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/version.h>
  16 #include <linux/mpage.h>
  17
  18 #include "hfs_fs.h"
  19 #include "btree.h"
  20
  21 static struct file_operations hfs_file_operations;
  22 static struct inode_operations hfs_file_inode_operations;
  23
  24 /*================ Variable-like macros ================*/
  25
  26 #define HFS_VALID_MODE_BITS  (S_IFREG | S_IFDIR | S_IRWXUGO)
  27
  28 static int hfs_writepage(struct page *page, struct writeback_control *wbc)
  29 {
  30         return block_write_full_page(page, hfs_get_block, wbc);
  31 }
  32
  33 static int hfs_readpage(struct file *file, struct page *page)
  34 {
  35         return block_read_full_page(page, hfs_get_block);
  36 }
  37
  38 static int hfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
  39 {
  40         return cont_prepare_write(page, from, to, hfs_get_block,
  41                                   &HFS_I(page->mapping->host)->phys_size);
  42 }
  43
  44 static sector_t hfs_bmap(struct address_space *mapping, sector_t block)
  45 {
  46         return generic_block_bmap(mapping, block, hfs_get_block);
  47 }
  48
  49 static int hfs_releasepage(struct page *page, int mask)
  50 {
  51         struct inode *inode = page->mapping->host;
  52         struct super_block *sb = inode->i_sb;
  53         struct hfs_btree *tree;
  54         struct hfs_bnode *node;
  55         u32 nidx;
  56         int i, res = 1;
  57
  58         switch (inode->i_ino) {
  59         case HFS_EXT_CNID:
  60                 tree = HFS_SB(sb)->ext_tree;
  61                 break;
  62         case HFS_CAT_CNID:
  63                 tree = HFS_SB(sb)->cat_tree;
  64                 break;
  65         default:
  66                 BUG();
  67                 return 0;
  68         }
  69         if (tree->node_size >= PAGE_CACHE_SIZE) {
  70                 nidx = page->index >> (tree->node_size_shift - PAGE_CACHE_SHIFT);
  71                 spin_lock(&tree->hash_lock);
  72                 node = hfs_bnode_findhash(tree, nidx);
  73                 if (!node)
  74                         ;
  75                 else if (atomic_read(&node->refcnt))
  76                         res = 0;
  77                 if (res && node) {
  78                         hfs_bnode_unhash(node);
  79                         hfs_bnode_free(node);
  80                 }
  81                 spin_unlock(&tree->hash_lock);
  82         } else {
  83                 nidx = page->index << (PAGE_CACHE_SHIFT - tree->node_size_shift);
  84                 i = 1 << (PAGE_CACHE_SHIFT - tree->node_size_shift);
  85                 spin_lock(&tree->hash_lock);
  86                 do {
  87                         node = hfs_bnode_findhash(tree, nidx++);
  88                         if (!node)
  89                                 continue;
  90                         if (atomic_read(&node->refcnt)) {
  91                                 res = 0;
  92                                 break;
  93                         }
  94                         hfs_bnode_unhash(node);
  95                         hfs_bnode_free(node);
  96                 } while (--i && nidx < tree->node_count);
  97                 spin_unlock(&tree->hash_lock);
  98         }
  99         //printk("releasepage: %lu,%x = %d\n", page->index, mask, res);
 100         return res ? try_to_free_buffers(page) : 0;
 101 }
 102
 103 static int hfs_get_blocks(struct inode *inode, sector_t iblock, unsigned long max_blocks,
 104                           struct buffer_head *bh_result, int create)
 105 {
 106         int ret;
 107
 108         ret = hfs_get_block(inode, iblock, bh_result, create);
 109         if (!ret)
 110                 bh_result->b_size = (1 << inode->i_blkbits);
 111         return ret;
 112 }
 113
 114 static ssize_t hfs_direct_IO(int rw, struct kiocb *iocb,
 115                 const struct iovec *iov, loff_t offset, unsigned long nr_segs)
 116 {
 117         struct file *file = iocb->ki_filp;
 118         struct inode *inode = file->f_dentry->d_inode->i_mapping->host;
 119
 120         return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
 121                                   offset, nr_segs, hfs_get_blocks, NULL);
 122 }
 123
 124 static int hfs_writepages(struct address_space *mapping,
 125                           struct writeback_control *wbc)
 126 {
 127         return mpage_writepages(mapping, wbc, hfs_get_block);
 128 }
 129
 130 struct address_space_operations hfs_btree_aops = {
 131         .readpage       = hfs_readpage,
 132         .writepage      = hfs_writepage,
 133         .sync_page      = block_sync_page,
 134         .prepare_write  = hfs_prepare_write,
 135         .commit_write   = generic_commit_write,
 136         .bmap           = hfs_bmap,
 137         .releasepage    = hfs_releasepage,
 138 };
 139
 140 struct address_space_operations hfs_aops = {
 141         .readpage       = hfs_readpage,
 142         .writepage      = hfs_writepage,
 143         .sync_page      = block_sync_page,
 144         .prepare_write  = hfs_prepare_write,
 145         .commit_write   = generic_commit_write,
 146         .bmap           = hfs_bmap,
 147         .direct_IO      = hfs_direct_IO,
 148         .writepages     = hfs_writepages,
 149 };
 150
 151 /*
 152  * hfs_new_inode
 153  */
 154 struct inode *hfs_new_inode(struct inode *dir, struct qstr *name, int mode)
 155 {
 156         struct super_block *sb = dir->i_sb;
 157         struct inode *inode = new_inode(sb);
 158         if (!inode)
 159                 return NULL;
 160
 161         init_MUTEX(&HFS_I(inode)->extents_lock);
 162         INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
 163         hfs_cat_build_key((btree_key *)&HFS_I(inode)->cat_key, dir->i_ino, name);
 164         inode->i_ino = HFS_SB(sb)->next_id++;
 165         inode->i_mode = mode;
 166         inode->i_uid = current->fsuid;
 167         inode->i_gid = current->fsgid;
 168         inode->i_nlink = 1;
 169         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
 170         inode->i_blksize = HFS_SB(sb)->alloc_blksz;
 171         HFS_I(inode)->flags = 0;
 172         HFS_I(inode)->rsrc_inode = NULL;
 173         HFS_I(inode)->fs_blocks = 0;
 174         if (S_ISDIR(mode)) {
 175                 inode->i_size = 2;
 176                 HFS_SB(sb)->folder_count++;
 177                 if (dir->i_ino == HFS_ROOT_CNID)
 178                         HFS_SB(sb)->root_dirs++;
 179                 inode->i_op = &hfs_dir_inode_operations;
 180                 inode->i_fop = &hfs_dir_operations;
 181                 inode->i_mode |= S_IRWXUGO;
 182                 inode->i_mode &= ~HFS_SB(inode->i_sb)->s_dir_umask;
 183         } else if (S_ISREG(mode)) {
 184                 HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
 185                 HFS_SB(sb)->file_count++;
 186                 if (dir->i_ino == HFS_ROOT_CNID)
 187                         HFS_SB(sb)->root_files++;
 188                 inode->i_op = &hfs_file_inode_operations;
 189                 inode->i_fop = &hfs_file_operations;
 190                 inode->i_mapping->a_ops = &hfs_aops;
 191                 inode->i_mode |= S_IRUGO|S_IXUGO;
 192                 if (mode & S_IWUSR)
 193                         inode->i_mode |= S_IWUGO;
 194                 inode->i_mode &= ~HFS_SB(inode->i_sb)->s_file_umask;
 195                 HFS_I(inode)->phys_size = 0;
 196                 HFS_I(inode)->alloc_blocks = 0;
 197                 HFS_I(inode)->first_blocks = 0;
 198                 HFS_I(inode)->cached_start = 0;
 199                 HFS_I(inode)->cached_blocks = 0;
 200                 memset(HFS_I(inode)->first_extents, 0, sizeof(hfs_extent_rec));
 201                 memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
 202         }
 203         insert_inode_hash(inode);
 204         mark_inode_dirty(inode);
 205         set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 206         sb->s_dirt = 1;
 207
 208         return inode;
 209 }
 210
 211 void hfs_delete_inode(struct inode *inode)
 212 {
 213         struct super_block *sb = inode->i_sb;
 214
 215         dprint(DBG_INODE, "delete_inode: %lu\n", inode->i_ino);
 216         if (S_ISDIR(inode->i_mode)) {
 217                 HFS_SB(sb)->folder_count--;
 218                 if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
 219                         HFS_SB(sb)->root_dirs--;
 220                 set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 221                 sb->s_dirt = 1;
 222                 return;
 223         }
 224         HFS_SB(sb)->file_count--;
 225         if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
 226                 HFS_SB(sb)->root_files--;
 227         if (S_ISREG(inode->i_mode)) {
 228                 if (!inode->i_nlink) {
 229                         inode->i_size = 0;
 230                         hfs_file_truncate(inode);
 231                 }
 232         }
 233         set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 234         sb->s_dirt = 1;
 235 }
 236
 237 void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
 238                          __be32 __log_size, __be32 phys_size, u32 clump_size)
 239 {
 240         struct super_block *sb = inode->i_sb;
 241         u32 log_size = be32_to_cpu(__log_size);
 242         u16 count;
 243         int i;
 244
 245         memcpy(HFS_I(inode)->first_extents, ext, sizeof(hfs_extent_rec));
 246         for (count = 0, i = 0; i < 3; i++)
 247                 count += be16_to_cpu(ext[i].count);
 248         HFS_I(inode)->first_blocks = count;
 249
 250         inode->i_size = HFS_I(inode)->phys_size = log_size;
 251         HFS_I(inode)->fs_blocks = (log_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 252         inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
 253         HFS_I(inode)->alloc_blocks = be32_to_cpu(phys_size) /
 254                                      HFS_SB(sb)->alloc_blksz;
 255         HFS_I(inode)->clump_blocks = clump_size / HFS_SB(sb)->alloc_blksz;
 256         if (!HFS_I(inode)->clump_blocks)
 257                 HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
 258 }
 259
 260 struct hfs_iget_data {
 261         struct hfs_cat_key *key;
 262         hfs_cat_rec *rec;
 263 };
 264
 265 static int hfs_test_inode(struct inode *inode, void *data)
 266 {
 267         struct hfs_iget_data *idata = data;
 268         hfs_cat_rec *rec;
 269
 270         rec = idata->rec;
 271         switch (rec->type) {
 272         case HFS_CDR_DIR:
 273                 return inode->i_ino == be32_to_cpu(rec->dir.DirID);
 274         case HFS_CDR_FIL:
 275                 return inode->i_ino == be32_to_cpu(rec->file.FlNum);
 276         default:
 277                 BUG();
 278                 return 1;
 279         }
 280 }
 281
 282 /*
 283  * hfs_read_inode
 284  */
 285 static int hfs_read_inode(struct inode *inode, void *data)
 286 {
 287         struct hfs_iget_data *idata = data;
 288         struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
 289         hfs_cat_rec *rec;
 290
 291         HFS_I(inode)->flags = 0;
 292         HFS_I(inode)->rsrc_inode = NULL;
 293         init_MUTEX(&HFS_I(inode)->extents_lock);
 294         INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
 295
 296         /* Initialize the inode */
 297         inode->i_uid = hsb->s_uid;
 298         inode->i_gid = hsb->s_gid;
 299         inode->i_nlink = 1;
 300         inode->i_blksize = HFS_SB(inode->i_sb)->alloc_blksz;
 301
 302         if (idata->key)
 303                 HFS_I(inode)->cat_key = *idata->key;
 304         else
 305                 HFS_I(inode)->flags |= HFS_FLG_RSRC;
 306         HFS_I(inode)->tz_secondswest = sys_tz.tz_minuteswest * 60;
 307
 308         rec = idata->rec;
 309         switch (rec->type) {
 310         case HFS_CDR_FIL:
 311                 if (!HFS_IS_RSRC(inode)) {
 312                         hfs_inode_read_fork(inode, rec->file.ExtRec, rec->file.LgLen,
 313                                             rec->file.PyLen, be16_to_cpu(rec->file.ClpSize));
 314                 } else {
 315                         hfs_inode_read_fork(inode, rec->file.RExtRec, rec->file.RLgLen,
 316                                             rec->file.RPyLen, be16_to_cpu(rec->file.ClpSize));
 317                 }
 318
 319                 inode->i_ino = be32_to_cpu(rec->file.FlNum);
 320                 inode->i_mode = S_IRUGO | S_IXUGO;
 321                 if (!(rec->file.Flags & HFS_FIL_LOCK))
 322                         inode->i_mode |= S_IWUGO;
 323                 inode->i_mode &= ~hsb->s_file_umask;
 324                 inode->i_mode |= S_IFREG;
 325                 inode->i_ctime = inode->i_atime = inode->i_mtime =
 326                                 hfs_m_to_utime(rec->file.MdDat);
 327                 inode->i_op = &hfs_file_inode_operations;
 328                 inode->i_fop = &hfs_file_operations;
 329                 inode->i_mapping->a_ops = &hfs_aops;
 330                 break;
 331         case HFS_CDR_DIR:
 332                 inode->i_ino = be32_to_cpu(rec->dir.DirID);
 333                 inode->i_size = be16_to_cpu(rec->dir.Val) + 2;
 334                 HFS_I(inode)->fs_blocks = 0;
 335                 inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask);
 336                 inode->i_ctime = inode->i_atime = inode->i_mtime =
 337                                 hfs_m_to_utime(rec->dir.MdDat);
 338                 inode->i_op = &hfs_dir_inode_operations;
 339                 inode->i_fop = &hfs_dir_operations;
 340                 break;
 341         default:
 342                 make_bad_inode(inode);
 343         }
 344         return 0;
 345 }
 346
 347 /*
 348  * __hfs_iget()
 349  *
 350  * Given the MDB for a HFS filesystem, a 'key' and an 'entry' in
 351  * the catalog B-tree and the 'type' of the desired file return the
 352  * inode for that file/directory or NULL.  Note that 'type' indicates
 353  * whether we want the actual file or directory, or the corresponding
 354  * metadata (AppleDouble header file or CAP metadata file).
 355  */
 356 struct inode *hfs_iget(struct super_block *sb, struct hfs_cat_key *key, hfs_cat_rec *rec)
 357 {
 358         struct hfs_iget_data data = { key, rec };
 359         struct inode *inode;
 360         u32 cnid;
 361
 362         switch (rec->type) {
 363         case HFS_CDR_DIR:
 364                 cnid = be32_to_cpu(rec->dir.DirID);
 365                 break;
 366         case HFS_CDR_FIL:
 367                 cnid = be32_to_cpu(rec->file.FlNum);
 368                 break;
 369         default:
 370                 return NULL;
 371         }
 372         inode = iget5_locked(sb, cnid, hfs_test_inode, hfs_read_inode, &data);
 373         if (inode && (inode->i_state & I_NEW))
 374                 unlock_new_inode(inode);
 375         return inode;
 376 }
 377
 378 void hfs_inode_write_fork(struct inode *inode, struct hfs_extent *ext,
 379                           __be32 *log_size, __be32 *phys_size)
 380 {
 381         memcpy(ext, HFS_I(inode)->first_extents, sizeof(hfs_extent_rec));
 382
 383         if (log_size)
 384                 *log_size = cpu_to_be32(inode->i_size);
 385         if (phys_size)
 386                 *phys_size = cpu_to_be32(HFS_I(inode)->alloc_blocks *
 387                                          HFS_SB(inode->i_sb)->alloc_blksz);
 388 }
 389
 390 int hfs_write_inode(struct inode *inode, int unused)
 391 {
 392         struct inode *main_inode = inode;
 393         struct hfs_find_data fd;
 394         hfs_cat_rec rec;
 395
 396         dprint(DBG_INODE, "hfs_write_inode: %lu\n", inode->i_ino);
 397         hfs_ext_write_extent(inode);
 398
 399         if (inode->i_ino < HFS_FIRSTUSER_CNID) {
 400                 switch (inode->i_ino) {
 401                 case HFS_ROOT_CNID:
 402                         break;
 403                 case HFS_EXT_CNID:
 404                         hfs_btree_write(HFS_SB(inode->i_sb)->ext_tree);
 405                         return 0;
 406                 case HFS_CAT_CNID:
 407                         hfs_btree_write(HFS_SB(inode->i_sb)->cat_tree);
 408                         return 0;
 409                 default:
 410                         BUG();
 411                         return -EIO;
 412                 }
 413         }
 414
 415         if (HFS_IS_RSRC(inode))
 416                 main_inode = HFS_I(inode)->rsrc_inode;
 417
 418         if (!main_inode->i_nlink)
 419                 return 0;
 420
 421         if (hfs_find_init(HFS_SB(main_inode->i_sb)->cat_tree, &fd))
 422                 /* panic? */
 423                 return -EIO;
 424
 425         fd.search_key->cat = HFS_I(main_inode)->cat_key;
 426         if (hfs_brec_find(&fd))
 427                 /* panic? */
 428                 goto out;
 429
 430         if (S_ISDIR(main_inode->i_mode)) {
 431                 if (fd.entrylength < sizeof(struct hfs_cat_dir))
 432                         /* panic? */;
 433                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 434                            sizeof(struct hfs_cat_dir));
 435                 if (rec.type != HFS_CDR_DIR ||
 436                     be32_to_cpu(rec.dir.DirID) != inode->i_ino) {
 437                 }
 438
 439                 rec.dir.MdDat = hfs_u_to_mtime(inode->i_mtime);
 440                 rec.dir.Val = cpu_to_be16(inode->i_size - 2);
 441
 442                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 443                             sizeof(struct hfs_cat_dir));
 444         } else if (HFS_IS_RSRC(inode)) {
 445                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 446                                sizeof(struct hfs_cat_file));
 447                 hfs_inode_write_fork(inode, rec.file.RExtRec,
 448                                      &rec.file.RLgLen, &rec.file.RPyLen);
 449                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 450                                 sizeof(struct hfs_cat_file));
 451         } else {
 452                 if (fd.entrylength < sizeof(struct hfs_cat_file))
 453                         /* panic? */;
 454                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 455                            sizeof(struct hfs_cat_file));
 456                 if (rec.type != HFS_CDR_FIL ||
 457                     be32_to_cpu(rec.file.FlNum) != inode->i_ino) {
 458                 }
 459
 460                 if (inode->i_mode & S_IWUSR)
 461                         rec.file.Flags &= ~HFS_FIL_LOCK;
 462                 else
 463                         rec.file.Flags |= HFS_FIL_LOCK;
 464                 hfs_inode_write_fork(inode, rec.file.ExtRec, &rec.file.LgLen, &rec.file.PyLen);
 465                 rec.file.MdDat = hfs_u_to_mtime(inode->i_mtime);
 466
 467                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 468                             sizeof(struct hfs_cat_file));
 469         }
 470 out:
 471         hfs_find_exit(&fd);
 472         return 0;
 473 }
 474
 475 static struct dentry *hfs_file_lookup(struct inode *dir, struct dentry *dentry,
 476                                       struct nameidata *nd)
 477 {
 478         struct inode *inode = NULL;
 479         hfs_cat_rec rec;
 480         struct hfs_find_data fd;
 481         int res;
 482
 483         if (HFS_IS_RSRC(dir) || strcmp(dentry->d_name.name, "rsrc"))
 484                 goto out;
 485
 486         inode = HFS_I(dir)->rsrc_inode;
 487         if (inode)
 488                 goto out;
 489
 490         inode = new_inode(dir->i_sb);
 491         if (!inode)
 492                 return ERR_PTR(-ENOMEM);
 493
 494         hfs_find_init(HFS_SB(dir->i_sb)->cat_tree, &fd);
 495         fd.search_key->cat = HFS_I(dir)->cat_key;
 496         res = hfs_brec_read(&fd, &rec, sizeof(rec));
 497         if (!res) {
 498                 struct hfs_iget_data idata = { NULL, &rec };
 499                 hfs_read_inode(inode, &idata);
 500         }
 501         hfs_find_exit(&fd);
 502         if (res) {
 503                 iput(inode);
 504                 return ERR_PTR(res);
 505         }
 506         HFS_I(inode)->rsrc_inode = dir;
 507         HFS_I(dir)->rsrc_inode = inode;
 508         igrab(dir);
 509         hlist_add_head(&inode->i_hash, &HFS_SB(dir->i_sb)->rsrc_inodes);
 510         mark_inode_dirty(inode);
 511 out:
 512         d_add(dentry, inode);
 513         return NULL;
 514 }
 515
 516 void hfs_clear_inode(struct inode *inode)
 517 {
 518         if (HFS_IS_RSRC(inode) && HFS_I(inode)->rsrc_inode) {
 519                 HFS_I(HFS_I(inode)->rsrc_inode)->rsrc_inode = NULL;
 520                 iput(HFS_I(inode)->rsrc_inode);
 521         }
 522 }
 523
 524 static int hfs_permission(struct inode *inode, int mask,
 525                           struct nameidata *nd)
 526 {
 527         if (S_ISREG(inode->i_mode) && mask & MAY_EXEC)
 528                 return 0;
 529         return generic_permission(inode, mask, NULL);
 530 }
 531
 532 static int hfs_file_open(struct inode *inode, struct file *file)
 533 {
 534         if (HFS_IS_RSRC(inode))
 535                 inode = HFS_I(inode)->rsrc_inode;
 536         if (atomic_read(&file->f_count) != 1)
 537                 return 0;
 538         atomic_inc(&HFS_I(inode)->opencnt);
 539         return 0;
 540 }
 541
 542 static int hfs_file_release(struct inode *inode, struct file *file)
 543 {
 544         //struct super_block *sb = inode->i_sb;
 545
 546         if (HFS_IS_RSRC(inode))
 547                 inode = HFS_I(inode)->rsrc_inode;
 548         if (atomic_read(&file->f_count) != 0)
 549                 return 0;
 550         if (atomic_dec_and_test(&HFS_I(inode)->opencnt)) {
 551                 down(&inode->i_sem);
 552                 hfs_file_truncate(inode);
 553                 //if (inode->i_flags & S_DEAD) {
 554                 //      hfs_delete_cat(inode->i_ino, HFSPLUS_SB(sb).hidden_dir, NULL);
 555                 //      hfs_delete_inode(inode);
 556                 //}
 557                 up(&inode->i_sem);
 558         }
 559         return 0;
 560 }
 561
 562 /*
 563  * hfs_notify_change()
 564  *
 565  * Based very closely on fs/msdos/inode.c by Werner Almesberger
 566  *
 567  * This is the notify_change() field in the super_operations structure
 568  * for HFS file systems.  The purpose is to take that changes made to
 569  * an inode and apply then in a filesystem-dependent manner.  In this
 570  * case the process has a few of tasks to do:
 571  *  1) prevent changes to the i_uid and i_gid fields.
 572  *  2) map file permissions to the closest allowable permissions
 573  *  3) Since multiple Linux files can share the same on-disk inode under
 574  *     HFS (for instance the data and resource forks of a file) a change
 575  *     to permissions must be applied to all other in-core inodes which
 576  *     correspond to the same HFS file.
 577  */
 578
 579 int hfs_inode_setattr(struct dentry *dentry, struct iattr * attr)
 580 {
 581         struct inode *inode = dentry->d_inode;
 582         struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
 583         int error;
 584
 585         error = inode_change_ok(inode, attr); /* basic permission checks */
 586         if (error)
 587                 return error;
 588
 589         /* no uig/gid changes and limit which mode bits can be set */
 590         if (((attr->ia_valid & ATTR_UID) &&
 591              (attr->ia_uid != hsb->s_uid)) ||
 592             ((attr->ia_valid & ATTR_GID) &&
 593              (attr->ia_gid != hsb->s_gid)) ||
 594             ((attr->ia_valid & ATTR_MODE) &&
 595              ((S_ISDIR(inode->i_mode) &&
 596                (attr->ia_mode != inode->i_mode)) ||
 597               (attr->ia_mode & ~HFS_VALID_MODE_BITS)))) {
 598                 return hsb->s_quiet ? 0 : error;
 599         }
 600
 601         if (attr->ia_valid & ATTR_MODE) {
 602                 /* Only the 'w' bits can ever change and only all together. */
 603                 if (attr->ia_mode & S_IWUSR)
 604                         attr->ia_mode = inode->i_mode | S_IWUGO;
 605                 else
 606                         attr->ia_mode = inode->i_mode & ~S_IWUGO;
 607                 attr->ia_mode &= S_ISDIR(inode->i_mode) ? ~hsb->s_dir_umask: ~hsb->s_file_umask;
 608         }
 609         error = inode_setattr(inode, attr);
 610         if (error)
 611                 return error;
 612
 613         return 0;
 614 }
 615
 616
 617 static struct file_operations hfs_file_operations = {
 618         .llseek         = generic_file_llseek,
 619         .read           = generic_file_read,
 620         .write          = generic_file_write,
 621         .mmap           = generic_file_mmap,
 622         .sendfile       = generic_file_sendfile,
 623         .fsync          = file_fsync,
 624         .open           = hfs_file_open,
 625         .release        = hfs_file_release,
 626 };
 627
 628 static struct inode_operations hfs_file_inode_operations = {
 629         .lookup         = hfs_file_lookup,
 630         .truncate       = hfs_file_truncate,
 631         .setattr        = hfs_inode_setattr,
 632         .permission     = hfs_permission,
 633         .setxattr       = hfs_setxattr,
 634         .getxattr       = hfs_getxattr,
 635         .listxattr      = hfs_listxattr,
 636 };