Denis Vlasenko | c4f623e | 2006-12-26 01:30:59 +0000 | [diff] [blame] | 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; |
Denys Vlasenko | 4b1100e | 2010-03-05 14:10:54 +0100 | [diff] [blame^] | 139 | char *buf = NULL; |
Denis Vlasenko | c4f623e | 2006-12-26 01:30:59 +0000 | [diff] [blame] | 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 | } |
| 262 | |
| 263 | |
| 264 | |