release/src/router/busybox/e2fsprogs/ext2fs/closefs.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * closefs.c --- close an ext2 filesystem
   4  *
   5  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdio.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #include <time.h>
  18 #include <string.h>
  19
  20 #include "ext2_fs.h"
  21 #include "ext2fsP.h"
  22
  23 static int test_root(int a, int b)
  24 {
  25         if (a == 0)
  26                 return 1;
  27         while (1) {
  28                 if (a == 1)
  29                         return 1;
  30                 if (a % b)
  31                         return 0;
  32                 a = a / b;
  33         }
  34 }
  35
  36 int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
  37 {
  38         if (!(fs->super->s_feature_ro_compat &
  39               EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
  40                 return 1;
  41
  42         if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
  43             test_root(group_block, 7))
  44                 return 1;
  45
  46         return 0;
  47 }
  48
  49 int ext2fs_super_and_bgd_loc(ext2_filsys fs,
  50                              dgrp_t group,
  51                              blk_t *ret_super_blk,
  52                              blk_t *ret_old_desc_blk,
  53                              blk_t *ret_new_desc_blk,
  54                              int *ret_meta_bg)
  55 {
  56         blk_t   group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
  57         unsigned int meta_bg, meta_bg_size;
  58         int     numblocks, has_super;
  59         int     old_desc_blocks;
  60
  61         group_block = fs->super->s_first_data_block +
  62                 (group * fs->super->s_blocks_per_group);
  63
  64         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
  65                 old_desc_blocks = fs->super->s_first_meta_bg;
  66         else
  67                 old_desc_blocks =
  68                         fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
  69
  70         if (group == fs->group_desc_count-1) {
  71                 numblocks = (fs->super->s_blocks_count -
  72                              fs->super->s_first_data_block) %
  73                         fs->super->s_blocks_per_group;
  74                 if (!numblocks)
  75                         numblocks = fs->super->s_blocks_per_group;
  76         } else
  77                 numblocks = fs->super->s_blocks_per_group;
  78
  79         has_super = ext2fs_bg_has_super(fs, group);
  80
  81         if (has_super) {
  82                 super_blk = group_block;
  83                 numblocks--;
  84         }
  85         meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
  86         meta_bg = group / meta_bg_size;
  87
  88         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  89             (meta_bg < fs->super->s_first_meta_bg)) {
  90                 if (has_super) {
  91                         old_desc_blk = group_block + 1;
  92                         numblocks -= old_desc_blocks;
  93                 }
  94         } else {
  95                 if (((group % meta_bg_size) == 0) ||
  96                     ((group % meta_bg_size) == 1) ||
  97                     ((group % meta_bg_size) == (meta_bg_size-1))) {
  98                         if (has_super)
  99                                 has_super = 1;
 100                         new_desc_blk = group_block + has_super;
 101                         numblocks--;
 102                 }
 103         }
 104
 105         numblocks -= 2 + fs->inode_blocks_per_group;
 106
 107         if (ret_super_blk)
 108                 *ret_super_blk = super_blk;
 109         if (ret_old_desc_blk)
 110                 *ret_old_desc_blk = old_desc_blk;
 111         if (ret_new_desc_blk)
 112                 *ret_new_desc_blk = new_desc_blk;
 113         if (ret_meta_bg)
 114                 *ret_meta_bg = meta_bg;
 115         return numblocks;
 116 }
 117
 118
 119 /*
 120  * This function forces out the primary superblock.  We need to only
 121  * write out those fields which we have changed, since if the
 122  * filesystem is mounted, it may have changed some of the other
 123  * fields.
 124  *
 125  * It takes as input a superblock which has already been byte swapped
 126  * (if necessary).
 127  *
 128  */
 129 static errcode_t write_primary_superblock(ext2_filsys fs,
 130                                           struct ext2_super_block *super)
 131 {
 132         __u16           *old_super, *new_super;
 133         int             check_idx, write_idx, size;
 134         errcode_t       retval;
 135
 136         if (!fs->io->manager->write_byte || !fs->orig_super) {
 137                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 138                 retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
 139                                               super);
 140                 io_channel_set_blksize(fs->io, fs->blocksize);
 141                 return retval;
 142         }
 143
 144         old_super = (__u16 *) fs->orig_super;
 145         new_super = (__u16 *) super;
 146
 147         for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
 148                 if (old_super[check_idx] == new_super[check_idx])
 149                         continue;
 150                 write_idx = check_idx;
 151                 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
 152                         if (old_super[check_idx] == new_super[check_idx])
 153                                 break;
 154                 size = 2 * (check_idx - write_idx);
 155                 retval = io_channel_write_byte(fs->io,
 156                                SUPERBLOCK_OFFSET + (2 * write_idx), size,
 157                                                new_super + write_idx);
 158                 if (retval)
 159                         return retval;
 160         }
 161         memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
 162         return 0;
 163 }
 164
 165
 166 /*
 167  * Updates the revision to EXT2_DYNAMIC_REV
 168  */
 169 void ext2fs_update_dynamic_rev(ext2_filsys fs)
 170 {
 171         struct ext2_super_block *sb = fs->super;
 172
 173         if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
 174                 return;
 175
 176         sb->s_rev_level = EXT2_DYNAMIC_REV;
 177         sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 178         sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 179         /* s_uuid is handled by e2fsck already */
 180         /* other fields should be left alone */
 181 }
 182
 183 static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
 184                                     blk_t group_block,
 185                                     struct ext2_super_block *super_shadow)
 186 {
 187         dgrp_t  sgrp = group;
 188
 189         if (sgrp > ((1 << 16) - 1))
 190                 sgrp = (1 << 16) - 1;
 191 #if BB_BIG_ENDIAN
 192         if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 193                 super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 194         else
 195 #endif
 196                 fs->super->s_block_group_nr = sgrp;
 197
 198         return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
 199                                     super_shadow);
 200 }
 201
 202
 203 errcode_t ext2fs_flush(ext2_filsys fs)
 204 {
 205         dgrp_t          i;
 206         blk_t           group_block;
 207         errcode_t       retval;
 208         unsigned long   fs_state;
 209         struct ext2_super_block *super_shadow = NULL;
 210         struct ext2_group_desc *group_shadow = NULL;
 211         char    *group_ptr;
 212         int     old_desc_blocks;
 213 #if BB_BIG_ENDIAN
 214         dgrp_t          j;
 215         struct ext2_group_desc *s, *t;
 216 #endif
 217
 218         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 219
 220         fs_state = fs->super->s_state;
 221
 222         fs->super->s_wtime = time(NULL);
 223         fs->super->s_block_group_nr = 0;
 224 #if BB_BIG_ENDIAN
 225         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 226                 retval = EXT2_ET_NO_MEMORY;
 227                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
 228                 if (retval)
 229                         goto errout;
 230                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
 231                                                  fs->desc_blocks),
 232                                         &group_shadow);
 233                 if (retval)
 234                         goto errout;
 235                 memset(group_shadow, 0, (size_t) fs->blocksize *
 236                        fs->desc_blocks);
 237
 238                 /* swap the group descriptors */
 239                 for (j=0, s=fs->group_desc, t=group_shadow;
 240                      j < fs->group_desc_count; j++, t++, s++) {
 241                         *t = *s;
 242                         ext2fs_swap_group_desc(t);
 243                 }
 244         } else {
 245                 super_shadow = fs->super;
 246                 group_shadow = fs->group_desc;
 247         }
 248 #else
 249         super_shadow = fs->super;
 250         group_shadow = fs->group_desc;
 251 #endif
 252
 253         /*
 254          * If this is an external journal device, don't write out the
 255          * block group descriptors or any of the backup superblocks
 256          */
 257         if (fs->super->s_feature_incompat &
 258             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
 259                 goto write_primary_superblock_only;
 260
 261         /*
 262          * Set the state of the FS to be non-valid.  (The state has
 263          * already been backed up earlier, and will be restored after
 264          * we write out the backup superblocks.)
 265          */
 266         fs->super->s_state &= ~EXT2_VALID_FS;
 267 #if BB_BIG_ENDIAN
 268         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 269                 *super_shadow = *fs->super;
 270                 ext2fs_swap_super(super_shadow);
 271         }
 272 #endif
 273
 274         /*
 275          * Write out the master group descriptors, and the backup
 276          * superblocks and group descriptors.
 277          */
 278         group_block = fs->super->s_first_data_block;
 279         group_ptr = (char *) group_shadow;
 280         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 281                 old_desc_blocks = fs->super->s_first_meta_bg;
 282         else
 283                 old_desc_blocks = fs->desc_blocks;
 284
 285         for (i = 0; i < fs->group_desc_count; i++) {
 286                 blk_t   super_blk, old_desc_blk, new_desc_blk;
 287                 int     meta_bg;
 288
 289                 ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
 290                                          &new_desc_blk, &meta_bg);
 291
 292                 if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
 293                         retval = write_backup_super(fs, i, super_blk,
 294                                                     super_shadow);
 295                         if (retval)
 296                                 goto errout;
 297                 }
 298                 if (fs->flags & EXT2_FLAG_SUPER_ONLY)
 299                         continue;
 300                 if ((old_desc_blk) &&
 301                     (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
 302                         retval = io_channel_write_blk(fs->io,
 303                               old_desc_blk, old_desc_blocks, group_ptr);
 304                         if (retval)
 305                                 goto errout;
 306                 }
 307                 if (new_desc_blk) {
 308                         retval = io_channel_write_blk(fs->io, new_desc_blk,
 309                                 1, group_ptr + (meta_bg*fs->blocksize));
 310                         if (retval)
 311                                 goto errout;
 312                 }
 313         }
 314         fs->super->s_block_group_nr = 0;
 315         fs->super->s_state = fs_state;
 316 #if BB_BIG_ENDIAN
 317         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 318                 *super_shadow = *fs->super;
 319                 ext2fs_swap_super(super_shadow);
 320         }
 321 #endif
 322
 323         /*
 324          * If the write_bitmaps() function is present, call it to
 325          * flush the bitmaps.  This is done this way so that a simple
 326          * program that doesn't mess with the bitmaps doesn't need to
 327          * drag in the bitmaps.c code.
 328          */
 329         if (fs->write_bitmaps) {
 330                 retval = fs->write_bitmaps(fs);
 331                 if (retval)
 332                         goto errout;
 333         }
 334
 335 write_primary_superblock_only:
 336         /*
 337          * Write out master superblock.  This has to be done
 338          * separately, since it is located at a fixed location
 339          * (SUPERBLOCK_OFFSET).  We flush all other pending changes
 340          * out to disk first, just to avoid a race condition with an
 341          * insy-tinsy window....
 342          */
 343         retval = io_channel_flush(fs->io);
 344         retval = write_primary_superblock(fs, super_shadow);
 345         if (retval)
 346                 goto errout;
 347
 348         fs->flags &= ~EXT2_FLAG_DIRTY;
 349
 350         retval = io_channel_flush(fs->io);
 351 errout:
 352         fs->super->s_state = fs_state;
 353         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 354                 if (super_shadow)
 355                         ext2fs_free_mem(&super_shadow);
 356                 if (group_shadow)
 357                         ext2fs_free_mem(&group_shadow);
 358         }
 359         return retval;
 360 }
 361
 362 errcode_t ext2fs_close(ext2_filsys fs)
 363 {
 364         errcode_t       retval;
 365
 366         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 367
 368         if (fs->flags & EXT2_FLAG_DIRTY) {
 369                 retval = ext2fs_flush(fs);
 370                 if (retval)
 371                         return retval;
 372         }
 373         if (fs->write_bitmaps) {
 374                 retval = fs->write_bitmaps(fs);
 375                 if (retval)
 376                         return retval;
 377         }
 378         ext2fs_free(fs);
 379         return 0;
 380 }