lib/ext2fs/bmap.c

   1 /*
   2  * bmap.c --- logical to physical 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
  18 #include "ext2_fs.h"
  19 #include "ext2fs.h"
  20
  21 #if defined(__GNUC__) && !defined(NO_INLINE_FUNCS)
  22 #define _BMAP_INLINE_   __inline__
  23 #else
  24 #define _BMAP_INLINE_
  25 #endif
  26
  27 extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
  28                              struct ext2_inode *inode,
  29                              char *block_buf, int bmap_flags,
  30                              blk_t block, blk_t *phys_blk);
  31
  32 #define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
  33
  34 static _BMAP_INLINE_ errcode_t block_ind_bmap(ext2_filsys fs, int flags,
  35                                               blk_t ind, char *block_buf,
  36                                               int *blocks_alloc,
  37                                               blk_t nr, blk_t *ret_blk)
  38 {
  39         errcode_t       retval;
  40         blk_t           b;
  41
  42         if (!ind) {
  43                 if (flags & BMAP_SET)
  44                         return EXT2_ET_SET_BMAP_NO_IND;
  45                 *ret_blk = 0;
  46                 return 0;
  47         }
  48         retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
  49         if (retval)
  50                 return retval;
  51
  52         if (flags & BMAP_SET) {
  53                 b = *ret_blk;
  54 #ifdef EXT2FS_ENABLE_SWAPFS
  55                 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  56                     (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
  57                         b = ext2fs_swab32(b);
  58 #endif
  59                 ((blk_t *) block_buf)[nr] = b;
  60                 return io_channel_write_blk(fs->io, ind, 1, block_buf);
  61         }
  62
  63         b = ((blk_t *) block_buf)[nr];
  64
  65 #ifdef EXT2FS_ENABLE_SWAPFS
  66         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  67             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
  68                 b = ext2fs_swab32(b);
  69 #endif
  70
  71         if (!b && (flags & BMAP_ALLOC)) {
  72                 b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
  73                 retval = ext2fs_alloc_block(fs, b,
  74                                             block_buf + fs->blocksize, &b);
  75                 if (retval)
  76                         return retval;
  77
  78 #ifdef EXT2FS_ENABLE_SWAPFS
  79                 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  80                     (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
  81                         ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
  82                 else
  83 #endif
  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 _BMAP_INLINE_ errcode_t 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         blk_t           addr_per_block;
 105
 106         addr_per_block = (blk_t) fs->blocksize >> 2;
 107
 108         retval = block_ind_bmap(fs, flags & ~BMAP_SET, dind, block_buf,
 109                                 blocks_alloc, 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 _BMAP_INLINE_ errcode_t 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         blk_t           addr_per_block;
 125
 126         addr_per_block = (blk_t) fs->blocksize >> 2;
 127
 128         retval = block_dind_bmap(fs, flags & ~BMAP_SET, tind, block_buf,
 129                                  blocks_alloc, 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, ext2_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         blk_t addr_per_block;
 143         blk_t   b;
 144         char    *buf = 0;
 145         errcode_t       retval = 0;
 146         int             blocks_alloc = 0, inode_dirty = 0;
 147
 148         if (!(bmap_flags & BMAP_SET))
 149                 *phys_blk = 0;
 150
 151         /* Read inode structure if necessary */
 152         if (!inode) {
 153                 retval = ext2fs_read_inode(fs, ino, &inode_buf);
 154                 if (retval)
 155                         return retval;
 156                 inode = &inode_buf;
 157         }
 158         addr_per_block = (blk_t) fs->blocksize >> 2;
 159
 160         if (!block_buf) {
 161                 retval = ext2fs_get_array(2, fs->blocksize, &buf);
 162                 if (retval)
 163                         return retval;
 164                 block_buf = buf;
 165         }
 166
 167         if (block < EXT2_NDIR_BLOCKS) {
 168                 if (bmap_flags & BMAP_SET) {
 169                         b = *phys_blk;
 170 #ifdef EXT2FS_ENABLE_SWAPFS
 171                         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 172                             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
 173                                 b = ext2fs_swab32(b);
 174 #endif
 175                         inode_bmap(inode, block) = b;
 176                         inode_dirty++;
 177                         goto done;
 178                 }
 179
 180                 *phys_blk = inode_bmap(inode, block);
 181                 b = block ? inode_bmap(inode, block-1) : 0;
 182
 183                 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
 184                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 185                         if (retval)
 186                                 goto done;
 187                         inode_bmap(inode, block) = b;
 188                         blocks_alloc++;
 189                         *phys_blk = b;
 190                 }
 191                 goto done;
 192         }
 193
 194         /* Indirect block */
 195         block -= EXT2_NDIR_BLOCKS;
 196         if (block < addr_per_block) {
 197                 b = inode_bmap(inode, EXT2_IND_BLOCK);
 198                 if (!b) {
 199                         if (!(bmap_flags & BMAP_ALLOC)) {
 200                                 if (bmap_flags & BMAP_SET)
 201                                         retval = EXT2_ET_SET_BMAP_NO_IND;
 202                                 goto done;
 203                         }
 204
 205                         b = inode_bmap(inode, EXT2_IND_BLOCK-1);
 206                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 207                         if (retval)
 208                                 goto done;
 209                         inode_bmap(inode, EXT2_IND_BLOCK) = b;
 210                         blocks_alloc++;
 211                 }
 212                 retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
 213                                         &blocks_alloc, block, phys_blk);
 214                 goto done;
 215         }
 216
 217         /* Doubly indirect block  */
 218         block -= addr_per_block;
 219         if (block < addr_per_block * addr_per_block) {
 220                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 221                 if (!b) {
 222                         if (!(bmap_flags & BMAP_ALLOC)) {
 223                                 if (bmap_flags & BMAP_SET)
 224                                         retval = EXT2_ET_SET_BMAP_NO_IND;
 225                                 goto done;
 226                         }
 227
 228                         b = inode_bmap(inode, EXT2_IND_BLOCK);
 229                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 230                         if (retval)
 231                                 goto done;
 232                         inode_bmap(inode, EXT2_DIND_BLOCK) = b;
 233                         blocks_alloc++;
 234                 }
 235                 retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
 236                                          &blocks_alloc, block, phys_blk);
 237                 goto done;
 238         }
 239
 240         /* Triply indirect block */
 241         block -= addr_per_block * addr_per_block;
 242         b = inode_bmap(inode, EXT2_TIND_BLOCK);
 243         if (!b) {
 244                 if (!(bmap_flags & BMAP_ALLOC)) {
 245                         if (bmap_flags & BMAP_SET)
 246                                 retval = EXT2_ET_SET_BMAP_NO_IND;
 247                         goto done;
 248                 }
 249
 250                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 251                 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 252                 if (retval)
 253                         goto done;
 254                 inode_bmap(inode, EXT2_TIND_BLOCK) = b;
 255                 blocks_alloc++;
 256         }
 257         retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
 258                                  &blocks_alloc, block, phys_blk);
 259 done:
 260         if (buf)
 261                 ext2fs_free_mem(&buf);
 262         if ((retval == 0) && (blocks_alloc || inode_dirty)) {
 263                 inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
 264                 retval = ext2fs_write_inode(fs, ino, inode);
 265         }
 266         return retval;
 267 }
 268
 269
 270