lwext4/ext4_ialloc.c

   1 /*
   2  * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
   3  *
   4  *
   5  * HelenOS:
   6  * Copyright (c) 2012 Martin Sucha
   7  * Copyright (c) 2012 Frantisek Princ
   8  * All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  * - Redistributions of source code must retain the above copyright
  15  *   notice, this list of conditions and the following disclaimer.
  16  * - Redistributions in binary form must reproduce the above copyright
  17  *   notice, this list of conditions and the following disclaimer in the
  18  *   documentation and/or other materials provided with the distribution.
  19  * - The name of the author may not be used to endorse or promote products
  20  *   derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 /** @addtogroup lwext4
  35  * @{
  36  */
  37 /**
  38  * @file  ext4_ialloc.c
  39  * @brief Inode allocation procedures.
  40  */
  41
  42 #include "ext4_config.h"
  43 #include "ext4_types.h"
  44 #include "ext4_ialloc.h"
  45 #include "ext4_super.h"
  46 #include "ext4_fs.h"
  47 #include "ext4_blockdev.h"
  48 #include "ext4_block_group.h"
  49 #include "ext4_bitmap.h"
  50
  51 /**@brief  Convert i-node number to relative index in block group.
  52  * @param sb    Superblock
  53  * @param inode I-node number to be converted
  54  * @return Index of the i-node in the block group
  55  */
  56 static uint32_t ext4_ialloc_inode2index_in_group(struct ext4_sblock *sb,
  57                                                  uint32_t inode)
  58 {
  59         uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
  60         return (inode - 1) % inodes_per_group;
  61 }
  62
  63 /**@brief Convert relative index of i-node to absolute i-node number.
  64  * @param sb    Superblock
  65  * @param index Index to be converted
  66  * @return Absolute number of the i-node
  67  *
  68  */
  69 static uint32_t ext4_ialloc_index_in_group2inode(struct ext4_sblock *sb,
  70                                                  uint32_t index, uint32_t bgid)
  71 {
  72         uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
  73         return bgid * inodes_per_group + (index + 1);
  74 }
  75
  76 /**@brief Compute block group number from the i-node number.
  77  * @param sb    Superblock
  78  * @param inode I-node number to be found the block group for
  79  * @return Block group number computed from i-node number
  80  */
  81 static uint32_t ext4_ialloc_get_bgid_of_inode(struct ext4_sblock *sb,
  82                                               uint32_t inode)
  83 {
  84         uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
  85         return (inode - 1) / inodes_per_group;
  86 }
  87
  88 int ext4_ialloc_free_inode(struct ext4_fs *fs, uint32_t index, bool is_dir)
  89 {
  90         struct ext4_sblock *sb = &fs->sb;
  91
  92         /* Compute index of block group and load it */
  93         uint32_t block_group = ext4_ialloc_get_bgid_of_inode(sb, index);
  94
  95         struct ext4_block_group_ref bg_ref;
  96         int rc = ext4_fs_get_block_group_ref(fs, block_group, &bg_ref);
  97         if (rc != EOK)
  98                 return rc;
  99
 100         /* Load i-node bitmap */
 101         uint32_t bitmap_block_addr =
 102             ext4_bg_get_inode_bitmap(bg_ref.block_group, sb);
 103
 104         struct ext4_block bitmap_block;
 105         rc = ext4_block_get(fs->bdev, &bitmap_block, bitmap_block_addr);
 106         if (rc != EOK)
 107                 return rc;
 108
 109         /* Free i-node in the bitmap */
 110         uint32_t index_in_group = ext4_ialloc_inode2index_in_group(sb, index);
 111         ext4_bmap_bit_clr(bitmap_block.data, index_in_group);
 112         bitmap_block.dirty = true;
 113
 114         /* Put back the block with bitmap */
 115         rc = ext4_block_set(fs->bdev, &bitmap_block);
 116         if (rc != EOK) {
 117                 /* Error in saving bitmap */
 118                 ext4_fs_put_block_group_ref(&bg_ref);
 119                 return rc;
 120         }
 121
 122         /* If released i-node is a directory, decrement used directories count
 123          */
 124         if (is_dir) {
 125                 uint32_t bg_used_dirs =
 126                     ext4_bg_get_used_dirs_count(bg_ref.block_group, sb);
 127                 bg_used_dirs--;
 128                 ext4_bg_set_used_dirs_count(bg_ref.block_group, sb,
 129                                             bg_used_dirs);
 130         }
 131
 132         /* Update block group free inodes count */
 133         uint32_t free_inodes =
 134             ext4_bg_get_free_inodes_count(bg_ref.block_group, sb);
 135         free_inodes++;
 136         ext4_bg_set_free_inodes_count(bg_ref.block_group, sb, free_inodes);
 137
 138         bg_ref.dirty = true;
 139
 140         /* Put back the modified block group */
 141         rc = ext4_fs_put_block_group_ref(&bg_ref);
 142         if (rc != EOK)
 143                 return rc;
 144
 145         /* Update superblock free inodes count */
 146         ext4_set32(sb, free_inodes_count,
 147                    ext4_get32(sb, free_inodes_count) + 1);
 148
 149         return EOK;
 150 }
 151
 152 int ext4_ialloc_alloc_inode(struct ext4_fs *fs, uint32_t *index, bool is_dir)
 153 {
 154         struct ext4_sblock *sb = &fs->sb;
 155
 156         uint32_t bgid = fs->last_inode_bg_id;
 157         uint32_t bg_count = ext4_block_group_cnt(sb);
 158         uint32_t sb_free_inodes = ext4_get32(sb, free_inodes_count);
 159         bool rewind = false;
 160
 161         /* Try to find free i-node in all block groups */
 162         while (bgid <= bg_count) {
 163
 164                 if (bgid == bg_count) {
 165                         if (rewind)
 166                                 break;
 167                         bg_count = fs->last_inode_bg_id;
 168                         bgid = 0;
 169                         rewind = true;
 170                         continue;
 171                 }
 172
 173                 /* Load block group to check */
 174                 struct ext4_block_group_ref bg_ref;
 175                 int rc = ext4_fs_get_block_group_ref(fs, bgid, &bg_ref);
 176                 if (rc != EOK)
 177                         return rc;
 178
 179                 struct ext4_bgroup *bg = bg_ref.block_group;
 180
 181                 /* Read necessary values for algorithm */
 182                 uint32_t free_inodes = ext4_bg_get_free_inodes_count(bg, sb);
 183                 uint32_t used_dirs = ext4_bg_get_used_dirs_count(bg, sb);
 184
 185                 /* Check if this block group is good candidate for allocation */
 186                 if (free_inodes > 0) {
 187                         /* Load block with bitmap */
 188                         uint32_t bitmap_block_addr =
 189                             ext4_bg_get_inode_bitmap(bg_ref.block_group, sb);
 190
 191                         struct ext4_block bitmap_block;
 192                         rc = ext4_block_get(fs->bdev, &bitmap_block,
 193                                             bitmap_block_addr);
 194                         if (rc != EOK) {
 195                                 ext4_fs_put_block_group_ref(&bg_ref);
 196                                 return rc;
 197                         }
 198
 199                         /* Try to allocate i-node in the bitmap */
 200                         uint32_t inodes_in_group =
 201                             ext4_inodes_in_group_cnt(sb, bgid);
 202                         uint32_t index_in_group;
 203
 204                         rc = ext4_bmap_bit_find_clr(bitmap_block.data, 0,
 205                                                     inodes_in_group,
 206                                                     &index_in_group);
 207                         /* Block group has not any free i-node */
 208                         if (rc == ENOSPC) {
 209                                 rc = ext4_block_set(fs->bdev, &bitmap_block);
 210                                 if (rc != EOK) {
 211                                         ext4_fs_put_block_group_ref(&bg_ref);
 212                                         return rc;
 213                                 }
 214
 215                                 rc = ext4_fs_put_block_group_ref(&bg_ref);
 216                                 if (rc != EOK)
 217                                         return rc;
 218
 219                                 continue;
 220                         }
 221
 222                         ext4_bmap_bit_set(bitmap_block.data, index_in_group);
 223
 224                         /* Free i-node found, save the bitmap */
 225                         bitmap_block.dirty = true;
 226
 227                         ext4_block_set(fs->bdev, &bitmap_block);
 228                         if (rc != EOK) {
 229                                 ext4_fs_put_block_group_ref(&bg_ref);
 230                                 return rc;
 231                         }
 232
 233                         /* Modify filesystem counters */
 234                         free_inodes--;
 235                         ext4_bg_set_free_inodes_count(bg, sb, free_inodes);
 236
 237                         /* Increment used directories counter */
 238                         if (is_dir) {
 239                                 used_dirs++;
 240                                 ext4_bg_set_used_dirs_count(bg, sb, used_dirs);
 241                         }
 242
 243                         /* Decrease unused inodes count */
 244                         if (ext4_bg_has_flag(bg,
 245                                              EXT4_BLOCK_GROUP_ITABLE_ZEROED)) {
 246                                 uint32_t unused =
 247                                     ext4_bg_get_itable_unused(bg, sb);
 248
 249                                 uint32_t inodes_in_group =
 250                                     ext4_inodes_in_group_cnt(sb, bgid);
 251
 252                                 uint32_t free = inodes_in_group - unused;
 253
 254                                 if (index_in_group >= free) {
 255                                         unused = inodes_in_group -
 256                                                  (index_in_group + 1);
 257                                         ext4_bg_set_itable_unused(bg, sb,
 258                                                                   unused);
 259                                 }
 260                         }
 261
 262                         /* Save modified block group */
 263                         bg_ref.dirty = true;
 264
 265                         rc = ext4_fs_put_block_group_ref(&bg_ref);
 266                         if (rc != EOK)
 267                                 return rc;
 268
 269                         /* Update superblock */
 270                         sb_free_inodes--;
 271                         ext4_set32(sb, free_inodes_count, sb_free_inodes);
 272
 273                         /* Compute the absolute i-nodex number */
 274                         *index = ext4_ialloc_index_in_group2inode(
 275                             sb, index_in_group, bgid);
 276
 277                         fs->last_inode_bg_id = bgid;
 278
 279                         return EOK;
 280                 }
 281
 282                 /* Block group not modified, put it and jump to the next block
 283                  * group */
 284                 ext4_fs_put_block_group_ref(&bg_ref);
 285                 if (rc != EOK)
 286                         return rc;
 287
 288                 ++bgid;
 289         }
 290
 291         return ENOSPC;
 292 }
 293
 294 /**
 295  * @}
 296  */