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 Library
   8  * General Public License, version 2.
   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 #include <errno.h>
  18
  19 #include "ext2_fs.h"
  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, ext2_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 inode_bmap(inode, nr) ((inode)->i_block[(nr)])
  34
  35 static _BMAP_INLINE_ errcode_t block_ind_bmap(ext2_filsys fs, int flags,
  36                                               blk_t ind, char *block_buf,
  37                                               int *blocks_alloc,
  38                                               blk_t nr, blk_t *ret_blk)
  39 {
  40         errcode_t       retval;
  41         blk_t           b;
  42
  43         if (!ind) {
  44                 if (flags & BMAP_SET)
  45                         return EXT2_ET_SET_BMAP_NO_IND;
  46                 *ret_blk = 0;
  47                 return 0;
  48         }
  49         retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
  50         if (retval)
  51                 return retval;
  52
  53         if (flags & BMAP_SET) {
  54                 b = *ret_blk;
  55 #ifdef WORDS_BIGENDIAN
  56                 b = ext2fs_swab32(b);
  57 #endif
  58                 ((blk_t *) block_buf)[nr] = b;
  59                 return io_channel_write_blk(fs->io, ind, 1, block_buf);
  60         }
  61
  62         b = ((blk_t *) block_buf)[nr];
  63
  64 #ifdef WORDS_BIGENDIAN
  65         b = ext2fs_swab32(b);
  66 #endif
  67
  68         if (!b && (flags & BMAP_ALLOC)) {
  69                 b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
  70                 retval = ext2fs_alloc_block(fs, b,
  71                                             block_buf + fs->blocksize, &b);
  72                 if (retval)
  73                         return retval;
  74
  75 #ifdef WORDS_BIGENDIAN
  76                 ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
  77 #else
  78                 ((blk_t *) block_buf)[nr] = b;
  79 #endif
  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 _BMAP_INLINE_ 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 _BMAP_INLINE_ 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_bmap2(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
 133                        char *block_buf, int bmap_flags, blk64_t block,
 134                        int *ret_flags, blk64_t *phys_blk)
 135 {
 136         struct ext2_inode inode_buf;
 137         ext2_extent_handle_t handle = 0;
 138         blk_t addr_per_block;
 139         blk_t   b, blk32;
 140         char    *buf = 0;
 141         errcode_t       retval = 0;
 142         int             blocks_alloc = 0, inode_dirty = 0;
 143
 144         if (!(bmap_flags & BMAP_SET))
 145                 *phys_blk = 0;
 146
 147         if (ret_flags)
 148                 *ret_flags = 0;
 149
 150         /* Read inode structure if necessary */
 151         if (!inode) {
 152                 retval = ext2fs_read_inode(fs, ino, &inode_buf);
 153                 if (retval)
 154                         return retval;
 155                 inode = &inode_buf;
 156         }
 157         addr_per_block = (blk_t) fs->blocksize >> 2;
 158
 159         if (inode->i_flags & EXT4_EXTENTS_FL) {
 160                 struct ext2fs_extent    extent;
 161                 unsigned int            offset;
 162
 163                 retval = ext2fs_extent_open2(fs, ino, inode, &handle);
 164                 if (retval)
 165                         goto done;
 166                 if (bmap_flags & BMAP_SET) {
 167                         retval = ext2fs_extent_set_bmap(handle, block,
 168                                                         *phys_blk, 0);
 169                         goto done;
 170                 }
 171                 retval = ext2fs_extent_goto(handle, block);
 172                 if (retval) {
 173                         /* If the extent is not found, return phys_blk = 0 */
 174                         if (retval == EXT2_ET_EXTENT_NOT_FOUND)
 175                                 goto got_block;
 176                         goto done;
 177                 }
 178                 retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
 179                 if (retval)
 180                         goto done;
 181                 offset = block - extent.e_lblk;
 182                 if (block >= extent.e_lblk && (offset <= extent.e_len)) {
 183                         *phys_blk = extent.e_pblk + offset;
 184                         if (ret_flags && extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
 185                                 *ret_flags |= BMAP_RET_UNINIT;
 186                 }
 187         got_block:
 188                 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
 189                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 190                         if (retval)
 191                                 goto done;
 192                         retval = ext2fs_extent_set_bmap(handle, block,
 193                                                         (blk64_t) b, 0);
 194                         if (retval)
 195                                 goto done;
 196                         /* Update inode after setting extent */
 197                         retval = ext2fs_read_inode(fs, ino, inode);
 198                         if (retval)
 199                                 return retval;
 200                         blocks_alloc++;
 201                         *phys_blk = b;
 202                 }
 203                 retval = 0;
 204                 goto done;
 205         }
 206
 207         if (!block_buf) {
 208                 retval = ext2fs_get_array(2, fs->blocksize, &buf);
 209                 if (retval)
 210                         return retval;
 211                 block_buf = buf;
 212         }
 213
 214         if (block < EXT2_NDIR_BLOCKS) {
 215                 if (bmap_flags & BMAP_SET) {
 216                         b = *phys_blk;
 217                         inode_bmap(inode, block) = b;
 218                         inode_dirty++;
 219                         goto done;
 220                 }
 221
 222                 *phys_blk = inode_bmap(inode, block);
 223                 b = block ? inode_bmap(inode, block-1) : 0;
 224
 225                 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
 226                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 227                         if (retval)
 228                                 goto done;
 229                         inode_bmap(inode, block) = b;
 230                         blocks_alloc++;
 231                         *phys_blk = b;
 232                 }
 233                 goto done;
 234         }
 235
 236         /* Indirect block */
 237         block -= EXT2_NDIR_BLOCKS;
 238         blk32 = *phys_blk;
 239         if (block < addr_per_block) {
 240                 b = inode_bmap(inode, EXT2_IND_BLOCK);
 241                 if (!b) {
 242                         if (!(bmap_flags & BMAP_ALLOC)) {
 243                                 if (bmap_flags & BMAP_SET)
 244                                         retval = EXT2_ET_SET_BMAP_NO_IND;
 245                                 goto done;
 246                         }
 247
 248                         b = inode_bmap(inode, EXT2_IND_BLOCK-1);
 249                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 250                         if (retval)
 251                                 goto done;
 252                         inode_bmap(inode, EXT2_IND_BLOCK) = b;
 253                         blocks_alloc++;
 254                 }
 255                 retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
 256                                         &blocks_alloc, block, &blk32);
 257                 if (retval == 0)
 258                         *phys_blk = blk32;
 259                 goto done;
 260         }
 261
 262         /* Doubly indirect block  */
 263         block -= addr_per_block;
 264         if (block < addr_per_block * addr_per_block) {
 265                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 266                 if (!b) {
 267                         if (!(bmap_flags & BMAP_ALLOC)) {
 268                                 if (bmap_flags & BMAP_SET)
 269                                         retval = EXT2_ET_SET_BMAP_NO_IND;
 270                                 goto done;
 271                         }
 272
 273                         b = inode_bmap(inode, EXT2_IND_BLOCK);
 274                         retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 275                         if (retval)
 276                                 goto done;
 277                         inode_bmap(inode, EXT2_DIND_BLOCK) = b;
 278                         blocks_alloc++;
 279                 }
 280                 retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
 281                                          &blocks_alloc, block, &blk32);
 282                 if (retval == 0)
 283                         *phys_blk = blk32;
 284                 goto done;
 285         }
 286
 287         /* Triply indirect block */
 288         block -= addr_per_block * addr_per_block;
 289         b = inode_bmap(inode, EXT2_TIND_BLOCK);
 290         if (!b) {
 291                 if (!(bmap_flags & BMAP_ALLOC)) {
 292                         if (bmap_flags & BMAP_SET)
 293                                 retval = EXT2_ET_SET_BMAP_NO_IND;
 294                         goto done;
 295                 }
 296
 297                 b = inode_bmap(inode, EXT2_DIND_BLOCK);
 298                 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
 299                 if (retval)
 300                         goto done;
 301                 inode_bmap(inode, EXT2_TIND_BLOCK) = b;
 302                 blocks_alloc++;
 303         }
 304         retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
 305                                  &blocks_alloc, block, &blk32);
 306         if (retval == 0)
 307                 *phys_blk = blk32;
 308 done:
 309         if (buf)
 310                 ext2fs_free_mem(&buf);
 311         if (handle)
 312                 ext2fs_extent_free(handle);
 313         if ((retval == 0) && (blocks_alloc || inode_dirty)) {
 314                 ext2fs_iblk_add_blocks(fs, inode, blocks_alloc);
 315                 retval = ext2fs_write_inode(fs, ino, inode);
 316         }
 317         return retval;
 318 }
 319
 320 errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
 321                       char *block_buf, int bmap_flags, blk_t block,
 322                       blk_t *phys_blk)
 323 {
 324         errcode_t ret;
 325         blk64_t ret_blk = *phys_blk;
 326
 327         ret = ext2fs_bmap2(fs, ino, inode, block_buf, bmap_flags, block,
 328                             0, &ret_blk);
 329         if (ret)
 330                 return ret;
 331         if (ret_blk >= ((long long) 1 << 32))
 332                 return EOVERFLOW;
 333         *phys_blk = ret_blk;
 334         return 0;
 335 }