source: mainline/uspace/lib/ext4/src/ialloc.c@ fcb0d76

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since fcb0d76 was fcb0d76, checked in by Jiri Svoboda <jiri@…>, 8 years ago

Libext4 should try to include what it uses.
  • Property mode set to 100644
File size: 9.2 KB
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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 <stdbool.h>
39#include "ext4/bitmap.h"
40#include "ext4/block_group.h"
41#include "ext4/filesystem.h"
42#include "ext4/ialloc.h"
43#include "ext4/superblock.h"
44
45
46/** Convert i-node number to relative index in block group.
47 *
48 * @param sb Superblock
49 * @param inode I-node number to be converted
50 *
51 * @return Index of the i-node in the block group
52 *
53 */
54static uint32_t ext4_ialloc_inode2index_in_group(ext4_superblock_t *sb,
55 uint32_t inode)
56{
57 uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
58 return (inode - 1) % inodes_per_group;
59}
60
61/** Convert relative index of i-node to absolute i-node number.
62 *
63 * @param sb Superblock
64 * @param inode Index to be converted
65 *
66 * @return Absolute number of the i-node
67 *
68 */
69static uint32_t ext4_ialloc_index_in_group2inode(ext4_superblock_t *sb,
70 uint32_t index, uint32_t bgid)
71{
72 uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
73 return bgid * inodes_per_group + (index + 1);
74}
75
76/** Compute block group number from the i-node number.
77 *
78 * @param sb Superblock
79 * @param inode I-node number to be found the block group for
80 *
81 * @return Block group number computed from i-node number
82 *
83 */
84static uint32_t ext4_ialloc_get_bgid_of_inode(ext4_superblock_t *sb,
85 uint32_t inode)
86{
87 uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
88 return (inode - 1) / inodes_per_group;
89}
90
91
92/** Free i-node number and modify filesystem data structers.
93 *
94 * @param fs Filesystem, where the i-node is located
95 * @param index Index of i-node to be release
96 * @param is_dir Flag us for information whether i-node is directory or not
97 *
98 */
99int ext4_ialloc_free_inode(ext4_filesystem_t *fs, uint32_t index, bool is_dir)
100{
101 ext4_superblock_t *sb = fs->superblock;
102
103 /* Compute index of block group and load it */
104 uint32_t block_group = ext4_ialloc_get_bgid_of_inode(sb, index);
105
106 ext4_block_group_ref_t *bg_ref;
107 int rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
108 if (rc != EOK)
109 return rc;
110
111 /* Load i-node bitmap */
112 uint32_t bitmap_block_addr = ext4_block_group_get_inode_bitmap(
113 bg_ref->block_group, sb);
114 block_t *bitmap_block;
115 rc = block_get(&bitmap_block, fs->device, bitmap_block_addr,
116 BLOCK_FLAGS_NONE);
117 if (rc != EOK)
118 return rc;
119
120 /* Free i-node in the bitmap */
121 uint32_t index_in_group = ext4_ialloc_inode2index_in_group(sb, index);
122 ext4_bitmap_free_bit(bitmap_block->data, index_in_group);
123 bitmap_block->dirty = true;
124
125 /* Put back the block with bitmap */
126 rc = block_put(bitmap_block);
127 if (rc != EOK) {
128 /* Error in saving bitmap */
129 ext4_filesystem_put_block_group_ref(bg_ref);
130 return rc;
131 }
132
133 /* If released i-node is a directory, decrement used directories count */
134 if (is_dir) {
135 uint32_t bg_used_dirs = ext4_block_group_get_used_dirs_count(
136 bg_ref->block_group, sb);
137 bg_used_dirs--;
138 ext4_block_group_set_used_dirs_count(bg_ref->block_group, sb,
139 bg_used_dirs);
140 }
141
142 /* Update block group free inodes count */
143 uint32_t free_inodes = ext4_block_group_get_free_inodes_count(
144 bg_ref->block_group, sb);
145 free_inodes++;
146 ext4_block_group_set_free_inodes_count(bg_ref->block_group, sb,
147 free_inodes);
148
149 bg_ref->dirty = true;
150
151 /* Put back the modified block group */
152 rc = ext4_filesystem_put_block_group_ref(bg_ref);
153 if (rc != EOK)
154 return rc;
155
156 /* Update superblock free inodes count */
157 uint32_t sb_free_inodes =
158 ext4_superblock_get_free_inodes_count(sb);
159 sb_free_inodes++;
160 ext4_superblock_set_free_inodes_count(sb, sb_free_inodes);
161
162 return EOK;
163}
164
165/** I-node allocation algorithm.
166 *
167 * This is more simple algorithm, than Orlov allocator used
168 * in the Linux kernel.
169 *
170 * @param fs Filesystem to allocate i-node on
171 * @param index Output value - allocated i-node number
172 * @param is_dir Flag if allocated i-node will be file or directory
173 *
174 * @return Error code
175 *
176 */
177int ext4_ialloc_alloc_inode(ext4_filesystem_t *fs, uint32_t *index, bool is_dir)
178{
179 ext4_superblock_t *sb = fs->superblock;
180
181 uint32_t bgid = 0;
182 uint32_t bg_count = ext4_superblock_get_block_group_count(sb);
183 uint32_t sb_free_inodes = ext4_superblock_get_free_inodes_count(sb);
184 uint32_t avg_free_inodes = sb_free_inodes / bg_count;
185
186 /* Try to find free i-node in all block groups */
187 while (bgid < bg_count) {
188 /* Load block group to check */
189 ext4_block_group_ref_t *bg_ref;
190 int rc = ext4_filesystem_get_block_group_ref(fs, bgid, &bg_ref);
191 if (rc != EOK)
192 return rc;
193
194 ext4_block_group_t *bg = bg_ref->block_group;
195
196 /* Read necessary values for algorithm */
197 uint32_t free_blocks = ext4_block_group_get_free_blocks_count(bg, sb);
198 uint32_t free_inodes = ext4_block_group_get_free_inodes_count(bg, sb);
199 uint32_t used_dirs = ext4_block_group_get_used_dirs_count(bg, sb);
200
201 /*
202 * Check if this block group is a good candidate
203 * for allocation.
204 *
205 * The criterion is based on the average number
206 * of free inodes, unless we examine the last block
207 * group. In that case the last block group might
208 * have less than the average number of free inodes,
209 * but it still needs to be taken as a candidate
210 * because the previous block groups have zero free
211 * blocks.
212 */
213 if (((free_inodes >= avg_free_inodes) || (bgid == bg_count - 1)) &&
214 (free_blocks > 0)) {
215 /* Load block with bitmap */
216 uint32_t bitmap_block_addr = ext4_block_group_get_inode_bitmap(
217 bg_ref->block_group, sb);
218
219 block_t *bitmap_block;
220 rc = block_get(&bitmap_block, fs->device, bitmap_block_addr,
221 BLOCK_FLAGS_NONE);
222 if (rc != EOK) {
223 ext4_filesystem_put_block_group_ref(bg_ref);
224 return rc;
225 }
226
227 /* Try to allocate i-node in the bitmap */
228 uint32_t inodes_in_group = ext4_superblock_get_inodes_in_group(sb, bgid);
229 uint32_t index_in_group;
230 rc = ext4_bitmap_find_free_bit_and_set(bitmap_block->data,
231 0, &index_in_group, inodes_in_group);
232
233 /* Block group has not any free i-node */
234 if (rc == ENOSPC) {
235 rc = block_put(bitmap_block);
236 if (rc != EOK) {
237 ext4_filesystem_put_block_group_ref(bg_ref);
238 return rc;
239 }
240
241 rc = ext4_filesystem_put_block_group_ref(bg_ref);
242 if (rc != EOK)
243 return rc;
244
245 bgid++;
246 continue;
247 }
248
249 /* Free i-node found, save the bitmap */
250 bitmap_block->dirty = true;
251
252 rc = block_put(bitmap_block);
253 if (rc != EOK) {
254 ext4_filesystem_put_block_group_ref(bg_ref);
255 return rc;
256 }
257
258 /* Modify filesystem counters */
259 free_inodes--;
260 ext4_block_group_set_free_inodes_count(bg, sb, free_inodes);
261
262 /* Increment used directories counter */
263 if (is_dir) {
264 used_dirs++;
265 ext4_block_group_set_used_dirs_count(bg, sb, used_dirs);
266 }
267
268 /* Decrease unused inodes count */
269 if (ext4_block_group_has_flag(bg,
270 EXT4_BLOCK_GROUP_ITABLE_ZEROED)) {
271 uint32_t unused =
272 ext4_block_group_get_itable_unused(bg, sb);
273
274 uint32_t inodes_in_group =
275 ext4_superblock_get_inodes_in_group(sb, bgid);
276
277 uint32_t free = inodes_in_group - unused;
278
279 if (index_in_group >= free) {
280 unused = inodes_in_group - (index_in_group + 1);
281 ext4_block_group_set_itable_unused(bg, sb, unused);
282 }
283 }
284
285 /* Save modified block group */
286 bg_ref->dirty = true;
287
288 rc = ext4_filesystem_put_block_group_ref(bg_ref);
289 if (rc != EOK)
290 return rc;
291
292 /* Update superblock */
293 sb_free_inodes--;
294 ext4_superblock_set_free_inodes_count(sb, sb_free_inodes);
295
296 /* Compute the absolute i-nodex number */
297 *index = ext4_ialloc_index_in_group2inode(sb, index_in_group, bgid);
298
299 return EOK;
300 }
301
302 /* Block group not modified, put it and jump to the next block group */
303 rc = ext4_filesystem_put_block_group_ref(bg_ref);
304 if (rc != EOK)
305 return rc;
306
307 ++bgid;
308 }
309
310 return ENOSPC;
311}
312
313/**
314 * @}
315 */
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