xref: /openbmc/linux/fs/hfs/inode.c (revision b18d2847)
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 	.dirty_folio	= block_dirty_folio,
163 	.invalidate_folio = block_invalidate_folio,
164 	.readpage	= hfs_readpage,
165 	.writepage	= hfs_writepage,
166 	.write_begin	= hfs_write_begin,
167 	.write_end	= generic_write_end,
168 	.bmap		= hfs_bmap,
169 	.releasepage	= hfs_releasepage,
170 };
171 
172 const struct address_space_operations hfs_aops = {
173 	.dirty_folio	= block_dirty_folio,
174 	.invalidate_folio = block_invalidate_folio,
175 	.readpage	= hfs_readpage,
176 	.writepage	= hfs_writepage,
177 	.write_begin	= hfs_write_begin,
178 	.write_end	= generic_write_end,
179 	.bmap		= hfs_bmap,
180 	.direct_IO	= hfs_direct_IO,
181 	.writepages	= hfs_writepages,
182 };
183 
184 /*
185  * hfs_new_inode
186  */
187 struct inode *hfs_new_inode(struct inode *dir, const struct qstr *name, umode_t mode)
188 {
189 	struct super_block *sb = dir->i_sb;
190 	struct inode *inode = new_inode(sb);
191 	if (!inode)
192 		return NULL;
193 
194 	mutex_init(&HFS_I(inode)->extents_lock);
195 	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
196 	spin_lock_init(&HFS_I(inode)->open_dir_lock);
197 	hfs_cat_build_key(sb, (btree_key *)&HFS_I(inode)->cat_key, dir->i_ino, name);
198 	inode->i_ino = HFS_SB(sb)->next_id++;
199 	inode->i_mode = mode;
200 	inode->i_uid = current_fsuid();
201 	inode->i_gid = current_fsgid();
202 	set_nlink(inode, 1);
203 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
204 	HFS_I(inode)->flags = 0;
205 	HFS_I(inode)->rsrc_inode = NULL;
206 	HFS_I(inode)->fs_blocks = 0;
207 	if (S_ISDIR(mode)) {
208 		inode->i_size = 2;
209 		HFS_SB(sb)->folder_count++;
210 		if (dir->i_ino == HFS_ROOT_CNID)
211 			HFS_SB(sb)->root_dirs++;
212 		inode->i_op = &hfs_dir_inode_operations;
213 		inode->i_fop = &hfs_dir_operations;
214 		inode->i_mode |= S_IRWXUGO;
215 		inode->i_mode &= ~HFS_SB(inode->i_sb)->s_dir_umask;
216 	} else if (S_ISREG(mode)) {
217 		HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
218 		HFS_SB(sb)->file_count++;
219 		if (dir->i_ino == HFS_ROOT_CNID)
220 			HFS_SB(sb)->root_files++;
221 		inode->i_op = &hfs_file_inode_operations;
222 		inode->i_fop = &hfs_file_operations;
223 		inode->i_mapping->a_ops = &hfs_aops;
224 		inode->i_mode |= S_IRUGO|S_IXUGO;
225 		if (mode & S_IWUSR)
226 			inode->i_mode |= S_IWUGO;
227 		inode->i_mode &= ~HFS_SB(inode->i_sb)->s_file_umask;
228 		HFS_I(inode)->phys_size = 0;
229 		HFS_I(inode)->alloc_blocks = 0;
230 		HFS_I(inode)->first_blocks = 0;
231 		HFS_I(inode)->cached_start = 0;
232 		HFS_I(inode)->cached_blocks = 0;
233 		memset(HFS_I(inode)->first_extents, 0, sizeof(hfs_extent_rec));
234 		memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
235 	}
236 	insert_inode_hash(inode);
237 	mark_inode_dirty(inode);
238 	set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
239 	hfs_mark_mdb_dirty(sb);
240 
241 	return inode;
242 }
243 
244 void hfs_delete_inode(struct inode *inode)
245 {
246 	struct super_block *sb = inode->i_sb;
247 
248 	hfs_dbg(INODE, "delete_inode: %lu\n", inode->i_ino);
249 	if (S_ISDIR(inode->i_mode)) {
250 		HFS_SB(sb)->folder_count--;
251 		if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
252 			HFS_SB(sb)->root_dirs--;
253 		set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
254 		hfs_mark_mdb_dirty(sb);
255 		return;
256 	}
257 	HFS_SB(sb)->file_count--;
258 	if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
259 		HFS_SB(sb)->root_files--;
260 	if (S_ISREG(inode->i_mode)) {
261 		if (!inode->i_nlink) {
262 			inode->i_size = 0;
263 			hfs_file_truncate(inode);
264 		}
265 	}
266 	set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
267 	hfs_mark_mdb_dirty(sb);
268 }
269 
270 void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
271 			 __be32 __log_size, __be32 phys_size, u32 clump_size)
272 {
273 	struct super_block *sb = inode->i_sb;
274 	u32 log_size = be32_to_cpu(__log_size);
275 	u16 count;
276 	int i;
277 
278 	memcpy(HFS_I(inode)->first_extents, ext, sizeof(hfs_extent_rec));
279 	for (count = 0, i = 0; i < 3; i++)
280 		count += be16_to_cpu(ext[i].count);
281 	HFS_I(inode)->first_blocks = count;
282 
283 	inode->i_size = HFS_I(inode)->phys_size = log_size;
284 	HFS_I(inode)->fs_blocks = (log_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
285 	inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
286 	HFS_I(inode)->alloc_blocks = be32_to_cpu(phys_size) /
287 				     HFS_SB(sb)->alloc_blksz;
288 	HFS_I(inode)->clump_blocks = clump_size / HFS_SB(sb)->alloc_blksz;
289 	if (!HFS_I(inode)->clump_blocks)
290 		HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
291 }
292 
293 struct hfs_iget_data {
294 	struct hfs_cat_key *key;
295 	hfs_cat_rec *rec;
296 };
297 
298 static int hfs_test_inode(struct inode *inode, void *data)
299 {
300 	struct hfs_iget_data *idata = data;
301 	hfs_cat_rec *rec;
302 
303 	rec = idata->rec;
304 	switch (rec->type) {
305 	case HFS_CDR_DIR:
306 		return inode->i_ino == be32_to_cpu(rec->dir.DirID);
307 	case HFS_CDR_FIL:
308 		return inode->i_ino == be32_to_cpu(rec->file.FlNum);
309 	default:
310 		BUG();
311 		return 1;
312 	}
313 }
314 
315 /*
316  * hfs_read_inode
317  */
318 static int hfs_read_inode(struct inode *inode, void *data)
319 {
320 	struct hfs_iget_data *idata = data;
321 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
322 	hfs_cat_rec *rec;
323 
324 	HFS_I(inode)->flags = 0;
325 	HFS_I(inode)->rsrc_inode = NULL;
326 	mutex_init(&HFS_I(inode)->extents_lock);
327 	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
328 	spin_lock_init(&HFS_I(inode)->open_dir_lock);
329 
330 	/* Initialize the inode */
331 	inode->i_uid = hsb->s_uid;
332 	inode->i_gid = hsb->s_gid;
333 	set_nlink(inode, 1);
334 
335 	if (idata->key)
336 		HFS_I(inode)->cat_key = *idata->key;
337 	else
338 		HFS_I(inode)->flags |= HFS_FLG_RSRC;
339 	HFS_I(inode)->tz_secondswest = sys_tz.tz_minuteswest * 60;
340 
341 	rec = idata->rec;
342 	switch (rec->type) {
343 	case HFS_CDR_FIL:
344 		if (!HFS_IS_RSRC(inode)) {
345 			hfs_inode_read_fork(inode, rec->file.ExtRec, rec->file.LgLen,
346 					    rec->file.PyLen, be16_to_cpu(rec->file.ClpSize));
347 		} else {
348 			hfs_inode_read_fork(inode, rec->file.RExtRec, rec->file.RLgLen,
349 					    rec->file.RPyLen, be16_to_cpu(rec->file.ClpSize));
350 		}
351 
352 		inode->i_ino = be32_to_cpu(rec->file.FlNum);
353 		inode->i_mode = S_IRUGO | S_IXUGO;
354 		if (!(rec->file.Flags & HFS_FIL_LOCK))
355 			inode->i_mode |= S_IWUGO;
356 		inode->i_mode &= ~hsb->s_file_umask;
357 		inode->i_mode |= S_IFREG;
358 		inode->i_ctime = inode->i_atime = inode->i_mtime =
359 				hfs_m_to_utime(rec->file.MdDat);
360 		inode->i_op = &hfs_file_inode_operations;
361 		inode->i_fop = &hfs_file_operations;
362 		inode->i_mapping->a_ops = &hfs_aops;
363 		break;
364 	case HFS_CDR_DIR:
365 		inode->i_ino = be32_to_cpu(rec->dir.DirID);
366 		inode->i_size = be16_to_cpu(rec->dir.Val) + 2;
367 		HFS_I(inode)->fs_blocks = 0;
368 		inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask);
369 		inode->i_ctime = inode->i_atime = inode->i_mtime =
370 				hfs_m_to_utime(rec->dir.MdDat);
371 		inode->i_op = &hfs_dir_inode_operations;
372 		inode->i_fop = &hfs_dir_operations;
373 		break;
374 	default:
375 		make_bad_inode(inode);
376 	}
377 	return 0;
378 }
379 
380 /*
381  * __hfs_iget()
382  *
383  * Given the MDB for a HFS filesystem, a 'key' and an 'entry' in
384  * the catalog B-tree and the 'type' of the desired file return the
385  * inode for that file/directory or NULL.  Note that 'type' indicates
386  * whether we want the actual file or directory, or the corresponding
387  * metadata (AppleDouble header file or CAP metadata file).
388  */
389 struct inode *hfs_iget(struct super_block *sb, struct hfs_cat_key *key, hfs_cat_rec *rec)
390 {
391 	struct hfs_iget_data data = { key, rec };
392 	struct inode *inode;
393 	u32 cnid;
394 
395 	switch (rec->type) {
396 	case HFS_CDR_DIR:
397 		cnid = be32_to_cpu(rec->dir.DirID);
398 		break;
399 	case HFS_CDR_FIL:
400 		cnid = be32_to_cpu(rec->file.FlNum);
401 		break;
402 	default:
403 		return NULL;
404 	}
405 	inode = iget5_locked(sb, cnid, hfs_test_inode, hfs_read_inode, &data);
406 	if (inode && (inode->i_state & I_NEW))
407 		unlock_new_inode(inode);
408 	return inode;
409 }
410 
411 void hfs_inode_write_fork(struct inode *inode, struct hfs_extent *ext,
412 			  __be32 *log_size, __be32 *phys_size)
413 {
414 	memcpy(ext, HFS_I(inode)->first_extents, sizeof(hfs_extent_rec));
415 
416 	if (log_size)
417 		*log_size = cpu_to_be32(inode->i_size);
418 	if (phys_size)
419 		*phys_size = cpu_to_be32(HFS_I(inode)->alloc_blocks *
420 					 HFS_SB(inode->i_sb)->alloc_blksz);
421 }
422 
423 int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
424 {
425 	struct inode *main_inode = inode;
426 	struct hfs_find_data fd;
427 	hfs_cat_rec rec;
428 	int res;
429 
430 	hfs_dbg(INODE, "hfs_write_inode: %lu\n", inode->i_ino);
431 	res = hfs_ext_write_extent(inode);
432 	if (res)
433 		return res;
434 
435 	if (inode->i_ino < HFS_FIRSTUSER_CNID) {
436 		switch (inode->i_ino) {
437 		case HFS_ROOT_CNID:
438 			break;
439 		case HFS_EXT_CNID:
440 			hfs_btree_write(HFS_SB(inode->i_sb)->ext_tree);
441 			return 0;
442 		case HFS_CAT_CNID:
443 			hfs_btree_write(HFS_SB(inode->i_sb)->cat_tree);
444 			return 0;
445 		default:
446 			BUG();
447 			return -EIO;
448 		}
449 	}
450 
451 	if (HFS_IS_RSRC(inode))
452 		main_inode = HFS_I(inode)->rsrc_inode;
453 
454 	if (!main_inode->i_nlink)
455 		return 0;
456 
457 	if (hfs_find_init(HFS_SB(main_inode->i_sb)->cat_tree, &fd))
458 		/* panic? */
459 		return -EIO;
460 
461 	fd.search_key->cat = HFS_I(main_inode)->cat_key;
462 	if (hfs_brec_find(&fd))
463 		/* panic? */
464 		goto out;
465 
466 	if (S_ISDIR(main_inode->i_mode)) {
467 		WARN_ON(fd.entrylength < sizeof(struct hfs_cat_dir));
468 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
469 			   sizeof(struct hfs_cat_dir));
470 		if (rec.type != HFS_CDR_DIR ||
471 		    be32_to_cpu(rec.dir.DirID) != inode->i_ino) {
472 		}
473 
474 		rec.dir.MdDat = hfs_u_to_mtime(inode->i_mtime);
475 		rec.dir.Val = cpu_to_be16(inode->i_size - 2);
476 
477 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
478 			    sizeof(struct hfs_cat_dir));
479 	} else if (HFS_IS_RSRC(inode)) {
480 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
481 			       sizeof(struct hfs_cat_file));
482 		hfs_inode_write_fork(inode, rec.file.RExtRec,
483 				     &rec.file.RLgLen, &rec.file.RPyLen);
484 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
485 				sizeof(struct hfs_cat_file));
486 	} else {
487 		WARN_ON(fd.entrylength < sizeof(struct hfs_cat_file));
488 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
489 			   sizeof(struct hfs_cat_file));
490 		if (rec.type != HFS_CDR_FIL ||
491 		    be32_to_cpu(rec.file.FlNum) != inode->i_ino) {
492 		}
493 
494 		if (inode->i_mode & S_IWUSR)
495 			rec.file.Flags &= ~HFS_FIL_LOCK;
496 		else
497 			rec.file.Flags |= HFS_FIL_LOCK;
498 		hfs_inode_write_fork(inode, rec.file.ExtRec, &rec.file.LgLen, &rec.file.PyLen);
499 		rec.file.MdDat = hfs_u_to_mtime(inode->i_mtime);
500 
501 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
502 			    sizeof(struct hfs_cat_file));
503 	}
504 out:
505 	hfs_find_exit(&fd);
506 	return 0;
507 }
508 
509 static struct dentry *hfs_file_lookup(struct inode *dir, struct dentry *dentry,
510 				      unsigned int flags)
511 {
512 	struct inode *inode = NULL;
513 	hfs_cat_rec rec;
514 	struct hfs_find_data fd;
515 	int res;
516 
517 	if (HFS_IS_RSRC(dir) || strcmp(dentry->d_name.name, "rsrc"))
518 		goto out;
519 
520 	inode = HFS_I(dir)->rsrc_inode;
521 	if (inode)
522 		goto out;
523 
524 	inode = new_inode(dir->i_sb);
525 	if (!inode)
526 		return ERR_PTR(-ENOMEM);
527 
528 	res = hfs_find_init(HFS_SB(dir->i_sb)->cat_tree, &fd);
529 	if (res) {
530 		iput(inode);
531 		return ERR_PTR(res);
532 	}
533 	fd.search_key->cat = HFS_I(dir)->cat_key;
534 	res = hfs_brec_read(&fd, &rec, sizeof(rec));
535 	if (!res) {
536 		struct hfs_iget_data idata = { NULL, &rec };
537 		hfs_read_inode(inode, &idata);
538 	}
539 	hfs_find_exit(&fd);
540 	if (res) {
541 		iput(inode);
542 		return ERR_PTR(res);
543 	}
544 	HFS_I(inode)->rsrc_inode = dir;
545 	HFS_I(dir)->rsrc_inode = inode;
546 	igrab(dir);
547 	inode_fake_hash(inode);
548 	mark_inode_dirty(inode);
549 	dont_mount(dentry);
550 out:
551 	return d_splice_alias(inode, dentry);
552 }
553 
554 void hfs_evict_inode(struct inode *inode)
555 {
556 	truncate_inode_pages_final(&inode->i_data);
557 	clear_inode(inode);
558 	if (HFS_IS_RSRC(inode) && HFS_I(inode)->rsrc_inode) {
559 		HFS_I(HFS_I(inode)->rsrc_inode)->rsrc_inode = NULL;
560 		iput(HFS_I(inode)->rsrc_inode);
561 	}
562 }
563 
564 static int hfs_file_open(struct inode *inode, struct file *file)
565 {
566 	if (HFS_IS_RSRC(inode))
567 		inode = HFS_I(inode)->rsrc_inode;
568 	atomic_inc(&HFS_I(inode)->opencnt);
569 	return 0;
570 }
571 
572 static int hfs_file_release(struct inode *inode, struct file *file)
573 {
574 	//struct super_block *sb = inode->i_sb;
575 
576 	if (HFS_IS_RSRC(inode))
577 		inode = HFS_I(inode)->rsrc_inode;
578 	if (atomic_dec_and_test(&HFS_I(inode)->opencnt)) {
579 		inode_lock(inode);
580 		hfs_file_truncate(inode);
581 		//if (inode->i_flags & S_DEAD) {
582 		//	hfs_delete_cat(inode->i_ino, HFSPLUS_SB(sb).hidden_dir, NULL);
583 		//	hfs_delete_inode(inode);
584 		//}
585 		inode_unlock(inode);
586 	}
587 	return 0;
588 }
589 
590 /*
591  * hfs_notify_change()
592  *
593  * Based very closely on fs/msdos/inode.c by Werner Almesberger
594  *
595  * This is the notify_change() field in the super_operations structure
596  * for HFS file systems.  The purpose is to take that changes made to
597  * an inode and apply then in a filesystem-dependent manner.  In this
598  * case the process has a few of tasks to do:
599  *  1) prevent changes to the i_uid and i_gid fields.
600  *  2) map file permissions to the closest allowable permissions
601  *  3) Since multiple Linux files can share the same on-disk inode under
602  *     HFS (for instance the data and resource forks of a file) a change
603  *     to permissions must be applied to all other in-core inodes which
604  *     correspond to the same HFS file.
605  */
606 
607 int hfs_inode_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
608 		      struct iattr *attr)
609 {
610 	struct inode *inode = d_inode(dentry);
611 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
612 	int error;
613 
614 	error = setattr_prepare(&init_user_ns, dentry,
615 				attr); /* basic permission checks */
616 	if (error)
617 		return error;
618 
619 	/* no uig/gid changes and limit which mode bits can be set */
620 	if (((attr->ia_valid & ATTR_UID) &&
621 	     (!uid_eq(attr->ia_uid, hsb->s_uid))) ||
622 	    ((attr->ia_valid & ATTR_GID) &&
623 	     (!gid_eq(attr->ia_gid, hsb->s_gid))) ||
624 	    ((attr->ia_valid & ATTR_MODE) &&
625 	     ((S_ISDIR(inode->i_mode) &&
626 	       (attr->ia_mode != inode->i_mode)) ||
627 	      (attr->ia_mode & ~HFS_VALID_MODE_BITS)))) {
628 		return hsb->s_quiet ? 0 : error;
629 	}
630 
631 	if (attr->ia_valid & ATTR_MODE) {
632 		/* Only the 'w' bits can ever change and only all together. */
633 		if (attr->ia_mode & S_IWUSR)
634 			attr->ia_mode = inode->i_mode | S_IWUGO;
635 		else
636 			attr->ia_mode = inode->i_mode & ~S_IWUGO;
637 		attr->ia_mode &= S_ISDIR(inode->i_mode) ? ~hsb->s_dir_umask: ~hsb->s_file_umask;
638 	}
639 
640 	if ((attr->ia_valid & ATTR_SIZE) &&
641 	    attr->ia_size != i_size_read(inode)) {
642 		inode_dio_wait(inode);
643 
644 		error = inode_newsize_ok(inode, attr->ia_size);
645 		if (error)
646 			return error;
647 
648 		truncate_setsize(inode, attr->ia_size);
649 		hfs_file_truncate(inode);
650 		inode->i_atime = inode->i_mtime = inode->i_ctime =
651 						  current_time(inode);
652 	}
653 
654 	setattr_copy(&init_user_ns, inode, attr);
655 	mark_inode_dirty(inode);
656 	return 0;
657 }
658 
659 static int hfs_file_fsync(struct file *filp, loff_t start, loff_t end,
660 			  int datasync)
661 {
662 	struct inode *inode = filp->f_mapping->host;
663 	struct super_block * sb;
664 	int ret, err;
665 
666 	ret = file_write_and_wait_range(filp, start, end);
667 	if (ret)
668 		return ret;
669 	inode_lock(inode);
670 
671 	/* sync the inode to buffers */
672 	ret = write_inode_now(inode, 0);
673 
674 	/* sync the superblock to buffers */
675 	sb = inode->i_sb;
676 	flush_delayed_work(&HFS_SB(sb)->mdb_work);
677 	/* .. finally sync the buffers to disk */
678 	err = sync_blockdev(sb->s_bdev);
679 	if (!ret)
680 		ret = err;
681 	inode_unlock(inode);
682 	return ret;
683 }
684 
685 static const struct file_operations hfs_file_operations = {
686 	.llseek		= generic_file_llseek,
687 	.read_iter	= generic_file_read_iter,
688 	.write_iter	= generic_file_write_iter,
689 	.mmap		= generic_file_mmap,
690 	.splice_read	= generic_file_splice_read,
691 	.fsync		= hfs_file_fsync,
692 	.open		= hfs_file_open,
693 	.release	= hfs_file_release,
694 };
695 
696 static const struct inode_operations hfs_file_inode_operations = {
697 	.lookup		= hfs_file_lookup,
698 	.setattr	= hfs_inode_setattr,
699 	.listxattr	= generic_listxattr,
700 };
701