source: mainline/uspace/lib/ext4/libext4_ialloc.c@ b3cf946

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since b3cf946 was 38542dc, checked in by Martin Decky <martin@…>, 13 years ago

ext4 code review and coding style cleanup
  • Property mode set to 100644
File size: 8.4 KB
Line 
1/*
2 * Copyright (c) 2012 Frantisek Princ
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup libext4
30 * @{
31 */
32/**
33 * @file libext4_ialloc.c
34 * @brief I-node (de)allocation operations.
35 */
36
37#include <errno.h>
38#include <time.h>
39#include "libext4.h"
40
41
42/** Convert i-node number to relative index in block group.
43 *
44 * @param sb Superblock
45 * @param inode I-node number to be converted
46 *
47 * @return Index of the i-node in the block group
48 *
49 */
50static uint32_t ext4_ialloc_inode2index_in_group(ext4_superblock_t *sb,
51 uint32_t inode)
52{
53 uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
54 return (inode - 1) % inodes_per_group;
55}
56
57/** Convert relative index of i-node to absolute i-node number.
58 *
59 * @param sb Superblock
60 * @param inode Index to be converted
61 *
62 * @return Absolute number of the i-node
63 *
64 */
65static uint32_t ext4_ialloc_index_in_group2inode(ext4_superblock_t *sb,
66 uint32_t index, uint32_t bgid)
67{
68 uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
69 return bgid * inodes_per_group + (index + 1);
70}
71
72/** Compute block group number from the i-node number.
73 *
74 * @param sb Superblock
75 * @param inode I-node number to be found the block group for
76 *
77 * @return Block group number computed from i-node number
78 *
79 */
80static uint32_t ext4_ialloc_get_bgid_of_inode(ext4_superblock_t *sb,
81 uint32_t inode)
82{
83 uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
84 return (inode - 1) / inodes_per_group;
85}
86
87
88/** Free i-node number and modify filesystem data structers.
89 *
90 * @param fs Filesystem, where the i-node is located
91 * @param index Index of i-node to be release
92 * @param is_dir Flag us for information whether i-node is directory or not
93 *
94 */
95int ext4_ialloc_free_inode(ext4_filesystem_t *fs, uint32_t index, bool is_dir)
96{
97 ext4_superblock_t *sb = fs->superblock;
98
99 /* Compute index of block group and load it */
100 uint32_t block_group = ext4_ialloc_get_bgid_of_inode(sb, index);
101
102 ext4_block_group_ref_t *bg_ref;
103 int rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
104 if (rc != EOK)
105 return rc;
106
107 /* Load i-node bitmap */
108 uint32_t bitmap_block_addr = ext4_block_group_get_inode_bitmap(
109 bg_ref->block_group, sb);
110 block_t *bitmap_block;
111 rc = block_get(&bitmap_block, fs->device, bitmap_block_addr,
112 BLOCK_FLAGS_NONE);
113 if (rc != EOK)
114 return rc;
115
116 /* Free i-node in the bitmap */
117 uint32_t index_in_group = ext4_ialloc_inode2index_in_group(sb, index);
118 ext4_bitmap_free_bit(bitmap_block->data, index_in_group);
119 bitmap_block->dirty = true;
120
121 /* Put back the block with bitmap */
122 rc = block_put(bitmap_block);
123 if (rc != EOK) {
124 /* Error in saving bitmap */
125 ext4_filesystem_put_block_group_ref(bg_ref);
126 return rc;
127 }
128
129 /* If released i-node is a directory, decrement used directories count */
130 if (is_dir) {
131 uint32_t bg_used_dirs = ext4_block_group_get_used_dirs_count(
132 bg_ref->block_group, sb);
133 bg_used_dirs--;
134 ext4_block_group_set_used_dirs_count(bg_ref->block_group, sb,
135 bg_used_dirs);
136 }
137
138 /* Update block group free inodes count */
139 uint32_t free_inodes = ext4_block_group_get_free_inodes_count(
140 bg_ref->block_group, sb);
141 free_inodes++;
142 ext4_block_group_set_free_inodes_count(bg_ref->block_group, sb,
143 free_inodes);
144
145 bg_ref->dirty = true;
146
147 /* Put back the modified block group */
148 rc = ext4_filesystem_put_block_group_ref(bg_ref);
149 if (rc != EOK)
150 return rc;
151
152 /* Update superblock free inodes count */
153 uint32_t sb_free_inodes =
154 ext4_superblock_get_free_inodes_count(sb);
155 sb_free_inodes++;
156 ext4_superblock_set_free_inodes_count(sb, sb_free_inodes);
157
158 return EOK;
159}
160
161/** I-node allocation algorithm.
162 *
163 * This is more simple algorithm, than Orlov allocator used
164 * in the Linux kernel.
165 *
166 * @param fs Filesystem to allocate i-node on
167 * @param index Output value - allocated i-node number
168 * @param is_dir Flag if allocated i-node will be file or directory
169 *
170 * @return Error code
171 *
172 */
173int ext4_ialloc_alloc_inode(ext4_filesystem_t *fs, uint32_t *index, bool is_dir)
174{
175 ext4_superblock_t *sb = fs->superblock;
176
177 uint32_t bgid = 0;
178 uint32_t bg_count = ext4_superblock_get_block_group_count(sb);
179 uint32_t sb_free_inodes = ext4_superblock_get_free_inodes_count(sb);
180 uint32_t avg_free_inodes = sb_free_inodes / bg_count;
181
182 /* Try to find free i-node in all block groups */
183 while (bgid < bg_count) {
184 /* Load block group to check */
185 ext4_block_group_ref_t *bg_ref;
186 int rc = ext4_filesystem_get_block_group_ref(fs, bgid, &bg_ref);
187 if (rc != EOK)
188 return rc;
189
190 ext4_block_group_t *bg = bg_ref->block_group;
191
192 /* Read necessary values for algorithm */
193 uint32_t free_blocks = ext4_block_group_get_free_blocks_count(bg, sb);
194 uint32_t free_inodes = ext4_block_group_get_free_inodes_count(bg, sb);
195 uint32_t used_dirs = ext4_block_group_get_used_dirs_count(bg, sb);
196
197 /* Check if this block group is good candidate for allocation */
198 if ((free_inodes >= avg_free_inodes) && (free_blocks > 0)) {
199 /* Load block with bitmap */
200 uint32_t bitmap_block_addr = ext4_block_group_get_inode_bitmap(
201 bg_ref->block_group, sb);
202
203 block_t *bitmap_block;
204 rc = block_get(&bitmap_block, fs->device, bitmap_block_addr,
205 BLOCK_FLAGS_NONE);
206 if (rc != EOK)
207 return rc;
208
209 /* Try to allocate i-node in the bitmap */
210 uint32_t inodes_in_group = ext4_superblock_get_inodes_in_group(sb, bgid);
211 uint32_t index_in_group;
212 rc = ext4_bitmap_find_free_bit_and_set(bitmap_block->data,
213 0, &index_in_group, inodes_in_group);
214
215 /* Block group has not any free i-node */
216 if (rc == ENOSPC) {
217 block_put(bitmap_block);
218 ext4_filesystem_put_block_group_ref(bg_ref);
219 continue;
220 }
221
222 /* Free i-node found, save the bitmap */
223 bitmap_block->dirty = true;
224
225 rc = block_put(bitmap_block);
226 if (rc != EOK)
227 return rc;
228
229 /* Modify filesystem counters */
230 free_inodes--;
231 ext4_block_group_set_free_inodes_count(bg, sb, free_inodes);
232
233 /* Increment used directories counter */
234 if (is_dir) {
235 used_dirs++;
236 ext4_block_group_set_used_dirs_count(bg, sb, used_dirs);
237 }
238
239 /* Decrease unused inodes count */
240 if (ext4_block_group_has_flag(bg,
241 EXT4_BLOCK_GROUP_ITABLE_ZEROED)) {
242 uint32_t unused =
243 ext4_block_group_get_itable_unused(bg, sb);
244
245 uint32_t inodes_in_group =
246 ext4_superblock_get_inodes_in_group(sb, bgid);
247
248 uint32_t free = inodes_in_group - unused;
249
250 if (index_in_group >= free) {
251 unused = inodes_in_group - (index_in_group + 1);
252 ext4_block_group_set_itable_unused(bg, sb, unused);
253 }
254 }
255
256 /* Save modified block group */
257 bg_ref->dirty = true;
258
259 rc = ext4_filesystem_put_block_group_ref(bg_ref);
260 if (rc != EOK)
261 return rc;
262
263 /* Update superblock */
264 sb_free_inodes--;
265 ext4_superblock_set_free_inodes_count(sb, sb_free_inodes);
266
267 /* Compute the absolute i-nodex number */
268 *index = ext4_ialloc_index_in_group2inode(sb, index_in_group, bgid);
269
270 return EOK;
271 }
272
273 /* Block group not modified, put it and jump to the next block group */
274 ext4_filesystem_put_block_group_ref(bg_ref);
275 ++bgid;
276 }
277
278 return ENOSPC;
279}
280
281/**
282 * @}
283 */
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