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
  18 #if EXT2_FLAT_INCLUDES
  19 #include "ext2_fs.h"
  20 #else
  21 #include <linux/ext2_fs.h>
  22 #endif
  23
  24 #include "ext2fs.h"
  25
  26 #if defined(__GNUC__) && !defined(NO_INLINE_FUNCS)
  27 #define _BMAP_INLINE_   __inline__
  28 #else
  29 #define _BMAP_INLINE_
  30 #endif
  31
  32 extern errcode_t ext2fs_bmap(ext2_filsys fs, ino_t ino,
  33                              struct ext2_inode *inode,
  34                              char *block_buf, int bmap_flags,
  35                              blk_t block, blk_t *phys_blk);
  36
  37 #define BMAP_ALLOC      1
  38
  39 #define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
  40
  41 static blk_t _BMAP_INLINE_ block_bmap(ext2_filsys fs, char *buf, blk_t nr)
  42 {
  43         blk_t tmp;
  44
  45         tmp = ((blk_t *) buf)[nr];
  46
  47         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  48             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
  49                 return ext2fs_swab32(tmp);
  50
  51         return tmp;
  52 }
  53
  54 static errcode_t _BMAP_INLINE_ block_ind_bmap(ext2_filsys fs, int flags,
  55                                               blk_t ind, char *block_buf,
  56                                               int *blocks_alloc,
  57                                               blk_t nr, blk_t *ret_blk)
  58 {
  59         errcode_t       retval;
  60         blk_t           b;
  61
  62         if (!ind) {
  63                 *ret_blk = 0;
  64                 return 0;
  65         }
  66         retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
  67         if (retval)
  68                 return retval;
  69
  70         b = ((blk_t *) block_buf)[nr];
  71
  72         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  73             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
  74                 b = ext2fs_swab32(b);
  75
  76         if (!b && (flags & BMAP_ALLOC)) {
  77                 b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
  78                 retval = ext2fs_alloc_block(fs, b,
  79                                             block_buf + fs->blocksize, &b);
  80                 if (retval)
  81                         return retval;
  82
  83                 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  84                     (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
  85                         ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
  86                 else
  87                         ((blk_t *) block_buf)[nr] = b;
  88
  89                 retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
  90                 if (retval)
  91                         return retval;
  92
  93                 (*blocks_alloc)++;
  94         }
  95
  96         *ret_blk = b;
  97         return 0;
  98 }
  99
 100 static errcode_t _BMAP_INLINE_ block_dind_bmap(ext2_filsys fs, int flags,
 101                                                blk_t dind, char *block_buf,
 102                                                int *blocks_alloc,
 103                                                blk_t nr, blk_t *ret_blk)
 104 {
 105         blk_t           b;
 106         errcode_t       retval;
 107         int             addr_per_block;
 108
 109         addr_per_block = fs->blocksize >> 2;
 110
 111         retval = block_ind_bmap(fs, flags, dind, block_buf, blocks_alloc,
 112                                 nr / addr_per_block, &b);
 113         if (retval)
 114                 return retval;
 115         retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
 116                                 nr % addr_per_block, ret_blk);
 117         return retval;
 118 }
 119
 120 static errcode_t _BMAP_INLINE_ block_tind_bmap(ext2_filsys fs, int flags,
 121                                                blk_t tind, char *block_buf,
 122                                                int *blocks_alloc,
 123                                                blk_t nr, blk_t *ret_blk)
 124 {
 125         blk_t           b;
 126         errcode_t       retval;
 127         int             addr_per_block;
 128
 129         addr_per_block = fs->blocksize >> 2;
 130
 131         retval = block_dind_bmap(fs, flags, tind, block_buf, blocks_alloc,
 132                                  nr / addr_per_block, &b);
 133         if (retval)
 134                 return retval;
 135         retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
 136                                 nr % addr_per_block, ret_blk);
 137         return retval;
 138 }
 139
 140 errcode_t ext2fs_bmap(ext2_filsys fs, ino_t ino, struct ext2_inode *inode,
 141                       char *block_buf, int bmap_flags, blk_t block,
 142                       blk_t *phys_blk)
 143 {
 144         struct ext2_inode inode_buf;
 145         int addr_per_block;
 146         blk_t   b;
 147         char    *buf = 0;
 148         errcode_t       retval = 0;
 149         int             blocks_alloc = 0;
 150
 151         *phys_blk = 0;
 152
 153         /* Read inode structure if necessary */
 154         if (!inode) {
 155                 retval = ext2fs_read_inode(fs, ino, &inode_buf);
 156                 if (!retval)
 157                         return retval;
 158                 inode = &inode_buf;
 159         }
 160         addr_per_block = fs->blocksize >> 2;
 161
 162         if (!block_buf) {
 163                 retval = ext2fs_get_mem(fs->blocksize * 2, (void **) &buf);
 164                 if (retval)
 165                         return retval;
 166                 block_buf = buf;
 167         }
 168
 169         if (block < EXT2_NDIR_BLOCKS) {
 170                 *phys_blk = inode_bmap(inode, block);
 171                 b = block ? inode_bmap(inode, block-1) : 0;
 172
 173                 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
 174                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 175                         if (retval)
 176                                 goto done;
 177                         inode_bmap(inode, block) = b;
 178                         blocks_alloc++;
 179                         *phys_blk = b;
 180                 }
 181                 goto done;
 182         }
 183
 184         /* Indirect block */
 185         block -= EXT2_NDIR_BLOCKS;
 186         if (block < addr_per_block) {
 187                 b = inode_bmap(inode, EXT2_IND_BLOCK);
 188                 if (!b) {
 189                         if (!(bmap_flags & BMAP_ALLOC))
 190                             goto done;
 191
 192                         b = inode_bmap(inode, EXT2_IND_BLOCK-1);
 193                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 194                         if (retval)
 195                                 goto done;
 196                         inode_bmap(inode, EXT2_IND_BLOCK) = b;
 197                         blocks_alloc++;
 198                 }
 199                 retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
 200                                         &blocks_alloc, block, phys_blk);
 201                 goto done;
 202         }
 203
 204         /* Doubly indirect block  */
 205         block -= addr_per_block;
 206         if (block < addr_per_block * addr_per_block) {
 207                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 208                 if (!b) {
 209                         if (!(bmap_flags & BMAP_ALLOC))
 210                             goto done;
 211
 212                         b = inode_bmap(inode, EXT2_IND_BLOCK);
 213                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 214                         if (retval)
 215                                 goto done;
 216                         inode_bmap(inode, EXT2_DIND_BLOCK) = b;
 217                         blocks_alloc++;
 218                 }
 219                 retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
 220                                          &blocks_alloc, block, phys_blk);
 221                 goto done;
 222         }
 223
 224         /* Triply indirect block */
 225         block -= addr_per_block * addr_per_block;
 226         b = inode_bmap(inode, EXT2_TIND_BLOCK);
 227         if (!b) {
 228                 if (!(bmap_flags & BMAP_ALLOC))
 229                         goto done;
 230
 231                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 232                 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 233                 if (retval)
 234                         goto done;
 235                 inode_bmap(inode, EXT2_TIND_BLOCK) = b;
 236                 blocks_alloc++;
 237         }
 238         retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
 239                                  &blocks_alloc, block, phys_blk);
 240 done:
 241         if (buf)
 242                 ext2fs_free_mem((void **) &buf);
 243         if ((retval == 0) && blocks_alloc) {
 244                 inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
 245                 retval = ext2fs_write_inode(fs, ino, inode);
 246         }
 247         return retval;
 248 }
 249
 250
 251