1 /* 2 * rw_bitmaps.c --- routines to read and write the inode and block bitmaps. 3 * 4 * Copyright (C) 1993, 1994, 1994, 1996 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 <fcntl.h> 18 #include <time.h> 19 #ifdef HAVE_SYS_STAT_H 20 #include <sys/stat.h> 21 #endif 22 #ifdef HAVE_SYS_TYPES_H 23 #include <sys/types.h> 24 #endif 25 26 #include "ext2_fs.h" 27 #include "ext2fs.h" 28 #include "e2image.h" 29 30 #if defined(__powerpc__) && defined(EXT2FS_ENABLE_SWAPFS) 31 /* 32 * On the PowerPC, the big-endian variant of the ext2 filesystem 33 * has its bitmaps stored as 32-bit words with bit 0 as the LSB 34 * of each word. Thus a bitmap with only bit 0 set would be, as 35 * a string of bytes, 00 00 00 01 00 ... 36 * To cope with this, we byte-reverse each word of a bitmap if 37 * we have a big-endian filesystem, that is, if we are *not* 38 * byte-swapping other word-sized numbers. 39 */ 40 #define EXT2_BIG_ENDIAN_BITMAPS 41 #endif 42 43 #ifdef EXT2_BIG_ENDIAN_BITMAPS 44 static void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes) 45 { 46 __u32 *p = (__u32 *) bitmap; 47 int n; 48 49 for (n = nbytes / sizeof(__u32); n > 0; --n, ++p) 50 *p = ext2fs_swab32(*p); 51 } 52 #endif 53 54 static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block) 55 { 56 dgrp_t i; 57 unsigned int j; 58 int block_nbytes, inode_nbytes; 59 unsigned int nbits; 60 errcode_t retval; 61 char *block_bitmap, *inode_bitmap; 62 char *block_buf, *inode_buf; 63 int lazy_flag = 0; 64 blk_t blk; 65 66 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 67 68 if (!(fs->flags & EXT2_FLAG_RW)) 69 return EXT2_ET_RO_FILSYS; 70 if (EXT2_HAS_COMPAT_FEATURE(fs->super, 71 EXT2_FEATURE_COMPAT_LAZY_BG)) 72 lazy_flag = 1; 73 inode_nbytes = block_nbytes = 0; 74 block_bitmap = inode_bitmap = 0; 75 if (do_block) { 76 block_bitmap = fs->block_map->bitmap; 77 block_nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8; 78 retval = ext2fs_get_mem(fs->blocksize, &block_buf); 79 if (retval) 80 return retval; 81 memset(block_buf, 0xff, fs->blocksize); 82 } 83 if (do_inode) { 84 inode_bitmap = fs->inode_map->bitmap; 85 inode_nbytes = (size_t) 86 ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8); 87 retval = ext2fs_get_mem(fs->blocksize, &inode_buf); 88 if (retval) 89 return retval; 90 memset(inode_buf, 0xff, fs->blocksize); 91 } 92 93 for (i = 0; i < fs->group_desc_count; i++) { 94 if (!block_bitmap || !do_block) 95 goto skip_block_bitmap; 96 97 if (lazy_flag && fs->group_desc[i].bg_flags & 98 EXT2_BG_BLOCK_UNINIT) 99 goto skip_this_block_bitmap; 100 101 memcpy(block_buf, block_bitmap, block_nbytes); 102 if (i == fs->group_desc_count - 1) { 103 /* Force bitmap padding for the last group */ 104 nbits = ((fs->super->s_blocks_count 105 - fs->super->s_first_data_block) 106 % EXT2_BLOCKS_PER_GROUP(fs->super)); 107 if (nbits) 108 for (j = nbits; j < fs->blocksize * 8; j++) 109 ext2fs_set_bit(j, block_buf); 110 } 111 blk = fs->group_desc[i].bg_block_bitmap; 112 if (blk) { 113 #ifdef EXT2_BIG_ENDIAN_BITMAPS 114 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) || 115 (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))) 116 ext2fs_swap_bitmap(fs, block_buf, 117 block_nbytes); 118 #endif 119 retval = io_channel_write_blk(fs->io, blk, 1, 120 block_buf); 121 if (retval) 122 return EXT2_ET_BLOCK_BITMAP_WRITE; 123 } 124 skip_this_block_bitmap: 125 block_bitmap += block_nbytes; 126 skip_block_bitmap: 127 128 if (!inode_bitmap || !do_inode) 129 continue; 130 131 if (lazy_flag && fs->group_desc[i].bg_flags & 132 EXT2_BG_INODE_UNINIT) 133 goto skip_this_inode_bitmap; 134 135 memcpy(inode_buf, inode_bitmap, inode_nbytes); 136 blk = fs->group_desc[i].bg_inode_bitmap; 137 if (blk) { 138 #ifdef EXT2_BIG_ENDIAN_BITMAPS 139 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) || 140 (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))) 141 ext2fs_swap_bitmap(fs, inode_buf, 142 inode_nbytes); 143 #endif 144 retval = io_channel_write_blk(fs->io, blk, 1, 145 inode_buf); 146 if (retval) 147 return EXT2_ET_INODE_BITMAP_WRITE; 148 } 149 skip_this_inode_bitmap: 150 inode_bitmap += inode_nbytes; 151 152 } 153 if (do_block) { 154 fs->flags &= ~EXT2_FLAG_BB_DIRTY; 155 ext2fs_free_mem(&block_buf); 156 } 157 if (do_inode) { 158 fs->flags &= ~EXT2_FLAG_IB_DIRTY; 159 ext2fs_free_mem(&inode_buf); 160 } 161 return 0; 162 } 163 164 static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block) 165 { 166 dgrp_t i; 167 char *block_bitmap = 0, *inode_bitmap = 0; 168 char *buf; 169 errcode_t retval; 170 int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8; 171 int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8; 172 int lazy_flag = 0; 173 blk_t blk; 174 175 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 176 177 fs->write_bitmaps = ext2fs_write_bitmaps; 178 179 if (EXT2_HAS_COMPAT_FEATURE(fs->super, 180 EXT2_FEATURE_COMPAT_LAZY_BG)) 181 lazy_flag = 1; 182 183 retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf); 184 if (retval) 185 return retval; 186 if (do_block) { 187 if (fs->block_map) 188 ext2fs_free_block_bitmap(fs->block_map); 189 sprintf(buf, "block bitmap for %s", fs->device_name); 190 retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map); 191 if (retval) 192 goto cleanup; 193 block_bitmap = fs->block_map->bitmap; 194 } 195 if (do_inode) { 196 if (fs->inode_map) 197 ext2fs_free_inode_bitmap(fs->inode_map); 198 sprintf(buf, "inode bitmap for %s", fs->device_name); 199 retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map); 200 if (retval) 201 goto cleanup; 202 inode_bitmap = fs->inode_map->bitmap; 203 } 204 ext2fs_free_mem(&buf); 205 206 if (fs->flags & EXT2_FLAG_IMAGE_FILE) { 207 if (inode_bitmap) { 208 blk = (fs->image_header->offset_inodemap / 209 fs->blocksize); 210 retval = io_channel_read_blk(fs->image_io, blk, 211 -(inode_nbytes * fs->group_desc_count), 212 inode_bitmap); 213 if (retval) 214 goto cleanup; 215 } 216 if (block_bitmap) { 217 blk = (fs->image_header->offset_blockmap / 218 fs->blocksize); 219 retval = io_channel_read_blk(fs->image_io, blk, 220 -(block_nbytes * fs->group_desc_count), 221 block_bitmap); 222 if (retval) 223 goto cleanup; 224 } 225 return 0; 226 } 227 228 for (i = 0; i < fs->group_desc_count; i++) { 229 if (block_bitmap) { 230 blk = fs->group_desc[i].bg_block_bitmap; 231 if (lazy_flag && fs->group_desc[i].bg_flags & 232 EXT2_BG_BLOCK_UNINIT) 233 blk = 0; 234 if (blk) { 235 retval = io_channel_read_blk(fs->io, blk, 236 -block_nbytes, block_bitmap); 237 if (retval) { 238 retval = EXT2_ET_BLOCK_BITMAP_READ; 239 goto cleanup; 240 } 241 #ifdef EXT2_BIG_ENDIAN_BITMAPS 242 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) || 243 (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))) 244 ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes); 245 #endif 246 } else 247 memset(block_bitmap, 0xff, block_nbytes); 248 block_bitmap += block_nbytes; 249 } 250 if (inode_bitmap) { 251 blk = fs->group_desc[i].bg_inode_bitmap; 252 if (lazy_flag && fs->group_desc[i].bg_flags & 253 EXT2_BG_INODE_UNINIT) 254 blk = 0; 255 if (blk) { 256 retval = io_channel_read_blk(fs->io, blk, 257 -inode_nbytes, inode_bitmap); 258 if (retval) { 259 retval = EXT2_ET_INODE_BITMAP_READ; 260 goto cleanup; 261 } 262 #ifdef EXT2_BIG_ENDIAN_BITMAPS 263 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) || 264 (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))) 265 ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes); 266 #endif 267 } else 268 memset(inode_bitmap, 0xff, inode_nbytes); 269 inode_bitmap += inode_nbytes; 270 } 271 } 272 return 0; 273 274 cleanup: 275 if (do_block) { 276 ext2fs_free_mem(&fs->block_map); 277 fs->block_map = 0; 278 } 279 if (do_inode) { 280 ext2fs_free_mem(&fs->inode_map); 281 fs->inode_map = 0; 282 } 283 if (buf) 284 ext2fs_free_mem(&buf); 285 return retval; 286 } 287 288 errcode_t ext2fs_read_inode_bitmap(ext2_filsys fs) 289 { 290 return read_bitmaps(fs, 1, 0); 291 } 292 293 errcode_t ext2fs_read_block_bitmap(ext2_filsys fs) 294 { 295 return read_bitmaps(fs, 0, 1); 296 } 297 298 errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs) 299 { 300 return write_bitmaps(fs, 1, 0); 301 } 302 303 errcode_t ext2fs_write_block_bitmap (ext2_filsys fs) 304 { 305 return write_bitmaps(fs, 0, 1); 306 } 307 308 errcode_t ext2fs_read_bitmaps(ext2_filsys fs) 309 { 310 if (fs->inode_map && fs->block_map) 311 return 0; 312 313 return read_bitmaps(fs, !fs->inode_map, !fs->block_map); 314 } 315 316 errcode_t ext2fs_write_bitmaps(ext2_filsys fs) 317 { 318 int do_inode = fs->inode_map && ext2fs_test_ib_dirty(fs); 319 int do_block = fs->block_map && ext2fs_test_bb_dirty(fs); 320 321 if (!do_inode && !do_block) 322 return 0; 323 324 return write_bitmaps(fs, do_inode, do_block); 325 } 326
