xref: /openbmc/linux/fs/hfs/inode.c (revision ccb01374)
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 
21 #include "hfs_fs.h"
22 #include "btree.h"
23 
24 static const struct file_operations hfs_file_operations;
25 static const struct inode_operations hfs_file_inode_operations;
26 
27 /*================ Variable-like macros ================*/
28 
29 #define HFS_VALID_MODE_BITS  (S_IFREG | S_IFDIR | S_IRWXUGO)
30 
31 static int hfs_writepage(struct page *page, struct writeback_control *wbc)
32 {
33 	return block_write_full_page(page, hfs_get_block, wbc);
34 }
35 
36 static int hfs_readpage(struct file *file, struct page *page)
37 {
38 	return block_read_full_page(page, hfs_get_block);
39 }
40 
41 static void hfs_write_failed(struct address_space *mapping, loff_t to)
42 {
43 	struct inode *inode = mapping->host;
44 
45 	if (to > inode->i_size) {
46 		truncate_pagecache(inode, inode->i_size);
47 		hfs_file_truncate(inode);
48 	}
49 }
50 
51 static int hfs_write_begin(struct file *file, struct address_space *mapping,
52 			loff_t pos, unsigned len, unsigned flags,
53 			struct page **pagep, void **fsdata)
54 {
55 	int ret;
56 
57 	*pagep = NULL;
58 	ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
59 				hfs_get_block,
60 				&HFS_I(mapping->host)->phys_size);
61 	if (unlikely(ret))
62 		hfs_write_failed(mapping, pos + len);
63 
64 	return ret;
65 }
66 
67 static sector_t hfs_bmap(struct address_space *mapping, sector_t block)
68 {
69 	return generic_block_bmap(mapping, block, hfs_get_block);
70 }
71 
72 static int hfs_releasepage(struct page *page, gfp_t mask)
73 {
74 	struct inode *inode = page->mapping->host;
75 	struct super_block *sb = inode->i_sb;
76 	struct hfs_btree *tree;
77 	struct hfs_bnode *node;
78 	u32 nidx;
79 	int i, res = 1;
80 
81 	switch (inode->i_ino) {
82 	case HFS_EXT_CNID:
83 		tree = HFS_SB(sb)->ext_tree;
84 		break;
85 	case HFS_CAT_CNID:
86 		tree = HFS_SB(sb)->cat_tree;
87 		break;
88 	default:
89 		BUG();
90 		return 0;
91 	}
92 
93 	if (!tree)
94 		return 0;
95 
96 	if (tree->node_size >= PAGE_SIZE) {
97 		nidx = page->index >> (tree->node_size_shift - PAGE_SHIFT);
98 		spin_lock(&tree->hash_lock);
99 		node = hfs_bnode_findhash(tree, nidx);
100 		if (!node)
101 			;
102 		else if (atomic_read(&node->refcnt))
103 			res = 0;
104 		if (res && node) {
105 			hfs_bnode_unhash(node);
106 			hfs_bnode_free(node);
107 		}
108 		spin_unlock(&tree->hash_lock);
109 	} else {
110 		nidx = page->index << (PAGE_SHIFT - tree->node_size_shift);
111 		i = 1 << (PAGE_SHIFT - tree->node_size_shift);
112 		spin_lock(&tree->hash_lock);
113 		do {
114 			node = hfs_bnode_findhash(tree, nidx++);
115 			if (!node)
116 				continue;
117 			if (atomic_read(&node->refcnt)) {
118 				res = 0;
119 				break;
120 			}
121 			hfs_bnode_unhash(node);
122 			hfs_bnode_free(node);
123 		} while (--i && nidx < tree->node_count);
124 		spin_unlock(&tree->hash_lock);
125 	}
126 	return res ? try_to_free_buffers(page) : 0;
127 }
128 
129 static ssize_t hfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
130 {
131 	struct file *file = iocb->ki_filp;
132 	struct address_space *mapping = file->f_mapping;
133 	struct inode *inode = mapping->host;
134 	size_t count = iov_iter_count(iter);
135 	ssize_t ret;
136 
137 	ret = blockdev_direct_IO(iocb, inode, iter, hfs_get_block);
138 
139 	/*
140 	 * In case of error extending write may have instantiated a few
141 	 * blocks outside i_size. Trim these off again.
142 	 */
143 	if (unlikely(iov_iter_rw(iter) == WRITE && ret < 0)) {
144 		loff_t isize = i_size_read(inode);
145 		loff_t end = iocb->ki_pos + count;
146 
147 		if (end > isize)
148 			hfs_write_failed(mapping, end);
149 	}
150 
151 	return ret;
152 }
153 
154 static int hfs_writepages(struct address_space *mapping,
155 			  struct writeback_control *wbc)
156 {
157 	return mpage_writepages(mapping, wbc, hfs_get_block);
158 }
159 
160 const struct address_space_operations hfs_btree_aops = {
161 	.readpage	= hfs_readpage,
162 	.writepage	= hfs_writepage,
163 	.write_begin	= hfs_write_begin,
164 	.write_end	= generic_write_end,
165 	.bmap		= hfs_bmap,
166 	.releasepage	= hfs_releasepage,
167 };
168 
169 const struct address_space_operations hfs_aops = {
170 	.readpage	= hfs_readpage,
171 	.writepage	= hfs_writepage,
172 	.write_begin	= hfs_write_begin,
173 	.write_end	= generic_write_end,
174 	.bmap		= hfs_bmap,
175 	.direct_IO	= hfs_direct_IO,
176 	.writepages	= hfs_writepages,
177 };
178 
179 /*
180  * hfs_new_inode
181  */
182 struct inode *hfs_new_inode(struct inode *dir, const struct qstr *name, umode_t mode)
183 {
184 	struct super_block *sb = dir->i_sb;
185 	struct inode *inode = new_inode(sb);
186 	if (!inode)
187 		return NULL;
188 
189 	mutex_init(&HFS_I(inode)->extents_lock);
190 	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
191 	spin_lock_init(&HFS_I(inode)->open_dir_lock);
192 	hfs_cat_build_key(sb, (btree_key *)&HFS_I(inode)->cat_key, dir->i_ino, name);
193 	inode->i_ino = HFS_SB(sb)->next_id++;
194 	inode->i_mode = mode;
195 	inode->i_uid = current_fsuid();
196 	inode->i_gid = current_fsgid();
197 	set_nlink(inode, 1);
198 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
199 	HFS_I(inode)->flags = 0;
200 	HFS_I(inode)->rsrc_inode = NULL;
201 	HFS_I(inode)->fs_blocks = 0;
202 	if (S_ISDIR(mode)) {
203 		inode->i_size = 2;
204 		HFS_SB(sb)->folder_count++;
205 		if (dir->i_ino == HFS_ROOT_CNID)
206 			HFS_SB(sb)->root_dirs++;
207 		inode->i_op = &hfs_dir_inode_operations;
208 		inode->i_fop = &hfs_dir_operations;
209 		inode->i_mode |= S_IRWXUGO;
210 		inode->i_mode &= ~HFS_SB(inode->i_sb)->s_dir_umask;
211 	} else if (S_ISREG(mode)) {
212 		HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
213 		HFS_SB(sb)->file_count++;
214 		if (dir->i_ino == HFS_ROOT_CNID)
215 			HFS_SB(sb)->root_files++;
216 		inode->i_op = &hfs_file_inode_operations;
217 		inode->i_fop = &hfs_file_operations;
218 		inode->i_mapping->a_ops = &hfs_aops;
219 		inode->i_mode |= S_IRUGO|S_IXUGO;
220 		if (mode & S_IWUSR)
221 			inode->i_mode |= S_IWUGO;
222 		inode->i_mode &= ~HFS_SB(inode->i_sb)->s_file_umask;
223 		HFS_I(inode)->phys_size = 0;
224 		HFS_I(inode)->alloc_blocks = 0;
225 		HFS_I(inode)->first_blocks = 0;
226 		HFS_I(inode)->cached_start = 0;
227 		HFS_I(inode)->cached_blocks = 0;
228 		memset(HFS_I(inode)->first_extents, 0, sizeof(hfs_extent_rec));
229 		memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
230 	}
231 	insert_inode_hash(inode);
232 	mark_inode_dirty(inode);
233 	set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
234 	hfs_mark_mdb_dirty(sb);
235 
236 	return inode;
237 }
238 
239 void hfs_delete_inode(struct inode *inode)
240 {
241 	struct super_block *sb = inode->i_sb;
242 
243 	hfs_dbg(INODE, "delete_inode: %lu\n", inode->i_ino);
244 	if (S_ISDIR(inode->i_mode)) {
245 		HFS_SB(sb)->folder_count--;
246 		if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
247 			HFS_SB(sb)->root_dirs--;
248 		set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
249 		hfs_mark_mdb_dirty(sb);
250 		return;
251 	}
252 	HFS_SB(sb)->file_count--;
253 	if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
254 		HFS_SB(sb)->root_files--;
255 	if (S_ISREG(inode->i_mode)) {
256 		if (!inode->i_nlink) {
257 			inode->i_size = 0;
258 			hfs_file_truncate(inode);
259 		}
260 	}
261 	set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
262 	hfs_mark_mdb_dirty(sb);
263 }
264 
265 void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
266 			 __be32 __log_size, __be32 phys_size, u32 clump_size)
267 {
268 	struct super_block *sb = inode->i_sb;
269 	u32 log_size = be32_to_cpu(__log_size);
270 	u16 count;
271 	int i;
272 
273 	memcpy(HFS_I(inode)->first_extents, ext, sizeof(hfs_extent_rec));
274 	for (count = 0, i = 0; i < 3; i++)
275 		count += be16_to_cpu(ext[i].count);
276 	HFS_I(inode)->first_blocks = count;
277 
278 	inode->i_size = HFS_I(inode)->phys_size = log_size;
279 	HFS_I(inode)->fs_blocks = (log_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
280 	inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
281 	HFS_I(inode)->alloc_blocks = be32_to_cpu(phys_size) /
282 				     HFS_SB(sb)->alloc_blksz;
283 	HFS_I(inode)->clump_blocks = clump_size / HFS_SB(sb)->alloc_blksz;
284 	if (!HFS_I(inode)->clump_blocks)
285 		HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
286 }
287 
288 struct hfs_iget_data {
289 	struct hfs_cat_key *key;
290 	hfs_cat_rec *rec;
291 };
292 
293 static int hfs_test_inode(struct inode *inode, void *data)
294 {
295 	struct hfs_iget_data *idata = data;
296 	hfs_cat_rec *rec;
297 
298 	rec = idata->rec;
299 	switch (rec->type) {
300 	case HFS_CDR_DIR:
301 		return inode->i_ino == be32_to_cpu(rec->dir.DirID);
302 	case HFS_CDR_FIL:
303 		return inode->i_ino == be32_to_cpu(rec->file.FlNum);
304 	default:
305 		BUG();
306 		return 1;
307 	}
308 }
309 
310 /*
311  * hfs_read_inode
312  */
313 static int hfs_read_inode(struct inode *inode, void *data)
314 {
315 	struct hfs_iget_data *idata = data;
316 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
317 	hfs_cat_rec *rec;
318 
319 	HFS_I(inode)->flags = 0;
320 	HFS_I(inode)->rsrc_inode = NULL;
321 	mutex_init(&HFS_I(inode)->extents_lock);
322 	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
323 	spin_lock_init(&HFS_I(inode)->open_dir_lock);
324 
325 	/* Initialize the inode */
326 	inode->i_uid = hsb->s_uid;
327 	inode->i_gid = hsb->s_gid;
328 	set_nlink(inode, 1);
329 
330 	if (idata->key)
331 		HFS_I(inode)->cat_key = *idata->key;
332 	else
333 		HFS_I(inode)->flags |= HFS_FLG_RSRC;
334 	HFS_I(inode)->tz_secondswest = sys_tz.tz_minuteswest * 60;
335 
336 	rec = idata->rec;
337 	switch (rec->type) {
338 	case HFS_CDR_FIL:
339 		if (!HFS_IS_RSRC(inode)) {
340 			hfs_inode_read_fork(inode, rec->file.ExtRec, rec->file.LgLen,
341 					    rec->file.PyLen, be16_to_cpu(rec->file.ClpSize));
342 		} else {
343 			hfs_inode_read_fork(inode, rec->file.RExtRec, rec->file.RLgLen,
344 					    rec->file.RPyLen, be16_to_cpu(rec->file.ClpSize));
345 		}
346 
347 		inode->i_ino = be32_to_cpu(rec->file.FlNum);
348 		inode->i_mode = S_IRUGO | S_IXUGO;
349 		if (!(rec->file.Flags & HFS_FIL_LOCK))
350 			inode->i_mode |= S_IWUGO;
351 		inode->i_mode &= ~hsb->s_file_umask;
352 		inode->i_mode |= S_IFREG;
353 		inode->i_ctime = inode->i_atime = inode->i_mtime =
354 				timespec_to_timespec64(hfs_m_to_utime(rec->file.MdDat));
355 		inode->i_op = &hfs_file_inode_operations;
356 		inode->i_fop = &hfs_file_operations;
357 		inode->i_mapping->a_ops = &hfs_aops;
358 		break;
359 	case HFS_CDR_DIR:
360 		inode->i_ino = be32_to_cpu(rec->dir.DirID);
361 		inode->i_size = be16_to_cpu(rec->dir.Val) + 2;
362 		HFS_I(inode)->fs_blocks = 0;
363 		inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask);
364 		inode->i_ctime = inode->i_atime = inode->i_mtime =
365 				timespec_to_timespec64(hfs_m_to_utime(rec->dir.MdDat));
366 		inode->i_op = &hfs_dir_inode_operations;
367 		inode->i_fop = &hfs_dir_operations;
368 		break;
369 	default:
370 		make_bad_inode(inode);
371 	}
372 	return 0;
373 }
374 
375 /*
376  * __hfs_iget()
377  *
378  * Given the MDB for a HFS filesystem, a 'key' and an 'entry' in
379  * the catalog B-tree and the 'type' of the desired file return the
380  * inode for that file/directory or NULL.  Note that 'type' indicates
381  * whether we want the actual file or directory, or the corresponding
382  * metadata (AppleDouble header file or CAP metadata file).
383  */
384 struct inode *hfs_iget(struct super_block *sb, struct hfs_cat_key *key, hfs_cat_rec *rec)
385 {
386 	struct hfs_iget_data data = { key, rec };
387 	struct inode *inode;
388 	u32 cnid;
389 
390 	switch (rec->type) {
391 	case HFS_CDR_DIR:
392 		cnid = be32_to_cpu(rec->dir.DirID);
393 		break;
394 	case HFS_CDR_FIL:
395 		cnid = be32_to_cpu(rec->file.FlNum);
396 		break;
397 	default:
398 		return NULL;
399 	}
400 	inode = iget5_locked(sb, cnid, hfs_test_inode, hfs_read_inode, &data);
401 	if (inode && (inode->i_state & I_NEW))
402 		unlock_new_inode(inode);
403 	return inode;
404 }
405 
406 void hfs_inode_write_fork(struct inode *inode, struct hfs_extent *ext,
407 			  __be32 *log_size, __be32 *phys_size)
408 {
409 	memcpy(ext, HFS_I(inode)->first_extents, sizeof(hfs_extent_rec));
410 
411 	if (log_size)
412 		*log_size = cpu_to_be32(inode->i_size);
413 	if (phys_size)
414 		*phys_size = cpu_to_be32(HFS_I(inode)->alloc_blocks *
415 					 HFS_SB(inode->i_sb)->alloc_blksz);
416 }
417 
418 int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
419 {
420 	struct inode *main_inode = inode;
421 	struct hfs_find_data fd;
422 	hfs_cat_rec rec;
423 	int res;
424 
425 	hfs_dbg(INODE, "hfs_write_inode: %lu\n", inode->i_ino);
426 	res = hfs_ext_write_extent(inode);
427 	if (res)
428 		return res;
429 
430 	if (inode->i_ino < HFS_FIRSTUSER_CNID) {
431 		switch (inode->i_ino) {
432 		case HFS_ROOT_CNID:
433 			break;
434 		case HFS_EXT_CNID:
435 			hfs_btree_write(HFS_SB(inode->i_sb)->ext_tree);
436 			return 0;
437 		case HFS_CAT_CNID:
438 			hfs_btree_write(HFS_SB(inode->i_sb)->cat_tree);
439 			return 0;
440 		default:
441 			BUG();
442 			return -EIO;
443 		}
444 	}
445 
446 	if (HFS_IS_RSRC(inode))
447 		main_inode = HFS_I(inode)->rsrc_inode;
448 
449 	if (!main_inode->i_nlink)
450 		return 0;
451 
452 	if (hfs_find_init(HFS_SB(main_inode->i_sb)->cat_tree, &fd))
453 		/* panic? */
454 		return -EIO;
455 
456 	fd.search_key->cat = HFS_I(main_inode)->cat_key;
457 	if (hfs_brec_find(&fd))
458 		/* panic? */
459 		goto out;
460 
461 	if (S_ISDIR(main_inode->i_mode)) {
462 		if (fd.entrylength < sizeof(struct hfs_cat_dir))
463 			/* panic? */;
464 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
465 			   sizeof(struct hfs_cat_dir));
466 		if (rec.type != HFS_CDR_DIR ||
467 		    be32_to_cpu(rec.dir.DirID) != inode->i_ino) {
468 		}
469 
470 		rec.dir.MdDat = hfs_u_to_mtime(inode->i_mtime);
471 		rec.dir.Val = cpu_to_be16(inode->i_size - 2);
472 
473 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
474 			    sizeof(struct hfs_cat_dir));
475 	} else if (HFS_IS_RSRC(inode)) {
476 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
477 			       sizeof(struct hfs_cat_file));
478 		hfs_inode_write_fork(inode, rec.file.RExtRec,
479 				     &rec.file.RLgLen, &rec.file.RPyLen);
480 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
481 				sizeof(struct hfs_cat_file));
482 	} else {
483 		if (fd.entrylength < sizeof(struct hfs_cat_file))
484 			/* panic? */;
485 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
486 			   sizeof(struct hfs_cat_file));
487 		if (rec.type != HFS_CDR_FIL ||
488 		    be32_to_cpu(rec.file.FlNum) != inode->i_ino) {
489 		}
490 
491 		if (inode->i_mode & S_IWUSR)
492 			rec.file.Flags &= ~HFS_FIL_LOCK;
493 		else
494 			rec.file.Flags |= HFS_FIL_LOCK;
495 		hfs_inode_write_fork(inode, rec.file.ExtRec, &rec.file.LgLen, &rec.file.PyLen);
496 		rec.file.MdDat = hfs_u_to_mtime(inode->i_mtime);
497 
498 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
499 			    sizeof(struct hfs_cat_file));
500 	}
501 out:
502 	hfs_find_exit(&fd);
503 	return 0;
504 }
505 
506 static struct dentry *hfs_file_lookup(struct inode *dir, struct dentry *dentry,
507 				      unsigned int flags)
508 {
509 	struct inode *inode = NULL;
510 	hfs_cat_rec rec;
511 	struct hfs_find_data fd;
512 	int res;
513 
514 	if (HFS_IS_RSRC(dir) || strcmp(dentry->d_name.name, "rsrc"))
515 		goto out;
516 
517 	inode = HFS_I(dir)->rsrc_inode;
518 	if (inode)
519 		goto out;
520 
521 	inode = new_inode(dir->i_sb);
522 	if (!inode)
523 		return ERR_PTR(-ENOMEM);
524 
525 	res = hfs_find_init(HFS_SB(dir->i_sb)->cat_tree, &fd);
526 	if (res) {
527 		iput(inode);
528 		return ERR_PTR(res);
529 	}
530 	fd.search_key->cat = HFS_I(dir)->cat_key;
531 	res = hfs_brec_read(&fd, &rec, sizeof(rec));
532 	if (!res) {
533 		struct hfs_iget_data idata = { NULL, &rec };
534 		hfs_read_inode(inode, &idata);
535 	}
536 	hfs_find_exit(&fd);
537 	if (res) {
538 		iput(inode);
539 		return ERR_PTR(res);
540 	}
541 	HFS_I(inode)->rsrc_inode = dir;
542 	HFS_I(dir)->rsrc_inode = inode;
543 	igrab(dir);
544 	inode_fake_hash(inode);
545 	mark_inode_dirty(inode);
546 	dont_mount(dentry);
547 out:
548 	return d_splice_alias(inode, dentry);
549 }
550 
551 void hfs_evict_inode(struct inode *inode)
552 {
553 	truncate_inode_pages_final(&inode->i_data);
554 	clear_inode(inode);
555 	if (HFS_IS_RSRC(inode) && HFS_I(inode)->rsrc_inode) {
556 		HFS_I(HFS_I(inode)->rsrc_inode)->rsrc_inode = NULL;
557 		iput(HFS_I(inode)->rsrc_inode);
558 	}
559 }
560 
561 static int hfs_file_open(struct inode *inode, struct file *file)
562 {
563 	if (HFS_IS_RSRC(inode))
564 		inode = HFS_I(inode)->rsrc_inode;
565 	atomic_inc(&HFS_I(inode)->opencnt);
566 	return 0;
567 }
568 
569 static int hfs_file_release(struct inode *inode, struct file *file)
570 {
571 	//struct super_block *sb = inode->i_sb;
572 
573 	if (HFS_IS_RSRC(inode))
574 		inode = HFS_I(inode)->rsrc_inode;
575 	if (atomic_dec_and_test(&HFS_I(inode)->opencnt)) {
576 		inode_lock(inode);
577 		hfs_file_truncate(inode);
578 		//if (inode->i_flags & S_DEAD) {
579 		//	hfs_delete_cat(inode->i_ino, HFSPLUS_SB(sb).hidden_dir, NULL);
580 		//	hfs_delete_inode(inode);
581 		//}
582 		inode_unlock(inode);
583 	}
584 	return 0;
585 }
586 
587 /*
588  * hfs_notify_change()
589  *
590  * Based very closely on fs/msdos/inode.c by Werner Almesberger
591  *
592  * This is the notify_change() field in the super_operations structure
593  * for HFS file systems.  The purpose is to take that changes made to
594  * an inode and apply then in a filesystem-dependent manner.  In this
595  * case the process has a few of tasks to do:
596  *  1) prevent changes to the i_uid and i_gid fields.
597  *  2) map file permissions to the closest allowable permissions
598  *  3) Since multiple Linux files can share the same on-disk inode under
599  *     HFS (for instance the data and resource forks of a file) a change
600  *     to permissions must be applied to all other in-core inodes which
601  *     correspond to the same HFS file.
602  */
603 
604 int hfs_inode_setattr(struct dentry *dentry, struct iattr * attr)
605 {
606 	struct inode *inode = d_inode(dentry);
607 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
608 	int error;
609 
610 	error = setattr_prepare(dentry, attr); /* basic permission checks */
611 	if (error)
612 		return error;
613 
614 	/* no uig/gid changes and limit which mode bits can be set */
615 	if (((attr->ia_valid & ATTR_UID) &&
616 	     (!uid_eq(attr->ia_uid, hsb->s_uid))) ||
617 	    ((attr->ia_valid & ATTR_GID) &&
618 	     (!gid_eq(attr->ia_gid, hsb->s_gid))) ||
619 	    ((attr->ia_valid & ATTR_MODE) &&
620 	     ((S_ISDIR(inode->i_mode) &&
621 	       (attr->ia_mode != inode->i_mode)) ||
622 	      (attr->ia_mode & ~HFS_VALID_MODE_BITS)))) {
623 		return hsb->s_quiet ? 0 : error;
624 	}
625 
626 	if (attr->ia_valid & ATTR_MODE) {
627 		/* Only the 'w' bits can ever change and only all together. */
628 		if (attr->ia_mode & S_IWUSR)
629 			attr->ia_mode = inode->i_mode | S_IWUGO;
630 		else
631 			attr->ia_mode = inode->i_mode & ~S_IWUGO;
632 		attr->ia_mode &= S_ISDIR(inode->i_mode) ? ~hsb->s_dir_umask: ~hsb->s_file_umask;
633 	}
634 
635 	if ((attr->ia_valid & ATTR_SIZE) &&
636 	    attr->ia_size != i_size_read(inode)) {
637 		inode_dio_wait(inode);
638 
639 		error = inode_newsize_ok(inode, attr->ia_size);
640 		if (error)
641 			return error;
642 
643 		truncate_setsize(inode, attr->ia_size);
644 		hfs_file_truncate(inode);
645 		inode->i_atime = inode->i_mtime = inode->i_ctime =
646 						  current_time(inode);
647 	}
648 
649 	setattr_copy(inode, attr);
650 	mark_inode_dirty(inode);
651 	return 0;
652 }
653 
654 static int hfs_file_fsync(struct file *filp, loff_t start, loff_t end,
655 			  int datasync)
656 {
657 	struct inode *inode = filp->f_mapping->host;
658 	struct super_block * sb;
659 	int ret, err;
660 
661 	ret = file_write_and_wait_range(filp, start, end);
662 	if (ret)
663 		return ret;
664 	inode_lock(inode);
665 
666 	/* sync the inode to buffers */
667 	ret = write_inode_now(inode, 0);
668 
669 	/* sync the superblock to buffers */
670 	sb = inode->i_sb;
671 	flush_delayed_work(&HFS_SB(sb)->mdb_work);
672 	/* .. finally sync the buffers to disk */
673 	err = sync_blockdev(sb->s_bdev);
674 	if (!ret)
675 		ret = err;
676 	inode_unlock(inode);
677 	return ret;
678 }
679 
680 static const struct file_operations hfs_file_operations = {
681 	.llseek		= generic_file_llseek,
682 	.read_iter	= generic_file_read_iter,
683 	.write_iter	= generic_file_write_iter,
684 	.mmap		= generic_file_mmap,
685 	.splice_read	= generic_file_splice_read,
686 	.fsync		= hfs_file_fsync,
687 	.open		= hfs_file_open,
688 	.release	= hfs_file_release,
689 };
690 
691 static const struct inode_operations hfs_file_inode_operations = {
692 	.lookup		= hfs_file_lookup,
693 	.setattr	= hfs_inode_setattr,
694 	.listxattr	= generic_listxattr,
695 };
696