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 #include "ext2_fs.h"
  20 #include "ext2fsP.h"
  21
  22 static int test_root(int a, int b)
  23 {
  24         if (a == 0)
  25                 return 1;
  26         while (1) {
  27                 if (a == 1)
  28                         return 1;
  29                 if (a % b)
  30                         return 0;
  31                 a = a / b;
  32         }
  33 }
  34
  35 int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
  36 {
  37         if (!(fs->super->s_feature_ro_compat &
  38               EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
  39                 return 1;
  40
  41         if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
  42             test_root(group_block, 7))
  43                 return 1;
  44
  45         return 0;
  46 }
  47
  48 /*
  49  * This function forces out the primary superblock.  We need to only
  50  * write out those fields which we have changed, since if the
  51  * filesystem is mounted, it may have changed some of the other
  52  * fields.
  53  *
  54  * It takes as input a superblock which has already been byte swapped
  55  * (if necessary).
  56  *
  57  */
  58 static errcode_t write_primary_superblock(ext2_filsys fs,
  59                                           struct ext2_super_block *super)
  60 {
  61         __u16           *old_super, *new_super;
  62         int             check_idx, write_idx, size;
  63         errcode_t       retval;
  64
  65         if (!fs->io->manager->write_byte || !fs->orig_super) {
  66                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
  67                 retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
  68                                               super);
  69                 io_channel_set_blksize(fs->io, fs->blocksize);
  70                 return retval;
  71         }
  72
  73         old_super = (__u16 *) fs->orig_super;
  74         new_super = (__u16 *) super;
  75
  76         for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
  77                 if (old_super[check_idx] == new_super[check_idx])
  78                         continue;
  79                 write_idx = check_idx;
  80                 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
  81                         if (old_super[check_idx] == new_super[check_idx])
  82                                 break;
  83                 size = 2 * (check_idx - write_idx);
  84 #if 0
  85                 printf("Writing %d bytes starting at %d\n",
  86                        size, write_idx*2);
  87 #endif
  88                 retval = io_channel_write_byte(fs->io,
  89                                SUPERBLOCK_OFFSET + (2 * write_idx), size,
  90                                                new_super + write_idx);
  91                 if (retval)
  92                         return retval;
  93         }
  94         memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
  95         return 0;
  96 }
  97
  98
  99 /*
 100  * Updates the revision to EXT2_DYNAMIC_REV
 101  */
 102 void ext2fs_update_dynamic_rev(ext2_filsys fs)
 103 {
 104         struct ext2_super_block *sb = fs->super;
 105
 106         if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
 107                 return;
 108
 109         sb->s_rev_level = EXT2_DYNAMIC_REV;
 110         sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 111         sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 112         /* s_uuid is handled by e2fsck already */
 113         /* other fields should be left alone */
 114 }
 115
 116 errcode_t ext2fs_flush(ext2_filsys fs)
 117 {
 118         dgrp_t          i,j,maxgroup,sgrp;
 119         blk_t           group_block;
 120         errcode_t       retval;
 121         char            *group_ptr;
 122         unsigned long   fs_state;
 123         struct ext2_super_block *super_shadow = 0;
 124         struct ext2_group_desc *group_shadow = 0;
 125         struct ext2_group_desc *s, *t;
 126
 127         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 128
 129         fs_state = fs->super->s_state;
 130
 131         fs->super->s_wtime = time(NULL);
 132         fs->super->s_block_group_nr = 0;
 133 #ifdef EXT2FS_ENABLE_SWAPFS
 134         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 135                 retval = EXT2_ET_NO_MEMORY;
 136                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
 137                                         (void **) &super_shadow);
 138                 if (retval)
 139                         goto errout;
 140                 retval = ext2fs_get_mem((size_t)(fs->blocksize *
 141                                                  fs->desc_blocks),
 142                                         (void **) &group_shadow);
 143                 if (retval)
 144                         goto errout;
 145                 memset(group_shadow, 0, (size_t) fs->blocksize *
 146                        fs->desc_blocks);
 147
 148                 /* swap the superblock */
 149                 *super_shadow = *fs->super;
 150                 ext2fs_swap_super(super_shadow);
 151
 152                 /* swap the group descriptors */
 153                 for (j=0, s=fs->group_desc, t=group_shadow;
 154                      j < fs->group_desc_count; j++, t++, s++) {
 155                         *t = *s;
 156                         ext2fs_swap_group_desc(t);
 157                 }
 158         } else {
 159                 super_shadow = fs->super;
 160                 group_shadow = fs->group_desc;
 161         }
 162 #else
 163         super_shadow = fs->super;
 164         group_shadow = fs->group_desc;
 165 #endif
 166
 167         /*
 168          * Write out master superblock.  This has to be done
 169          * separately, since it is located at a fixed location
 170          * (SUPERBLOCK_OFFSET).
 171          */
 172         retval = write_primary_superblock(fs, super_shadow);
 173         if (retval)
 174                 goto errout;
 175
 176         /*
 177          * If this is an external journal device, don't write out the
 178          * block group descriptors or any of the backup superblocks
 179          */
 180         if (fs->super->s_feature_incompat &
 181             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 182                 retval = 0;
 183                 goto errout;
 184         }
 185
 186         /*
 187          * Set the state of the FS to be non-valid.  (The state has
 188          * already been backed up earlier, and will be restored when
 189          * we exit.)
 190          */
 191         fs->super->s_state &= ~EXT2_VALID_FS;
 192 #ifdef EXT2FS_ENABLE_SWAPFS
 193         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 194                 *super_shadow = *fs->super;
 195                 ext2fs_swap_super(super_shadow);
 196         }
 197 #endif
 198
 199         /*
 200          * Write out the master group descriptors, and the backup
 201          * superblocks and group descriptors.
 202          */
 203         group_block = fs->super->s_first_data_block;
 204         maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
 205                 fs->group_desc_count;
 206         for (i = 0; i < maxgroup; i++) {
 207                 if (!ext2fs_bg_has_super(fs, i))
 208                         goto next_group;
 209
 210                 sgrp = i;
 211                 if (sgrp > ((1 << 16) - 1))
 212                         sgrp = (1 << 16) - 1;
 213 #ifdef EXT2FS_ENABLE_SWAPFS
 214                 if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 215                         super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
 216                 else
 217 #endif
 218                         fs->super->s_block_group_nr = sgrp;
 219
 220                 if (i !=0 ) {
 221                         retval = io_channel_write_blk(fs->io, group_block,
 222                                                       -SUPERBLOCK_SIZE,
 223                                                       super_shadow);
 224                         if (retval)
 225                                 goto errout;
 226                 }
 227                 if (fs->flags & EXT2_FLAG_SUPER_ONLY)
 228                         goto next_group;
 229                 group_ptr = (char *) group_shadow;
 230                 for (j=0; j < fs->desc_blocks; j++) {
 231                         retval = io_channel_write_blk(fs->io,
 232                                                       group_block+1+j, 1,
 233                                                       group_ptr);
 234                         if (retval)
 235                                 goto errout;
 236                         group_ptr += fs->blocksize;
 237                 }
 238         next_group:
 239                 group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
 240         }
 241         fs->super->s_block_group_nr = 0;
 242
 243         /*
 244          * If the write_bitmaps() function is present, call it to
 245          * flush the bitmaps.  This is done this way so that a simple
 246          * program that doesn't mess with the bitmaps doesn't need to
 247          * drag in the bitmaps.c code.
 248          */
 249         if (fs->write_bitmaps) {
 250                 retval = fs->write_bitmaps(fs);
 251                 if (retval)
 252                         goto errout;
 253         }
 254
 255         fs->flags &= ~EXT2_FLAG_DIRTY;
 256
 257         /*
 258          * Flush the blocks out to disk
 259          */
 260         retval = io_channel_flush(fs->io);
 261 errout:
 262         fs->super->s_state = fs_state;
 263         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 264                 if (super_shadow)
 265                         ext2fs_free_mem((void **) &super_shadow);
 266                 if (group_shadow)
 267                         ext2fs_free_mem((void **) &group_shadow);
 268         }
 269         return retval;
 270 }
 271
 272 errcode_t ext2fs_close(ext2_filsys fs)
 273 {
 274         errcode_t       retval;
 275
 276         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 277
 278         if (fs->flags & EXT2_FLAG_DIRTY) {
 279                 retval = ext2fs_flush(fs);
 280                 if (retval)
 281                         return retval;
 282         }
 283         if (fs->write_bitmaps) {
 284                 retval = fs->write_bitmaps(fs);
 285                 if (retval)
 286                         return retval;
 287         }
 288         ext2fs_free(fs);
 289         return 0;
 290 }
 291