lib/ext2fs/bmap.c

   1 /*
   2  * bmap.c --- logical to phiscal block mapping
   3  *
   4  * Copyright (C) 1997 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 #include <stdio.h>
  13 #include <string.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #include <stdlib.h>
  18
  19 #include <linux/ext2_fs.h>
  20
  21 #include "ext2fs.h"
  22
  23 #if defined(__GNUC__) && !defined(NO_INLINE_FUNCS)
  24 #define _BMAP_INLINE_   __inline__
  25 #else
  26 #define _BMAP_INLINE_
  27 #endif
  28
  29 extern errcode_t ext2fs_bmap(ext2_filsys fs, ino_t ino,
  30                              struct ext2_inode *inode,
  31                              char *block_buf, int bmap_flags,
  32                              blk_t block, blk_t *phys_blk);
  33
  34 #define BMAP_ALLOC      1
  35
  36 #define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
  37
  38 static blk_t _BMAP_INLINE_ block_bmap(ext2_filsys fs, char *buf, blk_t nr)
  39 {
  40         blk_t tmp;
  41
  42         tmp = ((blk_t *) buf)[nr];
  43
  44         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  45             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
  46                 return ext2fs_swab32(tmp);
  47
  48         return tmp;
  49 }
  50
  51 static errcode_t _BMAP_INLINE_ block_ind_bmap(ext2_filsys fs, int flags,
  52                                               blk_t ind, char *block_buf,
  53                                               int *blocks_alloc,
  54                                               blk_t nr, blk_t *ret_blk)
  55 {
  56         errcode_t       retval;
  57         blk_t           b;
  58
  59         if (!ind) {
  60                 *ret_blk = 0;
  61                 return 0;
  62         }
  63         retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
  64         if (retval)
  65                 return retval;
  66
  67         b = ((blk_t *) block_buf)[nr];
  68
  69         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  70             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
  71                 b = ext2fs_swab32(b);
  72
  73         if (!b && (flags & BMAP_ALLOC)) {
  74                 b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
  75                 retval = ext2fs_alloc_block(fs, b,
  76                                             block_buf + fs->blocksize, &b);
  77                 if (retval)
  78                         return retval;
  79
  80                 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  81                     (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
  82                         ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
  83                 else
  84                         ((blk_t *) block_buf)[nr] = b;
  85
  86                 retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
  87                 if (retval)
  88                         return retval;
  89
  90                 (*blocks_alloc)++;
  91         }
  92
  93         *ret_blk = b;
  94         return 0;
  95 }
  96
  97 static errcode_t _BMAP_INLINE_ block_dind_bmap(ext2_filsys fs, int flags,
  98                                                blk_t dind, char *block_buf,
  99                                                int *blocks_alloc,
 100                                                blk_t nr, blk_t *ret_blk)
 101 {
 102         blk_t           b;
 103         errcode_t       retval;
 104         int             addr_per_block;
 105
 106         addr_per_block = fs->blocksize >> 2;
 107
 108         retval = block_ind_bmap(fs, flags, dind, block_buf, blocks_alloc,
 109                                 nr / addr_per_block, &b);
 110         if (retval)
 111                 return retval;
 112         retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
 113                                 nr % addr_per_block, ret_blk);
 114         return retval;
 115 }
 116
 117 static errcode_t _BMAP_INLINE_ block_tind_bmap(ext2_filsys fs, int flags,
 118                                                blk_t tind, char *block_buf,
 119                                                int *blocks_alloc,
 120                                                blk_t nr, blk_t *ret_blk)
 121 {
 122         blk_t           b;
 123         errcode_t       retval;
 124         int             addr_per_block;
 125
 126         addr_per_block = fs->blocksize >> 2;
 127
 128         retval = block_dind_bmap(fs, flags, tind, block_buf, blocks_alloc,
 129                                  nr / addr_per_block, &b);
 130         if (retval)
 131                 return retval;
 132         retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
 133                                 nr % addr_per_block, ret_blk);
 134         return retval;
 135 }
 136
 137 errcode_t ext2fs_bmap(ext2_filsys fs, ino_t ino, struct ext2_inode *inode,
 138                       char *block_buf, int bmap_flags, blk_t block,
 139                       blk_t *phys_blk)
 140 {
 141         struct ext2_inode inode_buf;
 142         int addr_per_block;
 143         blk_t   b;
 144         char    *buf = 0;
 145         errcode_t       retval = 0;
 146         int             blocks_alloc = 0;
 147
 148         *phys_blk = 0;
 149
 150         /* Read inode structure if necessary */
 151         if (!inode) {
 152                 retval = ext2fs_read_inode(fs, ino, &inode_buf);
 153                 if (!retval)
 154                         return retval;
 155                 inode = &inode_buf;
 156         }
 157         addr_per_block = fs->blocksize >> 2;
 158
 159         if (!block_buf) {
 160                 buf = malloc(fs->blocksize * 2);
 161                 if (!buf)
 162                         return EXT2_NO_MEMORY;
 163                 block_buf = buf;
 164         }
 165
 166         if (block < EXT2_NDIR_BLOCKS) {
 167                 *phys_blk = inode_bmap(inode, block);
 168                 b = block ? inode_bmap(inode, block-1) : 0;
 169
 170                 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
 171                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 172                         if (retval)
 173                                 goto done;
 174                         inode_bmap(inode, block) = b;
 175                         blocks_alloc++;
 176                         *phys_blk = b;
 177                 }
 178                 goto done;
 179         }
 180
 181         /* Indirect block */
 182         block -= EXT2_NDIR_BLOCKS;
 183         if (block < addr_per_block) {
 184                 b = inode_bmap(inode, EXT2_IND_BLOCK);
 185                 if (!b) {
 186                         if (!(bmap_flags & BMAP_ALLOC))
 187                             goto done;
 188
 189                         b = inode_bmap(inode, EXT2_IND_BLOCK-1);
 190                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 191                         if (retval)
 192                                 goto done;
 193                         inode_bmap(inode, EXT2_IND_BLOCK) = b;
 194                         blocks_alloc++;
 195                 }
 196                 retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
 197                                         &blocks_alloc, block, phys_blk);
 198                 goto done;
 199         }
 200
 201         /* Doubly indirect block  */
 202         block -= addr_per_block;
 203         if (block < addr_per_block * addr_per_block) {
 204                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 205                 if (!b) {
 206                         if (!(bmap_flags & BMAP_ALLOC))
 207                             goto done;
 208
 209                         b = inode_bmap(inode, EXT2_IND_BLOCK);
 210                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 211                         if (retval)
 212                                 goto done;
 213                         inode_bmap(inode, EXT2_DIND_BLOCK) = b;
 214                         blocks_alloc++;
 215                 }
 216                 retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
 217                                          &blocks_alloc, block, phys_blk);
 218                 goto done;
 219         }
 220
 221         /* Triply indirect block */
 222         block -= addr_per_block * addr_per_block;
 223         b = inode_bmap(inode, EXT2_TIND_BLOCK);
 224         if (!b) {
 225                 if (!(bmap_flags & BMAP_ALLOC))
 226                         goto done;
 227
 228                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 229                 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 230                 if (retval)
 231                         goto done;
 232                 inode_bmap(inode, EXT2_TIND_BLOCK) = b;
 233                 blocks_alloc++;
 234         }
 235         retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
 236                                  &blocks_alloc, block, phys_blk);
 237 done:
 238         if (buf)
 239                 free(buf);
 240         if ((retval == 0) && blocks_alloc) {
 241                 inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
 242                 retval = ext2fs_write_inode(fs, ino, inode);
 243         }
 244         return retval;
 245 }
 246
 247
 248