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