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_crc32c.h"
  47 #include "ext4_fs.h"
  48 #include "ext4_blockdev.h"
  49 #include "ext4_block_group.h"
  50 #include "ext4_bitmap.h"
  51
  52 /**@brief  Convert i-node number to relative index in block group.
  53  * @param sb    Superblock
  54  * @param inode I-node number to be converted
  55  * @return Index of the i-node in the block group
  56  */
  57 static uint32_t ext4_ialloc_inode2index_in_group(struct ext4_sblock *sb,
  58                                                  uint32_t inode)
  59 {
  60         uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
  61         return (inode - 1) % inodes_per_group;
  62 }
  63
  64 /**@brief Convert relative index of i-node to absolute i-node number.
  65  * @param sb    Superblock
  66  * @param index Index to be converted
  67  * @return Absolute number of the i-node
  68  *
  69  */
  70 static uint32_t ext4_ialloc_index_in_group2inode(struct ext4_sblock *sb,
  71                                                  uint32_t index, uint32_t bgid)
  72 {
  73         uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
  74         return bgid * inodes_per_group + (index + 1);
  75 }
  76
  77 /**@brief Compute block group number from the i-node number.
  78  * @param sb    Superblock
  79  * @param inode I-node number to be found the block group for
  80  * @return Block group number computed from i-node number
  81  */
  82 static uint32_t ext4_ialloc_get_bgid_of_inode(struct ext4_sblock *sb,
  83                                               uint32_t inode)
  84 {
  85         uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
  86         return (inode - 1) / inodes_per_group;
  87 }
  88
  89 static uint32_t ext4_ialloc_bitmap_csum(struct ext4_sblock *sb,
  90                                         void *bitmap)
  91 {
  92         uint32_t checksum = 0;
  93         if (ext4_sb_has_feature_read_only(sb,
  94                                 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
  95                 uint32_t inodes_per_group =
  96                         ext4_get32(sb, inodes_per_group);
  97
  98                 /* First calculate crc32 checksum against fs uuid */
  99                 checksum = ext4_crc32c(~0, sb->uuid, sizeof(sb->uuid));
 100                 /* Then calculate crc32 checksum against inode bitmap */
 101                 checksum = ext4_crc32c(checksum, bitmap,
 102                                      (inodes_per_group + 7) / 8);
 103         }
 104         return checksum;
 105 }
 106
 107 /*
 108  * BIG FAT NOTES:
 109  *       Currently we do not verify the checksum of bitmaps.
 110  */
 111
 112 void ext4_ialloc_set_bitmap_csum(struct ext4_sblock *sb,
 113                                  struct ext4_bgroup *bg,
 114                                  void *bitmap)
 115 {
 116         int desc_size = ext4_sb_get_desc_size(sb);
 117         uint32_t checksum = ext4_ialloc_bitmap_csum(sb, bitmap);
 118         uint16_t lo_checksum = to_le16(checksum & 0xFFFF),
 119                  hi_checksum = to_le16(checksum >> 16);
 120
 121         /* See if we need to assign a 32bit checksum */
 122         bg->inode_bitmap_csum_lo = lo_checksum;
 123         if (desc_size == EXT4_MAX_BLOCK_GROUP_DESCRIPTOR_SIZE)
 124                 bg->inode_bitmap_csum_hi = hi_checksum;
 125
 126 }
 127
 128 int ext4_ialloc_free_inode(struct ext4_fs *fs, uint32_t index, bool is_dir)
 129 {
 130         struct ext4_sblock *sb = &fs->sb;
 131
 132         /* Compute index of block group and load it */
 133         uint32_t block_group = ext4_ialloc_get_bgid_of_inode(sb, index);
 134
 135         struct ext4_block_group_ref bg_ref;
 136         int rc = ext4_fs_get_block_group_ref(fs, block_group, &bg_ref);
 137         if (rc != EOK)
 138                 return rc;
 139
 140         /* Load i-node bitmap */
 141         uint32_t bitmap_block_addr =
 142             ext4_bg_get_inode_bitmap(bg_ref.block_group, sb);
 143
 144         struct ext4_block bitmap_block;
 145         rc = ext4_block_get(fs->bdev, &bitmap_block, bitmap_block_addr);
 146         if (rc != EOK)
 147                 return rc;
 148
 149         /* Free i-node in the bitmap */
 150         uint32_t index_in_group = ext4_ialloc_inode2index_in_group(sb, index);
 151         ext4_bmap_bit_clr(bitmap_block.data, index_in_group);
 152         ext4_ialloc_set_bitmap_csum(sb, bg_ref.block_group,
 153                                     bitmap_block.data);
 154         bitmap_block.dirty = true;
 155
 156         /* Put back the block with bitmap */
 157         rc = ext4_block_set(fs->bdev, &bitmap_block);
 158         if (rc != EOK) {
 159                 /* Error in saving bitmap */
 160                 ext4_fs_put_block_group_ref(&bg_ref);
 161                 return rc;
 162         }
 163
 164         /* If released i-node is a directory, decrement used directories count
 165          */
 166         if (is_dir) {
 167                 uint32_t bg_used_dirs =
 168                     ext4_bg_get_used_dirs_count(bg_ref.block_group, sb);
 169                 bg_used_dirs--;
 170                 ext4_bg_set_used_dirs_count(bg_ref.block_group, sb,
 171                                             bg_used_dirs);
 172         }
 173
 174         /* Update block group free inodes count */
 175         uint32_t free_inodes =
 176             ext4_bg_get_free_inodes_count(bg_ref.block_group, sb);
 177         free_inodes++;
 178         ext4_bg_set_free_inodes_count(bg_ref.block_group, sb, free_inodes);
 179
 180         bg_ref.dirty = true;
 181
 182         /* Put back the modified block group */
 183         rc = ext4_fs_put_block_group_ref(&bg_ref);
 184         if (rc != EOK)
 185                 return rc;
 186
 187         /* Update superblock free inodes count */
 188         ext4_set32(sb, free_inodes_count,
 189                    ext4_get32(sb, free_inodes_count) + 1);
 190
 191         return EOK;
 192 }
 193
 194 int ext4_ialloc_alloc_inode(struct ext4_fs *fs, uint32_t *index, bool is_dir)
 195 {
 196         struct ext4_sblock *sb = &fs->sb;
 197
 198         uint32_t bgid = fs->last_inode_bg_id;
 199         uint32_t bg_count = ext4_block_group_cnt(sb);
 200         uint32_t sb_free_inodes = ext4_get32(sb, free_inodes_count);
 201         bool rewind = false;
 202
 203         /* Try to find free i-node in all block groups */
 204         while (bgid <= bg_count) {
 205
 206                 if (bgid == bg_count) {
 207                         if (rewind)
 208                                 break;
 209                         bg_count = fs->last_inode_bg_id;
 210                         bgid = 0;
 211                         rewind = true;
 212                         continue;
 213                 }
 214
 215                 /* Load block group to check */
 216                 struct ext4_block_group_ref bg_ref;
 217                 int rc = ext4_fs_get_block_group_ref(fs, bgid, &bg_ref);
 218                 if (rc != EOK)
 219                         return rc;
 220
 221                 struct ext4_bgroup *bg = bg_ref.block_group;
 222
 223                 /* Read necessary values for algorithm */
 224                 uint32_t free_inodes = ext4_bg_get_free_inodes_count(bg, sb);
 225                 uint32_t used_dirs = ext4_bg_get_used_dirs_count(bg, sb);
 226
 227                 /* Check if this block group is good candidate for allocation */
 228                 if (free_inodes > 0) {
 229                         /* Load block with bitmap */
 230                         uint32_t bitmap_block_addr =
 231                             ext4_bg_get_inode_bitmap(bg_ref.block_group, sb);
 232
 233                         struct ext4_block bitmap_block;
 234                         rc = ext4_block_get(fs->bdev, &bitmap_block,
 235                                             bitmap_block_addr);
 236                         if (rc != EOK) {
 237                                 ext4_fs_put_block_group_ref(&bg_ref);
 238                                 return rc;
 239                         }
 240
 241                         /* Try to allocate i-node in the bitmap */
 242                         uint32_t inodes_in_group =
 243                             ext4_inodes_in_group_cnt(sb, bgid);
 244                         uint32_t index_in_group;
 245
 246                         rc = ext4_bmap_bit_find_clr(bitmap_block.data, 0,
 247                                                     inodes_in_group,
 248                                                     &index_in_group);
 249                         /* Block group has not any free i-node */
 250                         if (rc == ENOSPC) {
 251                                 rc = ext4_block_set(fs->bdev, &bitmap_block);
 252                                 if (rc != EOK) {
 253                                         ext4_fs_put_block_group_ref(&bg_ref);
 254                                         return rc;
 255                                 }
 256
 257                                 rc = ext4_fs_put_block_group_ref(&bg_ref);
 258                                 if (rc != EOK)
 259                                         return rc;
 260
 261                                 continue;
 262                         }
 263
 264                         ext4_bmap_bit_set(bitmap_block.data, index_in_group);
 265
 266                         /* Free i-node found, save the bitmap */
 267                         ext4_ialloc_set_bitmap_csum(sb, bg_ref.block_group,
 268                                                     bitmap_block.data);
 269                         bitmap_block.dirty = true;
 270
 271                         ext4_block_set(fs->bdev, &bitmap_block);
 272                         if (rc != EOK) {
 273                                 ext4_fs_put_block_group_ref(&bg_ref);
 274                                 return rc;
 275                         }
 276
 277                         /* Modify filesystem counters */
 278                         free_inodes--;
 279                         ext4_bg_set_free_inodes_count(bg, sb, free_inodes);
 280
 281                         /* Increment used directories counter */
 282                         if (is_dir) {
 283                                 used_dirs++;
 284                                 ext4_bg_set_used_dirs_count(bg, sb, used_dirs);
 285                         }
 286
 287                         /* Decrease unused inodes count */
 288                         uint32_t unused =
 289                             ext4_bg_get_itable_unused(bg, sb);
 290
 291                         uint32_t free = inodes_in_group - unused;
 292
 293                         if (index_in_group >= free) {
 294                                 unused = inodes_in_group -
 295                                          (index_in_group + 1);
 296                                 ext4_bg_set_itable_unused(bg, sb,
 297                                                           unused);
 298                         }
 299
 300                         /* Save modified block group */
 301                         bg_ref.dirty = true;
 302
 303                         rc = ext4_fs_put_block_group_ref(&bg_ref);
 304                         if (rc != EOK)
 305                                 return rc;
 306
 307                         /* Update superblock */
 308                         sb_free_inodes--;
 309                         ext4_set32(sb, free_inodes_count, sb_free_inodes);
 310
 311                         /* Compute the absolute i-nodex number */
 312                         *index = ext4_ialloc_index_in_group2inode(
 313                             sb, index_in_group, bgid);
 314
 315                         fs->last_inode_bg_id = bgid;
 316
 317                         return EOK;
 318                 }
 319
 320                 /* Block group not modified, put it and jump to the next block
 321                  * group */
 322                 ext4_fs_put_block_group_ref(&bg_ref);
 323                 if (rc != EOK)
 324                         return rc;
 325
 326                 ++bgid;
 327         }
 328
 329         return ENOSPC;
 330 }
 331
 332 /**
 333  * @}
 334  */