lib/ext2fs/alloc.c

   1 /*
   2  * alloc.c --- allocate new inodes, blocks for ext2fs
   3  *
   4  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Public
   8  * License.
   9  * %End-Header%
  10  *
  11  */
  12
  13 #include <stdio.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #include <time.h>
  18 #include <string.h>
  19 #if HAVE_SYS_STAT_H
  20 #include <sys/stat.h>
  21 #endif
  22 #if HAVE_SYS_TYPES_H
  23 #include <sys/types.h>
  24 #endif
  25
  26 #include "ext2_fs.h"
  27 #include "ext2fs.h"
  28
  29 /*
  30  * Check for uninit block bitmaps and deal with them appropriately
  31  */
  32 static void check_block_uninit(ext2_filsys fs, ext2fs_block_bitmap map,
  33                           dgrp_t group)
  34 {
  35         blk_t           i;
  36         blk_t           blk, super_blk, old_desc_blk, new_desc_blk;
  37         int             old_desc_blocks;
  38
  39         if (!(EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
  40                                          EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) ||
  41             !(fs->group_desc[group].bg_flags & EXT2_BG_BLOCK_UNINIT))
  42                 return;
  43
  44         blk = (group * fs->super->s_blocks_per_group) +
  45                 fs->super->s_first_data_block;
  46
  47         ext2fs_super_and_bgd_loc(fs, group, &super_blk,
  48                                  &old_desc_blk, &new_desc_blk, 0);
  49
  50         if (fs->super->s_feature_incompat &
  51             EXT2_FEATURE_INCOMPAT_META_BG)
  52                 old_desc_blocks = fs->super->s_first_meta_bg;
  53         else
  54                 old_desc_blocks = fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
  55
  56         for (i=0; i < fs->super->s_blocks_per_group; i++, blk++) {
  57                 if ((blk == super_blk) ||
  58                     (old_desc_blk && old_desc_blocks &&
  59                      (blk >= old_desc_blk) &&
  60                      (blk < old_desc_blk + old_desc_blocks)) ||
  61                     (new_desc_blk && (blk == new_desc_blk)) ||
  62                     (blk == fs->group_desc[group].bg_block_bitmap) ||
  63                     (blk == fs->group_desc[group].bg_inode_bitmap) ||
  64                     (blk >= fs->group_desc[group].bg_inode_table &&
  65                      (blk < fs->group_desc[group].bg_inode_table
  66                       + fs->inode_blocks_per_group)))
  67                         ext2fs_fast_mark_block_bitmap(map, blk);
  68                 else
  69                         ext2fs_fast_unmark_block_bitmap(map, blk);
  70         }
  71         fs->group_desc[group].bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
  72         ext2fs_group_desc_csum_set(fs, group);
  73 }
  74
  75 /*
  76  * Check for uninit inode bitmaps and deal with them appropriately
  77  */
  78 static void check_inode_uninit(ext2_filsys fs, ext2fs_inode_bitmap map,
  79                           dgrp_t group)
  80 {
  81         ext2_ino_t      i, ino;
  82
  83         if (!(EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
  84                                          EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) ||
  85             !(fs->group_desc[group].bg_flags & EXT2_BG_INODE_UNINIT))
  86                 return;
  87
  88         ino = (group * fs->super->s_inodes_per_group) + 1;
  89         for (i=0; i < fs->super->s_inodes_per_group; i++, ino++)
  90                 ext2fs_fast_unmark_inode_bitmap(map, ino);
  91
  92         fs->group_desc[group].bg_flags &= ~EXT2_BG_INODE_UNINIT;
  93         check_block_uninit(fs, fs->block_map, group);
  94 }
  95
  96 /*
  97  * Right now, just search forward from the parent directory's block
  98  * group to find the next free inode.
  99  *
 100  * Should have a special policy for directories.
 101  */
 102 errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
 103                            int mode EXT2FS_ATTR((unused)),
 104                            ext2fs_inode_bitmap map, ext2_ino_t *ret)
 105 {
 106         ext2_ino_t      dir_group = 0;
 107         ext2_ino_t      i;
 108         ext2_ino_t      start_inode;
 109
 110         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 111
 112         if (!map)
 113                 map = fs->inode_map;
 114         if (!map)
 115                 return EXT2_ET_NO_INODE_BITMAP;
 116
 117         if (dir > 0)
 118                 dir_group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
 119
 120         start_inode = (dir_group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
 121         if (start_inode < EXT2_FIRST_INODE(fs->super))
 122                 start_inode = EXT2_FIRST_INODE(fs->super);
 123         i = start_inode;
 124
 125         do {
 126                 if (((i - 1) % EXT2_INODES_PER_GROUP(fs->super)) == 0)
 127                         check_inode_uninit(fs, map, (i - 1) /
 128                                            EXT2_INODES_PER_GROUP(fs->super));
 129
 130                 if (!ext2fs_fast_test_inode_bitmap(map, i))
 131                         break;
 132                 i++;
 133                 if (i > fs->super->s_inodes_count)
 134                         i = EXT2_FIRST_INODE(fs->super);
 135         } while (i != start_inode);
 136
 137         if (ext2fs_test_inode_bitmap(map, i))
 138                 return EXT2_ET_INODE_ALLOC_FAIL;
 139         *ret = i;
 140         return 0;
 141 }
 142
 143 /*
 144  * Stupid algorithm --- we now just search forward starting from the
 145  * goal.  Should put in a smarter one someday....
 146  */
 147 errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
 148                            ext2fs_block_bitmap map, blk_t *ret)
 149 {
 150         blk_t   i;
 151
 152         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 153
 154         if (!map)
 155                 map = fs->block_map;
 156         if (!map)
 157                 return EXT2_ET_NO_BLOCK_BITMAP;
 158         if (!goal || (goal >= fs->super->s_blocks_count))
 159                 goal = fs->super->s_first_data_block;
 160         i = goal;
 161         check_block_uninit(fs, map,
 162                            (i - fs->super->s_first_data_block) /
 163                            EXT2_BLOCKS_PER_GROUP(fs->super));
 164         do {
 165                 if (((i - fs->super->s_first_data_block) %
 166                      EXT2_BLOCKS_PER_GROUP(fs->super)) == 0)
 167                         check_block_uninit(fs, map,
 168                                            (i - fs->super->s_first_data_block) /
 169                                            EXT2_BLOCKS_PER_GROUP(fs->super));
 170
 171                 if (!ext2fs_fast_test_block_bitmap(map, i)) {
 172                         *ret = i;
 173                         return 0;
 174                 }
 175                 i++;
 176                 if (i >= fs->super->s_blocks_count)
 177                         i = fs->super->s_first_data_block;
 178         } while (i != goal);
 179         return EXT2_ET_BLOCK_ALLOC_FAIL;
 180 }
 181
 182 /*
 183  * This function zeros out the allocated block, and updates all of the
 184  * appropriate filesystem records.
 185  */
 186 errcode_t ext2fs_alloc_block(ext2_filsys fs, blk_t goal,
 187                              char *block_buf, blk_t *ret)
 188 {
 189         errcode_t       retval;
 190         blk_t           block;
 191         char            *buf = 0;
 192
 193         if (!block_buf) {
 194                 retval = ext2fs_get_mem(fs->blocksize, &buf);
 195                 if (retval)
 196                         return retval;
 197                 block_buf = buf;
 198         }
 199         memset(block_buf, 0, fs->blocksize);
 200
 201         if (fs->get_alloc_block) {
 202                 blk64_t new;
 203
 204                 retval = (fs->get_alloc_block)(fs, (blk64_t) goal, &new);
 205                 if (retval)
 206                         goto fail;
 207                 block = (blk_t) new;
 208         } else {
 209                 if (!fs->block_map) {
 210                         retval = ext2fs_read_block_bitmap(fs);
 211                         if (retval)
 212                                 goto fail;
 213                 }
 214
 215                 retval = ext2fs_new_block(fs, goal, 0, &block);
 216                 if (retval)
 217                         goto fail;
 218         }
 219
 220         retval = io_channel_write_blk(fs->io, block, 1, block_buf);
 221         if (retval)
 222                 goto fail;
 223
 224         ext2fs_block_alloc_stats(fs, block, +1);
 225         *ret = block;
 226
 227 fail:
 228         if (buf)
 229                 ext2fs_free_mem(&buf);
 230         return retval;
 231 }
 232
 233 errcode_t ext2fs_get_free_blocks(ext2_filsys fs, blk_t start, blk_t finish,
 234                                  int num, ext2fs_block_bitmap map, blk_t *ret)
 235 {
 236         blk_t   b = start;
 237
 238         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 239
 240         if (!map)
 241                 map = fs->block_map;
 242         if (!map)
 243                 return EXT2_ET_NO_BLOCK_BITMAP;
 244         if (!b)
 245                 b = fs->super->s_first_data_block;
 246         if (!finish)
 247                 finish = start;
 248         if (!num)
 249                 num = 1;
 250         do {
 251                 if (b+num-1 > fs->super->s_blocks_count)
 252                         b = fs->super->s_first_data_block;
 253                 if (ext2fs_fast_test_block_bitmap_range(map, b, num)) {
 254                         *ret = b;
 255                         return 0;
 256                 }
 257                 b++;
 258         } while (b != finish);
 259         return EXT2_ET_BLOCK_ALLOC_FAIL;
 260 }
 261
 262 void ext2fs_set_alloc_block_callback(ext2_filsys fs,
 263                                      errcode_t (*func)(ext2_filsys fs,
 264                                                        blk64_t goal,
 265                                                        blk64_t *ret),
 266                                      errcode_t (**old)(ext2_filsys fs,
 267                                                        blk64_t goal,
 268                                                        blk64_t *ret))
 269 {
 270         if (!fs || fs->magic != EXT2_ET_MAGIC_EXT2FS_FILSYS)
 271                 return;
 272
 273         if (old)
 274                 *old = fs->get_alloc_block;
 275
 276         fs->get_alloc_block = func;
 277 }