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  * Right now, just search forward from the parent directory's block
  31  * group to find the next free inode.
  32  *
  33  * Should have a special policy for directories.
  34  */
  35 errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
  36                            int mode EXT2FS_ATTR((unused)),
  37                            ext2fs_inode_bitmap map, ext2_ino_t *ret)
  38 {
  39         ext2_ino_t      dir_group = 0;
  40         ext2_ino_t      i;
  41         ext2_ino_t      start_inode;
  42
  43         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  44
  45         if (!map)
  46                 map = fs->inode_map;
  47         if (!map)
  48                 return EXT2_ET_NO_INODE_BITMAP;
  49
  50         if (dir > 0)
  51                 dir_group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
  52
  53         start_inode = (dir_group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
  54         if (start_inode < EXT2_FIRST_INODE(fs->super))
  55                 start_inode = EXT2_FIRST_INODE(fs->super);
  56         i = start_inode;
  57
  58         do {
  59                 if (!ext2fs_fast_test_inode_bitmap(map, i))
  60                         break;
  61                 i++;
  62                 if (i > fs->super->s_inodes_count)
  63                         i = EXT2_FIRST_INODE(fs->super);
  64         } while (i != start_inode);
  65
  66         if (ext2fs_test_inode_bitmap(map, i))
  67                 return EXT2_ET_INODE_ALLOC_FAIL;
  68         *ret = i;
  69         return 0;
  70 }
  71
  72 /*
  73  * Stupid algorithm --- we now just search forward starting from the
  74  * goal.  Should put in a smarter one someday....
  75  */
  76 errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
  77                            ext2fs_block_bitmap map, blk_t *ret)
  78 {
  79         blk_t   i;
  80
  81         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  82
  83         if (!map)
  84                 map = fs->block_map;
  85         if (!map)
  86                 return EXT2_ET_NO_BLOCK_BITMAP;
  87         if (!goal || (goal >= fs->super->s_blocks_count))
  88                 goal = fs->super->s_first_data_block;
  89         i = goal;
  90         do {
  91                 if (!ext2fs_fast_test_block_bitmap(map, i)) {
  92                         *ret = i;
  93                         return 0;
  94                 }
  95                 i++;
  96                 if (i >= fs->super->s_blocks_count)
  97                         i = fs->super->s_first_data_block;
  98         } while (i != goal);
  99         return EXT2_ET_BLOCK_ALLOC_FAIL;
 100 }
 101
 102 /*
 103  * This function zeros out the allocated block, and updates all of the
 104  * appropriate filesystem records.
 105  */
 106 errcode_t ext2fs_alloc_block(ext2_filsys fs, blk_t goal,
 107                              char *block_buf, blk_t *ret)
 108 {
 109         errcode_t       retval;
 110         blk_t           block;
 111         char            *buf = 0;
 112
 113         if (!block_buf) {
 114                 retval = ext2fs_get_mem(fs->blocksize, &buf);
 115                 if (retval)
 116                         return retval;
 117                 block_buf = buf;
 118         }
 119         memset(block_buf, 0, fs->blocksize);
 120
 121         if (fs->get_alloc_block) {
 122                 blk64_t new;
 123
 124                 retval = (fs->get_alloc_block)(fs, (blk64_t) goal, &new);
 125                 if (retval)
 126                         goto fail;
 127                 block = (blk_t) new;
 128         } else {
 129                 if (!fs->block_map) {
 130                         retval = ext2fs_read_block_bitmap(fs);
 131                         if (retval)
 132                                 goto fail;
 133                 }
 134
 135                 retval = ext2fs_new_block(fs, goal, 0, &block);
 136                 if (retval)
 137                         goto fail;
 138         }
 139
 140         retval = io_channel_write_blk(fs->io, block, 1, block_buf);
 141         if (retval)
 142                 goto fail;
 143
 144         ext2fs_block_alloc_stats(fs, block, +1);
 145         *ret = block;
 146
 147 fail:
 148         if (buf)
 149                 ext2fs_free_mem(&buf);
 150         return retval;
 151 }
 152
 153 errcode_t ext2fs_get_free_blocks(ext2_filsys fs, blk_t start, blk_t finish,
 154                                  int num, ext2fs_block_bitmap map, blk_t *ret)
 155 {
 156         blk_t   b = start;
 157
 158         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 159
 160         if (!map)
 161                 map = fs->block_map;
 162         if (!map)
 163                 return EXT2_ET_NO_BLOCK_BITMAP;
 164         if (!b)
 165                 b = fs->super->s_first_data_block;
 166         if (!finish)
 167                 finish = start;
 168         if (!num)
 169                 num = 1;
 170         do {
 171                 if (b+num-1 > fs->super->s_blocks_count)
 172                         b = fs->super->s_first_data_block;
 173                 if (ext2fs_fast_test_block_bitmap_range(map, b, num)) {
 174                         *ret = b;
 175                         return 0;
 176                 }
 177                 b++;
 178         } while (b != finish);
 179         return EXT2_ET_BLOCK_ALLOC_FAIL;
 180 }
 181
 182 void ext2fs_set_alloc_block_callback(ext2_filsys fs,
 183                                      errcode_t (*func)(ext2_filsys fs,
 184                                                        blk64_t goal,
 185                                                        blk64_t *ret),
 186                                      errcode_t (**old)(ext2_filsys fs,
 187                                                        blk64_t goal,
 188                                                        blk64_t *ret))
 189 {
 190         if (!fs || fs->magic != EXT2_ET_MAGIC_EXT2FS_FILSYS)
 191                 return;
 192
 193         if (old)
 194                 *old = fs->get_alloc_block;
 195
 196         fs->get_alloc_block = func;
 197 }