fs/hfs/mdb.c

   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/genhd.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 = i_size_read(sb->s_bdev->bd_inode) >> 9;
  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 }