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 <stdlib.h>
  17 #include <time.h>
  18 #include <string.h>
  19
  20 #include <linux/ext2_fs.h>
  21
  22 #include "ext2fsP.h"
  23
  24 static int test_root(int a, int b)
  25 {
  26         if (a == 0)
  27                 return 1;
  28         while (1) {
  29                 if (a == 1)
  30                         return 1;
  31                 if (a % b)
  32                         return 0;
  33                 a = a / b;
  34         }
  35 }
  36
  37 int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
  38 {
  39 #ifdef EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER
  40         struct ext2fs_sb        *s;
  41
  42         s = (struct ext2fs_sb *) fs->super;
  43         if (!(s->s_feature_ro_compat & EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
  44                 return 1;
  45
  46         if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
  47             test_root(group_block, 7))
  48                 return 1;
  49
  50         return 0;
  51 #else
  52         return 1;
  53 #endif
  54 }
  55
  56 errcode_t ext2fs_flush(ext2_filsys fs)
  57 {
  58         dgrp_t          i,j,maxgroup;
  59         blk_t           group_block;
  60         errcode_t       retval;
  61         char            *group_ptr;
  62         unsigned long   fs_state;
  63         struct ext2_super_block *super_shadow = 0;
  64         struct ext2_group_desc *group_shadow = 0;
  65         struct ext2_group_desc *s, *t;
  66
  67         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  68
  69         fs_state = fs->super->s_state;
  70
  71         fs->super->s_wtime = time(NULL);
  72         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
  73                 retval = EXT2_ET_NO_MEMORY;
  74                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
  75                                         (void **) &super_shadow);
  76                 if (retval)
  77                         goto errout;
  78                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
  79                                                  fs->desc_blocks),
  80                                         (void **) &group_shadow);
  81                 if (retval)
  82                         goto errout;
  83                 memset(group_shadow, 0, (size_t) fs->blocksize *
  84                        fs->desc_blocks);
  85
  86                 /* swap the superblock */
  87                 *super_shadow = *fs->super;
  88                 ext2fs_swap_super(super_shadow);
  89
  90                 /* swap the group descriptors */
  91                 for (j=0, s=fs->group_desc, t=group_shadow;
  92                      j < fs->group_desc_count; j++, t++, s++) {
  93                         *t = *s;
  94                         ext2fs_swap_group_desc(t);
  95                 }
  96         } else {
  97                 super_shadow = fs->super;
  98                 group_shadow = fs->group_desc;
  99         }
 100
 101         /*
 102          * Write out master superblock.  This has to be done
 103          * separately, since it is located at a fixed location
 104          * (SUPERBLOCK_OFFSET).
 105          */
 106         io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 107         retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
 108                                       super_shadow);
 109         if (retval)
 110                 goto errout;
 111         io_channel_set_blksize(fs->io, fs->blocksize);
 112
 113         /*
 114          * Set the state of the FS to be non-valid.  (The state has
 115          * already been backed up earlier, and will be restored when
 116          * we exit.)
 117          */
 118         fs->super->s_state &= ~EXT2_VALID_FS;
 119         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 120                 *super_shadow = *fs->super;
 121                 ext2fs_swap_super(super_shadow);
 122         }
 123
 124         /*
 125          * Write out the master group descriptors, and the backup
 126          * superblocks and group descriptors.
 127          */
 128         group_block = fs->super->s_first_data_block;
 129         maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
 130                 fs->group_desc_count;
 131         for (i = 0; i < maxgroup; i++) {
 132                 if (!ext2fs_bg_has_super(fs, i))
 133                         goto next_group;
 134
 135                 if (i !=0 ) {
 136                         retval = io_channel_write_blk(fs->io, group_block,
 137                                                       -SUPERBLOCK_SIZE,
 138                                                       super_shadow);
 139                         if (retval)
 140                                 goto errout;
 141                 }
 142                 group_ptr = (char *) group_shadow;
 143                 for (j=0; j < fs->desc_blocks; j++) {
 144                         retval = io_channel_write_blk(fs->io,
 145                                                       group_block+1+j, 1,
 146                                                       group_ptr);
 147                         if (retval)
 148                                 goto errout;
 149                         group_ptr += fs->blocksize;
 150                 }
 151         next_group:
 152                 group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
 153         }
 154
 155         /*
 156          * If the write_bitmaps() function is present, call it to
 157          * flush the bitmaps.  This is done this way so that a simple
 158          * program that doesn't mess with the bitmaps doesn't need to
 159          * drag in the bitmaps.c code.
 160          */
 161         if (fs->write_bitmaps) {
 162                 retval = fs->write_bitmaps(fs);
 163                 if (retval)
 164                         goto errout;
 165         }
 166         retval = 0;
 167 errout:
 168         fs->super->s_state = fs_state;
 169         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 170                 if (super_shadow)
 171                         ext2fs_free_mem((void **) &super_shadow);
 172                 if (group_shadow)
 173                         ext2fs_free_mem((void **) &group_shadow);
 174         }
 175         return retval;
 176 }
 177
 178 errcode_t ext2fs_close(ext2_filsys fs)
 179 {
 180         errcode_t       retval;
 181
 182         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 183
 184         if (fs->flags & EXT2_FLAG_DIRTY) {
 185                 retval = ext2fs_flush(fs);
 186                 if (retval)
 187                         return retval;
 188         }
 189         if (fs->write_bitmaps) {
 190                 retval = fs->write_bitmaps(fs);
 191                 if (retval)
 192                         return retval;
 193         }
 194         ext2fs_free(fs);
 195         return 0;
 196 }
 197