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 forces out the primary superblock.  We need to only
  50  * write out those fields which we have changed, since if the
  51  * filesystem is mounted, it may have changed some of the other
  52  * fields.
  53  *
  54  * It takes as input a superblock which has already been byte swapped
  55  * (if necessary).
  56  *
  57  */
  58 static errcode_t write_primary_superblock(ext2_filsys fs,
  59                                           struct ext2_super_block *super)
  60 {
  61         __u16           *old_super, *new_super;
  62         int             check_idx, write_idx, size;
  63         errcode_t       retval;
  64
  65         if (!fs->io->manager->write_byte || !fs->orig_super) {
  66                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
  67                 retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
  68                                               super);
  69                 io_channel_set_blksize(fs->io, fs->blocksize);
  70                 return retval;
  71         }
  72
  73         old_super = (__u16 *) fs->orig_super;
  74         new_super = (__u16 *) super;
  75
  76         for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
  77                 if (old_super[check_idx] == new_super[check_idx])
  78                         continue;
  79                 write_idx = check_idx;
  80                 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
  81                         if (old_super[check_idx] == new_super[check_idx])
  82                                 break;
  83                 size = 2 * (check_idx - write_idx);
  84 #if 0
  85                 printf("Writing %d bytes starting at %d\n",
  86                        size, write_idx*2);
  87 #endif
  88                 retval = io_channel_write_byte(fs->io,
  89                                SUPERBLOCK_OFFSET + (2 * write_idx), size,
  90                                                new_super + write_idx);
  91                 if (retval)
  92                         return retval;
  93         }
  94         memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
  95         return 0;
  96 }
  97
  98
  99 /*
 100  * Updates the revision to EXT2_DYNAMIC_REV
 101  */
 102 void ext2fs_update_dynamic_rev(ext2_filsys fs)
 103 {
 104         struct ext2_super_block *sb = fs->super;
 105
 106         if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
 107                 return;
 108
 109         sb->s_rev_level = EXT2_DYNAMIC_REV;
 110         sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 111         sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 112         /* s_uuid is handled by e2fsck already */
 113         /* other fields should be left alone */
 114 }
 115
 116 /*
 117  * This writes out the block group descriptors the original,
 118  * old-fashioned way.
 119  */
 120 static errcode_t write_bgdesc(ext2_filsys fs, dgrp_t group, blk_t group_block,
 121                               struct ext2_group_desc *group_shadow)
 122 {
 123         errcode_t       retval;
 124         char            *group_ptr = (char *) group_shadow;
 125         int             j, old_desc_blocks;
 126         int             has_super = ext2fs_bg_has_super(fs, group);
 127         dgrp_t          meta_bg_size, meta_bg;
 128
 129         meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
 130         meta_bg = group / meta_bg_size;
 131         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 132                 old_desc_blocks = fs->super->s_first_meta_bg;
 133         else
 134                 old_desc_blocks = fs->desc_blocks;
 135         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
 136             (meta_bg < fs->super->s_first_meta_bg)) {
 137                 if (!has_super)
 138                         return 0;
 139                 for (j=0; j < old_desc_blocks; j++) {
 140                         retval = io_channel_write_blk(fs->io,
 141                                                       group_block+1+j, 1,
 142                                                       group_ptr);
 143                         if (retval)
 144                                 return retval;
 145                         group_ptr += fs->blocksize;
 146                 }
 147         } else {
 148                 if (has_super)
 149                         group_block++;
 150                 if (((group % meta_bg_size) == 0) ||
 151                     ((group % meta_bg_size) == 1) ||
 152                     ((group % meta_bg_size) == (meta_bg_size-1))) {
 153                         return io_channel_write_blk(fs->io, group_block,
 154                                 1, group_ptr + (meta_bg*fs->blocksize));
 155                 }
 156         }
 157         return 0;
 158 }
 159
 160
 161 static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
 162                                     blk_t group_block,
 163                                     struct ext2_super_block *super_shadow)
 164 {
 165         dgrp_t  sgrp = group;
 166
 167         if (sgrp > ((1 << 16) - 1))
 168                 sgrp = (1 << 16) - 1;
 169 #ifdef EXT2FS_ENABLE_SWAPFS
 170         if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 171                 super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 172         else
 173 #endif
 174                 fs->super->s_block_group_nr = sgrp;
 175
 176         return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
 177                                     super_shadow);
 178 }
 179
 180
 181 errcode_t ext2fs_flush(ext2_filsys fs)
 182 {
 183         dgrp_t          i,j,maxgroup;
 184         blk_t           group_block;
 185         errcode_t       retval;
 186         unsigned long   fs_state;
 187         struct ext2_super_block *super_shadow = 0;
 188         struct ext2_group_desc *group_shadow = 0;
 189         struct ext2_group_desc *s, *t;
 190
 191         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 192
 193         fs_state = fs->super->s_state;
 194
 195         fs->super->s_wtime = time(NULL);
 196         fs->super->s_block_group_nr = 0;
 197 #ifdef EXT2FS_ENABLE_SWAPFS
 198         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 199                 retval = EXT2_ET_NO_MEMORY;
 200                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
 201                                         (void **) &super_shadow);
 202                 if (retval)
 203                         goto errout;
 204                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
 205                                                  fs->desc_blocks),
 206                                         (void **) &group_shadow);
 207                 if (retval)
 208                         goto errout;
 209                 memset(group_shadow, 0, (size_t) fs->blocksize *
 210                        fs->desc_blocks);
 211
 212                 /* swap the superblock */
 213                 *super_shadow = *fs->super;
 214                 ext2fs_swap_super(super_shadow);
 215
 216                 /* swap the group descriptors */
 217                 for (j=0, s=fs->group_desc, t=group_shadow;
 218                      j < fs->group_desc_count; j++, t++, s++) {
 219                         *t = *s;
 220                         ext2fs_swap_group_desc(t);
 221                 }
 222         } else {
 223                 super_shadow = fs->super;
 224                 group_shadow = fs->group_desc;
 225         }
 226 #else
 227         super_shadow = fs->super;
 228         group_shadow = fs->group_desc;
 229 #endif
 230
 231         /*
 232          * Write out master superblock.  This has to be done
 233          * separately, since it is located at a fixed location
 234          * (SUPERBLOCK_OFFSET).
 235          */
 236         retval = write_primary_superblock(fs, super_shadow);
 237         if (retval)
 238                 goto errout;
 239
 240         /*
 241          * If this is an external journal device, don't write out the
 242          * block group descriptors or any of the backup superblocks
 243          */
 244         if (fs->super->s_feature_incompat &
 245             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 246                 retval = 0;
 247                 goto errout;
 248         }
 249
 250         /*
 251          * Set the state of the FS to be non-valid.  (The state has
 252          * already been backed up earlier, and will be restored when
 253          * we exit.)
 254          */
 255         fs->super->s_state &= ~EXT2_VALID_FS;
 256 #ifdef EXT2FS_ENABLE_SWAPFS
 257         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 258                 *super_shadow = *fs->super;
 259                 ext2fs_swap_super(super_shadow);
 260         }
 261 #endif
 262
 263         /*
 264          * Write out the master group descriptors, and the backup
 265          * superblocks and group descriptors.
 266          */
 267         group_block = fs->super->s_first_data_block;
 268         maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
 269                 fs->group_desc_count;
 270         for (i = 0; i < maxgroup; i++) {
 271                 if (i && ext2fs_bg_has_super(fs, i)) {
 272                         retval = write_backup_super(fs, i, group_block,
 273                                                     super_shadow);
 274                         if (retval)
 275                                 goto errout;
 276                 }
 277                 if (!(fs->flags & EXT2_FLAG_SUPER_ONLY)) {
 278                         if ((retval = write_bgdesc(fs, i, group_block,
 279                                                    group_shadow)))
 280                                 goto errout;
 281                 }
 282                 group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
 283         }
 284         fs->super->s_block_group_nr = 0;
 285
 286         /*
 287          * If the write_bitmaps() function is present, call it to
 288          * flush the bitmaps.  This is done this way so that a simple
 289          * program that doesn't mess with the bitmaps doesn't need to
 290          * drag in the bitmaps.c code.
 291          */
 292         if (fs->write_bitmaps) {
 293                 retval = fs->write_bitmaps(fs);
 294                 if (retval)
 295                         goto errout;
 296         }
 297
 298         fs->flags &= ~EXT2_FLAG_DIRTY;
 299
 300         /*
 301          * Flush the blocks out to disk
 302          */
 303         retval = io_channel_flush(fs->io);
 304 errout:
 305         fs->super->s_state = fs_state;
 306         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 307                 if (super_shadow)
 308                         ext2fs_free_mem((void **) &super_shadow);
 309                 if (group_shadow)
 310                         ext2fs_free_mem((void **) &group_shadow);
 311         }
 312         return retval;
 313 }
 314
 315 errcode_t ext2fs_close(ext2_filsys fs)
 316 {
 317         errcode_t       retval;
 318
 319         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 320
 321         if (fs->flags & EXT2_FLAG_DIRTY) {
 322                 retval = ext2fs_flush(fs);
 323                 if (retval)
 324                         return retval;
 325         }
 326         if (fs->write_bitmaps) {
 327                 retval = fs->write_bitmaps(fs);
 328                 if (retval)
 329                         return retval;
 330         }
 331         ext2fs_free(fs);
 332         return 0;
 333 }
 334