[1765] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * closefs.c --- close an ext2 filesystem
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| 4 | *
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| 5 | * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
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| 6 | *
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| 7 | * %Begin-Header%
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| 8 | * This file may be redistributed under the terms of the GNU Public
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| 9 | * License.
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| 10 | * %End-Header%
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| 11 | */
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| 12 |
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| 13 | #include <stdio.h>
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| 14 | #if HAVE_UNISTD_H
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| 15 | #include <unistd.h>
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| 16 | #endif
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| 17 | #include <time.h>
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| 18 | #include <string.h>
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| 19 |
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| 20 | #include "ext2_fs.h"
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| 21 | #include "ext2fsP.h"
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| 22 |
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| 23 | static int test_root(int a, int b)
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| 24 | {
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| 25 | if (a == 0)
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| 26 | return 1;
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| 27 | while (1) {
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| 28 | if (a == 1)
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| 29 | return 1;
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| 30 | if (a % b)
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| 31 | return 0;
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| 32 | a = a / b;
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| 33 | }
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| 34 | }
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| 35 |
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| 36 | int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
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| 37 | {
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| 38 | if (!(fs->super->s_feature_ro_compat &
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| 39 | EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
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| 40 | return 1;
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| 41 |
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| 42 | if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
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| 43 | test_root(group_block, 7))
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| 44 | return 1;
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| 45 |
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| 46 | return 0;
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| 47 | }
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| 48 |
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| 49 | int ext2fs_super_and_bgd_loc(ext2_filsys fs,
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| 50 | dgrp_t group,
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| 51 | blk_t *ret_super_blk,
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| 52 | blk_t *ret_old_desc_blk,
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| 53 | blk_t *ret_new_desc_blk,
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| 54 | int *ret_meta_bg)
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| 55 | {
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| 56 | blk_t group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
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| 57 | unsigned int meta_bg, meta_bg_size;
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| 58 | int numblocks, has_super;
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| 59 | int old_desc_blocks;
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| 60 |
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| 61 | group_block = fs->super->s_first_data_block +
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| 62 | (group * fs->super->s_blocks_per_group);
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| 63 |
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| 64 | if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
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| 65 | old_desc_blocks = fs->super->s_first_meta_bg;
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| 66 | else
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| 67 | old_desc_blocks =
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| 68 | fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
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| 69 |
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| 70 | if (group == fs->group_desc_count-1) {
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| 71 | numblocks = (fs->super->s_blocks_count -
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| 72 | fs->super->s_first_data_block) %
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| 73 | fs->super->s_blocks_per_group;
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| 74 | if (!numblocks)
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| 75 | numblocks = fs->super->s_blocks_per_group;
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| 76 | } else
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| 77 | numblocks = fs->super->s_blocks_per_group;
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| 78 |
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| 79 | has_super = ext2fs_bg_has_super(fs, group);
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| 80 |
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| 81 | if (has_super) {
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| 82 | super_blk = group_block;
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| 83 | numblocks--;
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| 84 | }
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| 85 | meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
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| 86 | meta_bg = group / meta_bg_size;
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| 87 |
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| 88 | if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
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| 89 | (meta_bg < fs->super->s_first_meta_bg)) {
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| 90 | if (has_super) {
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| 91 | old_desc_blk = group_block + 1;
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| 92 | numblocks -= old_desc_blocks;
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| 93 | }
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| 94 | } else {
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| 95 | if (((group % meta_bg_size) == 0) ||
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| 96 | ((group % meta_bg_size) == 1) ||
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| 97 | ((group % meta_bg_size) == (meta_bg_size-1))) {
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| 98 | if (has_super)
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| 99 | has_super = 1;
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| 100 | new_desc_blk = group_block + has_super;
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| 101 | numblocks--;
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| 102 | }
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| 103 | }
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| 104 |
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| 105 | numblocks -= 2 + fs->inode_blocks_per_group;
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| 106 |
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| 107 | if (ret_super_blk)
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| 108 | *ret_super_blk = super_blk;
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| 109 | if (ret_old_desc_blk)
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| 110 | *ret_old_desc_blk = old_desc_blk;
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| 111 | if (ret_new_desc_blk)
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| 112 | *ret_new_desc_blk = new_desc_blk;
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| 113 | if (ret_meta_bg)
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| 114 | *ret_meta_bg = meta_bg;
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| 115 | return numblocks;
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| 116 | }
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| 117 |
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| 118 |
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| 119 | /*
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| 120 | * This function forces out the primary superblock. We need to only
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| 121 | * write out those fields which we have changed, since if the
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| 122 | * filesystem is mounted, it may have changed some of the other
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| 123 | * fields.
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| 124 | *
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| 125 | * It takes as input a superblock which has already been byte swapped
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| 126 | * (if necessary).
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| 127 | *
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| 128 | */
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| 129 | static errcode_t write_primary_superblock(ext2_filsys fs,
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| 130 | struct ext2_super_block *super)
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| 131 | {
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| 132 | __u16 *old_super, *new_super;
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| 133 | int check_idx, write_idx, size;
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| 134 | errcode_t retval;
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| 135 |
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| 136 | if (!fs->io->manager->write_byte || !fs->orig_super) {
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| 137 | io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
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| 138 | retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
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| 139 | super);
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| 140 | io_channel_set_blksize(fs->io, fs->blocksize);
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| 141 | return retval;
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| 142 | }
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| 143 |
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| 144 | old_super = (__u16 *) fs->orig_super;
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| 145 | new_super = (__u16 *) super;
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| 146 |
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| 147 | for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
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| 148 | if (old_super[check_idx] == new_super[check_idx])
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| 149 | continue;
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| 150 | write_idx = check_idx;
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| 151 | for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
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| 152 | if (old_super[check_idx] == new_super[check_idx])
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| 153 | break;
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| 154 | size = 2 * (check_idx - write_idx);
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| 155 | retval = io_channel_write_byte(fs->io,
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| 156 | SUPERBLOCK_OFFSET + (2 * write_idx), size,
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| 157 | new_super + write_idx);
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| 158 | if (retval)
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| 159 | return retval;
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| 160 | }
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| 161 | memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
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| 162 | return 0;
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| 163 | }
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| 164 |
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| 165 |
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| 166 | /*
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| 167 | * Updates the revision to EXT2_DYNAMIC_REV
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| 168 | */
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| 169 | void ext2fs_update_dynamic_rev(ext2_filsys fs)
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| 170 | {
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| 171 | struct ext2_super_block *sb = fs->super;
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| 172 |
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| 173 | if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
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| 174 | return;
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| 175 |
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| 176 | sb->s_rev_level = EXT2_DYNAMIC_REV;
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| 177 | sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
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| 178 | sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
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| 179 | /* s_uuid is handled by e2fsck already */
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| 180 | /* other fields should be left alone */
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| 181 | }
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| 182 |
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| 183 | static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
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| 184 | blk_t group_block,
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| 185 | struct ext2_super_block *super_shadow)
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| 186 | {
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| 187 | dgrp_t sgrp = group;
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| 188 |
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| 189 | if (sgrp > ((1 << 16) - 1))
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| 190 | sgrp = (1 << 16) - 1;
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| 191 | #if BB_BIG_ENDIAN
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| 192 | if (fs->flags & EXT2_FLAG_SWAP_BYTES)
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| 193 | super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
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| 194 | else
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| 195 | #endif
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| 196 | fs->super->s_block_group_nr = sgrp;
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| 197 |
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| 198 | return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
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| 199 | super_shadow);
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| 200 | }
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| 201 |
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| 202 |
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| 203 | errcode_t ext2fs_flush(ext2_filsys fs)
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| 204 | {
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| 205 | dgrp_t i;
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| 206 | blk_t group_block;
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| 207 | errcode_t retval;
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| 208 | unsigned long fs_state;
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| 209 | struct ext2_super_block *super_shadow = 0;
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| 210 | struct ext2_group_desc *group_shadow = 0;
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| 211 | char *group_ptr;
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| 212 | int old_desc_blocks;
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| 213 | #if BB_BIG_ENDIAN
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| 214 | dgrp_t j;
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| 215 | struct ext2_group_desc *s, *t;
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| 216 | #endif
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| 217 |
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| 218 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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| 219 |
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| 220 | fs_state = fs->super->s_state;
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| 221 |
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| 222 | fs->super->s_wtime = time(NULL);
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| 223 | fs->super->s_block_group_nr = 0;
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| 224 | #if BB_BIG_ENDIAN
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| 225 | if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
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| 226 | retval = EXT2_ET_NO_MEMORY;
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| 227 | retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
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| 228 | if (retval)
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| 229 | goto errout;
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| 230 | retval = ext2fs_get_mem((size_t)(fs->blocksize *
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| 231 | fs->desc_blocks),
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| 232 | &group_shadow);
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| 233 | if (retval)
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| 234 | goto errout;
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| 235 | memset(group_shadow, 0, (size_t) fs->blocksize *
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| 236 | fs->desc_blocks);
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| 237 |
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| 238 | /* swap the group descriptors */
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| 239 | for (j=0, s=fs->group_desc, t=group_shadow;
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| 240 | j < fs->group_desc_count; j++, t++, s++) {
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| 241 | *t = *s;
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| 242 | ext2fs_swap_group_desc(t);
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| 243 | }
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| 244 | } else {
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| 245 | super_shadow = fs->super;
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| 246 | group_shadow = fs->group_desc;
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| 247 | }
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| 248 | #else
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| 249 | super_shadow = fs->super;
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| 250 | group_shadow = fs->group_desc;
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| 251 | #endif
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| 252 |
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| 253 | /*
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| 254 | * If this is an external journal device, don't write out the
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| 255 | * block group descriptors or any of the backup superblocks
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| 256 | */
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| 257 | if (fs->super->s_feature_incompat &
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| 258 | EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
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| 259 | goto write_primary_superblock_only;
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| 260 |
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| 261 | /*
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| 262 | * Set the state of the FS to be non-valid. (The state has
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| 263 | * already been backed up earlier, and will be restored after
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| 264 | * we write out the backup superblocks.)
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| 265 | */
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| 266 | fs->super->s_state &= ~EXT2_VALID_FS;
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| 267 | #if BB_BIG_ENDIAN
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| 268 | if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
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| 269 | *super_shadow = *fs->super;
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| 270 | ext2fs_swap_super(super_shadow);
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| 271 | }
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| 272 | #endif
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| 273 |
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| 274 | /*
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| 275 | * Write out the master group descriptors, and the backup
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| 276 | * superblocks and group descriptors.
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| 277 | */
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| 278 | group_block = fs->super->s_first_data_block;
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| 279 | group_ptr = (char *) group_shadow;
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| 280 | if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
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| 281 | old_desc_blocks = fs->super->s_first_meta_bg;
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| 282 | else
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| 283 | old_desc_blocks = fs->desc_blocks;
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| 284 |
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| 285 | for (i = 0; i < fs->group_desc_count; i++) {
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| 286 | blk_t super_blk, old_desc_blk, new_desc_blk;
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| 287 | int meta_bg;
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| 288 |
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| 289 | ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
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| 290 | &new_desc_blk, &meta_bg);
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| 291 |
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| 292 | if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
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| 293 | retval = write_backup_super(fs, i, super_blk,
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| 294 | super_shadow);
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| 295 | if (retval)
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| 296 | goto errout;
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| 297 | }
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| 298 | if (fs->flags & EXT2_FLAG_SUPER_ONLY)
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| 299 | continue;
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| 300 | if ((old_desc_blk) &&
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| 301 | (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
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| 302 | retval = io_channel_write_blk(fs->io,
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| 303 | old_desc_blk, old_desc_blocks, group_ptr);
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| 304 | if (retval)
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| 305 | goto errout;
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| 306 | }
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| 307 | if (new_desc_blk) {
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| 308 | retval = io_channel_write_blk(fs->io, new_desc_blk,
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| 309 | 1, group_ptr + (meta_bg*fs->blocksize));
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| 310 | if (retval)
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| 311 | goto errout;
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| 312 | }
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| 313 | }
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| 314 | fs->super->s_block_group_nr = 0;
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| 315 | fs->super->s_state = fs_state;
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| 316 | #if BB_BIG_ENDIAN
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| 317 | if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
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| 318 | *super_shadow = *fs->super;
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| 319 | ext2fs_swap_super(super_shadow);
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| 320 | }
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| 321 | #endif
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| 322 |
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| 323 | /*
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| 324 | * If the write_bitmaps() function is present, call it to
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| 325 | * flush the bitmaps. This is done this way so that a simple
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| 326 | * program that doesn't mess with the bitmaps doesn't need to
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| 327 | * drag in the bitmaps.c code.
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| 328 | */
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| 329 | if (fs->write_bitmaps) {
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| 330 | retval = fs->write_bitmaps(fs);
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| 331 | if (retval)
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| 332 | goto errout;
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| 333 | }
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| 334 |
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| 335 | write_primary_superblock_only:
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| 336 | /*
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| 337 | * Write out master superblock. This has to be done
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| 338 | * separately, since it is located at a fixed location
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| 339 | * (SUPERBLOCK_OFFSET). We flush all other pending changes
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| 340 | * out to disk first, just to avoid a race condition with an
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| 341 | * insy-tinsy window....
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| 342 | */
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| 343 | retval = io_channel_flush(fs->io);
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| 344 | retval = write_primary_superblock(fs, super_shadow);
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| 345 | if (retval)
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| 346 | goto errout;
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| 347 |
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| 348 | fs->flags &= ~EXT2_FLAG_DIRTY;
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| 349 |
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| 350 | retval = io_channel_flush(fs->io);
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| 351 | errout:
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| 352 | fs->super->s_state = fs_state;
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| 353 | if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
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| 354 | if (super_shadow)
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| 355 | ext2fs_free_mem(&super_shadow);
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| 356 | if (group_shadow)
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| 357 | ext2fs_free_mem(&group_shadow);
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| 358 | }
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| 359 | return retval;
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| 360 | }
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| 361 |
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| 362 | errcode_t ext2fs_close(ext2_filsys fs)
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| 363 | {
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| 364 | errcode_t retval;
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| 365 |
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| 366 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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| 367 |
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| 368 | if (fs->flags & EXT2_FLAG_DIRTY) {
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| 369 | retval = ext2fs_flush(fs);
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| 370 | if (retval)
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| 371 | return retval;
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| 372 | }
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| 373 | if (fs->write_bitmaps) {
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| 374 | retval = fs->write_bitmaps(fs);
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| 375 | if (retval)
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| 376 | return retval;
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| 377 | }
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| 378 | ext2fs_free(fs);
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| 379 | return 0;
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| 380 | }
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| 381 |
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