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 #include <linux/sched.h>
  17
  18 #include "hfs_fs.h"
  19 #include "btree.h"
  20
  21 static const struct file_operations hfs_file_operations;
  22 static const 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_write_begin(struct file *file, struct address_space *mapping,
  39                         loff_t pos, unsigned len, unsigned flags,
  40                         struct page **pagep, void **fsdata)
  41 {
  42         int ret;
  43
  44         *pagep = NULL;
  45         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
  46                                 hfs_get_block,
  47                                 &HFS_I(mapping->host)->phys_size);
  48         if (unlikely(ret)) {
  49                 loff_t isize = mapping->host->i_size;
  50                 if (pos + len > isize)
  51                         vmtruncate(mapping->host, isize);
  52         }
  53
  54         return ret;
  55 }
  56
  57 static sector_t hfs_bmap(struct address_space *mapping, sector_t block)
  58 {
  59         return generic_block_bmap(mapping, block, hfs_get_block);
  60 }
  61
  62 static int hfs_releasepage(struct page *page, gfp_t mask)
  63 {
  64         struct inode *inode = page->mapping->host;
  65         struct super_block *sb = inode->i_sb;
  66         struct hfs_btree *tree;
  67         struct hfs_bnode *node;
  68         u32 nidx;
  69         int i, res = 1;
  70
  71         switch (inode->i_ino) {
  72         case HFS_EXT_CNID:
  73                 tree = HFS_SB(sb)->ext_tree;
  74                 break;
  75         case HFS_CAT_CNID:
  76                 tree = HFS_SB(sb)->cat_tree;
  77                 break;
  78         default:
  79                 BUG();
  80                 return 0;
  81         }
  82
  83         if (!tree)
  84                 return 0;
  85
  86         if (tree->node_size >= PAGE_CACHE_SIZE) {
  87                 nidx = page->index >> (tree->node_size_shift - PAGE_CACHE_SHIFT);
  88                 spin_lock(&tree->hash_lock);
  89                 node = hfs_bnode_findhash(tree, nidx);
  90                 if (!node)
  91                         ;
  92                 else if (atomic_read(&node->refcnt))
  93                         res = 0;
  94                 if (res && node) {
  95                         hfs_bnode_unhash(node);
  96                         hfs_bnode_free(node);
  97                 }
  98                 spin_unlock(&tree->hash_lock);
  99         } else {
 100                 nidx = page->index << (PAGE_CACHE_SHIFT - tree->node_size_shift);
 101                 i = 1 << (PAGE_CACHE_SHIFT - tree->node_size_shift);
 102                 spin_lock(&tree->hash_lock);
 103                 do {
 104                         node = hfs_bnode_findhash(tree, nidx++);
 105                         if (!node)
 106                                 continue;
 107                         if (atomic_read(&node->refcnt)) {
 108                                 res = 0;
 109                                 break;
 110                         }
 111                         hfs_bnode_unhash(node);
 112                         hfs_bnode_free(node);
 113                 } while (--i && nidx < tree->node_count);
 114                 spin_unlock(&tree->hash_lock);
 115         }
 116         return res ? try_to_free_buffers(page) : 0;
 117 }
 118
 119 static ssize_t hfs_direct_IO(int rw, struct kiocb *iocb,
 120                 const struct iovec *iov, loff_t offset, unsigned long nr_segs)
 121 {
 122         struct file *file = iocb->ki_filp;
 123         struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
 124         ssize_t ret;
 125
 126         ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
 127                                   offset, nr_segs, hfs_get_block, NULL);
 128
 129         /*
 130          * In case of error extending write may have instantiated a few
 131          * blocks outside i_size. Trim these off again.
 132          */
 133         if (unlikely((rw & WRITE) && ret < 0)) {
 134                 loff_t isize = i_size_read(inode);
 135                 loff_t end = offset + iov_length(iov, nr_segs);
 136
 137                 if (end > isize)
 138                         vmtruncate(inode, isize);
 139         }
 140
 141         return ret;
 142 }
 143
 144 static int hfs_writepages(struct address_space *mapping,
 145                           struct writeback_control *wbc)
 146 {
 147         return mpage_writepages(mapping, wbc, hfs_get_block);
 148 }
 149
 150 const struct address_space_operations hfs_btree_aops = {
 151         .readpage       = hfs_readpage,
 152         .writepage      = hfs_writepage,
 153         .write_begin    = hfs_write_begin,
 154         .write_end      = generic_write_end,
 155         .bmap           = hfs_bmap,
 156         .releasepage    = hfs_releasepage,
 157 };
 158
 159 const struct address_space_operations hfs_aops = {
 160         .readpage       = hfs_readpage,
 161         .writepage      = hfs_writepage,
 162         .write_begin    = hfs_write_begin,
 163         .write_end      = generic_write_end,
 164         .bmap           = hfs_bmap,
 165         .direct_IO      = hfs_direct_IO,
 166         .writepages     = hfs_writepages,
 167 };
 168
 169 /*
 170  * hfs_new_inode
 171  */
 172 struct inode *hfs_new_inode(struct inode *dir, struct qstr *name, int mode)
 173 {
 174         struct super_block *sb = dir->i_sb;
 175         struct inode *inode = new_inode(sb);
 176         if (!inode)
 177                 return NULL;
 178
 179         mutex_init(&HFS_I(inode)->extents_lock);
 180         INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
 181         hfs_cat_build_key(sb, (btree_key *)&HFS_I(inode)->cat_key, dir->i_ino, name);
 182         inode->i_ino = HFS_SB(sb)->next_id++;
 183         inode->i_mode = mode;
 184         inode->i_uid = current_fsuid();
 185         inode->i_gid = current_fsgid();
 186         inode->i_nlink = 1;
 187         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
 188         HFS_I(inode)->flags = 0;
 189         HFS_I(inode)->rsrc_inode = NULL;
 190         HFS_I(inode)->fs_blocks = 0;
 191         if (S_ISDIR(mode)) {
 192                 inode->i_size = 2;
 193                 HFS_SB(sb)->folder_count++;
 194                 if (dir->i_ino == HFS_ROOT_CNID)
 195                         HFS_SB(sb)->root_dirs++;
 196                 inode->i_op = &hfs_dir_inode_operations;
 197                 inode->i_fop = &hfs_dir_operations;
 198                 inode->i_mode |= S_IRWXUGO;
 199                 inode->i_mode &= ~HFS_SB(inode->i_sb)->s_dir_umask;
 200         } else if (S_ISREG(mode)) {
 201                 HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
 202                 HFS_SB(sb)->file_count++;
 203                 if (dir->i_ino == HFS_ROOT_CNID)
 204                         HFS_SB(sb)->root_files++;
 205                 inode->i_op = &hfs_file_inode_operations;
 206                 inode->i_fop = &hfs_file_operations;
 207                 inode->i_mapping->a_ops = &hfs_aops;
 208                 inode->i_mode |= S_IRUGO|S_IXUGO;
 209                 if (mode & S_IWUSR)
 210                         inode->i_mode |= S_IWUGO;
 211                 inode->i_mode &= ~HFS_SB(inode->i_sb)->s_file_umask;
 212                 HFS_I(inode)->phys_size = 0;
 213                 HFS_I(inode)->alloc_blocks = 0;
 214                 HFS_I(inode)->first_blocks = 0;
 215                 HFS_I(inode)->cached_start = 0;
 216                 HFS_I(inode)->cached_blocks = 0;
 217                 memset(HFS_I(inode)->first_extents, 0, sizeof(hfs_extent_rec));
 218                 memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
 219         }
 220         insert_inode_hash(inode);
 221         mark_inode_dirty(inode);
 222         set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 223         sb->s_dirt = 1;
 224
 225         return inode;
 226 }
 227
 228 void hfs_delete_inode(struct inode *inode)
 229 {
 230         struct super_block *sb = inode->i_sb;
 231
 232         dprint(DBG_INODE, "delete_inode: %lu\n", inode->i_ino);
 233         if (S_ISDIR(inode->i_mode)) {
 234                 HFS_SB(sb)->folder_count--;
 235                 if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
 236                         HFS_SB(sb)->root_dirs--;
 237                 set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 238                 sb->s_dirt = 1;
 239                 return;
 240         }
 241         HFS_SB(sb)->file_count--;
 242         if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
 243                 HFS_SB(sb)->root_files--;
 244         if (S_ISREG(inode->i_mode)) {
 245                 if (!inode->i_nlink) {
 246                         inode->i_size = 0;
 247                         hfs_file_truncate(inode);
 248                 }
 249         }
 250         set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 251         sb->s_dirt = 1;
 252 }
 253
 254 void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
 255                          __be32 __log_size, __be32 phys_size, u32 clump_size)
 256 {
 257         struct super_block *sb = inode->i_sb;
 258         u32 log_size = be32_to_cpu(__log_size);
 259         u16 count;
 260         int i;
 261
 262         memcpy(HFS_I(inode)->first_extents, ext, sizeof(hfs_extent_rec));
 263         for (count = 0, i = 0; i < 3; i++)
 264                 count += be16_to_cpu(ext[i].count);
 265         HFS_I(inode)->first_blocks = count;
 266
 267         inode->i_size = HFS_I(inode)->phys_size = log_size;
 268         HFS_I(inode)->fs_blocks = (log_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 269         inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
 270         HFS_I(inode)->alloc_blocks = be32_to_cpu(phys_size) /
 271                                      HFS_SB(sb)->alloc_blksz;
 272         HFS_I(inode)->clump_blocks = clump_size / HFS_SB(sb)->alloc_blksz;
 273         if (!HFS_I(inode)->clump_blocks)
 274                 HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
 275 }
 276
 277 struct hfs_iget_data {
 278         struct hfs_cat_key *key;
 279         hfs_cat_rec *rec;
 280 };
 281
 282 static int hfs_test_inode(struct inode *inode, void *data)
 283 {
 284         struct hfs_iget_data *idata = data;
 285         hfs_cat_rec *rec;
 286
 287         rec = idata->rec;
 288         switch (rec->type) {
 289         case HFS_CDR_DIR:
 290                 return inode->i_ino == be32_to_cpu(rec->dir.DirID);
 291         case HFS_CDR_FIL:
 292                 return inode->i_ino == be32_to_cpu(rec->file.FlNum);
 293         default:
 294                 BUG();
 295                 return 1;
 296         }
 297 }
 298
 299 /*
 300  * hfs_read_inode
 301  */
 302 static int hfs_read_inode(struct inode *inode, void *data)
 303 {
 304         struct hfs_iget_data *idata = data;
 305         struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
 306         hfs_cat_rec *rec;
 307
 308         HFS_I(inode)->flags = 0;
 309         HFS_I(inode)->rsrc_inode = NULL;
 310         mutex_init(&HFS_I(inode)->extents_lock);
 311         INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
 312
 313         /* Initialize the inode */
 314         inode->i_uid = hsb->s_uid;
 315         inode->i_gid = hsb->s_gid;
 316         inode->i_nlink = 1;
 317
 318         if (idata->key)
 319                 HFS_I(inode)->cat_key = *idata->key;
 320         else
 321                 HFS_I(inode)->flags |= HFS_FLG_RSRC;
 322         HFS_I(inode)->tz_secondswest = sys_tz.tz_minuteswest * 60;
 323
 324         rec = idata->rec;
 325         switch (rec->type) {
 326         case HFS_CDR_FIL:
 327                 if (!HFS_IS_RSRC(inode)) {
 328                         hfs_inode_read_fork(inode, rec->file.ExtRec, rec->file.LgLen,
 329                                             rec->file.PyLen, be16_to_cpu(rec->file.ClpSize));
 330                 } else {
 331                         hfs_inode_read_fork(inode, rec->file.RExtRec, rec->file.RLgLen,
 332                                             rec->file.RPyLen, be16_to_cpu(rec->file.ClpSize));
 333                 }
 334
 335                 inode->i_ino = be32_to_cpu(rec->file.FlNum);
 336                 inode->i_mode = S_IRUGO | S_IXUGO;
 337                 if (!(rec->file.Flags & HFS_FIL_LOCK))
 338                         inode->i_mode |= S_IWUGO;
 339                 inode->i_mode &= ~hsb->s_file_umask;
 340                 inode->i_mode |= S_IFREG;
 341                 inode->i_ctime = inode->i_atime = inode->i_mtime =
 342                                 hfs_m_to_utime(rec->file.MdDat);
 343                 inode->i_op = &hfs_file_inode_operations;
 344                 inode->i_fop = &hfs_file_operations;
 345                 inode->i_mapping->a_ops = &hfs_aops;
 346                 break;
 347         case HFS_CDR_DIR:
 348                 inode->i_ino = be32_to_cpu(rec->dir.DirID);
 349                 inode->i_size = be16_to_cpu(rec->dir.Val) + 2;
 350                 HFS_I(inode)->fs_blocks = 0;
 351                 inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask);
 352                 inode->i_ctime = inode->i_atime = inode->i_mtime =
 353                                 hfs_m_to_utime(rec->dir.MdDat);
 354                 inode->i_op = &hfs_dir_inode_operations;
 355                 inode->i_fop = &hfs_dir_operations;
 356                 break;
 357         default:
 358                 make_bad_inode(inode);
 359         }
 360         return 0;
 361 }
 362
 363 /*
 364  * __hfs_iget()
 365  *
 366  * Given the MDB for a HFS filesystem, a 'key' and an 'entry' in
 367  * the catalog B-tree and the 'type' of the desired file return the
 368  * inode for that file/directory or NULL.  Note that 'type' indicates
 369  * whether we want the actual file or directory, or the corresponding
 370  * metadata (AppleDouble header file or CAP metadata file).
 371  */
 372 struct inode *hfs_iget(struct super_block *sb, struct hfs_cat_key *key, hfs_cat_rec *rec)
 373 {
 374         struct hfs_iget_data data = { key, rec };
 375         struct inode *inode;
 376         u32 cnid;
 377
 378         switch (rec->type) {
 379         case HFS_CDR_DIR:
 380                 cnid = be32_to_cpu(rec->dir.DirID);
 381                 break;
 382         case HFS_CDR_FIL:
 383                 cnid = be32_to_cpu(rec->file.FlNum);
 384                 break;
 385         default:
 386                 return NULL;
 387         }
 388         inode = iget5_locked(sb, cnid, hfs_test_inode, hfs_read_inode, &data);
 389         if (inode && (inode->i_state & I_NEW))
 390                 unlock_new_inode(inode);
 391         return inode;
 392 }
 393
 394 void hfs_inode_write_fork(struct inode *inode, struct hfs_extent *ext,
 395                           __be32 *log_size, __be32 *phys_size)
 396 {
 397         memcpy(ext, HFS_I(inode)->first_extents, sizeof(hfs_extent_rec));
 398
 399         if (log_size)
 400                 *log_size = cpu_to_be32(inode->i_size);
 401         if (phys_size)
 402                 *phys_size = cpu_to_be32(HFS_I(inode)->alloc_blocks *
 403                                          HFS_SB(inode->i_sb)->alloc_blksz);
 404 }
 405
 406 int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 407 {
 408         struct inode *main_inode = inode;
 409         struct hfs_find_data fd;
 410         hfs_cat_rec rec;
 411
 412         dprint(DBG_INODE, "hfs_write_inode: %lu\n", inode->i_ino);
 413         hfs_ext_write_extent(inode);
 414
 415         if (inode->i_ino < HFS_FIRSTUSER_CNID) {
 416                 switch (inode->i_ino) {
 417                 case HFS_ROOT_CNID:
 418                         break;
 419                 case HFS_EXT_CNID:
 420                         hfs_btree_write(HFS_SB(inode->i_sb)->ext_tree);
 421                         return 0;
 422                 case HFS_CAT_CNID:
 423                         hfs_btree_write(HFS_SB(inode->i_sb)->cat_tree);
 424                         return 0;
 425                 default:
 426                         BUG();
 427                         return -EIO;
 428                 }
 429         }
 430
 431         if (HFS_IS_RSRC(inode))
 432                 main_inode = HFS_I(inode)->rsrc_inode;
 433
 434         if (!main_inode->i_nlink)
 435                 return 0;
 436
 437         if (hfs_find_init(HFS_SB(main_inode->i_sb)->cat_tree, &fd))
 438                 /* panic? */
 439                 return -EIO;
 440
 441         fd.search_key->cat = HFS_I(main_inode)->cat_key;
 442         if (hfs_brec_find(&fd))
 443                 /* panic? */
 444                 goto out;
 445
 446         if (S_ISDIR(main_inode->i_mode)) {
 447                 if (fd.entrylength < sizeof(struct hfs_cat_dir))
 448                         /* panic? */;
 449                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 450                            sizeof(struct hfs_cat_dir));
 451                 if (rec.type != HFS_CDR_DIR ||
 452                     be32_to_cpu(rec.dir.DirID) != inode->i_ino) {
 453                 }
 454
 455                 rec.dir.MdDat = hfs_u_to_mtime(inode->i_mtime);
 456                 rec.dir.Val = cpu_to_be16(inode->i_size - 2);
 457
 458                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 459                             sizeof(struct hfs_cat_dir));
 460         } else if (HFS_IS_RSRC(inode)) {
 461                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 462                                sizeof(struct hfs_cat_file));
 463                 hfs_inode_write_fork(inode, rec.file.RExtRec,
 464                                      &rec.file.RLgLen, &rec.file.RPyLen);
 465                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 466                                 sizeof(struct hfs_cat_file));
 467         } else {
 468                 if (fd.entrylength < sizeof(struct hfs_cat_file))
 469                         /* panic? */;
 470                 hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 471                            sizeof(struct hfs_cat_file));
 472                 if (rec.type != HFS_CDR_FIL ||
 473                     be32_to_cpu(rec.file.FlNum) != inode->i_ino) {
 474                 }
 475
 476                 if (inode->i_mode & S_IWUSR)
 477                         rec.file.Flags &= ~HFS_FIL_LOCK;
 478                 else
 479                         rec.file.Flags |= HFS_FIL_LOCK;
 480                 hfs_inode_write_fork(inode, rec.file.ExtRec, &rec.file.LgLen, &rec.file.PyLen);
 481                 rec.file.MdDat = hfs_u_to_mtime(inode->i_mtime);
 482
 483                 hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 484                             sizeof(struct hfs_cat_file));
 485         }
 486 out:
 487         hfs_find_exit(&fd);
 488         return 0;
 489 }
 490
 491 static struct dentry *hfs_file_lookup(struct inode *dir, struct dentry *dentry,
 492                                       struct nameidata *nd)
 493 {
 494         struct inode *inode = NULL;
 495         hfs_cat_rec rec;
 496         struct hfs_find_data fd;
 497         int res;
 498
 499         if (HFS_IS_RSRC(dir) || strcmp(dentry->d_name.name, "rsrc"))
 500                 goto out;
 501
 502         inode = HFS_I(dir)->rsrc_inode;
 503         if (inode)
 504                 goto out;
 505
 506         inode = new_inode(dir->i_sb);
 507         if (!inode)
 508                 return ERR_PTR(-ENOMEM);
 509
 510         hfs_find_init(HFS_SB(dir->i_sb)->cat_tree, &fd);
 511         fd.search_key->cat = HFS_I(dir)->cat_key;
 512         res = hfs_brec_read(&fd, &rec, sizeof(rec));
 513         if (!res) {
 514                 struct hfs_iget_data idata = { NULL, &rec };
 515                 hfs_read_inode(inode, &idata);
 516         }
 517         hfs_find_exit(&fd);
 518         if (res) {
 519                 iput(inode);
 520                 return ERR_PTR(res);
 521         }
 522         HFS_I(inode)->rsrc_inode = dir;
 523         HFS_I(dir)->rsrc_inode = inode;
 524         igrab(dir);
 525         hlist_add_fake(&inode->i_hash);
 526         mark_inode_dirty(inode);
 527 out:
 528         d_add(dentry, inode);
 529         return NULL;
 530 }
 531
 532 void hfs_evict_inode(struct inode *inode)
 533 {
 534         truncate_inode_pages(&inode->i_data, 0);
 535         end_writeback(inode);
 536         if (HFS_IS_RSRC(inode) && HFS_I(inode)->rsrc_inode) {
 537                 HFS_I(HFS_I(inode)->rsrc_inode)->rsrc_inode = NULL;
 538                 iput(HFS_I(inode)->rsrc_inode);
 539         }
 540 }
 541
 542 static int hfs_file_open(struct inode *inode, struct file *file)
 543 {
 544         if (HFS_IS_RSRC(inode))
 545                 inode = HFS_I(inode)->rsrc_inode;
 546         atomic_inc(&HFS_I(inode)->opencnt);
 547         return 0;
 548 }
 549
 550 static int hfs_file_release(struct inode *inode, struct file *file)
 551 {
 552         //struct super_block *sb = inode->i_sb;
 553
 554         if (HFS_IS_RSRC(inode))
 555                 inode = HFS_I(inode)->rsrc_inode;
 556         if (atomic_dec_and_test(&HFS_I(inode)->opencnt)) {
 557                 mutex_lock(&inode->i_mutex);
 558                 hfs_file_truncate(inode);
 559                 //if (inode->i_flags & S_DEAD) {
 560                 //      hfs_delete_cat(inode->i_ino, HFSPLUS_SB(sb).hidden_dir, NULL);
 561                 //      hfs_delete_inode(inode);
 562                 //}
 563                 mutex_unlock(&inode->i_mutex);
 564         }
 565         return 0;
 566 }
 567
 568 /*
 569  * hfs_notify_change()
 570  *
 571  * Based very closely on fs/msdos/inode.c by Werner Almesberger
 572  *
 573  * This is the notify_change() field in the super_operations structure
 574  * for HFS file systems.  The purpose is to take that changes made to
 575  * an inode and apply then in a filesystem-dependent manner.  In this
 576  * case the process has a few of tasks to do:
 577  *  1) prevent changes to the i_uid and i_gid fields.
 578  *  2) map file permissions to the closest allowable permissions
 579  *  3) Since multiple Linux files can share the same on-disk inode under
 580  *     HFS (for instance the data and resource forks of a file) a change
 581  *     to permissions must be applied to all other in-core inodes which
 582  *     correspond to the same HFS file.
 583  */
 584
 585 int hfs_inode_setattr(struct dentry *dentry, struct iattr * attr)
 586 {
 587         struct inode *inode = dentry->d_inode;
 588         struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
 589         int error;
 590
 591         error = inode_change_ok(inode, attr); /* basic permission checks */
 592         if (error)
 593                 return error;
 594
 595         /* no uig/gid changes and limit which mode bits can be set */
 596         if (((attr->ia_valid & ATTR_UID) &&
 597              (attr->ia_uid != hsb->s_uid)) ||
 598             ((attr->ia_valid & ATTR_GID) &&
 599              (attr->ia_gid != hsb->s_gid)) ||
 600             ((attr->ia_valid & ATTR_MODE) &&
 601              ((S_ISDIR(inode->i_mode) &&
 602                (attr->ia_mode != inode->i_mode)) ||
 603               (attr->ia_mode & ~HFS_VALID_MODE_BITS)))) {
 604                 return hsb->s_quiet ? 0 : error;
 605         }
 606
 607         if (attr->ia_valid & ATTR_MODE) {
 608                 /* Only the 'w' bits can ever change and only all together. */
 609                 if (attr->ia_mode & S_IWUSR)
 610                         attr->ia_mode = inode->i_mode | S_IWUGO;
 611                 else
 612                         attr->ia_mode = inode->i_mode & ~S_IWUGO;
 613                 attr->ia_mode &= S_ISDIR(inode->i_mode) ? ~hsb->s_dir_umask: ~hsb->s_file_umask;
 614         }
 615
 616         if ((attr->ia_valid & ATTR_SIZE) &&
 617             attr->ia_size != i_size_read(inode)) {
 618                 error = vmtruncate(inode, attr->ia_size);
 619                 if (error)
 620                         return error;
 621         }
 622
 623         setattr_copy(inode, attr);
 624         mark_inode_dirty(inode);
 625         return 0;
 626 }
 627
 628 static int hfs_file_fsync(struct file *filp, int datasync)
 629 {
 630         struct inode *inode = filp->f_mapping->host;
 631         struct super_block * sb;
 632         int ret, err;
 633
 634         /* sync the inode to buffers */
 635         ret = write_inode_now(inode, 0);
 636
 637         /* sync the superblock to buffers */
 638         sb = inode->i_sb;
 639         if (sb->s_dirt) {
 640                 lock_super(sb);
 641                 sb->s_dirt = 0;
 642                 if (!(sb->s_flags & MS_RDONLY))
 643                         hfs_mdb_commit(sb);
 644                 unlock_super(sb);
 645         }
 646         /* .. finally sync the buffers to disk */
 647         err = sync_blockdev(sb->s_bdev);
 648         if (!ret)
 649                 ret = err;
 650         return ret;
 651 }
 652
 653 static const struct file_operations hfs_file_operations = {
 654         .llseek         = generic_file_llseek,
 655         .read           = do_sync_read,
 656         .aio_read       = generic_file_aio_read,
 657         .write          = do_sync_write,
 658         .aio_write      = generic_file_aio_write,
 659         .mmap           = generic_file_mmap,
 660         .splice_read    = generic_file_splice_read,
 661         .fsync          = hfs_file_fsync,
 662         .open           = hfs_file_open,
 663         .release        = hfs_file_release,
 664 };
 665
 666 static const struct inode_operations hfs_file_inode_operations = {
 667         .lookup         = hfs_file_lookup,
 668         .truncate       = hfs_file_truncate,
 669         .setattr        = hfs_inode_setattr,
 670         .setxattr       = hfs_setxattr,
 671         .getxattr       = hfs_getxattr,
 672         .listxattr      = hfs_listxattr,
 673 };