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 BMAP_ALLOC      1
  33
  34 #define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
  35
  36 static _BMAP_INLINE_ errcode_t block_ind_bmap(ext2_filsys fs, int flags,
  37                                               blk_t ind, char *block_buf,
  38                                               int *blocks_alloc,
  39                                               blk_t nr, blk_t *ret_blk)
  40 {
  41         errcode_t       retval;
  42         blk_t           b;
  43
  44         if (!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         b = ((blk_t *) block_buf)[nr];
  53
  54 #ifdef EXT2FS_ENABLE_SWAPFS
  55         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  56             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
  57                 b = ext2fs_swab32(b);
  58 #endif
  59
  60         if (!b && (flags & BMAP_ALLOC)) {
  61                 b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
  62                 retval = ext2fs_alloc_block(fs, b,
  63                                             block_buf + fs->blocksize, &b);
  64                 if (retval)
  65                         return retval;
  66
  67 #ifdef EXT2FS_ENABLE_SWAPFS
  68                 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  69                     (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
  70                         ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
  71                 else
  72 #endif
  73                         ((blk_t *) block_buf)[nr] = b;
  74
  75                 retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
  76                 if (retval)
  77                         return retval;
  78
  79                 (*blocks_alloc)++;
  80         }
  81
  82         *ret_blk = b;
  83         return 0;
  84 }
  85
  86 static _BMAP_INLINE_ errcode_t block_dind_bmap(ext2_filsys fs, int flags,
  87                                                blk_t dind, char *block_buf,
  88                                                int *blocks_alloc,
  89                                                blk_t nr, blk_t *ret_blk)
  90 {
  91         blk_t           b;
  92         errcode_t       retval;
  93         blk_t           addr_per_block;
  94
  95         addr_per_block = (blk_t) fs->blocksize >> 2;
  96
  97         retval = block_ind_bmap(fs, flags, dind, block_buf, blocks_alloc,
  98                                 nr / addr_per_block, &b);
  99         if (retval)
 100                 return retval;
 101         retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
 102                                 nr % addr_per_block, ret_blk);
 103         return retval;
 104 }
 105
 106 static _BMAP_INLINE_ errcode_t block_tind_bmap(ext2_filsys fs, int flags,
 107                                                blk_t tind, char *block_buf,
 108                                                int *blocks_alloc,
 109                                                blk_t nr, blk_t *ret_blk)
 110 {
 111         blk_t           b;
 112         errcode_t       retval;
 113         blk_t           addr_per_block;
 114
 115         addr_per_block = (blk_t) fs->blocksize >> 2;
 116
 117         retval = block_dind_bmap(fs, flags, tind, block_buf, blocks_alloc,
 118                                  nr / addr_per_block, &b);
 119         if (retval)
 120                 return retval;
 121         retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
 122                                 nr % addr_per_block, ret_blk);
 123         return retval;
 124 }
 125
 126 errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
 127                       char *block_buf, int bmap_flags, blk_t block,
 128                       blk_t *phys_blk)
 129 {
 130         struct ext2_inode inode_buf;
 131         blk_t addr_per_block;
 132         blk_t   b;
 133         char    *buf = 0;
 134         errcode_t       retval = 0;
 135         int             blocks_alloc = 0;
 136
 137         *phys_blk = 0;
 138
 139         /* Read inode structure if necessary */
 140         if (!inode) {
 141                 retval = ext2fs_read_inode(fs, ino, &inode_buf);
 142                 if (retval)
 143                         return retval;
 144                 inode = &inode_buf;
 145         }
 146         addr_per_block = (blk_t) fs->blocksize >> 2;
 147
 148         if (!block_buf) {
 149                 retval = ext2fs_get_mem(fs->blocksize * 2, &buf);
 150                 if (retval)
 151                         return retval;
 152                 block_buf = buf;
 153         }
 154
 155         if (block < EXT2_NDIR_BLOCKS) {
 156                 *phys_blk = inode_bmap(inode, block);
 157                 b = block ? inode_bmap(inode, block-1) : 0;
 158
 159                 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
 160                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 161                         if (retval)
 162                                 goto done;
 163                         inode_bmap(inode, block) = b;
 164                         blocks_alloc++;
 165                         *phys_blk = b;
 166                 }
 167                 goto done;
 168         }
 169
 170         /* Indirect block */
 171         block -= EXT2_NDIR_BLOCKS;
 172         if (block < addr_per_block) {
 173                 b = inode_bmap(inode, EXT2_IND_BLOCK);
 174                 if (!b) {
 175                         if (!(bmap_flags & BMAP_ALLOC))
 176                             goto done;
 177
 178                         b = inode_bmap(inode, EXT2_IND_BLOCK-1);
 179                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 180                         if (retval)
 181                                 goto done;
 182                         inode_bmap(inode, EXT2_IND_BLOCK) = b;
 183                         blocks_alloc++;
 184                 }
 185                 retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
 186                                         &blocks_alloc, block, phys_blk);
 187                 goto done;
 188         }
 189
 190         /* Doubly indirect block  */
 191         block -= addr_per_block;
 192         if (block < addr_per_block * addr_per_block) {
 193                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 194                 if (!b) {
 195                         if (!(bmap_flags & BMAP_ALLOC))
 196                             goto done;
 197
 198                         b = inode_bmap(inode, EXT2_IND_BLOCK);
 199                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 200                         if (retval)
 201                                 goto done;
 202                         inode_bmap(inode, EXT2_DIND_BLOCK) = b;
 203                         blocks_alloc++;
 204                 }
 205                 retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
 206                                          &blocks_alloc, block, phys_blk);
 207                 goto done;
 208         }
 209
 210         /* Triply indirect block */
 211         block -= addr_per_block * addr_per_block;
 212         b = inode_bmap(inode, EXT2_TIND_BLOCK);
 213         if (!b) {
 214                 if (!(bmap_flags & BMAP_ALLOC))
 215                         goto done;
 216
 217                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 218                 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 219                 if (retval)
 220                         goto done;
 221                 inode_bmap(inode, EXT2_TIND_BLOCK) = b;
 222                 blocks_alloc++;
 223         }
 224         retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
 225                                  &blocks_alloc, block, phys_blk);
 226 done:
 227         if (buf)
 228                 ext2fs_free_mem(&buf);
 229         if ((retval == 0) && blocks_alloc) {
 230                 inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
 231                 retval = ext2fs_write_inode(fs, ino, inode);
 232         }
 233         return retval;
 234 }
 235
 236
 237