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