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 errcode_t ext2fs_flush(ext2_filsys fs)
  60 {
  61         dgrp_t          i,j,maxgroup;
  62         blk_t           group_block;
  63         errcode_t       retval;
  64         char            *group_ptr;
  65         unsigned long   fs_state;
  66         struct ext2_super_block *super_shadow = 0;
  67         struct ext2_group_desc *group_shadow = 0;
  68         struct ext2_group_desc *s, *t;
  69
  70         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  71
  72         fs_state = fs->super->s_state;
  73
  74         fs->super->s_wtime = time(NULL);
  75         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
  76                 retval = EXT2_ET_NO_MEMORY;
  77                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
  78                                         (void **) &super_shadow);
  79                 if (retval)
  80                         goto errout;
  81                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
  82                                                  fs->desc_blocks),
  83                                         (void **) &group_shadow);
  84                 if (retval)
  85                         goto errout;
  86                 memset(group_shadow, 0, (size_t) fs->blocksize *
  87                        fs->desc_blocks);
  88
  89                 /* swap the superblock */
  90                 *super_shadow = *fs->super;
  91                 ext2fs_swap_super(super_shadow);
  92
  93                 /* swap the group descriptors */
  94                 for (j=0, s=fs->group_desc, t=group_shadow;
  95                      j < fs->group_desc_count; j++, t++, s++) {
  96                         *t = *s;
  97                         ext2fs_swap_group_desc(t);
  98                 }
  99         } else {
 100                 super_shadow = fs->super;
 101                 group_shadow = fs->group_desc;
 102         }
 103
 104         /*
 105          * Write out master superblock.  This has to be done
 106          * separately, since it is located at a fixed location
 107          * (SUPERBLOCK_OFFSET).
 108          */
 109         io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 110         retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
 111                                       super_shadow);
 112         if (retval)
 113                 goto errout;
 114         io_channel_set_blksize(fs->io, fs->blocksize);
 115
 116         /*
 117          * Set the state of the FS to be non-valid.  (The state has
 118          * already been backed up earlier, and will be restored when
 119          * we exit.)
 120          */
 121         fs->super->s_state &= ~EXT2_VALID_FS;
 122         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 123                 *super_shadow = *fs->super;
 124                 ext2fs_swap_super(super_shadow);
 125         }
 126
 127         /*
 128          * Write out the master group descriptors, and the backup
 129          * superblocks and group descriptors.
 130          */
 131         group_block = fs->super->s_first_data_block;
 132         maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
 133                 fs->group_desc_count;
 134         for (i = 0; i < maxgroup; i++) {
 135                 if (!ext2fs_bg_has_super(fs, i))
 136                         goto next_group;
 137
 138                 if (i !=0 ) {
 139                         retval = io_channel_write_blk(fs->io, group_block,
 140                                                       -SUPERBLOCK_SIZE,
 141                                                       super_shadow);
 142                         if (retval)
 143                                 goto errout;
 144                 }
 145                 group_ptr = (char *) group_shadow;
 146                 for (j=0; j < fs->desc_blocks; j++) {
 147                         retval = io_channel_write_blk(fs->io,
 148                                                       group_block+1+j, 1,
 149                                                       group_ptr);
 150                         if (retval)
 151                                 goto errout;
 152                         group_ptr += fs->blocksize;
 153                 }
 154         next_group:
 155                 group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
 156         }
 157
 158         /*
 159          * If the write_bitmaps() function is present, call it to
 160          * flush the bitmaps.  This is done this way so that a simple
 161          * program that doesn't mess with the bitmaps doesn't need to
 162          * drag in the bitmaps.c code.
 163          */
 164         if (fs->write_bitmaps) {
 165                 retval = fs->write_bitmaps(fs);
 166                 if (retval)
 167                         goto errout;
 168         }
 169
 170         /*
 171          * Flush the blocks out to disk
 172          */
 173         retval = io_channel_flush(fs->io);
 174 errout:
 175         fs->super->s_state = fs_state;
 176         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 177                 if (super_shadow)
 178                         ext2fs_free_mem((void **) &super_shadow);
 179                 if (group_shadow)
 180                         ext2fs_free_mem((void **) &group_shadow);
 181         }
 182         return retval;
 183 }
 184
 185 errcode_t ext2fs_close(ext2_filsys fs)
 186 {
 187         errcode_t       retval;
 188
 189         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 190
 191         if (fs->flags & EXT2_FLAG_DIRTY) {
 192                 retval = ext2fs_flush(fs);
 193                 if (retval)
 194                         return retval;
 195         }
 196         if (fs->write_bitmaps) {
 197                 retval = fs->write_bitmaps(fs);
 198                 if (retval)
 199                         return retval;
 200         }
 201         ext2fs_free(fs);
 202         return 0;
 203 }
 204