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 <linux/ext2_fs.h>
  27
  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, ino_t dir, int mode,
  37                            ext2fs_inode_bitmap map, ino_t *ret)
  38 {
  39         ino_t   dir_group = 0;
  40         ino_t   i;
  41         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_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_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         int             group;
 112         char            *buf = 0;
 113
 114         if (!block_buf) {
 115                 retval = ext2fs_get_mem(fs->blocksize, (void **) &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         fs->super->s_free_blocks_count--;
 137         group = ext2fs_group_of_blk(fs, block);
 138         fs->group_desc[group].bg_free_blocks_count--;
 139         ext2fs_mark_block_bitmap(fs->block_map, block);
 140         ext2fs_mark_super_dirty(fs);
 141         ext2fs_mark_bb_dirty(fs);
 142         *ret = block;
 143         return 0;
 144
 145 fail:
 146         if (buf)
 147                 ext2fs_free_mem((void **) &buf);
 148         return retval;
 149 }
 150
 151 errcode_t ext2fs_get_free_blocks(ext2_filsys fs, blk_t start, blk_t finish,
 152                                  int num, ext2fs_block_bitmap map, blk_t *ret)
 153 {
 154         blk_t   b = start;
 155
 156         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 157
 158         if (!map)
 159                 map = fs->block_map;
 160         if (!map)
 161                 return EXT2_ET_NO_BLOCK_BITMAP;
 162         if (!b)
 163                 b = fs->super->s_first_data_block;
 164         if (!finish)
 165                 finish = start;
 166         if (!num)
 167                 num = 1;
 168         do {
 169                 if (b+num-1 > fs->super->s_blocks_count)
 170                         b = fs->super->s_first_data_block;
 171                 if (ext2fs_fast_test_block_bitmap_range(map, b, num)) {
 172                         *ret = b;
 173                         return 0;
 174                 }
 175                 b++;
 176         } while (b != finish);
 177         return EXT2_ET_BLOCK_ALLOC_FAIL;
 178 }
 179