release/src/router/busybox/e2fsprogs/ext2fs/alloc.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * alloc.c --- allocate new inodes, blocks for ext2fs
   4  *
   5  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Public
   9  * License.
  10  * %End-Header%
  11  *
  12  */
  13
  14 #include <stdio.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18 #include <time.h>
  19 #include <string.h>
  20 #if HAVE_SYS_STAT_H
  21 #include <sys/stat.h>
  22 #endif
  23 #if HAVE_SYS_TYPES_H
  24 #include <sys/types.h>
  25 #endif
  26
  27 #include "ext2_fs.h"
  28 #include "ext2fs.h"
  29
  30 /*
  31  * Right now, just search forward from the parent directory's block
  32  * group to find the next free inode.
  33  *
  34  * Should have a special policy for directories.
  35  */
  36 errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
  37                            int mode EXT2FS_ATTR((unused)),
  38                            ext2fs_inode_bitmap map, ext2_ino_t *ret)
  39 {
  40         ext2_ino_t      dir_group = 0;
  41         ext2_ino_t      i;
  42         ext2_ino_t      start_inode;
  43
  44         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  45
  46         if (!map)
  47                 map = fs->inode_map;
  48         if (!map)
  49                 return EXT2_ET_NO_INODE_BITMAP;
  50
  51         if (dir > 0)
  52                 dir_group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
  53
  54         start_inode = (dir_group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
  55         if (start_inode < EXT2_FIRST_INODE(fs->super))
  56                 start_inode = EXT2_FIRST_INODE(fs->super);
  57         i = start_inode;
  58
  59         do {
  60                 if (!ext2fs_fast_test_inode_bitmap(map, i))
  61                         break;
  62                 i++;
  63                 if (i > fs->super->s_inodes_count)
  64                         i = EXT2_FIRST_INODE(fs->super);
  65         } while (i != start_inode);
  66
  67         if (ext2fs_test_inode_bitmap(map, i))
  68                 return EXT2_ET_INODE_ALLOC_FAIL;
  69         *ret = i;
  70         return 0;
  71 }
  72
  73 /*
  74  * Stupid algorithm --- we now just search forward starting from the
  75  * goal.  Should put in a smarter one someday....
  76  */
  77 errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
  78                            ext2fs_block_bitmap map, blk_t *ret)
  79 {
  80         blk_t   i;
  81
  82         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  83
  84         if (!map)
  85                 map = fs->block_map;
  86         if (!map)
  87                 return EXT2_ET_NO_BLOCK_BITMAP;
  88         if (!goal || (goal >= fs->super->s_blocks_count))
  89                 goal = fs->super->s_first_data_block;
  90         i = goal;
  91         do {
  92                 if (!ext2fs_fast_test_block_bitmap(map, i)) {
  93                         *ret = i;
  94                         return 0;
  95                 }
  96                 i++;
  97                 if (i >= fs->super->s_blocks_count)
  98                         i = fs->super->s_first_data_block;
  99         } while (i != goal);
 100         return EXT2_ET_BLOCK_ALLOC_FAIL;
 101 }
 102
 103 /*
 104  * This function zeros out the allocated block, and updates all of the
 105  * appropriate filesystem records.
 106  */
 107 errcode_t ext2fs_alloc_block(ext2_filsys fs, blk_t goal,
 108                              char *block_buf, blk_t *ret)
 109 {
 110         errcode_t       retval;
 111         blk_t           block;
 112         char            *buf = NULL;
 113
 114         if (!block_buf) {
 115                 retval = ext2fs_get_mem(fs->blocksize, &buf);
 116                 if (retval)
 117                         return retval;
 118                 block_buf = buf;
 119         }
 120         memset(block_buf, 0, fs->blocksize);
 121
 122         if (!fs->block_map) {
 123                 retval = ext2fs_read_block_bitmap(fs);
 124                 if (retval)
 125                         goto fail;
 126         }
 127
 128         retval = ext2fs_new_block(fs, goal, 0, &block);
 129         if (retval)
 130                 goto fail;
 131
 132         retval = io_channel_write_blk(fs->io, block, 1, block_buf);
 133         if (retval)
 134                 goto fail;
 135
 136         ext2fs_block_alloc_stats(fs, block, +1);
 137         *ret = block;
 138         return 0;
 139
 140 fail:
 141         if (buf)
 142                 ext2fs_free_mem(&buf);
 143         return retval;
 144 }
 145
 146 errcode_t ext2fs_get_free_blocks(ext2_filsys fs, blk_t start, blk_t finish,
 147                                  int num, ext2fs_block_bitmap map, blk_t *ret)
 148 {
 149         blk_t   b = start;
 150
 151         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 152
 153         if (!map)
 154                 map = fs->block_map;
 155         if (!map)
 156                 return EXT2_ET_NO_BLOCK_BITMAP;
 157         if (!b)
 158                 b = fs->super->s_first_data_block;
 159         if (!finish)
 160                 finish = start;
 161         if (!num)
 162                 num = 1;
 163         do {
 164                 if (b+num-1 > fs->super->s_blocks_count)
 165                         b = fs->super->s_first_data_block;
 166                 if (ext2fs_fast_test_block_bitmap_range(map, b, num)) {
 167                         *ret = b;
 168                         return 0;
 169                 }
 170                 b++;
 171         } while (b != finish);
 172         return EXT2_ET_BLOCK_ALLOC_FAIL;
 173 }