fs/hfs/inode.c

   1 /*
   2  *  linux/fs/hfs/inode.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 inode-related functions which do not depend on
   9  * which scheme is being used to represent forks.
  10  *
  11  * Based on the minix file system code, (C) 1991, 1992 by Linus Torvalds
  12  */
  13
  14 #include <linux/pagemap.h>
  15 #include <linux/mpage.h>
  16
  17 #include "hfs_fs.h"
  18 #include "btree.h"
  19
  20 static struct file_operations hfs_file_operations;
  21 static struct inode_operations hfs_file_inode_operations;
  22
  23 /*================ Variable-like macros ================*/
  24
  25 #define HFS_VALID_MODE_BITS  (S_IFREG | S_IFDIR | S_IRWXUGO)
  26
  27 static int hfs_writepage(struct page *page, struct writeback_control *wbc)
  28 {
  29         return block_write_full_page(page, hfs_get_block, wbc);
  30 }
  31
  32 static int hfs_readpage(struct file *file, struct page *page)
  33 {
  34         return block_read_full_page(page, hfs_get_block);
  35 }
  36
  37 static int hfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
  38 {
  39         return cont_prepare_write(page, from, to, hfs_get_block,
  40                                   &HFS_I(page->mapping->host)->phys_size);
  41 }
  42
  43 static sector_t hfs_bmap(struct address_space *mapping, sector_t block)
  44 {
  45         return generic_block_bmap(mapping, block, hfs_get_block);
  46 }
  47
  48 static int hfs_releasepage(struct page *page, gfp_t mask)
  49 {
  50         struct inode *inode = page->mapping->host;
  51         struct super_block *sb = inode->i_sb;
  52         struct hfs_btree *tree;
  53         struct hfs_bnode *node;
  54         u32 nidx;
  55         int i, res = 1;
  56
  57         switch (inode->i_ino) {
  58         case HFS_EXT_CNID:
  59                 tree = HFS_SB(sb)->ext_tree;
  60                 break;
  61         case HFS_CAT_CNID:
  62                 tree = HFS_SB(sb)->cat_tree;
  63                 break;
  64         default:
  65                 BUG();
  66                 return 0;
  67         }
  68         if (tree->node_size >= PAGE_CACHE_SIZE) {
  69                 nidx = page->index >> (tree->node_size_shift - PAGE_CACHE_SHIFT);
  70                 spin_lock(&tree->hash_lock);
  71                 node = hfs_bnode_findhash(tree, nidx);
  72                 if (!node)
  73                         ;
  74                 else if (atomic_read(&node->refcnt))
  75                         res = 0;
  76                 if (res && node) {
  77                         hfs_bnode_unhash(node);
  78                         hfs_bnode_free(node);
  79                 }
  80                 spin_unlock(&tree->hash_lock);
  81         } else {
  82                 nidx = page->index << (PAGE_CACHE_SHIFT - tree->node_size_shift);
  83                 i = 1 << (PAGE_CACHE_SHIFT - tree->node_size_shift);
  84                 spin_lock(&tree->hash_lock);
  85                 do {
  86                         node = hfs_bnode_findhash(tree, nidx++);
  87                         if (!node)
  88                                 continue;
  89                         if (atomic_read(&node->refcnt)) {
  90                                 res = 0;
  91                                 break;
  92                         }
  93                         hfs_bnode_unhash(node);
  94                         hfs_bnode_free(node);
  95                 } while (--i && nidx < tree->node_count);
  96                 spin_unlock(&tree->hash_lock);
  97         }
  98         return res ? try_to_free_buffers(page) : 0;
  99 }
 100
 101 static int hfs_get_blocks(struct inode *inode, sector_t iblock, unsigned long max_blocks,
 102                           struct buffer_head *bh_result, int create)
 103 {
 104         int ret;
 105
 106         ret = hfs_get_block(inode, iblock, bh_result, create);
 107         if (!ret)
 108                 bh_result->b_size = (1 << inode->i_blkbits);
 109         return ret;
 110 }
 111
 112 static ssize_t hfs_direct_IO(int rw, struct kiocb *iocb,
 113                 const struct iovec *iov, loff_t offset, unsigned long nr_segs)
 114 {
 115         struct file *file = iocb->ki_filp;
 116         struct inode *inode = file->f_dentry->d_inode->i_mapping->host;
 117
 118         return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
 119                                   offset, nr_segs, hfs_get_blocks, NULL);
 120 }
 121
 122 static int hfs_writepages(struct address_space *mapping,
 123                           struct writeback_control *wbc)
 124 {
 125         return mpage_writepages(mapping, wbc, hfs_get_block);
 126 }
 127
 128 struct address_space_operations hfs_btree_aops = {
 129         .readpage       = hfs_readpage,
 130         .writepage      = hfs_writepage,
 131         .sync_page      = block_sync_page,
 132         .prepare_write  = hfs_prepare_write,
 133         .commit_write   = generic_commit_write,
 134         .bmap           = hfs_bmap,
 135         .releasepage    = hfs_releasepage,
 136 };
 137
 138 struct address_space_operations hfs_aops = {
 139         .readpage       = hfs_readpage,
 140         .writepage      = hfs_writepage,
 141         .sync_page      = block_sync_page,
 142         .prepare_write  = hfs_prepare_write,
 143         .commit_write   = generic_commit_write,
 144         .bmap           = hfs_bmap,
 145         .direct_IO      = hfs_direct_IO,
 146         .writepages     = hfs_writepages,
 147 };
 148
 149 /*
 150  * hfs_new_inode
 151  */
 152 struct inode *hfs_new_inode(struct inode *dir, struct qstr *name, int mode)
 153 {
 154         struct super_block *sb = dir->i_sb;
 155         struct inode *inode = new_inode(sb);
 156         if (!inode)
 157                 return NULL;
 158
 159         init_MUTEX(&HFS_I(inode)->extents_lock);
 160         INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
 161         hfs_cat_build_key(sb, (btree_key *)&HFS_I(inode)->cat_key, dir->i_ino, name);
 162         inode->i_ino = HFS_SB(sb)->next_id++;
 163         inode->i_mode = mode;
 164         inode->i_uid = current->fsuid;
 165         inode->i_gid = current->fsgid;
 166         inode->i_nlink = 1;
 167         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
 168         inode->i_blksize = HFS_SB(sb)->alloc_blksz;
 169         HFS_I(inode)->flags = 0;
 170         HFS_I(inode)->rsrc_inode = NULL;
 171         HFS_I(inode)->fs_blocks = 0;
 172         if (S_ISDIR(mode)) {
 173                 inode->i_size = 2;
 174                 HFS_SB(sb)->folder_count++;
 175                 if (dir->i_ino == HFS_ROOT_CNID)
 176                         HFS_SB(sb)->root_dirs++;
 177                 inode->i_op = &hfs_dir_inode_operations;
 178                 inode->i_fop = &hfs_dir_operations;
 179                 inode->i_mode |= S_IRWXUGO;
 180                 inode->i_mode &= ~HFS_SB(inode->i_sb)->s_dir_umask;
 181         } else if (S_ISREG(mode)) {
 182                 HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
 183                 HFS_SB(sb)->file_count++;
 184                 if (dir->i_ino == HFS_ROOT_CNID)
 185                         HFS_SB(sb)->root_files++;
 186                 inode->i_op = &hfs_file_inode_operations;
 187                 inode->i_fop = &hfs_file_operations;
 188                 inode->i_mapping->a_ops = &hfs_aops;
 189                 inode->i_mode |= S_IRUGO|S_IXUGO;
 190                 if (mode & S_IWUSR)
 191                         inode->i_mode |= S_IWUGO;
 192                 inode->i_mode &= ~HFS_SB(inode->i_sb)->s_file_umask;
 193                 HFS_I(inode)->phys_size = 0;
 194                 HFS_I(inode)->alloc_blocks = 0;
 195                 HFS_I(inode)->first_blocks = 0;
 196                 HFS_I(inode)->cached_start = 0;
 197                 HFS_I(inode)->cached_blocks = 0;
 198                 memset(HFS_I(inode)->first_extents, 0, sizeof(hfs_extent_rec));
 199                 memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
 200         }
 201         insert_inode_hash(inode);
 202         mark_inode_dirty(inode);
 203         set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 204         sb->s_dirt = 1;
 205
 206         return inode;
 207 }
 208
 209 void hfs_delete_inode(struct inode *inode)
 210 {
 211         struct super_block *sb = inode->i_sb;
 212
 213         dprint(DBG_INODE, "delete_inode: %lu\n", inode->i_ino);
 214         if (S_ISDIR(inode->i_mode)) {
 215                 HFS_SB(sb)->folder_count--;
 216                 if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
 217                         HFS_SB(sb)->root_dirs--;
 218                 set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 219                 sb->s_dirt = 1;
 220                 return;
 221         }
 222         HFS_SB(sb)->file_count--;
 223         if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
 224                 HFS_SB(sb)->root_files--;
 225         if (S_ISREG(inode->i_mode)) {
 226                 if (!inode->i_nlink) {
 227                         inode->i_size = 0;
 228                         hfs_file_truncate(inode);
 229                 }
 230         }
 231         set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 232         sb->s_dirt = 1;
 233 }
 234
 235 void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
 236                          __be32 __log_size, __be32 phys_size, u32 clump_size)
 237 {
 238         struct super_block *sb = inode->i_sb;
 239         u32 log_size = be32_to_cpu(__log_size);
 240         u16 count;
 241         int i;
 242
 243         memcpy(HFS_I(inode)->first_extents, ext, sizeof(hfs_extent_rec));
 244         for (count = 0, i = 0; i < 3; i++)
 245                 count += be16_to_cpu(ext[i].count);
 246         HFS_I(inode)->first_blocks = count;
 247
 248         inode->i_size = HFS_I(inode)->phys_size = log_size;
 249         HFS_I(inode)->fs_blocks = (log_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 250         inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
 251         HFS_I(inode)->alloc_blocks = be32_to_cpu(phys_size) /
 252                                      HFS_SB(sb)->alloc_blksz;
 253         HFS_I(inode)->clump_blocks = clump_size / HFS_SB(sb)->alloc_blksz;
 254         if (!HFS_I(inode)->clump_blocks)
 255                 HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
 256 }
 257
 258 struct hfs_iget_data {
 259         struct hfs_cat_key *key;
 260         hfs_cat_rec *rec;
 261 };
 262
 263 static int hfs_test_inode(struct inode *inode, void *data)
 264 {
 265         struct hfs_iget_data *idata = data;
 266         hfs_cat_rec *rec;
 267
 268         rec = idata->rec;
 269         switch (rec->type) {
 270         case HFS_CDR_DIR:
 271                 return inode->i_ino == be32_to_cpu(rec->dir.DirID);
 272         case HFS_CDR_FIL:
 273                 return inode->i_ino == be32_to_cpu(rec->file.FlNum);
 274         default:
 275                 BUG();
 276                 return 1;
 277         }
 278 }
 279
 280 /*
 281  * hfs_read_inode
 282  */
 283 static int hfs_read_inode(struct inode *inode, void *data)
 284 {
 285         struct hfs_iget_data *idata = data;
 286         struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
 287         hfs_cat_rec *rec;
 288
 289         HFS_I(inode)->flags = 0;
 290         HFS_I(inode)->rsrc_inode = NULL;
 291         init_MUTEX(&HFS_I(inode)->extents_lock);
 292         INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
 293
 294         /* Initialize the inode */
 295         inode->i_uid = hsb->s_uid;
 296         inode->i_gid = hsb->s_gid;
 297         inode->i_nlink = 1;
 298         inode->i_blksize = HFS_SB(inode->i_sb)->alloc_blksz;
 299
 300         if (idata->key)
 301                 HFS_I(inode)->cat_key = *idata->key;
 302         else
 303                 HFS_I(inode)->flags |= HFS_FLG_RSRC;
 304         HFS_I(inode)->tz_secondswest = sys_tz.tz_minuteswest * 60;
 305
 306         rec = idata->rec;
 307         switch (rec->type) {
 308         case HFS_CDR_FIL:
 309                 if (!HFS_IS_RSRC(inode)) {
 310                         hfs_inode_read_fork(inode, rec->file.ExtRec, rec->file.LgLen,
 311                                             rec->file.PyLen, be16_to_cpu(rec->file.ClpSize));
 312                 } else {
 313                         hfs_inode_read_fork(inode, rec->file.RExtRec, rec->file.RLgLen,
 314                                             rec->file.RPyLen, be16_to_cpu(rec->file.ClpSize));
 315                 }
 316
 317                 inode->i_ino = be32_to_cpu(rec->file.FlNum);
 318                 inode->i_mode = S_IRUGO | S_IXUGO;
 319                 if (!(rec->file.Flags & HFS_FIL_LOCK))
 320                         inode->i_mode |= S_IWUGO;
 321                 inode->i_mode &= ~hsb->s_file_umask;
 322                 inode->i_mode |= S_IFREG;
 323                 inode->i_ctime = inode->i_atime = inode->i_mtime =
 324                                 hfs_m_to_utime(rec->file.MdDat);
 325                 inode->i_op = &hfs_file_inode_operations;
 326                 inode->i_fop = &hfs_file_operations;
 327                 inode->i_mapping->a_ops = &hfs_aops;
 328                 break;
 329         case HFS_CDR_DIR:
 330                 inode->i_ino = be32_to_cpu(rec->dir.DirID);
 331                 inode->i_size = be16_to_cpu(rec->dir.Val) + 2;
 332                 HFS_I(inode)->fs_blocks = 0;
 333                 inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask);
 334                 inode->i_ctime = inode->i_atime = inode->i_mtime =
 335                                 hfs_m_to_utime(rec->dir.MdDat);
 336                 inode->i_op = &hfs_dir_inode_operations;
 337                 inode->i_fop = &hfs_dir_operations;
 338                 break;
 339         default:
 340                 make_bad_inode(inode);
 341         }
 342         return 0;
 343 }
 344
 345 /*
 346  * __hfs_iget()
 347  *
 348  * Given the MDB for a HFS filesystem, a 'key' and an 'entry' in
 349  * the catalog B-tree and the 'type' of the desired file return the
 350  * inode for that file/directory or NULL.  Note that 'type' indicates
 351  * whether we want the actual file or directory, or the corresponding
 352  * metadata (AppleDouble header file or CAP metadata file).
 353  */
 354 struct inode *hfs_iget(struct super_block *sb, struct hfs_cat_key *key, hfs_cat_rec *rec)
 355 {
 356         struct hfs_iget_data data = { key, rec };
 357         struct inode *inode;
 358         u32 cnid;
 359
 360         switch (rec->type) {
 361         case HFS_CDR_DIR:
 362                 cnid = be32_to_cpu(rec->dir.DirID);
 363                 break;
 364         case HFS_CDR_FIL:
 365                 cnid = be32_to_cpu(rec->file.FlNum);
 366                 break;
 367         default:
 368                 return NULL;
 369         }
 370         inode = iget5_locked(sb, cnid, hfs_test_inode, hfs_read_inode, &data);
 371         if (inode && (inode->i_state & I_NEW))
 372                 unlock_new_inode(inode);
 373         return inode;
 374 }
 375
 376 void hfs_inode_write_fork(struct inode *inode, struct hfs_extent *ext,
 377                           __be32 *log_size, __be32 *phys_size)
 378 {
 379         memcpy(ext, HFS_I(inode)->first_extents, sizeof(hfs_extent_rec));
 380
 381         if (log_size)
 382                 *log_size = cpu_to_be32(inode->i_size);
 383         if (phys_size)
 384                 *phys_size = cpu_to_be32(HFS_I(inode)->alloc_blocks *
 385                                          HFS_SB(inode->i_sb)->alloc_blksz);
 386 }
 387
 388 int hfs_write_inode(struct inode *inode, int unused)
 389 {
 390         struct inode *main_inode = inode;
 391         struct hfs_find_data fd;
 392         hfs_cat_rec rec;
 393
 394         dprint(DBG_INODE, "hfs_write_inode: %lu\n", inode->i_ino);
 395         hfs_ext_write_extent(inode);
 396
 397         if (inode->i_ino < HFS_FIRSTUSER_CNID) {
 398                 switch (inode->i_ino) {
 399                 case HFS_ROOT_CNID:
 400                         break;
 401                 case HFS_EXT_CNID:
 402                         hfs_btree_write(HFS_SB(inode->i_sb)->ext_tree);
 403                         return 0;
 404                 case HFS_CAT_CNID:
 405                         hfs_btree_write(HFS_SB(inode->i_sb)->cat_tree);
 406                         return 0;
 407                 default:
 408                         BUG();
 409                         return -EIO;
 410                 }
 411         }
 412
 413         if (HFS_IS_RSRC(inode))
 414                 main_inode = HFS_I(inode)->rsrc_inode;
 415
 416         if (!main_inode->i_nlink)
 417                 return 0;
 418
 419         if (hfs_find_init(HFS_SB(main_inode->i_sb)->cat_tree, &fd))
 420                 /* panic? */
 421                 return -EIO;
 422
 423         fd.search_key->cat = HFS_I(main_inode)->cat_key;
 424         if (hfs_brec_find(&fd))
 425                 /* panic? */
 426                 goto out;
 427
 428         if (S_ISDIR(main_inode->i_mode)) {
 429                 if (fd.entrylength < sizeof(struct hfs_cat_dir))
 430                         /* panic? */;
 431                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 432                            sizeof(struct hfs_cat_dir));
 433                 if (rec.type != HFS_CDR_DIR ||
 434                     be32_to_cpu(rec.dir.DirID) != inode->i_ino) {
 435                 }
 436
 437                 rec.dir.MdDat = hfs_u_to_mtime(inode->i_mtime);
 438                 rec.dir.Val = cpu_to_be16(inode->i_size - 2);
 439
 440                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 441                             sizeof(struct hfs_cat_dir));
 442         } else if (HFS_IS_RSRC(inode)) {
 443                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 444                                sizeof(struct hfs_cat_file));
 445                 hfs_inode_write_fork(inode, rec.file.RExtRec,
 446                                      &rec.file.RLgLen, &rec.file.RPyLen);
 447                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 448                                 sizeof(struct hfs_cat_file));
 449         } else {
 450                 if (fd.entrylength < sizeof(struct hfs_cat_file))
 451                         /* panic? */;
 452                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 453                            sizeof(struct hfs_cat_file));
 454                 if (rec.type != HFS_CDR_FIL ||
 455                     be32_to_cpu(rec.file.FlNum) != inode->i_ino) {
 456                 }
 457
 458                 if (inode->i_mode & S_IWUSR)
 459                         rec.file.Flags &= ~HFS_FIL_LOCK;
 460                 else
 461                         rec.file.Flags |= HFS_FIL_LOCK;
 462                 hfs_inode_write_fork(inode, rec.file.ExtRec, &rec.file.LgLen, &rec.file.PyLen);
 463                 rec.file.MdDat = hfs_u_to_mtime(inode->i_mtime);
 464
 465                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 466                             sizeof(struct hfs_cat_file));
 467         }
 468 out:
 469         hfs_find_exit(&fd);
 470         return 0;
 471 }
 472
 473 static struct dentry *hfs_file_lookup(struct inode *dir, struct dentry *dentry,
 474                                       struct nameidata *nd)
 475 {
 476         struct inode *inode = NULL;
 477         hfs_cat_rec rec;
 478         struct hfs_find_data fd;
 479         int res;
 480
 481         if (HFS_IS_RSRC(dir) || strcmp(dentry->d_name.name, "rsrc"))
 482                 goto out;
 483
 484         inode = HFS_I(dir)->rsrc_inode;
 485         if (inode)
 486                 goto out;
 487
 488         inode = new_inode(dir->i_sb);
 489         if (!inode)
 490                 return ERR_PTR(-ENOMEM);
 491
 492         hfs_find_init(HFS_SB(dir->i_sb)->cat_tree, &fd);
 493         fd.search_key->cat = HFS_I(dir)->cat_key;
 494         res = hfs_brec_read(&fd, &rec, sizeof(rec));
 495         if (!res) {
 496                 struct hfs_iget_data idata = { NULL, &rec };
 497                 hfs_read_inode(inode, &idata);
 498         }
 499         hfs_find_exit(&fd);
 500         if (res) {
 501                 iput(inode);
 502                 return ERR_PTR(res);
 503         }
 504         HFS_I(inode)->rsrc_inode = dir;
 505         HFS_I(dir)->rsrc_inode = inode;
 506         igrab(dir);
 507         hlist_add_head(&inode->i_hash, &HFS_SB(dir->i_sb)->rsrc_inodes);
 508         mark_inode_dirty(inode);
 509 out:
 510         d_add(dentry, inode);
 511         return NULL;
 512 }
 513
 514 void hfs_clear_inode(struct inode *inode)
 515 {
 516         if (HFS_IS_RSRC(inode) && HFS_I(inode)->rsrc_inode) {
 517                 HFS_I(HFS_I(inode)->rsrc_inode)->rsrc_inode = NULL;
 518                 iput(HFS_I(inode)->rsrc_inode);
 519         }
 520 }
 521
 522 static int hfs_permission(struct inode *inode, int mask,
 523                           struct nameidata *nd)
 524 {
 525         if (S_ISREG(inode->i_mode) && mask & MAY_EXEC)
 526                 return 0;
 527         return generic_permission(inode, mask, NULL);
 528 }
 529
 530 static int hfs_file_open(struct inode *inode, struct file *file)
 531 {
 532         if (HFS_IS_RSRC(inode))
 533                 inode = HFS_I(inode)->rsrc_inode;
 534         if (atomic_read(&file->f_count) != 1)
 535                 return 0;
 536         atomic_inc(&HFS_I(inode)->opencnt);
 537         return 0;
 538 }
 539
 540 static int hfs_file_release(struct inode *inode, struct file *file)
 541 {
 542         //struct super_block *sb = inode->i_sb;
 543
 544         if (HFS_IS_RSRC(inode))
 545                 inode = HFS_I(inode)->rsrc_inode;
 546         if (atomic_read(&file->f_count) != 0)
 547                 return 0;
 548         if (atomic_dec_and_test(&HFS_I(inode)->opencnt)) {
 549                 mutex_lock(&inode->i_mutex);
 550                 hfs_file_truncate(inode);
 551                 //if (inode->i_flags & S_DEAD) {
 552                 //      hfs_delete_cat(inode->i_ino, HFSPLUS_SB(sb).hidden_dir, NULL);
 553                 //      hfs_delete_inode(inode);
 554                 //}
 555                 mutex_unlock(&inode->i_mutex);
 556         }
 557         return 0;
 558 }
 559
 560 /*
 561  * hfs_notify_change()
 562  *
 563  * Based very closely on fs/msdos/inode.c by Werner Almesberger
 564  *
 565  * This is the notify_change() field in the super_operations structure
 566  * for HFS file systems.  The purpose is to take that changes made to
 567  * an inode and apply then in a filesystem-dependent manner.  In this
 568  * case the process has a few of tasks to do:
 569  *  1) prevent changes to the i_uid and i_gid fields.
 570  *  2) map file permissions to the closest allowable permissions
 571  *  3) Since multiple Linux files can share the same on-disk inode under
 572  *     HFS (for instance the data and resource forks of a file) a change
 573  *     to permissions must be applied to all other in-core inodes which
 574  *     correspond to the same HFS file.
 575  */
 576
 577 int hfs_inode_setattr(struct dentry *dentry, struct iattr * attr)
 578 {
 579         struct inode *inode = dentry->d_inode;
 580         struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
 581         int error;
 582
 583         error = inode_change_ok(inode, attr); /* basic permission checks */
 584         if (error)
 585                 return error;
 586
 587         /* no uig/gid changes and limit which mode bits can be set */
 588         if (((attr->ia_valid & ATTR_UID) &&
 589              (attr->ia_uid != hsb->s_uid)) ||
 590             ((attr->ia_valid & ATTR_GID) &&
 591              (attr->ia_gid != hsb->s_gid)) ||
 592             ((attr->ia_valid & ATTR_MODE) &&
 593              ((S_ISDIR(inode->i_mode) &&
 594                (attr->ia_mode != inode->i_mode)) ||
 595               (attr->ia_mode & ~HFS_VALID_MODE_BITS)))) {
 596                 return hsb->s_quiet ? 0 : error;
 597         }
 598
 599         if (attr->ia_valid & ATTR_MODE) {
 600                 /* Only the 'w' bits can ever change and only all together. */
 601                 if (attr->ia_mode & S_IWUSR)
 602                         attr->ia_mode = inode->i_mode | S_IWUGO;
 603                 else
 604                         attr->ia_mode = inode->i_mode & ~S_IWUGO;
 605                 attr->ia_mode &= S_ISDIR(inode->i_mode) ? ~hsb->s_dir_umask: ~hsb->s_file_umask;
 606         }
 607         error = inode_setattr(inode, attr);
 608         if (error)
 609                 return error;
 610
 611         return 0;
 612 }
 613
 614
 615 static struct file_operations hfs_file_operations = {
 616         .llseek         = generic_file_llseek,
 617         .read           = generic_file_read,
 618         .write          = generic_file_write,
 619         .mmap           = generic_file_mmap,
 620         .sendfile       = generic_file_sendfile,
 621         .fsync          = file_fsync,
 622         .open           = hfs_file_open,
 623         .release        = hfs_file_release,
 624 };
 625
 626 static struct inode_operations hfs_file_inode_operations = {
 627         .lookup         = hfs_file_lookup,
 628         .truncate       = hfs_file_truncate,
 629         .setattr        = hfs_inode_setattr,
 630         .permission     = hfs_permission,
 631         .setxattr       = hfs_setxattr,
 632         .getxattr       = hfs_getxattr,
 633         .listxattr      = hfs_listxattr,
 634 };