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;
 126         int             has_super = ext2fs_bg_has_super(fs, group);
 127         dgrp_t          meta_bg_size, meta_bg;
 128         blk_t           blk;
 129
 130         meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
 131         meta_bg = group / meta_bg_size;
 132         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
 133             (meta_bg < fs->super->s_first_meta_bg)) {
 134                 if (!has_super)
 135                         return 0;
 136                 for (j=0; j < fs->desc_blocks; j++) {
 137                         retval = io_channel_write_blk(fs->io,
 138                                                       group_block+1+j, 1,
 139                                                       group_ptr);
 140                         if (retval)
 141                                 return retval;
 142                         group_ptr += fs->blocksize;
 143                 }
 144         } else {
 145                 if (has_super)
 146                         group_block++;
 147                 if (((group % meta_bg_size) == 0) ||
 148                     ((group % meta_bg_size) == 1) ||
 149                     ((group % meta_bg_size) == (meta_bg_size-1))) {
 150                         return io_channel_write_blk(fs->io, group_block,
 151                                 1, group_ptr + (meta_bg*fs->blocksize));
 152                 }
 153         }
 154         return 0;
 155 }
 156
 157
 158 static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
 159                                     blk_t group_block,
 160                                     struct ext2_super_block *super_shadow)
 161 {
 162         dgrp_t  sgrp = group;
 163
 164         if (sgrp > ((1 << 16) - 1))
 165                 sgrp = (1 << 16) - 1;
 166 #ifdef EXT2FS_ENABLE_SWAPFS
 167         if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 168                 super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 169         else
 170 #endif
 171                 fs->super->s_block_group_nr = sgrp;
 172
 173         return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
 174                                     super_shadow);
 175 }
 176
 177
 178 errcode_t ext2fs_flush(ext2_filsys fs)
 179 {
 180         dgrp_t          i,j,maxgroup;
 181         blk_t           group_block;
 182         errcode_t       retval;
 183         char            *group_ptr;
 184         unsigned long   fs_state;
 185         struct ext2_super_block *super_shadow = 0;
 186         struct ext2_group_desc *group_shadow = 0;
 187         struct ext2_group_desc *s, *t;
 188
 189         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 190
 191         fs_state = fs->super->s_state;
 192
 193         fs->super->s_wtime = time(NULL);
 194         fs->super->s_block_group_nr = 0;
 195 #ifdef EXT2FS_ENABLE_SWAPFS
 196         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 197                 retval = EXT2_ET_NO_MEMORY;
 198                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
 199                                         (void **) &super_shadow);
 200                 if (retval)
 201                         goto errout;
 202                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
 203                                                  fs->desc_blocks),
 204                                         (void **) &group_shadow);
 205                 if (retval)
 206                         goto errout;
 207                 memset(group_shadow, 0, (size_t) fs->blocksize *
 208                        fs->desc_blocks);
 209
 210                 /* swap the superblock */
 211                 *super_shadow = *fs->super;
 212                 ext2fs_swap_super(super_shadow);
 213
 214                 /* swap the group descriptors */
 215                 for (j=0, s=fs->group_desc, t=group_shadow;
 216                      j < fs->group_desc_count; j++, t++, s++) {
 217                         *t = *s;
 218                         ext2fs_swap_group_desc(t);
 219                 }
 220         } else {
 221                 super_shadow = fs->super;
 222                 group_shadow = fs->group_desc;
 223         }
 224 #else
 225         super_shadow = fs->super;
 226         group_shadow = fs->group_desc;
 227 #endif
 228
 229         /*
 230          * Write out master superblock.  This has to be done
 231          * separately, since it is located at a fixed location
 232          * (SUPERBLOCK_OFFSET).
 233          */
 234         retval = write_primary_superblock(fs, super_shadow);
 235         if (retval)
 236                 goto errout;
 237
 238         /*
 239          * If this is an external journal device, don't write out the
 240          * block group descriptors or any of the backup superblocks
 241          */
 242         if (fs->super->s_feature_incompat &
 243             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 244                 retval = 0;
 245                 goto errout;
 246         }
 247
 248         /*
 249          * Set the state of the FS to be non-valid.  (The state has
 250          * already been backed up earlier, and will be restored when
 251          * we exit.)
 252          */
 253         fs->super->s_state &= ~EXT2_VALID_FS;
 254 #ifdef EXT2FS_ENABLE_SWAPFS
 255         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 256                 *super_shadow = *fs->super;
 257                 ext2fs_swap_super(super_shadow);
 258         }
 259 #endif
 260
 261         /*
 262          * Write out the master group descriptors, and the backup
 263          * superblocks and group descriptors.
 264          */
 265         group_block = fs->super->s_first_data_block;
 266         maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
 267                 fs->group_desc_count;
 268         for (i = 0; i < maxgroup; i++) {
 269                 if (i && ext2fs_bg_has_super(fs, i)) {
 270                         retval = write_backup_super(fs, i, group_block,
 271                                                     super_shadow);
 272                         if (retval)
 273                                 goto errout;
 274                 }
 275                 if (!(fs->flags & EXT2_FLAG_SUPER_ONLY)) {
 276                         if ((retval = write_bgdesc(fs, i, group_block,
 277                                                    group_shadow)))
 278                                 goto errout;
 279                 }
 280         next_group:
 281                 group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
 282         }
 283         fs->super->s_block_group_nr = 0;
 284
 285         /*
 286          * If the write_bitmaps() function is present, call it to
 287          * flush the bitmaps.  This is done this way so that a simple
 288          * program that doesn't mess with the bitmaps doesn't need to
 289          * drag in the bitmaps.c code.
 290          */
 291         if (fs->write_bitmaps) {
 292                 retval = fs->write_bitmaps(fs);
 293                 if (retval)
 294                         goto errout;
 295         }
 296
 297         fs->flags &= ~EXT2_FLAG_DIRTY;
 298
 299         /*
 300          * Flush the blocks out to disk
 301          */
 302         retval = io_channel_flush(fs->io);
 303 errout:
 304         fs->super->s_state = fs_state;
 305         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 306                 if (super_shadow)
 307                         ext2fs_free_mem((void **) &super_shadow);
 308                 if (group_shadow)
 309                         ext2fs_free_mem((void **) &group_shadow);
 310         }
 311         return retval;
 312 }
 313
 314 errcode_t ext2fs_close(ext2_filsys fs)
 315 {
 316         errcode_t       retval;
 317
 318         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 319
 320         if (fs->flags & EXT2_FLAG_DIRTY) {
 321                 retval = ext2fs_flush(fs);
 322                 if (retval)
 323                         return retval;
 324         }
 325         if (fs->write_bitmaps) {
 326                 retval = fs->write_bitmaps(fs);
 327                 if (retval)
 328                         return retval;
 329         }
 330         ext2fs_free(fs);
 331         return 0;
 332 }
 333