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,sgrp;
  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         struct ext2fs_sb *sb, *sb_shadow;
  70
  71         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  72
  73         fs_state = fs->super->s_state;
  74
  75         fs->super->s_wtime = time(NULL);
  76         sb = (struct ext2fs_sb *) fs->super;
  77         sb->s_block_group_nr = 0;
  78         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
  79                 retval = EXT2_ET_NO_MEMORY;
  80                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
  81                                         (void **) &super_shadow);
  82                 if (retval)
  83                         goto errout;
  84                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
  85                                                  fs->desc_blocks),
  86                                         (void **) &group_shadow);
  87                 if (retval)
  88                         goto errout;
  89                 memset(group_shadow, 0, (size_t) fs->blocksize *
  90                        fs->desc_blocks);
  91
  92                 /* swap the superblock */
  93                 *super_shadow = *fs->super;
  94                 ext2fs_swap_super(super_shadow);
  95                 sb_shadow = (struct ext2fs_sb *) super_shadow;
  96
  97                 /* swap the group descriptors */
  98                 for (j=0, s=fs->group_desc, t=group_shadow;
  99                      j < fs->group_desc_count; j++, t++, s++) {
 100                         *t = *s;
 101                         ext2fs_swap_group_desc(t);
 102                 }
 103         } else {
 104                 super_shadow = fs->super;
 105                 sb_shadow = (struct ext2fs_sb *) fs->super;
 106                 group_shadow = fs->group_desc;
 107         }
 108
 109         /*
 110          * Write out master superblock.  This has to be done
 111          * separately, since it is located at a fixed location
 112          * (SUPERBLOCK_OFFSET).
 113          */
 114         io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 115         retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
 116                                       super_shadow);
 117         if (retval)
 118                 goto errout;
 119         io_channel_set_blksize(fs->io, fs->blocksize);
 120
 121         /*
 122          * Set the state of the FS to be non-valid.  (The state has
 123          * already been backed up earlier, and will be restored when
 124          * we exit.)
 125          */
 126         fs->super->s_state &= ~EXT2_VALID_FS;
 127         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 128                 *super_shadow = *fs->super;
 129                 ext2fs_swap_super(super_shadow);
 130         }
 131
 132         /*
 133          * Write out the master group descriptors, and the backup
 134          * superblocks and group descriptors.
 135          */
 136         group_block = fs->super->s_first_data_block;
 137         maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
 138                 fs->group_desc_count;
 139         for (i = 0; i < maxgroup; i++) {
 140                 if (!ext2fs_bg_has_super(fs, i))
 141                         goto next_group;
 142
 143                 sgrp = i;
 144                 if (sgrp > ((1 << 16) - 1))
 145                         sgrp = (1 << 16) - 1;
 146                 if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 147                         sb_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 148                 else
 149                         sb->s_block_group_nr = sgrp;
 150
 151                 if (i !=0 ) {
 152                         retval = io_channel_write_blk(fs->io, group_block,
 153                                                       -SUPERBLOCK_SIZE,
 154                                                       super_shadow);
 155                         if (retval)
 156                                 goto errout;
 157                 }
 158                 group_ptr = (char *) group_shadow;
 159                 for (j=0; j < fs->desc_blocks; j++) {
 160                         retval = io_channel_write_blk(fs->io,
 161                                                       group_block+1+j, 1,
 162                                                       group_ptr);
 163                         if (retval)
 164                                 goto errout;
 165                         group_ptr += fs->blocksize;
 166                 }
 167         next_group:
 168                 group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
 169         }
 170         sb->s_block_group_nr = 0;
 171
 172         /*
 173          * If the write_bitmaps() function is present, call it to
 174          * flush the bitmaps.  This is done this way so that a simple
 175          * program that doesn't mess with the bitmaps doesn't need to
 176          * drag in the bitmaps.c code.
 177          */
 178         if (fs->write_bitmaps) {
 179                 retval = fs->write_bitmaps(fs);
 180                 if (retval)
 181                         goto errout;
 182         }
 183
 184         /*
 185          * Flush the blocks out to disk
 186          */
 187         retval = io_channel_flush(fs->io);
 188 errout:
 189         fs->super->s_state = fs_state;
 190         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 191                 if (super_shadow)
 192                         ext2fs_free_mem((void **) &super_shadow);
 193                 if (group_shadow)
 194                         ext2fs_free_mem((void **) &group_shadow);
 195         }
 196         return retval;
 197 }
 198
 199 errcode_t ext2fs_close(ext2_filsys fs)
 200 {
 201         errcode_t       retval;
 202
 203         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 204
 205         if (fs->flags & EXT2_FLAG_DIRTY) {
 206                 retval = ext2fs_flush(fs);
 207                 if (retval)
 208                         return retval;
 209         }
 210         if (fs->write_bitmaps) {
 211                 retval = fs->write_bitmaps(fs);
 212                 if (retval)
 213                         return retval;
 214         }
 215         ext2fs_free(fs);
 216         return 0;
 217 }
 218