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 #if EXT2_FLAT_INCLUDES
  20 #include "ext2_fs.h"
  21 #else
  22 #include <linux/ext2_fs.h>
  23 #endif
  24
  25 #include "ext2fsP.h"
  26
  27 static int test_root(int a, int b)
  28 {
  29         if (a == 0)
  30                 return 1;
  31         while (1) {
  32                 if (a == 1)
  33                         return 1;
  34                 if (a % b)
  35                         return 0;
  36                 a = a / b;
  37         }
  38 }
  39
  40 int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
  41 {
  42 #ifdef EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER
  43         struct ext2fs_sb        *s;
  44
  45         s = (struct ext2fs_sb *) fs->super;
  46         if (!(s->s_feature_ro_compat & EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
  47                 return 1;
  48
  49         if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
  50             test_root(group_block, 7))
  51                 return 1;
  52
  53         return 0;
  54 #else
  55         return 1;
  56 #endif
  57 }
  58
  59 /*
  60  * This function forces out the primary superblock.  We need to only
  61  * write out those fields which we have changed, since if the
  62  * filesystem is mounted, it may have changed some of the other
  63  * fields.
  64  *
  65  * It takes as input a superblock which has already been byte swapped
  66  * (if necessary).
  67  *
  68  */
  69 static errcode_t write_primary_superblock(ext2_filsys fs,
  70                                           struct ext2_super_block *super)
  71 {
  72         __u16           *old_super, *new_super;
  73         int             check_idx, write_idx, size;
  74         errcode_t       retval;
  75
  76         if (!fs->io->manager->write_byte || !fs->orig_super) {
  77                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
  78                 retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
  79                                               super);
  80                 io_channel_set_blksize(fs->io, fs->blocksize);
  81                 return retval;
  82         }
  83
  84         old_super = (__u16 *) fs->orig_super;
  85         new_super = (__u16 *) super;
  86
  87         for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
  88                 if (old_super[check_idx] == new_super[check_idx])
  89                         continue;
  90                 write_idx = check_idx;
  91                 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
  92                         if (old_super[check_idx] == new_super[check_idx])
  93                                 break;
  94                 size = 2 * (check_idx - write_idx);
  95 #if 0
  96                 printf("Writing %d bytes starting at %d\n",
  97                        size, write_idx*2);
  98 #endif
  99                 retval = io_channel_write_byte(fs->io,
 100                                SUPERBLOCK_OFFSET + (2 * write_idx), size,
 101                                                new_super + write_idx);
 102                 if (retval)
 103                         return retval;
 104         }
 105         return 0;
 106 }
 107
 108
 109 /*
 110  * Updates the revision to EXT2_DYNAMIC_REV
 111  */
 112 void ext2fs_update_fs_dynamic_rev(ext2_filsys fs)
 113 {
 114         struct ext2_super_block *sb = fs->super;
 115
 116         if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
 117                 return;
 118
 119         sb->s_rev_level = EXT2_DYNAMIC_REV;
 120         sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 121         sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 122         /* s_uuid is handled by e2fsck already */
 123         /* other fields should be left alone */
 124 }
 125
 126 errcode_t ext2fs_flush(ext2_filsys fs)
 127 {
 128         dgrp_t          i,j,maxgroup,sgrp;
 129         blk_t           group_block;
 130         errcode_t       retval;
 131         char            *group_ptr;
 132         unsigned long   fs_state;
 133         struct ext2_super_block *super_shadow = 0;
 134         struct ext2_group_desc *group_shadow = 0;
 135         struct ext2_group_desc *s, *t;
 136         struct ext2fs_sb *sb, *sb_shadow;
 137
 138         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 139
 140         fs_state = fs->super->s_state;
 141
 142         fs->super->s_wtime = time(NULL);
 143         sb = (struct ext2fs_sb *) fs->super;
 144         sb->s_block_group_nr = 0;
 145         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 146                 retval = EXT2_ET_NO_MEMORY;
 147                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
 148                                         (void **) &super_shadow);
 149                 if (retval)
 150                         goto errout;
 151                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
 152                                                  fs->desc_blocks),
 153                                         (void **) &group_shadow);
 154                 if (retval)
 155                         goto errout;
 156                 memset(group_shadow, 0, (size_t) fs->blocksize *
 157                        fs->desc_blocks);
 158
 159                 /* swap the superblock */
 160                 *super_shadow = *fs->super;
 161                 ext2fs_swap_super(super_shadow);
 162                 sb_shadow = (struct ext2fs_sb *) super_shadow;
 163
 164                 /* swap the group descriptors */
 165                 for (j=0, s=fs->group_desc, t=group_shadow;
 166                      j < fs->group_desc_count; j++, t++, s++) {
 167                         *t = *s;
 168                         ext2fs_swap_group_desc(t);
 169                 }
 170         } else {
 171                 super_shadow = fs->super;
 172                 sb_shadow = (struct ext2fs_sb *) fs->super;
 173                 group_shadow = fs->group_desc;
 174         }
 175
 176         /*
 177          * Write out master superblock.  This has to be done
 178          * separately, since it is located at a fixed location
 179          * (SUPERBLOCK_OFFSET).
 180          */
 181         retval = write_primary_superblock(fs, super_shadow);
 182         if (retval)
 183                 goto errout;
 184
 185         /*
 186          * Set the state of the FS to be non-valid.  (The state has
 187          * already been backed up earlier, and will be restored when
 188          * we exit.)
 189          */
 190         fs->super->s_state &= ~EXT2_VALID_FS;
 191         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 192                 *super_shadow = *fs->super;
 193                 ext2fs_swap_super(super_shadow);
 194         }
 195
 196         /*
 197          * Write out the master group descriptors, and the backup
 198          * superblocks and group descriptors.
 199          */
 200         group_block = fs->super->s_first_data_block;
 201         maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
 202                 fs->group_desc_count;
 203         for (i = 0; i < maxgroup; i++) {
 204                 if (!ext2fs_bg_has_super(fs, i))
 205                         goto next_group;
 206
 207                 sgrp = i;
 208                 if (sgrp > ((1 << 16) - 1))
 209                         sgrp = (1 << 16) - 1;
 210                 if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 211                         sb_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 212                 else
 213                         sb->s_block_group_nr = sgrp;
 214
 215                 if (i !=0 ) {
 216                         retval = io_channel_write_blk(fs->io, group_block,
 217                                                       -SUPERBLOCK_SIZE,
 218                                                       super_shadow);
 219                         if (retval)
 220                                 goto errout;
 221                 }
 222                 group_ptr = (char *) group_shadow;
 223                 for (j=0; j < fs->desc_blocks; j++) {
 224                         retval = io_channel_write_blk(fs->io,
 225                                                       group_block+1+j, 1,
 226                                                       group_ptr);
 227                         if (retval)
 228                                 goto errout;
 229                         group_ptr += fs->blocksize;
 230                 }
 231         next_group:
 232                 group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
 233         }
 234         sb->s_block_group_nr = 0;
 235
 236         /*
 237          * If the write_bitmaps() function is present, call it to
 238          * flush the bitmaps.  This is done this way so that a simple
 239          * program that doesn't mess with the bitmaps doesn't need to
 240          * drag in the bitmaps.c code.
 241          */
 242         if (fs->write_bitmaps) {
 243                 retval = fs->write_bitmaps(fs);
 244                 if (retval)
 245                         goto errout;
 246         }
 247
 248         /*
 249          * Flush the blocks out to disk
 250          */
 251         retval = io_channel_flush(fs->io);
 252 errout:
 253         fs->super->s_state = fs_state;
 254         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 255                 if (super_shadow)
 256                         ext2fs_free_mem((void **) &super_shadow);
 257                 if (group_shadow)
 258                         ext2fs_free_mem((void **) &group_shadow);
 259         }
 260         return retval;
 261 }
 262
 263 errcode_t ext2fs_close(ext2_filsys fs)
 264 {
 265         errcode_t       retval;
 266
 267         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 268
 269         if (fs->flags & EXT2_FLAG_DIRTY) {
 270                 retval = ext2fs_flush(fs);
 271                 if (retval)
 272                         return retval;
 273         }
 274         if (fs->write_bitmaps) {
 275                 retval = fs->write_bitmaps(fs);
 276                 if (retval)
 277                         return retval;
 278         }
 279         ext2fs_free(fs);
 280         return 0;
 281 }
 282