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         if (!(fs->super->s_feature_ro_compat &
  43               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 }
  52
  53 /*
  54  * This function forces out the primary superblock.  We need to only
  55  * write out those fields which we have changed, since if the
  56  * filesystem is mounted, it may have changed some of the other
  57  * fields.
  58  *
  59  * It takes as input a superblock which has already been byte swapped
  60  * (if necessary).
  61  *
  62  */
  63 static errcode_t write_primary_superblock(ext2_filsys fs,
  64                                           struct ext2_super_block *super)
  65 {
  66         __u16           *old_super, *new_super;
  67         int             check_idx, write_idx, size;
  68         errcode_t       retval;
  69
  70         if (!fs->io->manager->write_byte || !fs->orig_super) {
  71                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
  72                 retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
  73                                               super);
  74                 io_channel_set_blksize(fs->io, fs->blocksize);
  75                 return retval;
  76         }
  77
  78         old_super = (__u16 *) fs->orig_super;
  79         new_super = (__u16 *) super;
  80
  81         for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
  82                 if (old_super[check_idx] == new_super[check_idx])
  83                         continue;
  84                 write_idx = check_idx;
  85                 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
  86                         if (old_super[check_idx] == new_super[check_idx])
  87                                 break;
  88                 size = 2 * (check_idx - write_idx);
  89 #if 0
  90                 printf("Writing %d bytes starting at %d\n",
  91                        size, write_idx*2);
  92 #endif
  93                 retval = io_channel_write_byte(fs->io,
  94                                SUPERBLOCK_OFFSET + (2 * write_idx), size,
  95                                                new_super + write_idx);
  96                 if (retval)
  97                         return retval;
  98         }
  99         return 0;
 100 }
 101
 102
 103 /*
 104  * Updates the revision to EXT2_DYNAMIC_REV
 105  */
 106 void ext2fs_update_dynamic_rev(ext2_filsys fs)
 107 {
 108         struct ext2_super_block *sb = fs->super;
 109
 110         if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
 111                 return;
 112
 113         sb->s_rev_level = EXT2_DYNAMIC_REV;
 114         sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 115         sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 116         /* s_uuid is handled by e2fsck already */
 117         /* other fields should be left alone */
 118 }
 119
 120 errcode_t ext2fs_flush(ext2_filsys fs)
 121 {
 122         dgrp_t          i,j,maxgroup,sgrp;
 123         blk_t           group_block;
 124         errcode_t       retval;
 125         char            *group_ptr;
 126         unsigned long   fs_state;
 127         struct ext2_super_block *super_shadow = 0;
 128         struct ext2_group_desc *group_shadow = 0;
 129         struct ext2_group_desc *s, *t;
 130
 131         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 132
 133         fs_state = fs->super->s_state;
 134
 135         fs->super->s_wtime = time(NULL);
 136         fs->super->s_block_group_nr = 0;
 137         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 138                 retval = EXT2_ET_NO_MEMORY;
 139                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
 140                                         (void **) &super_shadow);
 141                 if (retval)
 142                         goto errout;
 143                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
 144                                                  fs->desc_blocks),
 145                                         (void **) &group_shadow);
 146                 if (retval)
 147                         goto errout;
 148                 memset(group_shadow, 0, (size_t) fs->blocksize *
 149                        fs->desc_blocks);
 150
 151                 /* swap the superblock */
 152                 *super_shadow = *fs->super;
 153                 ext2fs_swap_super(super_shadow);
 154
 155                 /* swap the group descriptors */
 156                 for (j=0, s=fs->group_desc, t=group_shadow;
 157                      j < fs->group_desc_count; j++, t++, s++) {
 158                         *t = *s;
 159                         ext2fs_swap_group_desc(t);
 160                 }
 161         } else {
 162                 super_shadow = fs->super;
 163                 group_shadow = fs->group_desc;
 164         }
 165
 166         /*
 167          * Write out master superblock.  This has to be done
 168          * separately, since it is located at a fixed location
 169          * (SUPERBLOCK_OFFSET).
 170          */
 171         retval = write_primary_superblock(fs, super_shadow);
 172         if (retval)
 173                 goto errout;
 174
 175         /*
 176          * Set the state of the FS to be non-valid.  (The state has
 177          * already been backed up earlier, and will be restored when
 178          * we exit.)
 179          */
 180         fs->super->s_state &= ~EXT2_VALID_FS;
 181         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 182                 *super_shadow = *fs->super;
 183                 ext2fs_swap_super(super_shadow);
 184         }
 185
 186         /*
 187          * Write out the master group descriptors, and the backup
 188          * superblocks and group descriptors.
 189          */
 190         group_block = fs->super->s_first_data_block;
 191         maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
 192                 fs->group_desc_count;
 193         for (i = 0; i < maxgroup; i++) {
 194                 if (!ext2fs_bg_has_super(fs, i))
 195                         goto next_group;
 196
 197                 sgrp = i;
 198                 if (sgrp > ((1 << 16) - 1))
 199                         sgrp = (1 << 16) - 1;
 200                 if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 201                         super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 202                 else
 203                         fs->super->s_block_group_nr = sgrp;
 204
 205                 if (i !=0 ) {
 206                         retval = io_channel_write_blk(fs->io, group_block,
 207                                                       -SUPERBLOCK_SIZE,
 208                                                       super_shadow);
 209                         if (retval)
 210                                 goto errout;
 211                 }
 212                 if (fs->flags & EXT2_FLAG_SUPER_ONLY)
 213                         goto next_group;
 214                 group_ptr = (char *) group_shadow;
 215                 for (j=0; j < fs->desc_blocks; j++) {
 216                         retval = io_channel_write_blk(fs->io,
 217                                                       group_block+1+j, 1,
 218                                                       group_ptr);
 219                         if (retval)
 220                                 goto errout;
 221                         group_ptr += fs->blocksize;
 222                 }
 223         next_group:
 224                 group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
 225         }
 226         fs->super->s_block_group_nr = 0;
 227
 228         /*
 229          * If the write_bitmaps() function is present, call it to
 230          * flush the bitmaps.  This is done this way so that a simple
 231          * program that doesn't mess with the bitmaps doesn't need to
 232          * drag in the bitmaps.c code.
 233          */
 234         if (fs->write_bitmaps) {
 235                 retval = fs->write_bitmaps(fs);
 236                 if (retval)
 237                         goto errout;
 238         }
 239
 240         /*
 241          * Flush the blocks out to disk
 242          */
 243         retval = io_channel_flush(fs->io);
 244 errout:
 245         fs->super->s_state = fs_state;
 246         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 247                 if (super_shadow)
 248                         ext2fs_free_mem((void **) &super_shadow);
 249                 if (group_shadow)
 250                         ext2fs_free_mem((void **) &group_shadow);
 251         }
 252         return retval;
 253 }
 254
 255 errcode_t ext2fs_close(ext2_filsys fs)
 256 {
 257         errcode_t       retval;
 258
 259         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 260
 261         if (fs->flags & EXT2_FLAG_DIRTY) {
 262                 retval = ext2fs_flush(fs);
 263                 if (retval)
 264                         return retval;
 265         }
 266         if (fs->write_bitmaps) {
 267                 retval = fs->write_bitmaps(fs);
 268                 if (retval)
 269                         return retval;
 270         }
 271         ext2fs_free(fs);
 272         return 0;
 273 }
 274