1 /* 2 * linux/fs/hfs/mdb.c 3 * 4 * Copyright (C) 1995-1997 Paul H. Hargrove 5 * (C) 2003 Ardis Technologies <roman@ardistech.com> 6 * This file may be distributed under the terms of the GNU General Public License. 7 * 8 * This file contains functions for reading/writing the MDB. 9 */ 10 11 #include <linux/cdrom.h> 12 #include <linux/blkdev.h> 13 #include <linux/nls.h> 14 #include <linux/slab.h> 15 16 #include "hfs_fs.h" 17 #include "btree.h" 18 19 /*================ File-local data types ================*/ 20 21 /* 22 * The HFS Master Directory Block (MDB). 23 * 24 * Also known as the Volume Information Block (VIB), this structure is 25 * the HFS equivalent of a superblock. 26 * 27 * Reference: _Inside Macintosh: Files_ pages 2-59 through 2-62 28 * 29 * modified for HFS Extended 30 */ 31 32 static int hfs_get_last_session(struct super_block *sb, 33 sector_t *start, sector_t *size) 34 { 35 struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk); 36 37 /* default values */ 38 *start = 0; 39 *size = bdev_nr_sectors(sb->s_bdev); 40 41 if (HFS_SB(sb)->session >= 0) { 42 struct cdrom_tocentry te; 43 44 if (!cdi) 45 return -EINVAL; 46 47 te.cdte_track = HFS_SB(sb)->session; 48 te.cdte_format = CDROM_LBA; 49 if (cdrom_read_tocentry(cdi, &te) || 50 (te.cdte_ctrl & CDROM_DATA_TRACK) != 4) { 51 pr_err("invalid session number or type of track\n"); 52 return -EINVAL; 53 } 54 55 *start = (sector_t)te.cdte_addr.lba << 2; 56 } else if (cdi) { 57 struct cdrom_multisession ms_info; 58 59 ms_info.addr_format = CDROM_LBA; 60 if (cdrom_multisession(cdi, &ms_info) == 0 && ms_info.xa_flag) 61 *start = (sector_t)ms_info.addr.lba << 2; 62 } 63 64 return 0; 65 } 66 67 /* 68 * hfs_mdb_get() 69 * 70 * Build the in-core MDB for a filesystem, including 71 * the B-trees and the volume bitmap. 72 */ 73 int hfs_mdb_get(struct super_block *sb) 74 { 75 struct buffer_head *bh; 76 struct hfs_mdb *mdb, *mdb2; 77 unsigned int block; 78 char *ptr; 79 int off2, len, size, sect; 80 sector_t part_start, part_size; 81 loff_t off; 82 __be16 attrib; 83 84 /* set the device driver to 512-byte blocks */ 85 size = sb_min_blocksize(sb, HFS_SECTOR_SIZE); 86 if (!size) 87 return -EINVAL; 88 89 if (hfs_get_last_session(sb, &part_start, &part_size)) 90 return -EINVAL; 91 while (1) { 92 /* See if this is an HFS filesystem */ 93 bh = sb_bread512(sb, part_start + HFS_MDB_BLK, mdb); 94 if (!bh) 95 goto out; 96 97 if (mdb->drSigWord == cpu_to_be16(HFS_SUPER_MAGIC)) 98 break; 99 brelse(bh); 100 101 /* check for a partition block 102 * (should do this only for cdrom/loop though) 103 */ 104 if (hfs_part_find(sb, &part_start, &part_size)) 105 goto out; 106 } 107 108 HFS_SB(sb)->alloc_blksz = size = be32_to_cpu(mdb->drAlBlkSiz); 109 if (!size || (size & (HFS_SECTOR_SIZE - 1))) { 110 pr_err("bad allocation block size %d\n", size); 111 goto out_bh; 112 } 113 114 size = min(HFS_SB(sb)->alloc_blksz, (u32)PAGE_SIZE); 115 /* size must be a multiple of 512 */ 116 while (size & (size - 1)) 117 size -= HFS_SECTOR_SIZE; 118 sect = be16_to_cpu(mdb->drAlBlSt) + part_start; 119 /* align block size to first sector */ 120 while (sect & ((size - 1) >> HFS_SECTOR_SIZE_BITS)) 121 size >>= 1; 122 /* align block size to weird alloc size */ 123 while (HFS_SB(sb)->alloc_blksz & (size - 1)) 124 size >>= 1; 125 brelse(bh); 126 if (!sb_set_blocksize(sb, size)) { 127 pr_err("unable to set blocksize to %u\n", size); 128 goto out; 129 } 130 131 bh = sb_bread512(sb, part_start + HFS_MDB_BLK, mdb); 132 if (!bh) 133 goto out; 134 if (mdb->drSigWord != cpu_to_be16(HFS_SUPER_MAGIC)) 135 goto out_bh; 136 137 HFS_SB(sb)->mdb_bh = bh; 138 HFS_SB(sb)->mdb = mdb; 139 140 /* These parameters are read from the MDB, and never written */ 141 HFS_SB(sb)->part_start = part_start; 142 HFS_SB(sb)->fs_ablocks = be16_to_cpu(mdb->drNmAlBlks); 143 HFS_SB(sb)->fs_div = HFS_SB(sb)->alloc_blksz >> sb->s_blocksize_bits; 144 HFS_SB(sb)->clumpablks = be32_to_cpu(mdb->drClpSiz) / 145 HFS_SB(sb)->alloc_blksz; 146 if (!HFS_SB(sb)->clumpablks) 147 HFS_SB(sb)->clumpablks = 1; 148 HFS_SB(sb)->fs_start = (be16_to_cpu(mdb->drAlBlSt) + part_start) >> 149 (sb->s_blocksize_bits - HFS_SECTOR_SIZE_BITS); 150 151 /* These parameters are read from and written to the MDB */ 152 HFS_SB(sb)->free_ablocks = be16_to_cpu(mdb->drFreeBks); 153 HFS_SB(sb)->next_id = be32_to_cpu(mdb->drNxtCNID); 154 HFS_SB(sb)->root_files = be16_to_cpu(mdb->drNmFls); 155 HFS_SB(sb)->root_dirs = be16_to_cpu(mdb->drNmRtDirs); 156 HFS_SB(sb)->file_count = be32_to_cpu(mdb->drFilCnt); 157 HFS_SB(sb)->folder_count = be32_to_cpu(mdb->drDirCnt); 158 159 /* TRY to get the alternate (backup) MDB. */ 160 sect = part_start + part_size - 2; 161 bh = sb_bread512(sb, sect, mdb2); 162 if (bh) { 163 if (mdb2->drSigWord == cpu_to_be16(HFS_SUPER_MAGIC)) { 164 HFS_SB(sb)->alt_mdb_bh = bh; 165 HFS_SB(sb)->alt_mdb = mdb2; 166 } else 167 brelse(bh); 168 } 169 170 if (!HFS_SB(sb)->alt_mdb) { 171 pr_warn("unable to locate alternate MDB\n"); 172 pr_warn("continuing without an alternate MDB\n"); 173 } 174 175 HFS_SB(sb)->bitmap = kmalloc(8192, GFP_KERNEL); 176 if (!HFS_SB(sb)->bitmap) 177 goto out; 178 179 /* read in the bitmap */ 180 block = be16_to_cpu(mdb->drVBMSt) + part_start; 181 off = (loff_t)block << HFS_SECTOR_SIZE_BITS; 182 size = (HFS_SB(sb)->fs_ablocks + 8) / 8; 183 ptr = (u8 *)HFS_SB(sb)->bitmap; 184 while (size) { 185 bh = sb_bread(sb, off >> sb->s_blocksize_bits); 186 if (!bh) { 187 pr_err("unable to read volume bitmap\n"); 188 goto out; 189 } 190 off2 = off & (sb->s_blocksize - 1); 191 len = min((int)sb->s_blocksize - off2, size); 192 memcpy(ptr, bh->b_data + off2, len); 193 brelse(bh); 194 ptr += len; 195 off += len; 196 size -= len; 197 } 198 199 HFS_SB(sb)->ext_tree = hfs_btree_open(sb, HFS_EXT_CNID, hfs_ext_keycmp); 200 if (!HFS_SB(sb)->ext_tree) { 201 pr_err("unable to open extent tree\n"); 202 goto out; 203 } 204 HFS_SB(sb)->cat_tree = hfs_btree_open(sb, HFS_CAT_CNID, hfs_cat_keycmp); 205 if (!HFS_SB(sb)->cat_tree) { 206 pr_err("unable to open catalog tree\n"); 207 goto out; 208 } 209 210 attrib = mdb->drAtrb; 211 if (!(attrib & cpu_to_be16(HFS_SB_ATTRIB_UNMNT))) { 212 pr_warn("filesystem was not cleanly unmounted, running fsck.hfs is recommended. mounting read-only.\n"); 213 sb->s_flags |= SB_RDONLY; 214 } 215 if ((attrib & cpu_to_be16(HFS_SB_ATTRIB_SLOCK))) { 216 pr_warn("filesystem is marked locked, mounting read-only.\n"); 217 sb->s_flags |= SB_RDONLY; 218 } 219 if (!sb_rdonly(sb)) { 220 /* Mark the volume uncleanly unmounted in case we crash */ 221 attrib &= cpu_to_be16(~HFS_SB_ATTRIB_UNMNT); 222 attrib |= cpu_to_be16(HFS_SB_ATTRIB_INCNSTNT); 223 mdb->drAtrb = attrib; 224 be32_add_cpu(&mdb->drWrCnt, 1); 225 mdb->drLsMod = hfs_mtime(); 226 227 mark_buffer_dirty(HFS_SB(sb)->mdb_bh); 228 sync_dirty_buffer(HFS_SB(sb)->mdb_bh); 229 } 230 231 return 0; 232 233 out_bh: 234 brelse(bh); 235 out: 236 hfs_mdb_put(sb); 237 return -EIO; 238 } 239 240 /* 241 * hfs_mdb_commit() 242 * 243 * Description: 244 * This updates the MDB on disk. 245 * It does not check, if the superblock has been modified, or 246 * if the filesystem has been mounted read-only. It is mainly 247 * called by hfs_sync_fs() and flush_mdb(). 248 * Input Variable(s): 249 * struct hfs_mdb *mdb: Pointer to the hfs MDB 250 * int backup; 251 * Output Variable(s): 252 * NONE 253 * Returns: 254 * void 255 * Preconditions: 256 * 'mdb' points to a "valid" (struct hfs_mdb). 257 * Postconditions: 258 * The HFS MDB and on disk will be updated, by copying the possibly 259 * modified fields from the in memory MDB (in native byte order) to 260 * the disk block buffer. 261 * If 'backup' is non-zero then the alternate MDB is also written 262 * and the function doesn't return until it is actually on disk. 263 */ 264 void hfs_mdb_commit(struct super_block *sb) 265 { 266 struct hfs_mdb *mdb = HFS_SB(sb)->mdb; 267 268 if (sb_rdonly(sb)) 269 return; 270 271 lock_buffer(HFS_SB(sb)->mdb_bh); 272 if (test_and_clear_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags)) { 273 /* These parameters may have been modified, so write them back */ 274 mdb->drLsMod = hfs_mtime(); 275 mdb->drFreeBks = cpu_to_be16(HFS_SB(sb)->free_ablocks); 276 mdb->drNxtCNID = cpu_to_be32(HFS_SB(sb)->next_id); 277 mdb->drNmFls = cpu_to_be16(HFS_SB(sb)->root_files); 278 mdb->drNmRtDirs = cpu_to_be16(HFS_SB(sb)->root_dirs); 279 mdb->drFilCnt = cpu_to_be32(HFS_SB(sb)->file_count); 280 mdb->drDirCnt = cpu_to_be32(HFS_SB(sb)->folder_count); 281 282 /* write MDB to disk */ 283 mark_buffer_dirty(HFS_SB(sb)->mdb_bh); 284 } 285 286 /* write the backup MDB, not returning until it is written. 287 * we only do this when either the catalog or extents overflow 288 * files grow. */ 289 if (test_and_clear_bit(HFS_FLG_ALT_MDB_DIRTY, &HFS_SB(sb)->flags) && 290 HFS_SB(sb)->alt_mdb) { 291 hfs_inode_write_fork(HFS_SB(sb)->ext_tree->inode, mdb->drXTExtRec, 292 &mdb->drXTFlSize, NULL); 293 hfs_inode_write_fork(HFS_SB(sb)->cat_tree->inode, mdb->drCTExtRec, 294 &mdb->drCTFlSize, NULL); 295 296 lock_buffer(HFS_SB(sb)->alt_mdb_bh); 297 memcpy(HFS_SB(sb)->alt_mdb, HFS_SB(sb)->mdb, HFS_SECTOR_SIZE); 298 HFS_SB(sb)->alt_mdb->drAtrb |= cpu_to_be16(HFS_SB_ATTRIB_UNMNT); 299 HFS_SB(sb)->alt_mdb->drAtrb &= cpu_to_be16(~HFS_SB_ATTRIB_INCNSTNT); 300 unlock_buffer(HFS_SB(sb)->alt_mdb_bh); 301 302 mark_buffer_dirty(HFS_SB(sb)->alt_mdb_bh); 303 sync_dirty_buffer(HFS_SB(sb)->alt_mdb_bh); 304 } 305 306 if (test_and_clear_bit(HFS_FLG_BITMAP_DIRTY, &HFS_SB(sb)->flags)) { 307 struct buffer_head *bh; 308 sector_t block; 309 char *ptr; 310 int off, size, len; 311 312 block = be16_to_cpu(HFS_SB(sb)->mdb->drVBMSt) + HFS_SB(sb)->part_start; 313 off = (block << HFS_SECTOR_SIZE_BITS) & (sb->s_blocksize - 1); 314 block >>= sb->s_blocksize_bits - HFS_SECTOR_SIZE_BITS; 315 size = (HFS_SB(sb)->fs_ablocks + 7) / 8; 316 ptr = (u8 *)HFS_SB(sb)->bitmap; 317 while (size) { 318 bh = sb_bread(sb, block); 319 if (!bh) { 320 pr_err("unable to read volume bitmap\n"); 321 break; 322 } 323 len = min((int)sb->s_blocksize - off, size); 324 325 lock_buffer(bh); 326 memcpy(bh->b_data + off, ptr, len); 327 unlock_buffer(bh); 328 329 mark_buffer_dirty(bh); 330 brelse(bh); 331 block++; 332 off = 0; 333 ptr += len; 334 size -= len; 335 } 336 } 337 unlock_buffer(HFS_SB(sb)->mdb_bh); 338 } 339 340 void hfs_mdb_close(struct super_block *sb) 341 { 342 /* update volume attributes */ 343 if (sb_rdonly(sb)) 344 return; 345 HFS_SB(sb)->mdb->drAtrb |= cpu_to_be16(HFS_SB_ATTRIB_UNMNT); 346 HFS_SB(sb)->mdb->drAtrb &= cpu_to_be16(~HFS_SB_ATTRIB_INCNSTNT); 347 mark_buffer_dirty(HFS_SB(sb)->mdb_bh); 348 } 349 350 /* 351 * hfs_mdb_put() 352 * 353 * Release the resources associated with the in-core MDB. */ 354 void hfs_mdb_put(struct super_block *sb) 355 { 356 if (!HFS_SB(sb)) 357 return; 358 /* free the B-trees */ 359 hfs_btree_close(HFS_SB(sb)->ext_tree); 360 hfs_btree_close(HFS_SB(sb)->cat_tree); 361 362 /* free the buffers holding the primary and alternate MDBs */ 363 brelse(HFS_SB(sb)->mdb_bh); 364 brelse(HFS_SB(sb)->alt_mdb_bh); 365 366 unload_nls(HFS_SB(sb)->nls_io); 367 unload_nls(HFS_SB(sb)->nls_disk); 368 369 kfree(HFS_SB(sb)->bitmap); 370 kfree(HFS_SB(sb)); 371 sb->s_fs_info = NULL; 372 } 373