 359                                 goto errout;
 360                 }
 361                 if (new_desc_blk) {
 362                         int meta_bg = i / EXT2_DESC_PER_BLOCK(fs->super);
 363
 364                         retval = io_channel_write_blk64(fs->io, new_desc_blk,
 365                                 1, group_ptr + (meta_bg*fs->blocksize));
 366                         if (retval)
 367                                 goto errout;
 368                 }
 369         }
 370
 371         /*
 372          * If the write_bitmaps() function is present, call it to
 373          * flush the bitmaps.  This is done this way so that a simple
 374          * program that doesn't mess with the bitmaps doesn't need to
 375          * drag in the bitmaps.c code.
 376          */
 377         if (fs->write_bitmaps) {
 378                 retval = fs->write_bitmaps(fs);
 379                 if (retval)
 380                         goto errout;
 381         }
 382
 383 write_primary_superblock_only:
 384         /*
 385          * Write out master superblock.  This has to be done
 386          * separately, since it is located at a fixed location
 387          * (SUPERBLOCK_OFFSET).  We flush all other pending changes
 388          * out to disk first, just to avoid a race condition with an
 389          * insy-tinsy window....
 390          */
 391
 392         fs->super->s_block_group_nr = 0;
 393         fs->super->s_state = fs_state;
 394         fs->super->s_feature_incompat = feature_incompat;
 395 #ifdef WORDS_BIGENDIAN
 396         *super_shadow = *fs->super;
 397         ext2fs_swap_super(super_shadow);
 398 #endif
 399
 400         retval = io_channel_flush(fs->io);
 401         retval = write_primary_superblock(fs, super_shadow);
 402         if (retval)
 403                 goto errout;
 404
 405         fs->flags &= ~EXT2_FLAG_DIRTY;
 406
 407         retval = io_channel_flush(fs->io);
 408 errout:
 409         fs->super->s_state = fs_state;
 410 #ifdef WORDS_BIGENDIAN
 411         if (super_shadow)
 412                 ext2fs_free_mem(&super_shadow);
 413         if (group_shadow)
 414                 ext2fs_free_mem(&group_shadow);
 415 #endif
 416         return retval;
 417 }
 418
 419 errcode_t ext2fs_close(ext2_filsys fs)
 420 {
 421         errcode_t       retval;
 422         int             meta_blks;
 423         io_stats stats = 0;
 424
 425         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 426
 427         if (fs->write_bitmaps) {
 428                 retval = fs->write_bitmaps(fs);
 429                 if (retval)
 430                         return retval;
 431         }
 432         if (fs->super->s_kbytes_written &&
 433             fs->io->manager->get_stats)
 434                 fs->io->manager->get_stats(fs->io, &stats);
 435         if (stats && stats->bytes_written && (fs->flags & EXT2_FLAG_RW)) {
 436                 fs->super->s_kbytes_written += stats->bytes_written >> 10;
 437                 meta_blks = fs->desc_blocks + 1;
 438                 if (!(fs->flags & EXT2_FLAG_SUPER_ONLY))
 439                         fs->super->s_kbytes_written += meta_blks /
 440                                 (fs->blocksize / 1024);
 441                 if ((fs->flags & EXT2_FLAG_DIRTY) == 0)
 442                         fs->flags |= EXT2_FLAG_SUPER_ONLY | EXT2_FLAG_DIRTY;
 443         }
 444         if (fs->flags & EXT2_FLAG_DIRTY) {
 445                 retval = ext2fs_flush(fs);
 446                 if (retval)
 447                         return retval;
 448         }
 449         ext2fs_free(fs);
 450         return 0;
 451 }
 452