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  * 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  */
  61 int 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  */
 140 static 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  */
 184 void 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
 198 static 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
 217 errcode_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
 334 write_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);
 359 errout:
 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
 370 errcode_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