release/src/router/busybox/e2fsprogs/old_e2fsprogs/ext2fs/bmap.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * bmap.c --- logical to physical block mapping
   4  *
   5  * Copyright (C) 1997 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18
  19 #include "ext2_fs.h"
  20 #include "ext2fs.h"
  21
  22 extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
  23                              struct ext2_inode *inode,
  24                              char *block_buf, int bmap_flags,
  25                              blk_t block, blk_t *phys_blk);
  26
  27 #define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
  28
  29 static errcode_t block_ind_bmap(ext2_filsys fs, int flags,
  30                                               blk_t ind, char *block_buf,
  31                                               int *blocks_alloc,
  32                                               blk_t nr, blk_t *ret_blk)
  33 {
  34         errcode_t       retval;
  35         blk_t           b;
  36
  37         if (!ind) {
  38                 if (flags & BMAP_SET)
  39                         return EXT2_ET_SET_BMAP_NO_IND;
  40                 *ret_blk = 0;
  41                 return 0;
  42         }
  43         retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
  44         if (retval)
  45                 return retval;
  46
  47         if (flags & BMAP_SET) {
  48                 b = *ret_blk;
  49 #if BB_BIG_ENDIAN
  50                 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  51                     (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
  52                         b = ext2fs_swab32(b);
  53 #endif
  54                 ((blk_t *) block_buf)[nr] = b;
  55                 return io_channel_write_blk(fs->io, ind, 1, block_buf);
  56         }
  57
  58         b = ((blk_t *) block_buf)[nr];
  59
  60 #if BB_BIG_ENDIAN
  61         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  62             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
  63                 b = ext2fs_swab32(b);
  64 #endif
  65
  66         if (!b && (flags & BMAP_ALLOC)) {
  67                 b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
  68                 retval = ext2fs_alloc_block(fs, b,
  69                                             block_buf + fs->blocksize, &b);
  70                 if (retval)
  71                         return retval;
  72
  73 #if BB_BIG_ENDIAN
  74                 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  75                     (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
  76                         ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
  77                 else
  78 #endif
  79                         ((blk_t *) block_buf)[nr] = b;
  80
  81                 retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
  82                 if (retval)
  83                         return retval;
  84
  85                 (*blocks_alloc)++;
  86         }
  87
  88         *ret_blk = b;
  89         return 0;
  90 }
  91
  92 static errcode_t block_dind_bmap(ext2_filsys fs, int flags,
  93                                                blk_t dind, char *block_buf,
  94                                                int *blocks_alloc,
  95                                                blk_t nr, blk_t *ret_blk)
  96 {
  97         blk_t           b;
  98         errcode_t       retval;
  99         blk_t           addr_per_block;
 100
 101         addr_per_block = (blk_t) fs->blocksize >> 2;
 102
 103         retval = block_ind_bmap(fs, flags & ~BMAP_SET, dind, block_buf,
 104                                 blocks_alloc, nr / addr_per_block, &b);
 105         if (retval)
 106                 return retval;
 107         retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
 108                                 nr % addr_per_block, ret_blk);
 109         return retval;
 110 }
 111
 112 static errcode_t block_tind_bmap(ext2_filsys fs, int flags,
 113                                                blk_t tind, char *block_buf,
 114                                                int *blocks_alloc,
 115                                                blk_t nr, blk_t *ret_blk)
 116 {
 117         blk_t           b;
 118         errcode_t       retval;
 119         blk_t           addr_per_block;
 120
 121         addr_per_block = (blk_t) fs->blocksize >> 2;
 122
 123         retval = block_dind_bmap(fs, flags & ~BMAP_SET, tind, block_buf,
 124                                  blocks_alloc, nr / addr_per_block, &b);
 125         if (retval)
 126                 return retval;
 127         retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
 128                                 nr % addr_per_block, ret_blk);
 129         return retval;
 130 }
 131
 132 errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
 133                       char *block_buf, int bmap_flags, blk_t block,
 134                       blk_t *phys_blk)
 135 {
 136         struct ext2_inode inode_buf;
 137         blk_t addr_per_block;
 138         blk_t   b;
 139         char    *buf = NULL;
 140         errcode_t       retval = 0;
 141         int             blocks_alloc = 0, inode_dirty = 0;
 142
 143         if (!(bmap_flags & BMAP_SET))
 144                 *phys_blk = 0;
 145
 146         /* Read inode structure if necessary */
 147         if (!inode) {
 148                 retval = ext2fs_read_inode(fs, ino, &inode_buf);
 149                 if (retval)
 150                         return retval;
 151                 inode = &inode_buf;
 152         }
 153         addr_per_block = (blk_t) fs->blocksize >> 2;
 154
 155         if (!block_buf) {
 156                 retval = ext2fs_get_mem(fs->blocksize * 2, &buf);
 157                 if (retval)
 158                         return retval;
 159                 block_buf = buf;
 160         }
 161
 162         if (block < EXT2_NDIR_BLOCKS) {
 163                 if (bmap_flags & BMAP_SET) {
 164                         b = *phys_blk;
 165 #if BB_BIG_ENDIAN
 166                         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 167                             (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
 168                                 b = ext2fs_swab32(b);
 169 #endif
 170                         inode_bmap(inode, block) = b;
 171                         inode_dirty++;
 172                         goto done;
 173                 }
 174
 175                 *phys_blk = inode_bmap(inode, block);
 176                 b = block ? inode_bmap(inode, block-1) : 0;
 177
 178                 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
 179                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 180                         if (retval)
 181                                 goto done;
 182                         inode_bmap(inode, block) = b;
 183                         blocks_alloc++;
 184                         *phys_blk = b;
 185                 }
 186                 goto done;
 187         }
 188
 189         /* Indirect block */
 190         block -= EXT2_NDIR_BLOCKS;
 191         if (block < addr_per_block) {
 192                 b = inode_bmap(inode, EXT2_IND_BLOCK);
 193                 if (!b) {
 194                         if (!(bmap_flags & BMAP_ALLOC)) {
 195                                 if (bmap_flags & BMAP_SET)
 196                                         retval = EXT2_ET_SET_BMAP_NO_IND;
 197                                 goto done;
 198                         }
 199
 200                         b = inode_bmap(inode, EXT2_IND_BLOCK-1);
 201                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 202                         if (retval)
 203                                 goto done;
 204                         inode_bmap(inode, EXT2_IND_BLOCK) = b;
 205                         blocks_alloc++;
 206                 }
 207                 retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
 208                                         &blocks_alloc, block, phys_blk);
 209                 goto done;
 210         }
 211
 212         /* Doubly indirect block  */
 213         block -= addr_per_block;
 214         if (block < addr_per_block * addr_per_block) {
 215                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 216                 if (!b) {
 217                         if (!(bmap_flags & BMAP_ALLOC)) {
 218                                 if (bmap_flags & BMAP_SET)
 219                                         retval = EXT2_ET_SET_BMAP_NO_IND;
 220                                 goto done;
 221                         }
 222
 223                         b = inode_bmap(inode, EXT2_IND_BLOCK);
 224                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 225                         if (retval)
 226                                 goto done;
 227                         inode_bmap(inode, EXT2_DIND_BLOCK) = b;
 228                         blocks_alloc++;
 229                 }
 230                 retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
 231                                          &blocks_alloc, block, phys_blk);
 232                 goto done;
 233         }
 234
 235         /* Triply indirect block */
 236         block -= addr_per_block * addr_per_block;
 237         b = inode_bmap(inode, EXT2_TIND_BLOCK);
 238         if (!b) {
 239                 if (!(bmap_flags & BMAP_ALLOC)) {
 240                         if (bmap_flags & BMAP_SET)
 241                                 retval = EXT2_ET_SET_BMAP_NO_IND;
 242                         goto done;
 243                 }
 244
 245                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 246                 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 247                 if (retval)
 248                         goto done;
 249                 inode_bmap(inode, EXT2_TIND_BLOCK) = b;
 250                 blocks_alloc++;
 251         }
 252         retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
 253                                  &blocks_alloc, block, phys_blk);
 254 done:
 255         ext2fs_free_mem(&buf);
 256         if ((retval == 0) && (blocks_alloc || inode_dirty)) {
 257                 inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
 258                 retval = ext2fs_write_inode(fs, ino, inode);
 259         }
 260         return retval;
 261 }