1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * bmap.c --- logical to physical block mapping
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4 | *
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5 | * Copyright (C) 1997 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 | #include <string.h>
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15 | #if HAVE_UNISTD_H
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16 | #include <unistd.h>
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17 | #endif
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18 |
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19 | #include "ext2_fs.h"
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20 | #include "ext2fs.h"
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21 |
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22 | extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
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23 | struct ext2_inode *inode,
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24 | char *block_buf, int bmap_flags,
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25 | blk_t block, blk_t *phys_blk);
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26 |
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27 | #define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
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28 |
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29 | static errcode_t block_ind_bmap(ext2_filsys fs, int flags,
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30 | blk_t ind, char *block_buf,
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31 | int *blocks_alloc,
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32 | blk_t nr, blk_t *ret_blk)
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33 | {
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34 | errcode_t retval;
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35 | blk_t b;
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36 |
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37 | if (!ind) {
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38 | if (flags & BMAP_SET)
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39 | return EXT2_ET_SET_BMAP_NO_IND;
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40 | *ret_blk = 0;
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41 | return 0;
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42 | }
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43 | retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
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44 | if (retval)
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45 | return retval;
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46 |
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47 | if (flags & BMAP_SET) {
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48 | b = *ret_blk;
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49 | #if BB_BIG_ENDIAN
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50 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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51 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
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52 | b = ext2fs_swab32(b);
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53 | #endif
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54 | ((blk_t *) block_buf)[nr] = b;
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55 | return io_channel_write_blk(fs->io, ind, 1, block_buf);
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56 | }
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57 |
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58 | b = ((blk_t *) block_buf)[nr];
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59 |
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60 | #if BB_BIG_ENDIAN
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61 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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62 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
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63 | b = ext2fs_swab32(b);
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64 | #endif
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65 |
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66 | if (!b && (flags & BMAP_ALLOC)) {
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67 | b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
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68 | retval = ext2fs_alloc_block(fs, b,
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69 | block_buf + fs->blocksize, &b);
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70 | if (retval)
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71 | return retval;
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72 |
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73 | #if BB_BIG_ENDIAN
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74 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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75 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
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76 | ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
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77 | else
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78 | #endif
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79 | ((blk_t *) block_buf)[nr] = b;
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80 |
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81 | retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
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82 | if (retval)
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83 | return retval;
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84 |
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85 | (*blocks_alloc)++;
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86 | }
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87 |
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88 | *ret_blk = b;
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89 | return 0;
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90 | }
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91 |
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92 | static errcode_t block_dind_bmap(ext2_filsys fs, int flags,
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93 | blk_t dind, char *block_buf,
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94 | int *blocks_alloc,
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95 | blk_t nr, blk_t *ret_blk)
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96 | {
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97 | blk_t b;
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98 | errcode_t retval;
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99 | blk_t addr_per_block;
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100 |
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101 | addr_per_block = (blk_t) fs->blocksize >> 2;
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102 |
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103 | retval = block_ind_bmap(fs, flags & ~BMAP_SET, dind, block_buf,
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104 | blocks_alloc, nr / addr_per_block, &b);
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105 | if (retval)
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106 | return retval;
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107 | retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
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108 | nr % addr_per_block, ret_blk);
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109 | return retval;
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110 | }
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111 |
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112 | static errcode_t block_tind_bmap(ext2_filsys fs, int flags,
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113 | blk_t tind, char *block_buf,
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114 | int *blocks_alloc,
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115 | blk_t nr, blk_t *ret_blk)
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116 | {
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117 | blk_t b;
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118 | errcode_t retval;
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119 | blk_t addr_per_block;
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120 |
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121 | addr_per_block = (blk_t) fs->blocksize >> 2;
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122 |
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123 | retval = block_dind_bmap(fs, flags & ~BMAP_SET, tind, block_buf,
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124 | blocks_alloc, nr / addr_per_block, &b);
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125 | if (retval)
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126 | return retval;
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127 | retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
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128 | nr % addr_per_block, ret_blk);
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129 | return retval;
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130 | }
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131 |
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132 | errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
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133 | char *block_buf, int bmap_flags, blk_t block,
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134 | blk_t *phys_blk)
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135 | {
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136 | struct ext2_inode inode_buf;
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137 | blk_t addr_per_block;
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138 | blk_t b;
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139 | char *buf = 0;
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140 | errcode_t retval = 0;
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141 | int blocks_alloc = 0, inode_dirty = 0;
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142 |
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143 | if (!(bmap_flags & BMAP_SET))
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144 | *phys_blk = 0;
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145 |
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146 | /* Read inode structure if necessary */
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147 | if (!inode) {
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148 | retval = ext2fs_read_inode(fs, ino, &inode_buf);
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149 | if (retval)
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150 | return retval;
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151 | inode = &inode_buf;
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152 | }
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153 | addr_per_block = (blk_t) fs->blocksize >> 2;
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154 |
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155 | if (!block_buf) {
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156 | retval = ext2fs_get_mem(fs->blocksize * 2, &buf);
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157 | if (retval)
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158 | return retval;
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159 | block_buf = buf;
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160 | }
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161 |
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162 | if (block < EXT2_NDIR_BLOCKS) {
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163 | if (bmap_flags & BMAP_SET) {
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164 | b = *phys_blk;
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165 | #if BB_BIG_ENDIAN
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166 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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167 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
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168 | b = ext2fs_swab32(b);
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169 | #endif
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170 | inode_bmap(inode, block) = b;
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171 | inode_dirty++;
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172 | goto done;
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173 | }
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174 |
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175 | *phys_blk = inode_bmap(inode, block);
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176 | b = block ? inode_bmap(inode, block-1) : 0;
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177 |
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178 | if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
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179 | retval = ext2fs_alloc_block(fs, b, block_buf, &b);
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180 | if (retval)
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181 | goto done;
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182 | inode_bmap(inode, block) = b;
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183 | blocks_alloc++;
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184 | *phys_blk = b;
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185 | }
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186 | goto done;
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187 | }
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188 |
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189 | /* Indirect block */
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190 | block -= EXT2_NDIR_BLOCKS;
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191 | if (block < addr_per_block) {
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192 | b = inode_bmap(inode, EXT2_IND_BLOCK);
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193 | if (!b) {
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194 | if (!(bmap_flags & BMAP_ALLOC)) {
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195 | if (bmap_flags & BMAP_SET)
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196 | retval = EXT2_ET_SET_BMAP_NO_IND;
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197 | goto done;
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198 | }
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199 |
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200 | b = inode_bmap(inode, EXT2_IND_BLOCK-1);
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201 | retval = ext2fs_alloc_block(fs, b, block_buf, &b);
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202 | if (retval)
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203 | goto done;
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204 | inode_bmap(inode, EXT2_IND_BLOCK) = b;
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205 | blocks_alloc++;
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206 | }
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207 | retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
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208 | &blocks_alloc, block, phys_blk);
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209 | goto done;
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210 | }
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211 |
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212 | /* Doubly indirect block */
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213 | block -= addr_per_block;
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214 | if (block < addr_per_block * addr_per_block) {
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215 | b = inode_bmap(inode, EXT2_DIND_BLOCK);
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216 | if (!b) {
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217 | if (!(bmap_flags & BMAP_ALLOC)) {
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218 | if (bmap_flags & BMAP_SET)
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219 | retval = EXT2_ET_SET_BMAP_NO_IND;
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220 | goto done;
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221 | }
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222 |
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223 | b = inode_bmap(inode, EXT2_IND_BLOCK);
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224 | retval = ext2fs_alloc_block(fs, b, block_buf, &b);
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225 | if (retval)
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226 | goto done;
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227 | inode_bmap(inode, EXT2_DIND_BLOCK) = b;
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228 | blocks_alloc++;
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229 | }
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230 | retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
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231 | &blocks_alloc, block, phys_blk);
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232 | goto done;
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233 | }
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234 |
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235 | /* Triply indirect block */
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236 | block -= addr_per_block * addr_per_block;
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237 | b = inode_bmap(inode, EXT2_TIND_BLOCK);
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238 | if (!b) {
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239 | if (!(bmap_flags & BMAP_ALLOC)) {
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240 | if (bmap_flags & BMAP_SET)
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241 | retval = EXT2_ET_SET_BMAP_NO_IND;
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242 | goto done;
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243 | }
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244 |
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245 | b = inode_bmap(inode, EXT2_DIND_BLOCK);
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246 | retval = ext2fs_alloc_block(fs, b, block_buf, &b);
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247 | if (retval)
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248 | goto done;
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249 | inode_bmap(inode, EXT2_TIND_BLOCK) = b;
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250 | blocks_alloc++;
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251 | }
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252 | retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
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253 | &blocks_alloc, block, phys_blk);
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254 | done:
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255 | ext2fs_free_mem(&buf);
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256 | if ((retval == 0) && (blocks_alloc || inode_dirty)) {
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257 | inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
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258 | retval = ext2fs_write_inode(fs, ino, inode);
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259 | }
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260 | return retval;
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261 | }
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262 |
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263 |
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264 |
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