bmap.c revision cc9bf5d246fc23267e14cc328728f146aee142e2
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#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 28extern 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 35static _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 92static _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 112static _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 132errcode_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 int offset; 162 163 if (bmap_flags & BMAP_SET) { 164 retval = EXT2_ET_EXTENT_NOT_SUPPORTED; 165 goto done; 166 } 167 retval = ext2fs_extent_open(fs, ino, &handle); 168 if (retval) 169 goto done; 170 retval = ext2fs_extent_goto(handle, block); 171 if (retval) { 172 /* If the extent is not found, return phys_blk = 0 */ 173 if (retval == EXT2_ET_EXTENT_NOT_FOUND) 174 retval = 0; 175 goto done; 176 } 177 retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent); 178 if (retval) 179 goto done; 180 offset = block - extent.e_lblk; 181 if (block >= extent.e_lblk && (offset <= extent.e_len)) { 182 *phys_blk = extent.e_pblk + offset; 183 if (ret_flags && extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT) 184 *ret_flags |= BMAP_RET_UNINIT; 185 } 186 retval = 0; 187 goto done; 188 } 189 190 if (!block_buf) { 191 retval = ext2fs_get_array(2, fs->blocksize, &buf); 192 if (retval) 193 return retval; 194 block_buf = buf; 195 } 196 197 if (block < EXT2_NDIR_BLOCKS) { 198 if (bmap_flags & BMAP_SET) { 199 b = *phys_blk; 200#ifdef WORDS_BIGENDIAN 201 b = ext2fs_swab32(b); 202#endif 203 inode_bmap(inode, block) = b; 204 inode_dirty++; 205 goto done; 206 } 207 208 *phys_blk = inode_bmap(inode, block); 209 b = block ? inode_bmap(inode, block-1) : 0; 210 211 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) { 212 retval = ext2fs_alloc_block(fs, b, block_buf, &b); 213 if (retval) 214 goto done; 215 inode_bmap(inode, block) = b; 216 blocks_alloc++; 217 *phys_blk = b; 218 } 219 goto done; 220 } 221 222 /* Indirect block */ 223 block -= EXT2_NDIR_BLOCKS; 224 blk32 = *phys_blk; 225 if (block < addr_per_block) { 226 b = inode_bmap(inode, EXT2_IND_BLOCK); 227 if (!b) { 228 if (!(bmap_flags & BMAP_ALLOC)) { 229 if (bmap_flags & BMAP_SET) 230 retval = EXT2_ET_SET_BMAP_NO_IND; 231 goto done; 232 } 233 234 b = inode_bmap(inode, EXT2_IND_BLOCK-1); 235 retval = ext2fs_alloc_block(fs, b, block_buf, &b); 236 if (retval) 237 goto done; 238 inode_bmap(inode, EXT2_IND_BLOCK) = b; 239 blocks_alloc++; 240 } 241 retval = block_ind_bmap(fs, bmap_flags, b, block_buf, 242 &blocks_alloc, block, &blk32); 243 if (retval == 0) 244 *phys_blk = blk32; 245 goto done; 246 } 247 248 /* Doubly indirect block */ 249 block -= addr_per_block; 250 if (block < addr_per_block * addr_per_block) { 251 b = inode_bmap(inode, EXT2_DIND_BLOCK); 252 if (!b) { 253 if (!(bmap_flags & BMAP_ALLOC)) { 254 if (bmap_flags & BMAP_SET) 255 retval = EXT2_ET_SET_BMAP_NO_IND; 256 goto done; 257 } 258 259 b = inode_bmap(inode, EXT2_IND_BLOCK); 260 retval = ext2fs_alloc_block(fs, b, block_buf, &b); 261 if (retval) 262 goto done; 263 inode_bmap(inode, EXT2_DIND_BLOCK) = b; 264 blocks_alloc++; 265 } 266 retval = block_dind_bmap(fs, bmap_flags, b, block_buf, 267 &blocks_alloc, block, &blk32); 268 if (retval == 0) 269 *phys_blk = blk32; 270 goto done; 271 } 272 273 /* Triply indirect block */ 274 block -= addr_per_block * addr_per_block; 275 b = inode_bmap(inode, EXT2_TIND_BLOCK); 276 if (!b) { 277 if (!(bmap_flags & BMAP_ALLOC)) { 278 if (bmap_flags & BMAP_SET) 279 retval = EXT2_ET_SET_BMAP_NO_IND; 280 goto done; 281 } 282 283 b = inode_bmap(inode, EXT2_DIND_BLOCK); 284 retval = ext2fs_alloc_block(fs, b, block_buf, &b); 285 if (retval) 286 goto done; 287 inode_bmap(inode, EXT2_TIND_BLOCK) = b; 288 blocks_alloc++; 289 } 290 retval = block_tind_bmap(fs, bmap_flags, b, block_buf, 291 &blocks_alloc, block, &blk32); 292 if (retval == 0) 293 *phys_blk = blk32; 294done: 295 if (buf) 296 ext2fs_free_mem(&buf); 297 if (handle) 298 ext2fs_extent_free(handle); 299 if ((retval == 0) && (blocks_alloc || inode_dirty)) { 300 inode->i_blocks += (blocks_alloc * fs->blocksize) / 512; 301 retval = ext2fs_write_inode(fs, ino, inode); 302 } 303 return retval; 304} 305 306errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode, 307 char *block_buf, int bmap_flags, blk_t block, 308 blk_t *phys_blk) 309{ 310 errcode_t ret; 311 blk64_t ret_blk; 312 313 ret = ext2fs_bmap2(fs, ino, inode, block_buf, bmap_flags, block, 314 0, &ret_blk); 315 if (ret) 316 return ret; 317 if (ret_blk >= ((long long) 1 << 32)) 318 return EOVERFLOW; 319 *phys_blk = ret_blk; 320 return 0; 321} 322