1 | /*
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2 | * bmap.c --- logical to physical block mapping
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3 | *
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4 | * Copyright (C) 1997 Theodore Ts'o.
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5 | *
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6 | * %Begin-Header%
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7 | * This file may be redistributed under the terms of the GNU Public
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8 | * License.
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9 | * %End-Header%
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10 | */
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11 |
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12 | #include <stdio.h>
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13 | #include <string.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 |
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18 | #include "ext2_fs.h"
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19 | #include "ext2fs.h"
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20 |
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21 | extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
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22 | struct ext2_inode *inode,
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23 | char *block_buf, int bmap_flags,
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24 | blk_t block, blk_t *phys_blk);
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25 |
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26 | #define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
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27 |
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28 | static errcode_t block_ind_bmap(ext2_filsys fs, int flags,
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29 | blk_t ind, char *block_buf,
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30 | int *blocks_alloc,
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31 | blk_t nr, blk_t *ret_blk)
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32 | {
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33 | errcode_t retval;
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34 | blk_t b;
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35 |
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36 | if (!ind) {
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37 | if (flags & BMAP_SET)
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38 | return EXT2_ET_SET_BMAP_NO_IND;
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39 | *ret_blk = 0;
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40 | return 0;
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41 | }
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42 | retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
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43 | if (retval)
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44 | return retval;
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45 |
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46 | if (flags & BMAP_SET) {
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47 | b = *ret_blk;
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48 | #if BB_BIG_ENDIAN
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49 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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50 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
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51 | b = ext2fs_swab32(b);
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52 | #endif
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53 | ((blk_t *) block_buf)[nr] = b;
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54 | return io_channel_write_blk(fs->io, ind, 1, block_buf);
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55 | }
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56 |
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57 | b = ((blk_t *) block_buf)[nr];
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58 |
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59 | #if BB_BIG_ENDIAN
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60 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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61 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
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62 | b = ext2fs_swab32(b);
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63 | #endif
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64 |
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65 | if (!b && (flags & BMAP_ALLOC)) {
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66 | b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
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67 | retval = ext2fs_alloc_block(fs, b,
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68 | block_buf + fs->blocksize, &b);
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69 | if (retval)
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70 | return retval;
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71 |
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72 | #if BB_BIG_ENDIAN
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73 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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74 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
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75 | ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
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76 | else
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77 | #endif
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78 | ((blk_t *) block_buf)[nr] = b;
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79 |
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80 | retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
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81 | if (retval)
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82 | return retval;
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83 |
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84 | (*blocks_alloc)++;
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85 | }
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86 |
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87 | *ret_blk = b;
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88 | return 0;
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89 | }
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90 |
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91 | static errcode_t block_dind_bmap(ext2_filsys fs, int flags,
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92 | blk_t dind, char *block_buf,
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93 | int *blocks_alloc,
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94 | blk_t nr, blk_t *ret_blk)
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95 | {
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96 | blk_t b;
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97 | errcode_t retval;
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98 | blk_t addr_per_block;
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99 |
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100 | addr_per_block = (blk_t) fs->blocksize >> 2;
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101 |
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102 | retval = block_ind_bmap(fs, flags & ~BMAP_SET, dind, block_buf,
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103 | blocks_alloc, nr / addr_per_block, &b);
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104 | if (retval)
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105 | return retval;
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106 | retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
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107 | nr % addr_per_block, ret_blk);
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108 | return retval;
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109 | }
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110 |
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111 | static errcode_t block_tind_bmap(ext2_filsys fs, int flags,
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112 | blk_t tind, char *block_buf,
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113 | int *blocks_alloc,
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114 | blk_t nr, blk_t *ret_blk)
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115 | {
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116 | blk_t b;
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117 | errcode_t retval;
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118 | blk_t addr_per_block;
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119 |
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120 | addr_per_block = (blk_t) fs->blocksize >> 2;
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121 |
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122 | retval = block_dind_bmap(fs, flags & ~BMAP_SET, tind, block_buf,
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123 | blocks_alloc, nr / addr_per_block, &b);
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124 | if (retval)
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125 | return retval;
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126 | retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
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127 | nr % addr_per_block, ret_blk);
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128 | return retval;
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129 | }
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130 |
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131 | errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
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132 | char *block_buf, int bmap_flags, blk_t block,
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133 | blk_t *phys_blk)
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134 | {
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135 | struct ext2_inode inode_buf;
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136 | blk_t addr_per_block;
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137 | blk_t b;
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138 | char *buf = 0;
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139 | errcode_t retval = 0;
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140 | int blocks_alloc = 0, inode_dirty = 0;
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141 |
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142 | if (!(bmap_flags & BMAP_SET))
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143 | *phys_blk = 0;
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144 |
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145 | /* Read inode structure if necessary */
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146 | if (!inode) {
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147 | retval = ext2fs_read_inode(fs, ino, &inode_buf);
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148 | if (retval)
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149 | return retval;
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150 | inode = &inode_buf;
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151 | }
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152 | addr_per_block = (blk_t) fs->blocksize >> 2;
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153 |
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154 | if (!block_buf) {
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155 | retval = ext2fs_get_mem(fs->blocksize * 2, &buf);
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156 | if (retval)
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157 | return retval;
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158 | block_buf = buf;
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159 | }
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160 |
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161 | if (block < EXT2_NDIR_BLOCKS) {
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162 | if (bmap_flags & BMAP_SET) {
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163 | b = *phys_blk;
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164 | #if BB_BIG_ENDIAN
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165 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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166 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
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167 | b = ext2fs_swab32(b);
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168 | #endif
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169 | inode_bmap(inode, block) = b;
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170 | inode_dirty++;
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171 | goto done;
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172 | }
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173 |
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174 | *phys_blk = inode_bmap(inode, block);
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175 | b = block ? inode_bmap(inode, block-1) : 0;
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176 |
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177 | if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
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178 | retval = ext2fs_alloc_block(fs, b, block_buf, &b);
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179 | if (retval)
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180 | goto done;
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181 | inode_bmap(inode, block) = b;
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182 | blocks_alloc++;
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183 | *phys_blk = b;
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184 | }
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185 | goto done;
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186 | }
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187 |
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188 | /* Indirect block */
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189 | block -= EXT2_NDIR_BLOCKS;
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190 | if (block < addr_per_block) {
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191 | b = inode_bmap(inode, EXT2_IND_BLOCK);
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192 | if (!b) {
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193 | if (!(bmap_flags & BMAP_ALLOC)) {
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194 | if (bmap_flags & BMAP_SET)
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195 | retval = EXT2_ET_SET_BMAP_NO_IND;
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196 | goto done;
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197 | }
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198 |
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199 | b = inode_bmap(inode, EXT2_IND_BLOCK-1);
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200 | retval = ext2fs_alloc_block(fs, b, block_buf, &b);
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201 | if (retval)
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202 | goto done;
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203 | inode_bmap(inode, EXT2_IND_BLOCK) = b;
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204 | blocks_alloc++;
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205 | }
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206 | retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
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207 | &blocks_alloc, block, phys_blk);
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208 | goto done;
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209 | }
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210 |
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211 | /* Doubly indirect block */
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212 | block -= addr_per_block;
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213 | if (block < addr_per_block * addr_per_block) {
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214 | b = inode_bmap(inode, EXT2_DIND_BLOCK);
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215 | if (!b) {
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216 | if (!(bmap_flags & BMAP_ALLOC)) {
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217 | if (bmap_flags & BMAP_SET)
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218 | retval = EXT2_ET_SET_BMAP_NO_IND;
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219 | goto done;
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220 | }
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221 |
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222 | b = inode_bmap(inode, EXT2_IND_BLOCK);
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223 | retval = ext2fs_alloc_block(fs, b, block_buf, &b);
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224 | if (retval)
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225 | goto done;
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226 | inode_bmap(inode, EXT2_DIND_BLOCK) = b;
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227 | blocks_alloc++;
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228 | }
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229 | retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
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230 | &blocks_alloc, block, phys_blk);
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231 | goto done;
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232 | }
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233 |
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234 | /* Triply indirect block */
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235 | block -= addr_per_block * addr_per_block;
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236 | b = inode_bmap(inode, EXT2_TIND_BLOCK);
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237 | if (!b) {
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238 | if (!(bmap_flags & BMAP_ALLOC)) {
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239 | if (bmap_flags & BMAP_SET)
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240 | retval = EXT2_ET_SET_BMAP_NO_IND;
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241 | goto done;
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242 | }
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243 |
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244 | b = inode_bmap(inode, EXT2_DIND_BLOCK);
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245 | retval = ext2fs_alloc_block(fs, b, block_buf, &b);
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246 | if (retval)
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247 | goto done;
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248 | inode_bmap(inode, EXT2_TIND_BLOCK) = b;
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249 | blocks_alloc++;
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250 | }
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251 | retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
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252 | &blocks_alloc, block, phys_blk);
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253 | done:
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254 | ext2fs_free_mem(&buf);
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255 | if ((retval == 0) && (blocks_alloc || inode_dirty)) {
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256 | inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
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257 | retval = ext2fs_write_inode(fs, ino, inode);
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258 | }
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259 | return retval;
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260 | }
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261 |
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262 |
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263 |
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