2 * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
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6 * Copyright (c) 2012 Martin Sucha
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7 * Copyright (c) 2012 Frantisek Princ
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8 * All rights reserved.
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10 * Redistribution and use in source and binary forms, with or without
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11 * modification, are permitted provided that the following conditions
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14 * - Redistributions of source code must retain the above copyright
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15 * notice, this list of conditions and the following disclaimer.
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16 * - Redistributions in binary form must reproduce the above copyright
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17 * notice, this list of conditions and the following disclaimer in the
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18 * documentation and/or other materials provided with the distribution.
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19 * - The name of the author may not be used to endorse or promote products
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20 * derived from this software without specific prior written permission.
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22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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34 /** @addtogroup lwext4
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38 * @file ext4_ialloc.c
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39 * @brief Inode allocation procedures.
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42 #include <ext4_config.h>
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43 #include <ext4_types.h>
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44 #include <ext4_ialloc.h>
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45 #include <ext4_super.h>
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46 #include <ext4_fs.h>
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47 #include <ext4_blockdev.h>
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48 #include <ext4_block_group.h>
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49 #include <ext4_bitmap.h>
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51 /**@brief Convert i-node number to relative index in block group.
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52 * @param sb Superblock
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53 * @param inode I-node number to be converted
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54 * @return Index of the i-node in the block group
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56 static uint32_t ext4_ialloc_inode2index_in_group(struct ext4_sblock *sb,
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59 uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
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60 return (inode - 1) % inodes_per_group;
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63 /**@brief Convert relative index of i-node to absolute i-node number.
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64 * @param sb Superblock
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65 * @param index Index to be converted
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66 * @return Absolute number of the i-node
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69 static uint32_t ext4_ialloc_index_in_group2inode(struct ext4_sblock *sb,
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70 uint32_t index, uint32_t bgid)
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72 uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
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73 return bgid * inodes_per_group + (index + 1);
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76 /**@brief Compute block group number from the i-node number.
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77 * @param sb Superblock
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78 * @param inode I-node number to be found the block group for
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79 * @return Block group number computed from i-node number
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81 static uint32_t ext4_ialloc_get_bgid_of_inode(struct ext4_sblock *sb,
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84 uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
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85 return (inode - 1) / inodes_per_group;
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88 int ext4_ialloc_free_inode(struct ext4_fs *fs, uint32_t index, bool is_dir)
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90 struct ext4_sblock *sb = &fs->sb;
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92 /* Compute index of block group and load it */
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93 uint32_t block_group = ext4_ialloc_get_bgid_of_inode(sb, index);
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95 struct ext4_block_group_ref bg_ref;
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96 int rc = ext4_fs_get_block_group_ref(fs, block_group, &bg_ref);
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100 /* Load i-node bitmap */
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101 uint32_t bitmap_block_addr =
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102 ext4_bg_get_inode_bitmap(bg_ref.block_group, sb);
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104 struct ext4_block bitmap_block;
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105 rc = ext4_block_get(fs->bdev, &bitmap_block, bitmap_block_addr);
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109 /* Free i-node in the bitmap */
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110 uint32_t index_in_group = ext4_ialloc_inode2index_in_group(sb, index);
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111 ext4_bmap_bit_clr(bitmap_block.data, index_in_group);
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112 bitmap_block.dirty = true;
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114 /* Put back the block with bitmap */
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115 rc = ext4_block_set(fs->bdev, &bitmap_block);
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117 /* Error in saving bitmap */
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118 ext4_fs_put_block_group_ref(&bg_ref);
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122 /* If released i-node is a directory, decrement used directories count */
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124 uint32_t bg_used_dirs =
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125 ext4_bg_get_used_dirs_count(bg_ref.block_group, sb);
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127 ext4_bg_set_used_dirs_count(bg_ref.block_group, sb, bg_used_dirs);
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130 /* Update block group free inodes count */
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131 uint32_t free_inodes =
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132 ext4_bg_get_free_inodes_count(bg_ref.block_group, sb);
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134 ext4_bg_set_free_inodes_count(bg_ref.block_group, sb, free_inodes);
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136 bg_ref.dirty = true;
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138 /* Put back the modified block group */
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139 rc = ext4_fs_put_block_group_ref(&bg_ref);
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143 /* Update superblock free inodes count */
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144 ext4_set32(sb, free_inodes_count, ext4_get32(sb, free_inodes_count) + 1);
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149 int ext4_ialloc_alloc_inode(struct ext4_fs *fs, uint32_t *index, bool is_dir)
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151 struct ext4_sblock *sb = &fs->sb;
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153 uint32_t bgid = fs->last_inode_bg_id;
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154 uint32_t bg_count = ext4_block_group_cnt(sb);
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155 uint32_t sb_free_inodes = ext4_get32(sb, free_inodes_count);
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156 bool rewind = false;
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158 /* Try to find free i-node in all block groups */
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159 while (bgid <= bg_count) {
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161 if (bgid == bg_count) {
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164 bg_count = fs->last_inode_bg_id;
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170 /* Load block group to check */
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171 struct ext4_block_group_ref bg_ref;
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172 int rc = ext4_fs_get_block_group_ref(fs, bgid, &bg_ref);
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176 struct ext4_bgroup *bg = bg_ref.block_group;
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178 /* Read necessary values for algorithm */
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179 uint32_t free_inodes = ext4_bg_get_free_inodes_count(bg, sb);
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180 uint32_t used_dirs = ext4_bg_get_used_dirs_count(bg, sb);
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182 /* Check if this block group is good candidate for allocation */
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183 if (free_inodes > 0) {
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184 /* Load block with bitmap */
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185 uint32_t bitmap_block_addr =
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186 ext4_bg_get_inode_bitmap(bg_ref.block_group, sb);
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188 struct ext4_block bitmap_block;
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189 rc = ext4_block_get(fs->bdev, &bitmap_block, bitmap_block_addr);
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191 ext4_fs_put_block_group_ref(&bg_ref);
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195 /* Try to allocate i-node in the bitmap */
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196 uint32_t inodes_in_group = ext4_inodes_in_group_cnt(sb, bgid);
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197 uint32_t index_in_group;
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199 rc = ext4_bmap_bit_find_clr(bitmap_block.data, 0, inodes_in_group,
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201 /* Block group has not any free i-node */
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202 if (rc == ENOSPC) {
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203 rc = ext4_block_set(fs->bdev, &bitmap_block);
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205 ext4_fs_put_block_group_ref(&bg_ref);
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209 rc = ext4_fs_put_block_group_ref(&bg_ref);
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216 ext4_bmap_bit_set(bitmap_block.data, index_in_group);
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218 /* Free i-node found, save the bitmap */
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219 bitmap_block.dirty = true;
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221 ext4_block_set(fs->bdev, &bitmap_block);
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223 ext4_fs_put_block_group_ref(&bg_ref);
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227 /* Modify filesystem counters */
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229 ext4_bg_set_free_inodes_count(bg, sb, free_inodes);
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231 /* Increment used directories counter */
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234 ext4_bg_set_used_dirs_count(bg, sb, used_dirs);
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237 /* Decrease unused inodes count */
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238 if (ext4_bg_has_flag(bg, EXT4_BLOCK_GROUP_ITABLE_ZEROED)) {
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239 uint32_t unused = ext4_bg_get_itable_unused(bg, sb);
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241 uint32_t inodes_in_group = ext4_inodes_in_group_cnt(sb, bgid);
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243 uint32_t free = inodes_in_group - unused;
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245 if (index_in_group >= free) {
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246 unused = inodes_in_group - (index_in_group + 1);
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247 ext4_bg_set_itable_unused(bg, sb, unused);
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251 /* Save modified block group */
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252 bg_ref.dirty = true;
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254 rc = ext4_fs_put_block_group_ref(&bg_ref);
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258 /* Update superblock */
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260 ext4_set32(sb, free_inodes_count, sb_free_inodes);
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262 /* Compute the absolute i-nodex number */
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263 *index = ext4_ialloc_index_in_group2inode(sb, index_in_group, bgid);
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265 fs->last_inode_bg_id = bgid;
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270 /* Block group not modified, put it and jump to the next block group */
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271 ext4_fs_put_block_group_ref(&bg_ref);
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