xref: /linux/fs/hfs/inode.c (revision e5e95a7639ed5f7dc3e404858ad7910de5fa2057)
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 #include <linux/cred.h>
18 #include <linux/uio.h>
19 #include <linux/xattr.h>
20 #include <linux/blkdev.h>
21 
22 #include "hfs_fs.h"
23 #include "btree.h"
24 
25 static const struct file_operations hfs_file_operations;
26 static const struct inode_operations hfs_file_inode_operations;
27 
28 /*================ Variable-like macros ================*/
29 
30 #define HFS_VALID_MODE_BITS  (S_IFREG | S_IFDIR | S_IRWXUGO)
31 
32 static int hfs_writepage(struct page *page, struct writeback_control *wbc)
33 {
34 	return block_write_full_page(page, hfs_get_block, wbc);
35 }
36 
37 static int hfs_readpage(struct file *file, struct page *page)
38 {
39 	return block_read_full_page(page, hfs_get_block);
40 }
41 
42 static void hfs_write_failed(struct address_space *mapping, loff_t to)
43 {
44 	struct inode *inode = mapping->host;
45 
46 	if (to > inode->i_size) {
47 		truncate_pagecache(inode, inode->i_size);
48 		hfs_file_truncate(inode);
49 	}
50 }
51 
52 static int hfs_write_begin(struct file *file, struct address_space *mapping,
53 			loff_t pos, unsigned len, unsigned flags,
54 			struct page **pagep, void **fsdata)
55 {
56 	int ret;
57 
58 	*pagep = NULL;
59 	ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
60 				hfs_get_block,
61 				&HFS_I(mapping->host)->phys_size);
62 	if (unlikely(ret))
63 		hfs_write_failed(mapping, pos + len);
64 
65 	return ret;
66 }
67 
68 static sector_t hfs_bmap(struct address_space *mapping, sector_t block)
69 {
70 	return generic_block_bmap(mapping, block, hfs_get_block);
71 }
72 
73 static int hfs_releasepage(struct page *page, gfp_t mask)
74 {
75 	struct inode *inode = page->mapping->host;
76 	struct super_block *sb = inode->i_sb;
77 	struct hfs_btree *tree;
78 	struct hfs_bnode *node;
79 	u32 nidx;
80 	int i, res = 1;
81 
82 	switch (inode->i_ino) {
83 	case HFS_EXT_CNID:
84 		tree = HFS_SB(sb)->ext_tree;
85 		break;
86 	case HFS_CAT_CNID:
87 		tree = HFS_SB(sb)->cat_tree;
88 		break;
89 	default:
90 		BUG();
91 		return 0;
92 	}
93 
94 	if (!tree)
95 		return 0;
96 
97 	if (tree->node_size >= PAGE_SIZE) {
98 		nidx = page->index >> (tree->node_size_shift - PAGE_SHIFT);
99 		spin_lock(&tree->hash_lock);
100 		node = hfs_bnode_findhash(tree, nidx);
101 		if (!node)
102 			;
103 		else if (atomic_read(&node->refcnt))
104 			res = 0;
105 		if (res && node) {
106 			hfs_bnode_unhash(node);
107 			hfs_bnode_free(node);
108 		}
109 		spin_unlock(&tree->hash_lock);
110 	} else {
111 		nidx = page->index << (PAGE_SHIFT - tree->node_size_shift);
112 		i = 1 << (PAGE_SHIFT - tree->node_size_shift);
113 		spin_lock(&tree->hash_lock);
114 		do {
115 			node = hfs_bnode_findhash(tree, nidx++);
116 			if (!node)
117 				continue;
118 			if (atomic_read(&node->refcnt)) {
119 				res = 0;
120 				break;
121 			}
122 			hfs_bnode_unhash(node);
123 			hfs_bnode_free(node);
124 		} while (--i && nidx < tree->node_count);
125 		spin_unlock(&tree->hash_lock);
126 	}
127 	return res ? try_to_free_buffers(page) : 0;
128 }
129 
130 static ssize_t hfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
131 {
132 	struct file *file = iocb->ki_filp;
133 	struct address_space *mapping = file->f_mapping;
134 	struct inode *inode = mapping->host;
135 	size_t count = iov_iter_count(iter);
136 	ssize_t ret;
137 
138 	ret = blockdev_direct_IO(iocb, inode, iter, hfs_get_block);
139 
140 	/*
141 	 * In case of error extending write may have instantiated a few
142 	 * blocks outside i_size. Trim these off again.
143 	 */
144 	if (unlikely(iov_iter_rw(iter) == WRITE && ret < 0)) {
145 		loff_t isize = i_size_read(inode);
146 		loff_t end = iocb->ki_pos + count;
147 
148 		if (end > isize)
149 			hfs_write_failed(mapping, end);
150 	}
151 
152 	return ret;
153 }
154 
155 static int hfs_writepages(struct address_space *mapping,
156 			  struct writeback_control *wbc)
157 {
158 	return mpage_writepages(mapping, wbc, hfs_get_block);
159 }
160 
161 const struct address_space_operations hfs_btree_aops = {
162 	.readpage	= hfs_readpage,
163 	.writepage	= hfs_writepage,
164 	.write_begin	= hfs_write_begin,
165 	.write_end	= generic_write_end,
166 	.bmap		= hfs_bmap,
167 	.releasepage	= hfs_releasepage,
168 };
169 
170 const struct address_space_operations hfs_aops = {
171 	.readpage	= hfs_readpage,
172 	.writepage	= hfs_writepage,
173 	.write_begin	= hfs_write_begin,
174 	.write_end	= generic_write_end,
175 	.bmap		= hfs_bmap,
176 	.direct_IO	= hfs_direct_IO,
177 	.writepages	= hfs_writepages,
178 };
179 
180 /*
181  * hfs_new_inode
182  */
183 struct inode *hfs_new_inode(struct inode *dir, const struct qstr *name, umode_t mode)
184 {
185 	struct super_block *sb = dir->i_sb;
186 	struct inode *inode = new_inode(sb);
187 	if (!inode)
188 		return NULL;
189 
190 	mutex_init(&HFS_I(inode)->extents_lock);
191 	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
192 	spin_lock_init(&HFS_I(inode)->open_dir_lock);
193 	hfs_cat_build_key(sb, (btree_key *)&HFS_I(inode)->cat_key, dir->i_ino, name);
194 	inode->i_ino = HFS_SB(sb)->next_id++;
195 	inode->i_mode = mode;
196 	inode->i_uid = current_fsuid();
197 	inode->i_gid = current_fsgid();
198 	set_nlink(inode, 1);
199 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
200 	HFS_I(inode)->flags = 0;
201 	HFS_I(inode)->rsrc_inode = NULL;
202 	HFS_I(inode)->fs_blocks = 0;
203 	if (S_ISDIR(mode)) {
204 		inode->i_size = 2;
205 		HFS_SB(sb)->folder_count++;
206 		if (dir->i_ino == HFS_ROOT_CNID)
207 			HFS_SB(sb)->root_dirs++;
208 		inode->i_op = &hfs_dir_inode_operations;
209 		inode->i_fop = &hfs_dir_operations;
210 		inode->i_mode |= S_IRWXUGO;
211 		inode->i_mode &= ~HFS_SB(inode->i_sb)->s_dir_umask;
212 	} else if (S_ISREG(mode)) {
213 		HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
214 		HFS_SB(sb)->file_count++;
215 		if (dir->i_ino == HFS_ROOT_CNID)
216 			HFS_SB(sb)->root_files++;
217 		inode->i_op = &hfs_file_inode_operations;
218 		inode->i_fop = &hfs_file_operations;
219 		inode->i_mapping->a_ops = &hfs_aops;
220 		inode->i_mode |= S_IRUGO|S_IXUGO;
221 		if (mode & S_IWUSR)
222 			inode->i_mode |= S_IWUGO;
223 		inode->i_mode &= ~HFS_SB(inode->i_sb)->s_file_umask;
224 		HFS_I(inode)->phys_size = 0;
225 		HFS_I(inode)->alloc_blocks = 0;
226 		HFS_I(inode)->first_blocks = 0;
227 		HFS_I(inode)->cached_start = 0;
228 		HFS_I(inode)->cached_blocks = 0;
229 		memset(HFS_I(inode)->first_extents, 0, sizeof(hfs_extent_rec));
230 		memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
231 	}
232 	insert_inode_hash(inode);
233 	mark_inode_dirty(inode);
234 	set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
235 	hfs_mark_mdb_dirty(sb);
236 
237 	return inode;
238 }
239 
240 void hfs_delete_inode(struct inode *inode)
241 {
242 	struct super_block *sb = inode->i_sb;
243 
244 	hfs_dbg(INODE, "delete_inode: %lu\n", inode->i_ino);
245 	if (S_ISDIR(inode->i_mode)) {
246 		HFS_SB(sb)->folder_count--;
247 		if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
248 			HFS_SB(sb)->root_dirs--;
249 		set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
250 		hfs_mark_mdb_dirty(sb);
251 		return;
252 	}
253 	HFS_SB(sb)->file_count--;
254 	if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
255 		HFS_SB(sb)->root_files--;
256 	if (S_ISREG(inode->i_mode)) {
257 		if (!inode->i_nlink) {
258 			inode->i_size = 0;
259 			hfs_file_truncate(inode);
260 		}
261 	}
262 	set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
263 	hfs_mark_mdb_dirty(sb);
264 }
265 
266 void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
267 			 __be32 __log_size, __be32 phys_size, u32 clump_size)
268 {
269 	struct super_block *sb = inode->i_sb;
270 	u32 log_size = be32_to_cpu(__log_size);
271 	u16 count;
272 	int i;
273 
274 	memcpy(HFS_I(inode)->first_extents, ext, sizeof(hfs_extent_rec));
275 	for (count = 0, i = 0; i < 3; i++)
276 		count += be16_to_cpu(ext[i].count);
277 	HFS_I(inode)->first_blocks = count;
278 
279 	inode->i_size = HFS_I(inode)->phys_size = log_size;
280 	HFS_I(inode)->fs_blocks = (log_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
281 	inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
282 	HFS_I(inode)->alloc_blocks = be32_to_cpu(phys_size) /
283 				     HFS_SB(sb)->alloc_blksz;
284 	HFS_I(inode)->clump_blocks = clump_size / HFS_SB(sb)->alloc_blksz;
285 	if (!HFS_I(inode)->clump_blocks)
286 		HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
287 }
288 
289 struct hfs_iget_data {
290 	struct hfs_cat_key *key;
291 	hfs_cat_rec *rec;
292 };
293 
294 static int hfs_test_inode(struct inode *inode, void *data)
295 {
296 	struct hfs_iget_data *idata = data;
297 	hfs_cat_rec *rec;
298 
299 	rec = idata->rec;
300 	switch (rec->type) {
301 	case HFS_CDR_DIR:
302 		return inode->i_ino == be32_to_cpu(rec->dir.DirID);
303 	case HFS_CDR_FIL:
304 		return inode->i_ino == be32_to_cpu(rec->file.FlNum);
305 	default:
306 		BUG();
307 		return 1;
308 	}
309 }
310 
311 /*
312  * hfs_read_inode
313  */
314 static int hfs_read_inode(struct inode *inode, void *data)
315 {
316 	struct hfs_iget_data *idata = data;
317 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
318 	hfs_cat_rec *rec;
319 
320 	HFS_I(inode)->flags = 0;
321 	HFS_I(inode)->rsrc_inode = NULL;
322 	mutex_init(&HFS_I(inode)->extents_lock);
323 	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
324 	spin_lock_init(&HFS_I(inode)->open_dir_lock);
325 
326 	/* Initialize the inode */
327 	inode->i_uid = hsb->s_uid;
328 	inode->i_gid = hsb->s_gid;
329 	set_nlink(inode, 1);
330 
331 	if (idata->key)
332 		HFS_I(inode)->cat_key = *idata->key;
333 	else
334 		HFS_I(inode)->flags |= HFS_FLG_RSRC;
335 	HFS_I(inode)->tz_secondswest = sys_tz.tz_minuteswest * 60;
336 
337 	rec = idata->rec;
338 	switch (rec->type) {
339 	case HFS_CDR_FIL:
340 		if (!HFS_IS_RSRC(inode)) {
341 			hfs_inode_read_fork(inode, rec->file.ExtRec, rec->file.LgLen,
342 					    rec->file.PyLen, be16_to_cpu(rec->file.ClpSize));
343 		} else {
344 			hfs_inode_read_fork(inode, rec->file.RExtRec, rec->file.RLgLen,
345 					    rec->file.RPyLen, be16_to_cpu(rec->file.ClpSize));
346 		}
347 
348 		inode->i_ino = be32_to_cpu(rec->file.FlNum);
349 		inode->i_mode = S_IRUGO | S_IXUGO;
350 		if (!(rec->file.Flags & HFS_FIL_LOCK))
351 			inode->i_mode |= S_IWUGO;
352 		inode->i_mode &= ~hsb->s_file_umask;
353 		inode->i_mode |= S_IFREG;
354 		inode->i_ctime = inode->i_atime = inode->i_mtime =
355 				hfs_m_to_utime(rec->file.MdDat);
356 		inode->i_op = &hfs_file_inode_operations;
357 		inode->i_fop = &hfs_file_operations;
358 		inode->i_mapping->a_ops = &hfs_aops;
359 		break;
360 	case HFS_CDR_DIR:
361 		inode->i_ino = be32_to_cpu(rec->dir.DirID);
362 		inode->i_size = be16_to_cpu(rec->dir.Val) + 2;
363 		HFS_I(inode)->fs_blocks = 0;
364 		inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask);
365 		inode->i_ctime = inode->i_atime = inode->i_mtime =
366 				hfs_m_to_utime(rec->dir.MdDat);
367 		inode->i_op = &hfs_dir_inode_operations;
368 		inode->i_fop = &hfs_dir_operations;
369 		break;
370 	default:
371 		make_bad_inode(inode);
372 	}
373 	return 0;
374 }
375 
376 /*
377  * __hfs_iget()
378  *
379  * Given the MDB for a HFS filesystem, a 'key' and an 'entry' in
380  * the catalog B-tree and the 'type' of the desired file return the
381  * inode for that file/directory or NULL.  Note that 'type' indicates
382  * whether we want the actual file or directory, or the corresponding
383  * metadata (AppleDouble header file or CAP metadata file).
384  */
385 struct inode *hfs_iget(struct super_block *sb, struct hfs_cat_key *key, hfs_cat_rec *rec)
386 {
387 	struct hfs_iget_data data = { key, rec };
388 	struct inode *inode;
389 	u32 cnid;
390 
391 	switch (rec->type) {
392 	case HFS_CDR_DIR:
393 		cnid = be32_to_cpu(rec->dir.DirID);
394 		break;
395 	case HFS_CDR_FIL:
396 		cnid = be32_to_cpu(rec->file.FlNum);
397 		break;
398 	default:
399 		return NULL;
400 	}
401 	inode = iget5_locked(sb, cnid, hfs_test_inode, hfs_read_inode, &data);
402 	if (inode && (inode->i_state & I_NEW))
403 		unlock_new_inode(inode);
404 	return inode;
405 }
406 
407 void hfs_inode_write_fork(struct inode *inode, struct hfs_extent *ext,
408 			  __be32 *log_size, __be32 *phys_size)
409 {
410 	memcpy(ext, HFS_I(inode)->first_extents, sizeof(hfs_extent_rec));
411 
412 	if (log_size)
413 		*log_size = cpu_to_be32(inode->i_size);
414 	if (phys_size)
415 		*phys_size = cpu_to_be32(HFS_I(inode)->alloc_blocks *
416 					 HFS_SB(inode->i_sb)->alloc_blksz);
417 }
418 
419 int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
420 {
421 	struct inode *main_inode = inode;
422 	struct hfs_find_data fd;
423 	hfs_cat_rec rec;
424 	int res;
425 
426 	hfs_dbg(INODE, "hfs_write_inode: %lu\n", inode->i_ino);
427 	res = hfs_ext_write_extent(inode);
428 	if (res)
429 		return res;
430 
431 	if (inode->i_ino < HFS_FIRSTUSER_CNID) {
432 		switch (inode->i_ino) {
433 		case HFS_ROOT_CNID:
434 			break;
435 		case HFS_EXT_CNID:
436 			hfs_btree_write(HFS_SB(inode->i_sb)->ext_tree);
437 			return 0;
438 		case HFS_CAT_CNID:
439 			hfs_btree_write(HFS_SB(inode->i_sb)->cat_tree);
440 			return 0;
441 		default:
442 			BUG();
443 			return -EIO;
444 		}
445 	}
446 
447 	if (HFS_IS_RSRC(inode))
448 		main_inode = HFS_I(inode)->rsrc_inode;
449 
450 	if (!main_inode->i_nlink)
451 		return 0;
452 
453 	if (hfs_find_init(HFS_SB(main_inode->i_sb)->cat_tree, &fd))
454 		/* panic? */
455 		return -EIO;
456 
457 	fd.search_key->cat = HFS_I(main_inode)->cat_key;
458 	if (hfs_brec_find(&fd))
459 		/* panic? */
460 		goto out;
461 
462 	if (S_ISDIR(main_inode->i_mode)) {
463 		if (fd.entrylength < sizeof(struct hfs_cat_dir))
464 			/* panic? */;
465 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
466 			   sizeof(struct hfs_cat_dir));
467 		if (rec.type != HFS_CDR_DIR ||
468 		    be32_to_cpu(rec.dir.DirID) != inode->i_ino) {
469 		}
470 
471 		rec.dir.MdDat = hfs_u_to_mtime(inode->i_mtime);
472 		rec.dir.Val = cpu_to_be16(inode->i_size - 2);
473 
474 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
475 			    sizeof(struct hfs_cat_dir));
476 	} else if (HFS_IS_RSRC(inode)) {
477 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
478 			       sizeof(struct hfs_cat_file));
479 		hfs_inode_write_fork(inode, rec.file.RExtRec,
480 				     &rec.file.RLgLen, &rec.file.RPyLen);
481 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
482 				sizeof(struct hfs_cat_file));
483 	} else {
484 		if (fd.entrylength < sizeof(struct hfs_cat_file))
485 			/* panic? */;
486 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
487 			   sizeof(struct hfs_cat_file));
488 		if (rec.type != HFS_CDR_FIL ||
489 		    be32_to_cpu(rec.file.FlNum) != inode->i_ino) {
490 		}
491 
492 		if (inode->i_mode & S_IWUSR)
493 			rec.file.Flags &= ~HFS_FIL_LOCK;
494 		else
495 			rec.file.Flags |= HFS_FIL_LOCK;
496 		hfs_inode_write_fork(inode, rec.file.ExtRec, &rec.file.LgLen, &rec.file.PyLen);
497 		rec.file.MdDat = hfs_u_to_mtime(inode->i_mtime);
498 
499 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
500 			    sizeof(struct hfs_cat_file));
501 	}
502 out:
503 	hfs_find_exit(&fd);
504 	return 0;
505 }
506 
507 static struct dentry *hfs_file_lookup(struct inode *dir, struct dentry *dentry,
508 				      unsigned int flags)
509 {
510 	struct inode *inode = NULL;
511 	hfs_cat_rec rec;
512 	struct hfs_find_data fd;
513 	int res;
514 
515 	if (HFS_IS_RSRC(dir) || strcmp(dentry->d_name.name, "rsrc"))
516 		goto out;
517 
518 	inode = HFS_I(dir)->rsrc_inode;
519 	if (inode)
520 		goto out;
521 
522 	inode = new_inode(dir->i_sb);
523 	if (!inode)
524 		return ERR_PTR(-ENOMEM);
525 
526 	res = hfs_find_init(HFS_SB(dir->i_sb)->cat_tree, &fd);
527 	if (res) {
528 		iput(inode);
529 		return ERR_PTR(res);
530 	}
531 	fd.search_key->cat = HFS_I(dir)->cat_key;
532 	res = hfs_brec_read(&fd, &rec, sizeof(rec));
533 	if (!res) {
534 		struct hfs_iget_data idata = { NULL, &rec };
535 		hfs_read_inode(inode, &idata);
536 	}
537 	hfs_find_exit(&fd);
538 	if (res) {
539 		iput(inode);
540 		return ERR_PTR(res);
541 	}
542 	HFS_I(inode)->rsrc_inode = dir;
543 	HFS_I(dir)->rsrc_inode = inode;
544 	igrab(dir);
545 	inode_fake_hash(inode);
546 	mark_inode_dirty(inode);
547 	dont_mount(dentry);
548 out:
549 	return d_splice_alias(inode, dentry);
550 }
551 
552 void hfs_evict_inode(struct inode *inode)
553 {
554 	truncate_inode_pages_final(&inode->i_data);
555 	clear_inode(inode);
556 	if (HFS_IS_RSRC(inode) && HFS_I(inode)->rsrc_inode) {
557 		HFS_I(HFS_I(inode)->rsrc_inode)->rsrc_inode = NULL;
558 		iput(HFS_I(inode)->rsrc_inode);
559 	}
560 }
561 
562 static int hfs_file_open(struct inode *inode, struct file *file)
563 {
564 	if (HFS_IS_RSRC(inode))
565 		inode = HFS_I(inode)->rsrc_inode;
566 	atomic_inc(&HFS_I(inode)->opencnt);
567 	return 0;
568 }
569 
570 static int hfs_file_release(struct inode *inode, struct file *file)
571 {
572 	//struct super_block *sb = inode->i_sb;
573 
574 	if (HFS_IS_RSRC(inode))
575 		inode = HFS_I(inode)->rsrc_inode;
576 	if (atomic_dec_and_test(&HFS_I(inode)->opencnt)) {
577 		inode_lock(inode);
578 		hfs_file_truncate(inode);
579 		//if (inode->i_flags & S_DEAD) {
580 		//	hfs_delete_cat(inode->i_ino, HFSPLUS_SB(sb).hidden_dir, NULL);
581 		//	hfs_delete_inode(inode);
582 		//}
583 		inode_unlock(inode);
584 	}
585 	return 0;
586 }
587 
588 /*
589  * hfs_notify_change()
590  *
591  * Based very closely on fs/msdos/inode.c by Werner Almesberger
592  *
593  * This is the notify_change() field in the super_operations structure
594  * for HFS file systems.  The purpose is to take that changes made to
595  * an inode and apply then in a filesystem-dependent manner.  In this
596  * case the process has a few of tasks to do:
597  *  1) prevent changes to the i_uid and i_gid fields.
598  *  2) map file permissions to the closest allowable permissions
599  *  3) Since multiple Linux files can share the same on-disk inode under
600  *     HFS (for instance the data and resource forks of a file) a change
601  *     to permissions must be applied to all other in-core inodes which
602  *     correspond to the same HFS file.
603  */
604 
605 int hfs_inode_setattr(struct dentry *dentry, struct iattr * attr)
606 {
607 	struct inode *inode = d_inode(dentry);
608 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
609 	int error;
610 
611 	error = setattr_prepare(dentry, attr); /* basic permission checks */
612 	if (error)
613 		return error;
614 
615 	/* no uig/gid changes and limit which mode bits can be set */
616 	if (((attr->ia_valid & ATTR_UID) &&
617 	     (!uid_eq(attr->ia_uid, hsb->s_uid))) ||
618 	    ((attr->ia_valid & ATTR_GID) &&
619 	     (!gid_eq(attr->ia_gid, hsb->s_gid))) ||
620 	    ((attr->ia_valid & ATTR_MODE) &&
621 	     ((S_ISDIR(inode->i_mode) &&
622 	       (attr->ia_mode != inode->i_mode)) ||
623 	      (attr->ia_mode & ~HFS_VALID_MODE_BITS)))) {
624 		return hsb->s_quiet ? 0 : error;
625 	}
626 
627 	if (attr->ia_valid & ATTR_MODE) {
628 		/* Only the 'w' bits can ever change and only all together. */
629 		if (attr->ia_mode & S_IWUSR)
630 			attr->ia_mode = inode->i_mode | S_IWUGO;
631 		else
632 			attr->ia_mode = inode->i_mode & ~S_IWUGO;
633 		attr->ia_mode &= S_ISDIR(inode->i_mode) ? ~hsb->s_dir_umask: ~hsb->s_file_umask;
634 	}
635 
636 	if ((attr->ia_valid & ATTR_SIZE) &&
637 	    attr->ia_size != i_size_read(inode)) {
638 		inode_dio_wait(inode);
639 
640 		error = inode_newsize_ok(inode, attr->ia_size);
641 		if (error)
642 			return error;
643 
644 		truncate_setsize(inode, attr->ia_size);
645 		hfs_file_truncate(inode);
646 		inode->i_atime = inode->i_mtime = inode->i_ctime =
647 						  current_time(inode);
648 	}
649 
650 	setattr_copy(inode, attr);
651 	mark_inode_dirty(inode);
652 	return 0;
653 }
654 
655 static int hfs_file_fsync(struct file *filp, loff_t start, loff_t end,
656 			  int datasync)
657 {
658 	struct inode *inode = filp->f_mapping->host;
659 	struct super_block * sb;
660 	int ret, err;
661 
662 	ret = file_write_and_wait_range(filp, start, end);
663 	if (ret)
664 		return ret;
665 	inode_lock(inode);
666 
667 	/* sync the inode to buffers */
668 	ret = write_inode_now(inode, 0);
669 
670 	/* sync the superblock to buffers */
671 	sb = inode->i_sb;
672 	flush_delayed_work(&HFS_SB(sb)->mdb_work);
673 	/* .. finally sync the buffers to disk */
674 	err = sync_blockdev(sb->s_bdev);
675 	if (!ret)
676 		ret = err;
677 	inode_unlock(inode);
678 	return ret;
679 }
680 
681 static const struct file_operations hfs_file_operations = {
682 	.llseek		= generic_file_llseek,
683 	.read_iter	= generic_file_read_iter,
684 	.write_iter	= generic_file_write_iter,
685 	.mmap		= generic_file_mmap,
686 	.splice_read	= generic_file_splice_read,
687 	.fsync		= hfs_file_fsync,
688 	.open		= hfs_file_open,
689 	.release	= hfs_file_release,
690 };
691 
692 static const struct inode_operations hfs_file_inode_operations = {
693 	.lookup		= hfs_file_lookup,
694 	.setattr	= hfs_inode_setattr,
695 	.listxattr	= generic_listxattr,
696 };
697