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 int ext2fs_super_and_bgd_loc(ext2_filsys fs,
  49                              dgrp_t group,
  50                              blk_t *ret_super_blk,
  51                              blk_t *ret_old_desc_blk,
  52                              blk_t *ret_new_desc_blk,
  53                              int *ret_meta_bg)
  54 {
  55         blk_t   group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
  56         unsigned int meta_bg, meta_bg_size;
  57         int     numblocks, has_super;
  58         int     old_desc_blocks;
  59
  60         group_block = fs->super->s_first_data_block +
  61                 (group * fs->super->s_blocks_per_group);
  62
  63         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
  64                 old_desc_blocks = fs->super->s_first_meta_bg;
  65         else
  66                 old_desc_blocks =
  67                         fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
  68
  69         if (group == fs->group_desc_count-1) {
  70                 numblocks = (fs->super->s_blocks_count -
  71                              fs->super->s_first_data_block) %
  72                         fs->super->s_blocks_per_group;
  73                 if (!numblocks)
  74                         numblocks = fs->super->s_blocks_per_group;
  75         } else
  76                 numblocks = fs->super->s_blocks_per_group;
  77
  78         has_super = ext2fs_bg_has_super(fs, group);
  79
  80         if (has_super) {
  81                 super_blk = group_block;
  82                 numblocks--;
  83         }
  84         meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
  85         meta_bg = group / meta_bg_size;
  86
  87         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  88             (meta_bg < fs->super->s_first_meta_bg)) {
  89                 if (has_super) {
  90                         old_desc_blk = group_block + 1;
  91                         numblocks -= old_desc_blocks;
  92                 }
  93         } else {
  94                 if (((group % meta_bg_size) == 0) ||
  95                     ((group % meta_bg_size) == 1) ||
  96                     ((group % meta_bg_size) == (meta_bg_size-1))) {
  97                         if (has_super)
  98                                 has_super = 1;
  99                         new_desc_blk = group_block + has_super;
 100                         numblocks--;
 101                 }
 102         }
 103
 104         numblocks -= 2 + fs->inode_blocks_per_group;
 105
 106         if (ret_super_blk)
 107                 *ret_super_blk = super_blk;
 108         if (ret_old_desc_blk)
 109                 *ret_old_desc_blk = old_desc_blk;
 110         if (ret_new_desc_blk)
 111                 *ret_new_desc_blk = new_desc_blk;
 112         if (ret_meta_bg)
 113                 *ret_meta_bg = meta_bg;
 114         return (numblocks);
 115 }
 116
 117
 118 /*
 119  * This function forces out the primary superblock.  We need to only
 120  * write out those fields which we have changed, since if the
 121  * filesystem is mounted, it may have changed some of the other
 122  * fields.
 123  *
 124  * It takes as input a superblock which has already been byte swapped
 125  * (if necessary).
 126  *
 127  */
 128 static errcode_t write_primary_superblock(ext2_filsys fs,
 129                                           struct ext2_super_block *super)
 130 {
 131         __u16           *old_super, *new_super;
 132         int             check_idx, write_idx, size;
 133         errcode_t       retval;
 134
 135         if (!fs->io->manager->write_byte || !fs->orig_super) {
 136                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 137                 retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
 138                                               super);
 139                 io_channel_set_blksize(fs->io, fs->blocksize);
 140                 return retval;
 141         }
 142
 143         old_super = (__u16 *) fs->orig_super;
 144         new_super = (__u16 *) super;
 145
 146         for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
 147                 if (old_super[check_idx] == new_super[check_idx])
 148                         continue;
 149                 write_idx = check_idx;
 150                 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
 151                         if (old_super[check_idx] == new_super[check_idx])
 152                                 break;
 153                 size = 2 * (check_idx - write_idx);
 154 #if 0
 155                 printf("Writing %d bytes starting at %d\n",
 156                        size, write_idx*2);
 157 #endif
 158                 retval = io_channel_write_byte(fs->io,
 159                                SUPERBLOCK_OFFSET + (2 * write_idx), size,
 160                                                new_super + write_idx);
 161                 if (retval)
 162                         return retval;
 163         }
 164         memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
 165         return 0;
 166 }
 167
 168
 169 /*
 170  * Updates the revision to EXT2_DYNAMIC_REV
 171  */
 172 void ext2fs_update_dynamic_rev(ext2_filsys fs)
 173 {
 174         struct ext2_super_block *sb = fs->super;
 175
 176         if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
 177                 return;
 178
 179         sb->s_rev_level = EXT2_DYNAMIC_REV;
 180         sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 181         sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 182         /* s_uuid is handled by e2fsck already */
 183         /* other fields should be left alone */
 184 }
 185
 186 static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
 187                                     blk_t group_block,
 188                                     struct ext2_super_block *super_shadow)
 189 {
 190         dgrp_t  sgrp = group;
 191
 192         if (sgrp > ((1 << 16) - 1))
 193                 sgrp = (1 << 16) - 1;
 194 #ifdef EXT2FS_ENABLE_SWAPFS
 195         if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 196                 super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 197         else
 198 #endif
 199                 fs->super->s_block_group_nr = sgrp;
 200
 201         return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
 202                                     super_shadow);
 203 }
 204
 205
 206 errcode_t ext2fs_flush(ext2_filsys fs)
 207 {
 208         dgrp_t          i,j;
 209         errcode_t       retval;
 210         unsigned long   fs_state;
 211         struct ext2_super_block *super_shadow = 0;
 212         struct ext2_group_desc *group_shadow = 0;
 213         struct ext2_group_desc *s, *t;
 214         char    *group_ptr;
 215         int     old_desc_blocks;
 216
 217         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 218
 219         fs_state = fs->super->s_state;
 220
 221         fs->super->s_wtime = fs->now ? fs->now : time(NULL);
 222         fs->super->s_block_group_nr = 0;
 223 #ifdef EXT2FS_ENABLE_SWAPFS
 224         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 225                 retval = EXT2_ET_NO_MEMORY;
 226                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
 227                 if (retval)
 228                         goto errout;
 229                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
 230                                                  fs->desc_blocks),
 231                                         &group_shadow);
 232                 if (retval)
 233                         goto errout;
 234                 memset(group_shadow, 0, (size_t) fs->blocksize *
 235                        fs->desc_blocks);
 236
 237                 /* swap the group descriptors */
 238                 for (j=0, s=fs->group_desc, t=group_shadow;
 239                      j < fs->group_desc_count; j++, t++, s++) {
 240                         *t = *s;
 241                         ext2fs_swap_group_desc(t);
 242                 }
 243         } else {
 244                 super_shadow = fs->super;
 245                 group_shadow = fs->group_desc;
 246         }
 247 #else
 248         super_shadow = fs->super;
 249         group_shadow = fs->group_desc;
 250 #endif
 251
 252         /*
 253          * Set the state of the FS to be non-valid.  (The state has
 254          * already been backed up earlier, and will be restored after
 255          * we write out the backup superblocks.)
 256          */
 257         fs->super->s_state &= ~EXT2_VALID_FS;
 258 #ifdef EXT2FS_ENABLE_SWAPFS
 259         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 260                 *super_shadow = *fs->super;
 261                 ext2fs_swap_super(super_shadow);
 262         }
 263 #endif
 264
 265         /*
 266          * If this is an external journal device, don't write out the
 267          * block group descriptors or any of the backup superblocks
 268          */
 269         if (fs->super->s_feature_incompat &
 270             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
 271                 goto write_primary_superblock_only;
 272
 273         /*
 274          * Write out the master group descriptors, and the backup
 275          * superblocks and group descriptors.
 276          */
 277         group_ptr = (char *) group_shadow;
 278         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 279                 old_desc_blocks = fs->super->s_first_meta_bg;
 280         else
 281                 old_desc_blocks = fs->desc_blocks;
 282
 283         for (i = 0; i < fs->group_desc_count; i++) {
 284                 blk_t   super_blk, old_desc_blk, new_desc_blk;
 285                 int     meta_bg;
 286
 287                 ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
 288                                          &new_desc_blk, &meta_bg);
 289
 290                 if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
 291                         retval = write_backup_super(fs, i, super_blk,
 292                                                     super_shadow);
 293                         if (retval)
 294                                 goto errout;
 295                 }
 296                 if (fs->flags & EXT2_FLAG_SUPER_ONLY)
 297                         continue;
 298                 if ((old_desc_blk) &&
 299                     (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
 300                         retval = io_channel_write_blk(fs->io,
 301                               old_desc_blk, old_desc_blocks, group_ptr);
 302                         if (retval)
 303                                 goto errout;
 304                 }
 305                 if (new_desc_blk) {
 306                         retval = io_channel_write_blk(fs->io, new_desc_blk,
 307                                 1, group_ptr + (meta_bg*fs->blocksize));
 308                         if (retval)
 309                                 goto errout;
 310                 }
 311         }
 312
 313         /*
 314          * If the write_bitmaps() function is present, call it to
 315          * flush the bitmaps.  This is done this way so that a simple
 316          * program that doesn't mess with the bitmaps doesn't need to
 317          * drag in the bitmaps.c code.
 318          */
 319         if (fs->write_bitmaps) {
 320                 retval = fs->write_bitmaps(fs);
 321                 if (retval)
 322                         goto errout;
 323         }
 324
 325 write_primary_superblock_only:
 326         /*
 327          * Write out master superblock.  This has to be done
 328          * separately, since it is located at a fixed location
 329          * (SUPERBLOCK_OFFSET).  We flush all other pending changes
 330          * out to disk first, just to avoid a race condition with an
 331          * insy-tinsy window....
 332          */
 333
 334         fs->super->s_block_group_nr = 0;
 335         fs->super->s_state = fs_state;
 336 #ifdef EXT2FS_ENABLE_SWAPFS
 337         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 338                 *super_shadow = *fs->super;
 339                 ext2fs_swap_super(super_shadow);
 340         }
 341 #endif
 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 }
 381