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