xref: /openbmc/linux/fs/hfs/inode.c (revision 2cf1c348)
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 	.set_page_dirty	= __set_page_dirty_buffers,
163 	.readpage	= hfs_readpage,
164 	.writepage	= hfs_writepage,
165 	.write_begin	= hfs_write_begin,
166 	.write_end	= generic_write_end,
167 	.bmap		= hfs_bmap,
168 	.releasepage	= hfs_releasepage,
169 };
170 
171 const struct address_space_operations hfs_aops = {
172 	.set_page_dirty	= __set_page_dirty_buffers,
173 	.readpage	= hfs_readpage,
174 	.writepage	= hfs_writepage,
175 	.write_begin	= hfs_write_begin,
176 	.write_end	= generic_write_end,
177 	.bmap		= hfs_bmap,
178 	.direct_IO	= hfs_direct_IO,
179 	.writepages	= hfs_writepages,
180 };
181 
182 /*
183  * hfs_new_inode
184  */
185 struct inode *hfs_new_inode(struct inode *dir, const struct qstr *name, umode_t mode)
186 {
187 	struct super_block *sb = dir->i_sb;
188 	struct inode *inode = new_inode(sb);
189 	if (!inode)
190 		return NULL;
191 
192 	mutex_init(&HFS_I(inode)->extents_lock);
193 	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
194 	spin_lock_init(&HFS_I(inode)->open_dir_lock);
195 	hfs_cat_build_key(sb, (btree_key *)&HFS_I(inode)->cat_key, dir->i_ino, name);
196 	inode->i_ino = HFS_SB(sb)->next_id++;
197 	inode->i_mode = mode;
198 	inode->i_uid = current_fsuid();
199 	inode->i_gid = current_fsgid();
200 	set_nlink(inode, 1);
201 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
202 	HFS_I(inode)->flags = 0;
203 	HFS_I(inode)->rsrc_inode = NULL;
204 	HFS_I(inode)->fs_blocks = 0;
205 	if (S_ISDIR(mode)) {
206 		inode->i_size = 2;
207 		HFS_SB(sb)->folder_count++;
208 		if (dir->i_ino == HFS_ROOT_CNID)
209 			HFS_SB(sb)->root_dirs++;
210 		inode->i_op = &hfs_dir_inode_operations;
211 		inode->i_fop = &hfs_dir_operations;
212 		inode->i_mode |= S_IRWXUGO;
213 		inode->i_mode &= ~HFS_SB(inode->i_sb)->s_dir_umask;
214 	} else if (S_ISREG(mode)) {
215 		HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
216 		HFS_SB(sb)->file_count++;
217 		if (dir->i_ino == HFS_ROOT_CNID)
218 			HFS_SB(sb)->root_files++;
219 		inode->i_op = &hfs_file_inode_operations;
220 		inode->i_fop = &hfs_file_operations;
221 		inode->i_mapping->a_ops = &hfs_aops;
222 		inode->i_mode |= S_IRUGO|S_IXUGO;
223 		if (mode & S_IWUSR)
224 			inode->i_mode |= S_IWUGO;
225 		inode->i_mode &= ~HFS_SB(inode->i_sb)->s_file_umask;
226 		HFS_I(inode)->phys_size = 0;
227 		HFS_I(inode)->alloc_blocks = 0;
228 		HFS_I(inode)->first_blocks = 0;
229 		HFS_I(inode)->cached_start = 0;
230 		HFS_I(inode)->cached_blocks = 0;
231 		memset(HFS_I(inode)->first_extents, 0, sizeof(hfs_extent_rec));
232 		memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
233 	}
234 	insert_inode_hash(inode);
235 	mark_inode_dirty(inode);
236 	set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
237 	hfs_mark_mdb_dirty(sb);
238 
239 	return inode;
240 }
241 
242 void hfs_delete_inode(struct inode *inode)
243 {
244 	struct super_block *sb = inode->i_sb;
245 
246 	hfs_dbg(INODE, "delete_inode: %lu\n", inode->i_ino);
247 	if (S_ISDIR(inode->i_mode)) {
248 		HFS_SB(sb)->folder_count--;
249 		if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
250 			HFS_SB(sb)->root_dirs--;
251 		set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
252 		hfs_mark_mdb_dirty(sb);
253 		return;
254 	}
255 	HFS_SB(sb)->file_count--;
256 	if (HFS_I(inode)->cat_key.ParID == cpu_to_be32(HFS_ROOT_CNID))
257 		HFS_SB(sb)->root_files--;
258 	if (S_ISREG(inode->i_mode)) {
259 		if (!inode->i_nlink) {
260 			inode->i_size = 0;
261 			hfs_file_truncate(inode);
262 		}
263 	}
264 	set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
265 	hfs_mark_mdb_dirty(sb);
266 }
267 
268 void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
269 			 __be32 __log_size, __be32 phys_size, u32 clump_size)
270 {
271 	struct super_block *sb = inode->i_sb;
272 	u32 log_size = be32_to_cpu(__log_size);
273 	u16 count;
274 	int i;
275 
276 	memcpy(HFS_I(inode)->first_extents, ext, sizeof(hfs_extent_rec));
277 	for (count = 0, i = 0; i < 3; i++)
278 		count += be16_to_cpu(ext[i].count);
279 	HFS_I(inode)->first_blocks = count;
280 
281 	inode->i_size = HFS_I(inode)->phys_size = log_size;
282 	HFS_I(inode)->fs_blocks = (log_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
283 	inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
284 	HFS_I(inode)->alloc_blocks = be32_to_cpu(phys_size) /
285 				     HFS_SB(sb)->alloc_blksz;
286 	HFS_I(inode)->clump_blocks = clump_size / HFS_SB(sb)->alloc_blksz;
287 	if (!HFS_I(inode)->clump_blocks)
288 		HFS_I(inode)->clump_blocks = HFS_SB(sb)->clumpablks;
289 }
290 
291 struct hfs_iget_data {
292 	struct hfs_cat_key *key;
293 	hfs_cat_rec *rec;
294 };
295 
296 static int hfs_test_inode(struct inode *inode, void *data)
297 {
298 	struct hfs_iget_data *idata = data;
299 	hfs_cat_rec *rec;
300 
301 	rec = idata->rec;
302 	switch (rec->type) {
303 	case HFS_CDR_DIR:
304 		return inode->i_ino == be32_to_cpu(rec->dir.DirID);
305 	case HFS_CDR_FIL:
306 		return inode->i_ino == be32_to_cpu(rec->file.FlNum);
307 	default:
308 		BUG();
309 		return 1;
310 	}
311 }
312 
313 /*
314  * hfs_read_inode
315  */
316 static int hfs_read_inode(struct inode *inode, void *data)
317 {
318 	struct hfs_iget_data *idata = data;
319 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
320 	hfs_cat_rec *rec;
321 
322 	HFS_I(inode)->flags = 0;
323 	HFS_I(inode)->rsrc_inode = NULL;
324 	mutex_init(&HFS_I(inode)->extents_lock);
325 	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
326 	spin_lock_init(&HFS_I(inode)->open_dir_lock);
327 
328 	/* Initialize the inode */
329 	inode->i_uid = hsb->s_uid;
330 	inode->i_gid = hsb->s_gid;
331 	set_nlink(inode, 1);
332 
333 	if (idata->key)
334 		HFS_I(inode)->cat_key = *idata->key;
335 	else
336 		HFS_I(inode)->flags |= HFS_FLG_RSRC;
337 	HFS_I(inode)->tz_secondswest = sys_tz.tz_minuteswest * 60;
338 
339 	rec = idata->rec;
340 	switch (rec->type) {
341 	case HFS_CDR_FIL:
342 		if (!HFS_IS_RSRC(inode)) {
343 			hfs_inode_read_fork(inode, rec->file.ExtRec, rec->file.LgLen,
344 					    rec->file.PyLen, be16_to_cpu(rec->file.ClpSize));
345 		} else {
346 			hfs_inode_read_fork(inode, rec->file.RExtRec, rec->file.RLgLen,
347 					    rec->file.RPyLen, be16_to_cpu(rec->file.ClpSize));
348 		}
349 
350 		inode->i_ino = be32_to_cpu(rec->file.FlNum);
351 		inode->i_mode = S_IRUGO | S_IXUGO;
352 		if (!(rec->file.Flags & HFS_FIL_LOCK))
353 			inode->i_mode |= S_IWUGO;
354 		inode->i_mode &= ~hsb->s_file_umask;
355 		inode->i_mode |= S_IFREG;
356 		inode->i_ctime = inode->i_atime = inode->i_mtime =
357 				hfs_m_to_utime(rec->file.MdDat);
358 		inode->i_op = &hfs_file_inode_operations;
359 		inode->i_fop = &hfs_file_operations;
360 		inode->i_mapping->a_ops = &hfs_aops;
361 		break;
362 	case HFS_CDR_DIR:
363 		inode->i_ino = be32_to_cpu(rec->dir.DirID);
364 		inode->i_size = be16_to_cpu(rec->dir.Val) + 2;
365 		HFS_I(inode)->fs_blocks = 0;
366 		inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask);
367 		inode->i_ctime = inode->i_atime = inode->i_mtime =
368 				hfs_m_to_utime(rec->dir.MdDat);
369 		inode->i_op = &hfs_dir_inode_operations;
370 		inode->i_fop = &hfs_dir_operations;
371 		break;
372 	default:
373 		make_bad_inode(inode);
374 	}
375 	return 0;
376 }
377 
378 /*
379  * __hfs_iget()
380  *
381  * Given the MDB for a HFS filesystem, a 'key' and an 'entry' in
382  * the catalog B-tree and the 'type' of the desired file return the
383  * inode for that file/directory or NULL.  Note that 'type' indicates
384  * whether we want the actual file or directory, or the corresponding
385  * metadata (AppleDouble header file or CAP metadata file).
386  */
387 struct inode *hfs_iget(struct super_block *sb, struct hfs_cat_key *key, hfs_cat_rec *rec)
388 {
389 	struct hfs_iget_data data = { key, rec };
390 	struct inode *inode;
391 	u32 cnid;
392 
393 	switch (rec->type) {
394 	case HFS_CDR_DIR:
395 		cnid = be32_to_cpu(rec->dir.DirID);
396 		break;
397 	case HFS_CDR_FIL:
398 		cnid = be32_to_cpu(rec->file.FlNum);
399 		break;
400 	default:
401 		return NULL;
402 	}
403 	inode = iget5_locked(sb, cnid, hfs_test_inode, hfs_read_inode, &data);
404 	if (inode && (inode->i_state & I_NEW))
405 		unlock_new_inode(inode);
406 	return inode;
407 }
408 
409 void hfs_inode_write_fork(struct inode *inode, struct hfs_extent *ext,
410 			  __be32 *log_size, __be32 *phys_size)
411 {
412 	memcpy(ext, HFS_I(inode)->first_extents, sizeof(hfs_extent_rec));
413 
414 	if (log_size)
415 		*log_size = cpu_to_be32(inode->i_size);
416 	if (phys_size)
417 		*phys_size = cpu_to_be32(HFS_I(inode)->alloc_blocks *
418 					 HFS_SB(inode->i_sb)->alloc_blksz);
419 }
420 
421 int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
422 {
423 	struct inode *main_inode = inode;
424 	struct hfs_find_data fd;
425 	hfs_cat_rec rec;
426 	int res;
427 
428 	hfs_dbg(INODE, "hfs_write_inode: %lu\n", inode->i_ino);
429 	res = hfs_ext_write_extent(inode);
430 	if (res)
431 		return res;
432 
433 	if (inode->i_ino < HFS_FIRSTUSER_CNID) {
434 		switch (inode->i_ino) {
435 		case HFS_ROOT_CNID:
436 			break;
437 		case HFS_EXT_CNID:
438 			hfs_btree_write(HFS_SB(inode->i_sb)->ext_tree);
439 			return 0;
440 		case HFS_CAT_CNID:
441 			hfs_btree_write(HFS_SB(inode->i_sb)->cat_tree);
442 			return 0;
443 		default:
444 			BUG();
445 			return -EIO;
446 		}
447 	}
448 
449 	if (HFS_IS_RSRC(inode))
450 		main_inode = HFS_I(inode)->rsrc_inode;
451 
452 	if (!main_inode->i_nlink)
453 		return 0;
454 
455 	if (hfs_find_init(HFS_SB(main_inode->i_sb)->cat_tree, &fd))
456 		/* panic? */
457 		return -EIO;
458 
459 	fd.search_key->cat = HFS_I(main_inode)->cat_key;
460 	if (hfs_brec_find(&fd))
461 		/* panic? */
462 		goto out;
463 
464 	if (S_ISDIR(main_inode->i_mode)) {
465 		WARN_ON(fd.entrylength < sizeof(struct hfs_cat_dir));
466 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
467 			   sizeof(struct hfs_cat_dir));
468 		if (rec.type != HFS_CDR_DIR ||
469 		    be32_to_cpu(rec.dir.DirID) != inode->i_ino) {
470 		}
471 
472 		rec.dir.MdDat = hfs_u_to_mtime(inode->i_mtime);
473 		rec.dir.Val = cpu_to_be16(inode->i_size - 2);
474 
475 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
476 			    sizeof(struct hfs_cat_dir));
477 	} else if (HFS_IS_RSRC(inode)) {
478 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
479 			       sizeof(struct hfs_cat_file));
480 		hfs_inode_write_fork(inode, rec.file.RExtRec,
481 				     &rec.file.RLgLen, &rec.file.RPyLen);
482 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
483 				sizeof(struct hfs_cat_file));
484 	} else {
485 		WARN_ON(fd.entrylength < sizeof(struct hfs_cat_file));
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 user_namespace *mnt_userns, struct dentry *dentry,
606 		      struct iattr *attr)
607 {
608 	struct inode *inode = d_inode(dentry);
609 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
610 	int error;
611 
612 	error = setattr_prepare(&init_user_ns, dentry,
613 				attr); /* basic permission checks */
614 	if (error)
615 		return error;
616 
617 	/* no uig/gid changes and limit which mode bits can be set */
618 	if (((attr->ia_valid & ATTR_UID) &&
619 	     (!uid_eq(attr->ia_uid, hsb->s_uid))) ||
620 	    ((attr->ia_valid & ATTR_GID) &&
621 	     (!gid_eq(attr->ia_gid, hsb->s_gid))) ||
622 	    ((attr->ia_valid & ATTR_MODE) &&
623 	     ((S_ISDIR(inode->i_mode) &&
624 	       (attr->ia_mode != inode->i_mode)) ||
625 	      (attr->ia_mode & ~HFS_VALID_MODE_BITS)))) {
626 		return hsb->s_quiet ? 0 : error;
627 	}
628 
629 	if (attr->ia_valid & ATTR_MODE) {
630 		/* Only the 'w' bits can ever change and only all together. */
631 		if (attr->ia_mode & S_IWUSR)
632 			attr->ia_mode = inode->i_mode | S_IWUGO;
633 		else
634 			attr->ia_mode = inode->i_mode & ~S_IWUGO;
635 		attr->ia_mode &= S_ISDIR(inode->i_mode) ? ~hsb->s_dir_umask: ~hsb->s_file_umask;
636 	}
637 
638 	if ((attr->ia_valid & ATTR_SIZE) &&
639 	    attr->ia_size != i_size_read(inode)) {
640 		inode_dio_wait(inode);
641 
642 		error = inode_newsize_ok(inode, attr->ia_size);
643 		if (error)
644 			return error;
645 
646 		truncate_setsize(inode, attr->ia_size);
647 		hfs_file_truncate(inode);
648 		inode->i_atime = inode->i_mtime = inode->i_ctime =
649 						  current_time(inode);
650 	}
651 
652 	setattr_copy(&init_user_ns, inode, attr);
653 	mark_inode_dirty(inode);
654 	return 0;
655 }
656 
657 static int hfs_file_fsync(struct file *filp, loff_t start, loff_t end,
658 			  int datasync)
659 {
660 	struct inode *inode = filp->f_mapping->host;
661 	struct super_block * sb;
662 	int ret, err;
663 
664 	ret = file_write_and_wait_range(filp, start, end);
665 	if (ret)
666 		return ret;
667 	inode_lock(inode);
668 
669 	/* sync the inode to buffers */
670 	ret = write_inode_now(inode, 0);
671 
672 	/* sync the superblock to buffers */
673 	sb = inode->i_sb;
674 	flush_delayed_work(&HFS_SB(sb)->mdb_work);
675 	/* .. finally sync the buffers to disk */
676 	err = sync_blockdev(sb->s_bdev);
677 	if (!ret)
678 		ret = err;
679 	inode_unlock(inode);
680 	return ret;
681 }
682 
683 static const struct file_operations hfs_file_operations = {
684 	.llseek		= generic_file_llseek,
685 	.read_iter	= generic_file_read_iter,
686 	.write_iter	= generic_file_write_iter,
687 	.mmap		= generic_file_mmap,
688 	.splice_read	= generic_file_splice_read,
689 	.fsync		= hfs_file_fsync,
690 	.open		= hfs_file_open,
691 	.release	= hfs_file_release,
692 };
693 
694 static const struct inode_operations hfs_file_inode_operations = {
695 	.lookup		= hfs_file_lookup,
696 	.setattr	= hfs_inode_setattr,
697 	.listxattr	= generic_listxattr,
698 };
699