1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * (C) 1997 Linus Torvalds
4  * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation)
5  */
6 #include <linux/export.h>
7 #include <linux/fs.h>
8 #include <linux/filelock.h>
9 #include <linux/mm.h>
10 #include <linux/backing-dev.h>
11 #include <linux/hash.h>
12 #include <linux/swap.h>
13 #include <linux/security.h>
14 #include <linux/cdev.h>
15 #include <linux/memblock.h>
16 #include <linux/fsnotify.h>
17 #include <linux/mount.h>
18 #include <linux/posix_acl.h>
19 #include <linux/buffer_head.h> /* for inode_has_buffers */
20 #include <linux/ratelimit.h>
21 #include <linux/list_lru.h>
22 #include <linux/iversion.h>
23 #include <trace/events/writeback.h>
24 #include "internal.h"
25 
26 /*
27  * Inode locking rules:
28  *
29  * inode->i_lock protects:
30  *   inode->i_state, inode->i_hash, __iget(), inode->i_io_list
31  * Inode LRU list locks protect:
32  *   inode->i_sb->s_inode_lru, inode->i_lru
33  * inode->i_sb->s_inode_list_lock protects:
34  *   inode->i_sb->s_inodes, inode->i_sb_list
35  * bdi->wb.list_lock protects:
36  *   bdi->wb.b_{dirty,io,more_io,dirty_time}, inode->i_io_list
37  * inode_hash_lock protects:
38  *   inode_hashtable, inode->i_hash
39  *
40  * Lock ordering:
41  *
42  * inode->i_sb->s_inode_list_lock
43  *   inode->i_lock
44  *     Inode LRU list locks
45  *
46  * bdi->wb.list_lock
47  *   inode->i_lock
48  *
49  * inode_hash_lock
50  *   inode->i_sb->s_inode_list_lock
51  *   inode->i_lock
52  *
53  * iunique_lock
54  *   inode_hash_lock
55  */
56 
57 static unsigned int i_hash_mask __read_mostly;
58 static unsigned int i_hash_shift __read_mostly;
59 static struct hlist_head *inode_hashtable __read_mostly;
60 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
61 
62 /*
63  * Empty aops. Can be used for the cases where the user does not
64  * define any of the address_space operations.
65  */
66 const struct address_space_operations empty_aops = {
67 };
68 EXPORT_SYMBOL(empty_aops);
69 
70 static DEFINE_PER_CPU(unsigned long, nr_inodes);
71 static DEFINE_PER_CPU(unsigned long, nr_unused);
72 
73 static struct kmem_cache *inode_cachep __read_mostly;
74 
get_nr_inodes(void)75 static long get_nr_inodes(void)
76 {
77 	int i;
78 	long sum = 0;
79 	for_each_possible_cpu(i)
80 		sum += per_cpu(nr_inodes, i);
81 	return sum < 0 ? 0 : sum;
82 }
83 
get_nr_inodes_unused(void)84 static inline long get_nr_inodes_unused(void)
85 {
86 	int i;
87 	long sum = 0;
88 	for_each_possible_cpu(i)
89 		sum += per_cpu(nr_unused, i);
90 	return sum < 0 ? 0 : sum;
91 }
92 
get_nr_dirty_inodes(void)93 long get_nr_dirty_inodes(void)
94 {
95 	/* not actually dirty inodes, but a wild approximation */
96 	long nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
97 	return nr_dirty > 0 ? nr_dirty : 0;
98 }
99 
100 /*
101  * Handle nr_inode sysctl
102  */
103 #ifdef CONFIG_SYSCTL
104 /*
105  * Statistics gathering..
106  */
107 static struct inodes_stat_t inodes_stat;
108 
proc_nr_inodes(struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)109 static int proc_nr_inodes(struct ctl_table *table, int write, void *buffer,
110 			  size_t *lenp, loff_t *ppos)
111 {
112 	inodes_stat.nr_inodes = get_nr_inodes();
113 	inodes_stat.nr_unused = get_nr_inodes_unused();
114 	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
115 }
116 
117 static struct ctl_table inodes_sysctls[] = {
118 	{
119 		.procname	= "inode-nr",
120 		.data		= &inodes_stat,
121 		.maxlen		= 2*sizeof(long),
122 		.mode		= 0444,
123 		.proc_handler	= proc_nr_inodes,
124 	},
125 	{
126 		.procname	= "inode-state",
127 		.data		= &inodes_stat,
128 		.maxlen		= 7*sizeof(long),
129 		.mode		= 0444,
130 		.proc_handler	= proc_nr_inodes,
131 	},
132 	{ }
133 };
134 
init_fs_inode_sysctls(void)135 static int __init init_fs_inode_sysctls(void)
136 {
137 	register_sysctl_init("fs", inodes_sysctls);
138 	return 0;
139 }
140 early_initcall(init_fs_inode_sysctls);
141 #endif
142 
no_open(struct inode * inode,struct file * file)143 static int no_open(struct inode *inode, struct file *file)
144 {
145 	return -ENXIO;
146 }
147 
148 /**
149  * inode_init_always - perform inode structure initialisation
150  * @sb: superblock inode belongs to
151  * @inode: inode to initialise
152  *
153  * These are initializations that need to be done on every inode
154  * allocation as the fields are not initialised by slab allocation.
155  */
inode_init_always(struct super_block * sb,struct inode * inode)156 int inode_init_always(struct super_block *sb, struct inode *inode)
157 {
158 	static const struct inode_operations empty_iops;
159 	static const struct file_operations no_open_fops = {.open = no_open};
160 	struct address_space *const mapping = &inode->i_data;
161 
162 	inode->i_sb = sb;
163 	inode->i_blkbits = sb->s_blocksize_bits;
164 	inode->i_flags = 0;
165 	atomic64_set(&inode->i_sequence, 0);
166 	atomic_set(&inode->i_count, 1);
167 	inode->i_op = &empty_iops;
168 	inode->i_fop = &no_open_fops;
169 	inode->i_ino = 0;
170 	inode->__i_nlink = 1;
171 	inode->i_opflags = 0;
172 	if (sb->s_xattr)
173 		inode->i_opflags |= IOP_XATTR;
174 	i_uid_write(inode, 0);
175 	i_gid_write(inode, 0);
176 	atomic_set(&inode->i_writecount, 0);
177 	inode->i_size = 0;
178 	inode->i_write_hint = WRITE_LIFE_NOT_SET;
179 	inode->i_blocks = 0;
180 	inode->i_bytes = 0;
181 	inode->i_generation = 0;
182 	inode->i_pipe = NULL;
183 	inode->i_cdev = NULL;
184 	inode->i_link = NULL;
185 	inode->i_dir_seq = 0;
186 	inode->i_rdev = 0;
187 	inode->dirtied_when = 0;
188 
189 #ifdef CONFIG_CGROUP_WRITEBACK
190 	inode->i_wb_frn_winner = 0;
191 	inode->i_wb_frn_avg_time = 0;
192 	inode->i_wb_frn_history = 0;
193 #endif
194 
195 	spin_lock_init(&inode->i_lock);
196 	lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
197 
198 	init_rwsem(&inode->i_rwsem);
199 	lockdep_set_class(&inode->i_rwsem, &sb->s_type->i_mutex_key);
200 
201 	atomic_set(&inode->i_dio_count, 0);
202 
203 	mapping->a_ops = &empty_aops;
204 	mapping->host = inode;
205 	mapping->flags = 0;
206 	mapping->wb_err = 0;
207 	atomic_set(&mapping->i_mmap_writable, 0);
208 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
209 	atomic_set(&mapping->nr_thps, 0);
210 #endif
211 	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
212 	mapping->private_data = NULL;
213 	mapping->writeback_index = 0;
214 	init_rwsem(&mapping->invalidate_lock);
215 	lockdep_set_class_and_name(&mapping->invalidate_lock,
216 				   &sb->s_type->invalidate_lock_key,
217 				   "mapping.invalidate_lock");
218 	if (sb->s_iflags & SB_I_STABLE_WRITES)
219 		mapping_set_stable_writes(mapping);
220 	inode->i_private = NULL;
221 	inode->i_mapping = mapping;
222 	INIT_HLIST_HEAD(&inode->i_dentry);	/* buggered by rcu freeing */
223 #ifdef CONFIG_FS_POSIX_ACL
224 	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
225 #endif
226 
227 #ifdef CONFIG_FSNOTIFY
228 	inode->i_fsnotify_mask = 0;
229 #endif
230 	inode->i_flctx = NULL;
231 
232 	if (unlikely(security_inode_alloc(inode)))
233 		return -ENOMEM;
234 	this_cpu_inc(nr_inodes);
235 
236 	return 0;
237 }
238 EXPORT_SYMBOL(inode_init_always);
239 
free_inode_nonrcu(struct inode * inode)240 void free_inode_nonrcu(struct inode *inode)
241 {
242 	kmem_cache_free(inode_cachep, inode);
243 }
244 EXPORT_SYMBOL(free_inode_nonrcu);
245 
i_callback(struct rcu_head * head)246 static void i_callback(struct rcu_head *head)
247 {
248 	struct inode *inode = container_of(head, struct inode, i_rcu);
249 	if (inode->free_inode)
250 		inode->free_inode(inode);
251 	else
252 		free_inode_nonrcu(inode);
253 }
254 
alloc_inode(struct super_block * sb)255 static struct inode *alloc_inode(struct super_block *sb)
256 {
257 	const struct super_operations *ops = sb->s_op;
258 	struct inode *inode;
259 
260 	if (ops->alloc_inode)
261 		inode = ops->alloc_inode(sb);
262 	else
263 		inode = alloc_inode_sb(sb, inode_cachep, GFP_KERNEL);
264 
265 	if (!inode)
266 		return NULL;
267 
268 	if (unlikely(inode_init_always(sb, inode))) {
269 		if (ops->destroy_inode) {
270 			ops->destroy_inode(inode);
271 			if (!ops->free_inode)
272 				return NULL;
273 		}
274 		inode->free_inode = ops->free_inode;
275 		i_callback(&inode->i_rcu);
276 		return NULL;
277 	}
278 
279 	return inode;
280 }
281 
__destroy_inode(struct inode * inode)282 void __destroy_inode(struct inode *inode)
283 {
284 	BUG_ON(inode_has_buffers(inode));
285 	inode_detach_wb(inode);
286 	security_inode_free(inode);
287 	fsnotify_inode_delete(inode);
288 	locks_free_lock_context(inode);
289 	if (!inode->i_nlink) {
290 		WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);
291 		atomic_long_dec(&inode->i_sb->s_remove_count);
292 	}
293 
294 #ifdef CONFIG_FS_POSIX_ACL
295 	if (inode->i_acl && !is_uncached_acl(inode->i_acl))
296 		posix_acl_release(inode->i_acl);
297 	if (inode->i_default_acl && !is_uncached_acl(inode->i_default_acl))
298 		posix_acl_release(inode->i_default_acl);
299 #endif
300 	this_cpu_dec(nr_inodes);
301 }
302 EXPORT_SYMBOL(__destroy_inode);
303 
destroy_inode(struct inode * inode)304 static void destroy_inode(struct inode *inode)
305 {
306 	const struct super_operations *ops = inode->i_sb->s_op;
307 
308 	BUG_ON(!list_empty(&inode->i_lru));
309 	__destroy_inode(inode);
310 	if (ops->destroy_inode) {
311 		ops->destroy_inode(inode);
312 		if (!ops->free_inode)
313 			return;
314 	}
315 	inode->free_inode = ops->free_inode;
316 	call_rcu(&inode->i_rcu, i_callback);
317 }
318 
319 /**
320  * drop_nlink - directly drop an inode's link count
321  * @inode: inode
322  *
323  * This is a low-level filesystem helper to replace any
324  * direct filesystem manipulation of i_nlink.  In cases
325  * where we are attempting to track writes to the
326  * filesystem, a decrement to zero means an imminent
327  * write when the file is truncated and actually unlinked
328  * on the filesystem.
329  */
drop_nlink(struct inode * inode)330 void drop_nlink(struct inode *inode)
331 {
332 	WARN_ON(inode->i_nlink == 0);
333 	inode->__i_nlink--;
334 	if (!inode->i_nlink)
335 		atomic_long_inc(&inode->i_sb->s_remove_count);
336 }
337 EXPORT_SYMBOL(drop_nlink);
338 
339 /**
340  * clear_nlink - directly zero an inode's link count
341  * @inode: inode
342  *
343  * This is a low-level filesystem helper to replace any
344  * direct filesystem manipulation of i_nlink.  See
345  * drop_nlink() for why we care about i_nlink hitting zero.
346  */
clear_nlink(struct inode * inode)347 void clear_nlink(struct inode *inode)
348 {
349 	if (inode->i_nlink) {
350 		inode->__i_nlink = 0;
351 		atomic_long_inc(&inode->i_sb->s_remove_count);
352 	}
353 }
354 EXPORT_SYMBOL(clear_nlink);
355 
356 /**
357  * set_nlink - directly set an inode's link count
358  * @inode: inode
359  * @nlink: new nlink (should be non-zero)
360  *
361  * This is a low-level filesystem helper to replace any
362  * direct filesystem manipulation of i_nlink.
363  */
set_nlink(struct inode * inode,unsigned int nlink)364 void set_nlink(struct inode *inode, unsigned int nlink)
365 {
366 	if (!nlink) {
367 		clear_nlink(inode);
368 	} else {
369 		/* Yes, some filesystems do change nlink from zero to one */
370 		if (inode->i_nlink == 0)
371 			atomic_long_dec(&inode->i_sb->s_remove_count);
372 
373 		inode->__i_nlink = nlink;
374 	}
375 }
376 EXPORT_SYMBOL(set_nlink);
377 
378 /**
379  * inc_nlink - directly increment an inode's link count
380  * @inode: inode
381  *
382  * This is a low-level filesystem helper to replace any
383  * direct filesystem manipulation of i_nlink.  Currently,
384  * it is only here for parity with dec_nlink().
385  */
inc_nlink(struct inode * inode)386 void inc_nlink(struct inode *inode)
387 {
388 	if (unlikely(inode->i_nlink == 0)) {
389 		WARN_ON(!(inode->i_state & I_LINKABLE));
390 		atomic_long_dec(&inode->i_sb->s_remove_count);
391 	}
392 
393 	inode->__i_nlink++;
394 }
395 EXPORT_SYMBOL(inc_nlink);
396 
__address_space_init_once(struct address_space * mapping)397 static void __address_space_init_once(struct address_space *mapping)
398 {
399 	xa_init_flags(&mapping->i_pages, XA_FLAGS_LOCK_IRQ | XA_FLAGS_ACCOUNT);
400 	init_rwsem(&mapping->i_mmap_rwsem);
401 	INIT_LIST_HEAD(&mapping->private_list);
402 	spin_lock_init(&mapping->private_lock);
403 	mapping->i_mmap = RB_ROOT_CACHED;
404 }
405 
address_space_init_once(struct address_space * mapping)406 void address_space_init_once(struct address_space *mapping)
407 {
408 	memset(mapping, 0, sizeof(*mapping));
409 	__address_space_init_once(mapping);
410 }
411 EXPORT_SYMBOL(address_space_init_once);
412 
413 /*
414  * These are initializations that only need to be done
415  * once, because the fields are idempotent across use
416  * of the inode, so let the slab aware of that.
417  */
inode_init_once(struct inode * inode)418 void inode_init_once(struct inode *inode)
419 {
420 	memset(inode, 0, sizeof(*inode));
421 	INIT_HLIST_NODE(&inode->i_hash);
422 	INIT_LIST_HEAD(&inode->i_devices);
423 	INIT_LIST_HEAD(&inode->i_io_list);
424 	INIT_LIST_HEAD(&inode->i_wb_list);
425 	INIT_LIST_HEAD(&inode->i_lru);
426 	INIT_LIST_HEAD(&inode->i_sb_list);
427 	__address_space_init_once(&inode->i_data);
428 	i_size_ordered_init(inode);
429 }
430 EXPORT_SYMBOL(inode_init_once);
431 
init_once(void * foo)432 static void init_once(void *foo)
433 {
434 	struct inode *inode = (struct inode *) foo;
435 
436 	inode_init_once(inode);
437 }
438 
439 /*
440  * inode->i_lock must be held
441  */
__iget(struct inode * inode)442 void __iget(struct inode *inode)
443 {
444 	atomic_inc(&inode->i_count);
445 }
446 
447 /*
448  * get additional reference to inode; caller must already hold one.
449  */
ihold(struct inode * inode)450 void ihold(struct inode *inode)
451 {
452 	WARN_ON(atomic_inc_return(&inode->i_count) < 2);
453 }
454 EXPORT_SYMBOL(ihold);
455 
__inode_add_lru(struct inode * inode,bool rotate)456 static void __inode_add_lru(struct inode *inode, bool rotate)
457 {
458 	if (inode->i_state & (I_DIRTY_ALL | I_SYNC | I_FREEING | I_WILL_FREE))
459 		return;
460 	if (atomic_read(&inode->i_count))
461 		return;
462 	if (!(inode->i_sb->s_flags & SB_ACTIVE))
463 		return;
464 	if (!mapping_shrinkable(&inode->i_data))
465 		return;
466 
467 	if (list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru))
468 		this_cpu_inc(nr_unused);
469 	else if (rotate)
470 		inode->i_state |= I_REFERENCED;
471 }
472 
473 /*
474  * Add inode to LRU if needed (inode is unused and clean).
475  *
476  * Needs inode->i_lock held.
477  */
inode_add_lru(struct inode * inode)478 void inode_add_lru(struct inode *inode)
479 {
480 	__inode_add_lru(inode, false);
481 }
482 
inode_lru_list_del(struct inode * inode)483 static void inode_lru_list_del(struct inode *inode)
484 {
485 	if (list_lru_del(&inode->i_sb->s_inode_lru, &inode->i_lru))
486 		this_cpu_dec(nr_unused);
487 }
488 
489 /**
490  * inode_sb_list_add - add inode to the superblock list of inodes
491  * @inode: inode to add
492  */
inode_sb_list_add(struct inode * inode)493 void inode_sb_list_add(struct inode *inode)
494 {
495 	spin_lock(&inode->i_sb->s_inode_list_lock);
496 	list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
497 	spin_unlock(&inode->i_sb->s_inode_list_lock);
498 }
499 EXPORT_SYMBOL_GPL(inode_sb_list_add);
500 
inode_sb_list_del(struct inode * inode)501 static inline void inode_sb_list_del(struct inode *inode)
502 {
503 	if (!list_empty(&inode->i_sb_list)) {
504 		spin_lock(&inode->i_sb->s_inode_list_lock);
505 		list_del_init(&inode->i_sb_list);
506 		spin_unlock(&inode->i_sb->s_inode_list_lock);
507 	}
508 }
509 
hash(struct super_block * sb,unsigned long hashval)510 static unsigned long hash(struct super_block *sb, unsigned long hashval)
511 {
512 	unsigned long tmp;
513 
514 	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
515 			L1_CACHE_BYTES;
516 	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
517 	return tmp & i_hash_mask;
518 }
519 
520 /**
521  *	__insert_inode_hash - hash an inode
522  *	@inode: unhashed inode
523  *	@hashval: unsigned long value used to locate this object in the
524  *		inode_hashtable.
525  *
526  *	Add an inode to the inode hash for this superblock.
527  */
__insert_inode_hash(struct inode * inode,unsigned long hashval)528 void __insert_inode_hash(struct inode *inode, unsigned long hashval)
529 {
530 	struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
531 
532 	spin_lock(&inode_hash_lock);
533 	spin_lock(&inode->i_lock);
534 	hlist_add_head_rcu(&inode->i_hash, b);
535 	spin_unlock(&inode->i_lock);
536 	spin_unlock(&inode_hash_lock);
537 }
538 EXPORT_SYMBOL(__insert_inode_hash);
539 
540 /**
541  *	__remove_inode_hash - remove an inode from the hash
542  *	@inode: inode to unhash
543  *
544  *	Remove an inode from the superblock.
545  */
__remove_inode_hash(struct inode * inode)546 void __remove_inode_hash(struct inode *inode)
547 {
548 	spin_lock(&inode_hash_lock);
549 	spin_lock(&inode->i_lock);
550 	hlist_del_init_rcu(&inode->i_hash);
551 	spin_unlock(&inode->i_lock);
552 	spin_unlock(&inode_hash_lock);
553 }
554 EXPORT_SYMBOL(__remove_inode_hash);
555 
dump_mapping(const struct address_space * mapping)556 void dump_mapping(const struct address_space *mapping)
557 {
558 	struct inode *host;
559 	const struct address_space_operations *a_ops;
560 	struct hlist_node *dentry_first;
561 	struct dentry *dentry_ptr;
562 	struct dentry dentry;
563 	unsigned long ino;
564 
565 	/*
566 	 * If mapping is an invalid pointer, we don't want to crash
567 	 * accessing it, so probe everything depending on it carefully.
568 	 */
569 	if (get_kernel_nofault(host, &mapping->host) ||
570 	    get_kernel_nofault(a_ops, &mapping->a_ops)) {
571 		pr_warn("invalid mapping:%px\n", mapping);
572 		return;
573 	}
574 
575 	if (!host) {
576 		pr_warn("aops:%ps\n", a_ops);
577 		return;
578 	}
579 
580 	if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
581 	    get_kernel_nofault(ino, &host->i_ino)) {
582 		pr_warn("aops:%ps invalid inode:%px\n", a_ops, host);
583 		return;
584 	}
585 
586 	if (!dentry_first) {
587 		pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
588 		return;
589 	}
590 
591 	dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
592 	if (get_kernel_nofault(dentry, dentry_ptr)) {
593 		pr_warn("aops:%ps ino:%lx invalid dentry:%px\n",
594 				a_ops, ino, dentry_ptr);
595 		return;
596 	}
597 
598 	/*
599 	 * if dentry is corrupted, the %pd handler may still crash,
600 	 * but it's unlikely that we reach here with a corrupt mapping
601 	 */
602 	pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n", a_ops, ino, &dentry);
603 }
604 
clear_inode(struct inode * inode)605 void clear_inode(struct inode *inode)
606 {
607 	/*
608 	 * We have to cycle the i_pages lock here because reclaim can be in the
609 	 * process of removing the last page (in __filemap_remove_folio())
610 	 * and we must not free the mapping under it.
611 	 */
612 	xa_lock_irq(&inode->i_data.i_pages);
613 	BUG_ON(inode->i_data.nrpages);
614 	/*
615 	 * Almost always, mapping_empty(&inode->i_data) here; but there are
616 	 * two known and long-standing ways in which nodes may get left behind
617 	 * (when deep radix-tree node allocation failed partway; or when THP
618 	 * collapse_file() failed). Until those two known cases are cleaned up,
619 	 * or a cleanup function is called here, do not BUG_ON(!mapping_empty),
620 	 * nor even WARN_ON(!mapping_empty).
621 	 */
622 	xa_unlock_irq(&inode->i_data.i_pages);
623 	BUG_ON(!list_empty(&inode->i_data.private_list));
624 	BUG_ON(!(inode->i_state & I_FREEING));
625 	BUG_ON(inode->i_state & I_CLEAR);
626 	BUG_ON(!list_empty(&inode->i_wb_list));
627 	/* don't need i_lock here, no concurrent mods to i_state */
628 	inode->i_state = I_FREEING | I_CLEAR;
629 }
630 EXPORT_SYMBOL(clear_inode);
631 
632 /*
633  * Free the inode passed in, removing it from the lists it is still connected
634  * to. We remove any pages still attached to the inode and wait for any IO that
635  * is still in progress before finally destroying the inode.
636  *
637  * An inode must already be marked I_FREEING so that we avoid the inode being
638  * moved back onto lists if we race with other code that manipulates the lists
639  * (e.g. writeback_single_inode). The caller is responsible for setting this.
640  *
641  * An inode must already be removed from the LRU list before being evicted from
642  * the cache. This should occur atomically with setting the I_FREEING state
643  * flag, so no inodes here should ever be on the LRU when being evicted.
644  */
evict(struct inode * inode)645 static void evict(struct inode *inode)
646 {
647 	const struct super_operations *op = inode->i_sb->s_op;
648 
649 	BUG_ON(!(inode->i_state & I_FREEING));
650 	BUG_ON(!list_empty(&inode->i_lru));
651 
652 	if (!list_empty(&inode->i_io_list))
653 		inode_io_list_del(inode);
654 
655 	inode_sb_list_del(inode);
656 
657 	/*
658 	 * Wait for flusher thread to be done with the inode so that filesystem
659 	 * does not start destroying it while writeback is still running. Since
660 	 * the inode has I_FREEING set, flusher thread won't start new work on
661 	 * the inode.  We just have to wait for running writeback to finish.
662 	 */
663 	inode_wait_for_writeback(inode);
664 
665 	if (op->evict_inode) {
666 		op->evict_inode(inode);
667 	} else {
668 		truncate_inode_pages_final(&inode->i_data);
669 		clear_inode(inode);
670 	}
671 	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
672 		cd_forget(inode);
673 
674 	remove_inode_hash(inode);
675 
676 	spin_lock(&inode->i_lock);
677 	wake_up_bit(&inode->i_state, __I_NEW);
678 	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
679 	spin_unlock(&inode->i_lock);
680 
681 	destroy_inode(inode);
682 }
683 
684 /*
685  * dispose_list - dispose of the contents of a local list
686  * @head: the head of the list to free
687  *
688  * Dispose-list gets a local list with local inodes in it, so it doesn't
689  * need to worry about list corruption and SMP locks.
690  */
dispose_list(struct list_head * head)691 static void dispose_list(struct list_head *head)
692 {
693 	while (!list_empty(head)) {
694 		struct inode *inode;
695 
696 		inode = list_first_entry(head, struct inode, i_lru);
697 		list_del_init(&inode->i_lru);
698 
699 		evict(inode);
700 		cond_resched();
701 	}
702 }
703 
704 /**
705  * evict_inodes	- evict all evictable inodes for a superblock
706  * @sb:		superblock to operate on
707  *
708  * Make sure that no inodes with zero refcount are retained.  This is
709  * called by superblock shutdown after having SB_ACTIVE flag removed,
710  * so any inode reaching zero refcount during or after that call will
711  * be immediately evicted.
712  */
evict_inodes(struct super_block * sb)713 void evict_inodes(struct super_block *sb)
714 {
715 	struct inode *inode, *next;
716 	LIST_HEAD(dispose);
717 
718 again:
719 	spin_lock(&sb->s_inode_list_lock);
720 	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
721 		if (atomic_read(&inode->i_count))
722 			continue;
723 
724 		spin_lock(&inode->i_lock);
725 		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
726 			spin_unlock(&inode->i_lock);
727 			continue;
728 		}
729 
730 		inode->i_state |= I_FREEING;
731 		inode_lru_list_del(inode);
732 		spin_unlock(&inode->i_lock);
733 		list_add(&inode->i_lru, &dispose);
734 
735 		/*
736 		 * We can have a ton of inodes to evict at unmount time given
737 		 * enough memory, check to see if we need to go to sleep for a
738 		 * bit so we don't livelock.
739 		 */
740 		if (need_resched()) {
741 			spin_unlock(&sb->s_inode_list_lock);
742 			cond_resched();
743 			dispose_list(&dispose);
744 			goto again;
745 		}
746 	}
747 	spin_unlock(&sb->s_inode_list_lock);
748 
749 	dispose_list(&dispose);
750 }
751 EXPORT_SYMBOL_GPL(evict_inodes);
752 
753 /**
754  * invalidate_inodes	- attempt to free all inodes on a superblock
755  * @sb:		superblock to operate on
756  *
757  * Attempts to free all inodes (including dirty inodes) for a given superblock.
758  */
invalidate_inodes(struct super_block * sb)759 void invalidate_inodes(struct super_block *sb)
760 {
761 	struct inode *inode, *next;
762 	LIST_HEAD(dispose);
763 
764 again:
765 	spin_lock(&sb->s_inode_list_lock);
766 	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
767 		spin_lock(&inode->i_lock);
768 		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
769 			spin_unlock(&inode->i_lock);
770 			continue;
771 		}
772 		if (atomic_read(&inode->i_count)) {
773 			spin_unlock(&inode->i_lock);
774 			continue;
775 		}
776 
777 		inode->i_state |= I_FREEING;
778 		inode_lru_list_del(inode);
779 		spin_unlock(&inode->i_lock);
780 		list_add(&inode->i_lru, &dispose);
781 		if (need_resched()) {
782 			spin_unlock(&sb->s_inode_list_lock);
783 			cond_resched();
784 			dispose_list(&dispose);
785 			goto again;
786 		}
787 	}
788 	spin_unlock(&sb->s_inode_list_lock);
789 
790 	dispose_list(&dispose);
791 }
792 
793 /*
794  * Isolate the inode from the LRU in preparation for freeing it.
795  *
796  * If the inode has the I_REFERENCED flag set, then it means that it has been
797  * used recently - the flag is set in iput_final(). When we encounter such an
798  * inode, clear the flag and move it to the back of the LRU so it gets another
799  * pass through the LRU before it gets reclaimed. This is necessary because of
800  * the fact we are doing lazy LRU updates to minimise lock contention so the
801  * LRU does not have strict ordering. Hence we don't want to reclaim inodes
802  * with this flag set because they are the inodes that are out of order.
803  */
inode_lru_isolate(struct list_head * item,struct list_lru_one * lru,spinlock_t * lru_lock,void * arg)804 static enum lru_status inode_lru_isolate(struct list_head *item,
805 		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
806 {
807 	struct list_head *freeable = arg;
808 	struct inode	*inode = container_of(item, struct inode, i_lru);
809 
810 	/*
811 	 * We are inverting the lru lock/inode->i_lock here, so use a
812 	 * trylock. If we fail to get the lock, just skip it.
813 	 */
814 	if (!spin_trylock(&inode->i_lock))
815 		return LRU_SKIP;
816 
817 	/*
818 	 * Inodes can get referenced, redirtied, or repopulated while
819 	 * they're already on the LRU, and this can make them
820 	 * unreclaimable for a while. Remove them lazily here; iput,
821 	 * sync, or the last page cache deletion will requeue them.
822 	 */
823 	if (atomic_read(&inode->i_count) ||
824 	    (inode->i_state & ~I_REFERENCED) ||
825 	    !mapping_shrinkable(&inode->i_data)) {
826 		list_lru_isolate(lru, &inode->i_lru);
827 		spin_unlock(&inode->i_lock);
828 		this_cpu_dec(nr_unused);
829 		return LRU_REMOVED;
830 	}
831 
832 	/* Recently referenced inodes get one more pass */
833 	if (inode->i_state & I_REFERENCED) {
834 		inode->i_state &= ~I_REFERENCED;
835 		spin_unlock(&inode->i_lock);
836 		return LRU_ROTATE;
837 	}
838 
839 	/*
840 	 * On highmem systems, mapping_shrinkable() permits dropping
841 	 * page cache in order to free up struct inodes: lowmem might
842 	 * be under pressure before the cache inside the highmem zone.
843 	 */
844 	if (inode_has_buffers(inode) || !mapping_empty(&inode->i_data)) {
845 		__iget(inode);
846 		spin_unlock(&inode->i_lock);
847 		spin_unlock(lru_lock);
848 		if (remove_inode_buffers(inode)) {
849 			unsigned long reap;
850 			reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
851 			if (current_is_kswapd())
852 				__count_vm_events(KSWAPD_INODESTEAL, reap);
853 			else
854 				__count_vm_events(PGINODESTEAL, reap);
855 			mm_account_reclaimed_pages(reap);
856 		}
857 		iput(inode);
858 		spin_lock(lru_lock);
859 		return LRU_RETRY;
860 	}
861 
862 	WARN_ON(inode->i_state & I_NEW);
863 	inode->i_state |= I_FREEING;
864 	list_lru_isolate_move(lru, &inode->i_lru, freeable);
865 	spin_unlock(&inode->i_lock);
866 
867 	this_cpu_dec(nr_unused);
868 	return LRU_REMOVED;
869 }
870 
871 /*
872  * Walk the superblock inode LRU for freeable inodes and attempt to free them.
873  * This is called from the superblock shrinker function with a number of inodes
874  * to trim from the LRU. Inodes to be freed are moved to a temporary list and
875  * then are freed outside inode_lock by dispose_list().
876  */
prune_icache_sb(struct super_block * sb,struct shrink_control * sc)877 long prune_icache_sb(struct super_block *sb, struct shrink_control *sc)
878 {
879 	LIST_HEAD(freeable);
880 	long freed;
881 
882 	freed = list_lru_shrink_walk(&sb->s_inode_lru, sc,
883 				     inode_lru_isolate, &freeable);
884 	dispose_list(&freeable);
885 	return freed;
886 }
887 
888 static void __wait_on_freeing_inode(struct inode *inode);
889 /*
890  * Called with the inode lock held.
891  */
find_inode(struct super_block * sb,struct hlist_head * head,int (* test)(struct inode *,void *),void * data)892 static struct inode *find_inode(struct super_block *sb,
893 				struct hlist_head *head,
894 				int (*test)(struct inode *, void *),
895 				void *data)
896 {
897 	struct inode *inode = NULL;
898 
899 repeat:
900 	hlist_for_each_entry(inode, head, i_hash) {
901 		if (inode->i_sb != sb)
902 			continue;
903 		if (!test(inode, data))
904 			continue;
905 		spin_lock(&inode->i_lock);
906 		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
907 			__wait_on_freeing_inode(inode);
908 			goto repeat;
909 		}
910 		if (unlikely(inode->i_state & I_CREATING)) {
911 			spin_unlock(&inode->i_lock);
912 			return ERR_PTR(-ESTALE);
913 		}
914 		__iget(inode);
915 		spin_unlock(&inode->i_lock);
916 		return inode;
917 	}
918 	return NULL;
919 }
920 
921 /*
922  * find_inode_fast is the fast path version of find_inode, see the comment at
923  * iget_locked for details.
924  */
find_inode_fast(struct super_block * sb,struct hlist_head * head,unsigned long ino)925 static struct inode *find_inode_fast(struct super_block *sb,
926 				struct hlist_head *head, unsigned long ino)
927 {
928 	struct inode *inode = NULL;
929 
930 repeat:
931 	hlist_for_each_entry(inode, head, i_hash) {
932 		if (inode->i_ino != ino)
933 			continue;
934 		if (inode->i_sb != sb)
935 			continue;
936 		spin_lock(&inode->i_lock);
937 		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
938 			__wait_on_freeing_inode(inode);
939 			goto repeat;
940 		}
941 		if (unlikely(inode->i_state & I_CREATING)) {
942 			spin_unlock(&inode->i_lock);
943 			return ERR_PTR(-ESTALE);
944 		}
945 		__iget(inode);
946 		spin_unlock(&inode->i_lock);
947 		return inode;
948 	}
949 	return NULL;
950 }
951 
952 /*
953  * Each cpu owns a range of LAST_INO_BATCH numbers.
954  * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
955  * to renew the exhausted range.
956  *
957  * This does not significantly increase overflow rate because every CPU can
958  * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
959  * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
960  * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
961  * overflow rate by 2x, which does not seem too significant.
962  *
963  * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
964  * error if st_ino won't fit in target struct field. Use 32bit counter
965  * here to attempt to avoid that.
966  */
967 #define LAST_INO_BATCH 1024
968 static DEFINE_PER_CPU(unsigned int, last_ino);
969 
get_next_ino(void)970 unsigned int get_next_ino(void)
971 {
972 	unsigned int *p = &get_cpu_var(last_ino);
973 	unsigned int res = *p;
974 
975 #ifdef CONFIG_SMP
976 	if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
977 		static atomic_t shared_last_ino;
978 		int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
979 
980 		res = next - LAST_INO_BATCH;
981 	}
982 #endif
983 
984 	res++;
985 	/* get_next_ino should not provide a 0 inode number */
986 	if (unlikely(!res))
987 		res++;
988 	*p = res;
989 	put_cpu_var(last_ino);
990 	return res;
991 }
992 EXPORT_SYMBOL(get_next_ino);
993 
994 /**
995  *	new_inode_pseudo 	- obtain an inode
996  *	@sb: superblock
997  *
998  *	Allocates a new inode for given superblock.
999  *	Inode wont be chained in superblock s_inodes list
1000  *	This means :
1001  *	- fs can't be unmount
1002  *	- quotas, fsnotify, writeback can't work
1003  */
new_inode_pseudo(struct super_block * sb)1004 struct inode *new_inode_pseudo(struct super_block *sb)
1005 {
1006 	struct inode *inode = alloc_inode(sb);
1007 
1008 	if (inode) {
1009 		spin_lock(&inode->i_lock);
1010 		inode->i_state = 0;
1011 		spin_unlock(&inode->i_lock);
1012 	}
1013 	return inode;
1014 }
1015 
1016 /**
1017  *	new_inode 	- obtain an inode
1018  *	@sb: superblock
1019  *
1020  *	Allocates a new inode for given superblock. The default gfp_mask
1021  *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
1022  *	If HIGHMEM pages are unsuitable or it is known that pages allocated
1023  *	for the page cache are not reclaimable or migratable,
1024  *	mapping_set_gfp_mask() must be called with suitable flags on the
1025  *	newly created inode's mapping
1026  *
1027  */
new_inode(struct super_block * sb)1028 struct inode *new_inode(struct super_block *sb)
1029 {
1030 	struct inode *inode;
1031 
1032 	inode = new_inode_pseudo(sb);
1033 	if (inode)
1034 		inode_sb_list_add(inode);
1035 	return inode;
1036 }
1037 EXPORT_SYMBOL(new_inode);
1038 
1039 #ifdef CONFIG_DEBUG_LOCK_ALLOC
lockdep_annotate_inode_mutex_key(struct inode * inode)1040 void lockdep_annotate_inode_mutex_key(struct inode *inode)
1041 {
1042 	if (S_ISDIR(inode->i_mode)) {
1043 		struct file_system_type *type = inode->i_sb->s_type;
1044 
1045 		/* Set new key only if filesystem hasn't already changed it */
1046 		if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) {
1047 			/*
1048 			 * ensure nobody is actually holding i_mutex
1049 			 */
1050 			// mutex_destroy(&inode->i_mutex);
1051 			init_rwsem(&inode->i_rwsem);
1052 			lockdep_set_class(&inode->i_rwsem,
1053 					  &type->i_mutex_dir_key);
1054 		}
1055 	}
1056 }
1057 EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
1058 #endif
1059 
1060 /**
1061  * unlock_new_inode - clear the I_NEW state and wake up any waiters
1062  * @inode:	new inode to unlock
1063  *
1064  * Called when the inode is fully initialised to clear the new state of the
1065  * inode and wake up anyone waiting for the inode to finish initialisation.
1066  */
unlock_new_inode(struct inode * inode)1067 void unlock_new_inode(struct inode *inode)
1068 {
1069 	lockdep_annotate_inode_mutex_key(inode);
1070 	spin_lock(&inode->i_lock);
1071 	WARN_ON(!(inode->i_state & I_NEW));
1072 	inode->i_state &= ~I_NEW & ~I_CREATING;
1073 	smp_mb();
1074 	wake_up_bit(&inode->i_state, __I_NEW);
1075 	spin_unlock(&inode->i_lock);
1076 }
1077 EXPORT_SYMBOL(unlock_new_inode);
1078 
discard_new_inode(struct inode * inode)1079 void discard_new_inode(struct inode *inode)
1080 {
1081 	lockdep_annotate_inode_mutex_key(inode);
1082 	spin_lock(&inode->i_lock);
1083 	WARN_ON(!(inode->i_state & I_NEW));
1084 	inode->i_state &= ~I_NEW;
1085 	smp_mb();
1086 	wake_up_bit(&inode->i_state, __I_NEW);
1087 	spin_unlock(&inode->i_lock);
1088 	iput(inode);
1089 }
1090 EXPORT_SYMBOL(discard_new_inode);
1091 
1092 /**
1093  * lock_two_inodes - lock two inodes (may be regular files but also dirs)
1094  *
1095  * Lock any non-NULL argument. The caller must make sure that if he is passing
1096  * in two directories, one is not ancestor of the other.  Zero, one or two
1097  * objects may be locked by this function.
1098  *
1099  * @inode1: first inode to lock
1100  * @inode2: second inode to lock
1101  * @subclass1: inode lock subclass for the first lock obtained
1102  * @subclass2: inode lock subclass for the second lock obtained
1103  */
lock_two_inodes(struct inode * inode1,struct inode * inode2,unsigned subclass1,unsigned subclass2)1104 void lock_two_inodes(struct inode *inode1, struct inode *inode2,
1105 		     unsigned subclass1, unsigned subclass2)
1106 {
1107 	if (!inode1 || !inode2) {
1108 		/*
1109 		 * Make sure @subclass1 will be used for the acquired lock.
1110 		 * This is not strictly necessary (no current caller cares) but
1111 		 * let's keep things consistent.
1112 		 */
1113 		if (!inode1)
1114 			swap(inode1, inode2);
1115 		goto lock;
1116 	}
1117 
1118 	/*
1119 	 * If one object is directory and the other is not, we must make sure
1120 	 * to lock directory first as the other object may be its child.
1121 	 */
1122 	if (S_ISDIR(inode2->i_mode) == S_ISDIR(inode1->i_mode)) {
1123 		if (inode1 > inode2)
1124 			swap(inode1, inode2);
1125 	} else if (!S_ISDIR(inode1->i_mode))
1126 		swap(inode1, inode2);
1127 lock:
1128 	if (inode1)
1129 		inode_lock_nested(inode1, subclass1);
1130 	if (inode2 && inode2 != inode1)
1131 		inode_lock_nested(inode2, subclass2);
1132 }
1133 
1134 /**
1135  * lock_two_nondirectories - take two i_mutexes on non-directory objects
1136  *
1137  * Lock any non-NULL argument. Passed objects must not be directories.
1138  * Zero, one or two objects may be locked by this function.
1139  *
1140  * @inode1: first inode to lock
1141  * @inode2: second inode to lock
1142  */
lock_two_nondirectories(struct inode * inode1,struct inode * inode2)1143 void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1144 {
1145 	if (inode1)
1146 		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
1147 	if (inode2)
1148 		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
1149 	lock_two_inodes(inode1, inode2, I_MUTEX_NORMAL, I_MUTEX_NONDIR2);
1150 }
1151 EXPORT_SYMBOL(lock_two_nondirectories);
1152 
1153 /**
1154  * unlock_two_nondirectories - release locks from lock_two_nondirectories()
1155  * @inode1: first inode to unlock
1156  * @inode2: second inode to unlock
1157  */
unlock_two_nondirectories(struct inode * inode1,struct inode * inode2)1158 void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1159 {
1160 	if (inode1) {
1161 		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
1162 		inode_unlock(inode1);
1163 	}
1164 	if (inode2 && inode2 != inode1) {
1165 		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
1166 		inode_unlock(inode2);
1167 	}
1168 }
1169 EXPORT_SYMBOL(unlock_two_nondirectories);
1170 
1171 /**
1172  * inode_insert5 - obtain an inode from a mounted file system
1173  * @inode:	pre-allocated inode to use for insert to cache
1174  * @hashval:	hash value (usually inode number) to get
1175  * @test:	callback used for comparisons between inodes
1176  * @set:	callback used to initialize a new struct inode
1177  * @data:	opaque data pointer to pass to @test and @set
1178  *
1179  * Search for the inode specified by @hashval and @data in the inode cache,
1180  * and if present it is return it with an increased reference count. This is
1181  * a variant of iget5_locked() for callers that don't want to fail on memory
1182  * allocation of inode.
1183  *
1184  * If the inode is not in cache, insert the pre-allocated inode to cache and
1185  * return it locked, hashed, and with the I_NEW flag set. The file system gets
1186  * to fill it in before unlocking it via unlock_new_inode().
1187  *
1188  * Note both @test and @set are called with the inode_hash_lock held, so can't
1189  * sleep.
1190  */
inode_insert5(struct inode * inode,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1191 struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
1192 			    int (*test)(struct inode *, void *),
1193 			    int (*set)(struct inode *, void *), void *data)
1194 {
1195 	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
1196 	struct inode *old;
1197 
1198 again:
1199 	spin_lock(&inode_hash_lock);
1200 	old = find_inode(inode->i_sb, head, test, data);
1201 	if (unlikely(old)) {
1202 		/*
1203 		 * Uhhuh, somebody else created the same inode under us.
1204 		 * Use the old inode instead of the preallocated one.
1205 		 */
1206 		spin_unlock(&inode_hash_lock);
1207 		if (IS_ERR(old))
1208 			return NULL;
1209 		wait_on_inode(old);
1210 		if (unlikely(inode_unhashed(old))) {
1211 			iput(old);
1212 			goto again;
1213 		}
1214 		return old;
1215 	}
1216 
1217 	if (set && unlikely(set(inode, data))) {
1218 		inode = NULL;
1219 		goto unlock;
1220 	}
1221 
1222 	/*
1223 	 * Return the locked inode with I_NEW set, the
1224 	 * caller is responsible for filling in the contents
1225 	 */
1226 	spin_lock(&inode->i_lock);
1227 	inode->i_state |= I_NEW;
1228 	hlist_add_head_rcu(&inode->i_hash, head);
1229 	spin_unlock(&inode->i_lock);
1230 
1231 	/*
1232 	 * Add inode to the sb list if it's not already. It has I_NEW at this
1233 	 * point, so it should be safe to test i_sb_list locklessly.
1234 	 */
1235 	if (list_empty(&inode->i_sb_list))
1236 		inode_sb_list_add(inode);
1237 unlock:
1238 	spin_unlock(&inode_hash_lock);
1239 
1240 	return inode;
1241 }
1242 EXPORT_SYMBOL(inode_insert5);
1243 
1244 /**
1245  * iget5_locked - obtain an inode from a mounted file system
1246  * @sb:		super block of file system
1247  * @hashval:	hash value (usually inode number) to get
1248  * @test:	callback used for comparisons between inodes
1249  * @set:	callback used to initialize a new struct inode
1250  * @data:	opaque data pointer to pass to @test and @set
1251  *
1252  * Search for the inode specified by @hashval and @data in the inode cache,
1253  * and if present it is return it with an increased reference count. This is
1254  * a generalized version of iget_locked() for file systems where the inode
1255  * number is not sufficient for unique identification of an inode.
1256  *
1257  * If the inode is not in cache, allocate a new inode and return it locked,
1258  * hashed, and with the I_NEW flag set. The file system gets to fill it in
1259  * before unlocking it via unlock_new_inode().
1260  *
1261  * Note both @test and @set are called with the inode_hash_lock held, so can't
1262  * sleep.
1263  */
iget5_locked(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1264 struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1265 		int (*test)(struct inode *, void *),
1266 		int (*set)(struct inode *, void *), void *data)
1267 {
1268 	struct inode *inode = ilookup5(sb, hashval, test, data);
1269 
1270 	if (!inode) {
1271 		struct inode *new = alloc_inode(sb);
1272 
1273 		if (new) {
1274 			new->i_state = 0;
1275 			inode = inode_insert5(new, hashval, test, set, data);
1276 			if (unlikely(inode != new))
1277 				destroy_inode(new);
1278 		}
1279 	}
1280 	return inode;
1281 }
1282 EXPORT_SYMBOL(iget5_locked);
1283 
1284 /**
1285  * iget_locked - obtain an inode from a mounted file system
1286  * @sb:		super block of file system
1287  * @ino:	inode number to get
1288  *
1289  * Search for the inode specified by @ino in the inode cache and if present
1290  * return it with an increased reference count. This is for file systems
1291  * where the inode number is sufficient for unique identification of an inode.
1292  *
1293  * If the inode is not in cache, allocate a new inode and return it locked,
1294  * hashed, and with the I_NEW flag set.  The file system gets to fill it in
1295  * before unlocking it via unlock_new_inode().
1296  */
iget_locked(struct super_block * sb,unsigned long ino)1297 struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1298 {
1299 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1300 	struct inode *inode;
1301 again:
1302 	spin_lock(&inode_hash_lock);
1303 	inode = find_inode_fast(sb, head, ino);
1304 	spin_unlock(&inode_hash_lock);
1305 	if (inode) {
1306 		if (IS_ERR(inode))
1307 			return NULL;
1308 		wait_on_inode(inode);
1309 		if (unlikely(inode_unhashed(inode))) {
1310 			iput(inode);
1311 			goto again;
1312 		}
1313 		return inode;
1314 	}
1315 
1316 	inode = alloc_inode(sb);
1317 	if (inode) {
1318 		struct inode *old;
1319 
1320 		spin_lock(&inode_hash_lock);
1321 		/* We released the lock, so.. */
1322 		old = find_inode_fast(sb, head, ino);
1323 		if (!old) {
1324 			inode->i_ino = ino;
1325 			spin_lock(&inode->i_lock);
1326 			inode->i_state = I_NEW;
1327 			hlist_add_head_rcu(&inode->i_hash, head);
1328 			spin_unlock(&inode->i_lock);
1329 			inode_sb_list_add(inode);
1330 			spin_unlock(&inode_hash_lock);
1331 
1332 			/* Return the locked inode with I_NEW set, the
1333 			 * caller is responsible for filling in the contents
1334 			 */
1335 			return inode;
1336 		}
1337 
1338 		/*
1339 		 * Uhhuh, somebody else created the same inode under
1340 		 * us. Use the old inode instead of the one we just
1341 		 * allocated.
1342 		 */
1343 		spin_unlock(&inode_hash_lock);
1344 		destroy_inode(inode);
1345 		if (IS_ERR(old))
1346 			return NULL;
1347 		inode = old;
1348 		wait_on_inode(inode);
1349 		if (unlikely(inode_unhashed(inode))) {
1350 			iput(inode);
1351 			goto again;
1352 		}
1353 	}
1354 	return inode;
1355 }
1356 EXPORT_SYMBOL(iget_locked);
1357 
1358 /*
1359  * search the inode cache for a matching inode number.
1360  * If we find one, then the inode number we are trying to
1361  * allocate is not unique and so we should not use it.
1362  *
1363  * Returns 1 if the inode number is unique, 0 if it is not.
1364  */
test_inode_iunique(struct super_block * sb,unsigned long ino)1365 static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1366 {
1367 	struct hlist_head *b = inode_hashtable + hash(sb, ino);
1368 	struct inode *inode;
1369 
1370 	hlist_for_each_entry_rcu(inode, b, i_hash) {
1371 		if (inode->i_ino == ino && inode->i_sb == sb)
1372 			return 0;
1373 	}
1374 	return 1;
1375 }
1376 
1377 /**
1378  *	iunique - get a unique inode number
1379  *	@sb: superblock
1380  *	@max_reserved: highest reserved inode number
1381  *
1382  *	Obtain an inode number that is unique on the system for a given
1383  *	superblock. This is used by file systems that have no natural
1384  *	permanent inode numbering system. An inode number is returned that
1385  *	is higher than the reserved limit but unique.
1386  *
1387  *	BUGS:
1388  *	With a large number of inodes live on the file system this function
1389  *	currently becomes quite slow.
1390  */
iunique(struct super_block * sb,ino_t max_reserved)1391 ino_t iunique(struct super_block *sb, ino_t max_reserved)
1392 {
1393 	/*
1394 	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1395 	 * error if st_ino won't fit in target struct field. Use 32bit counter
1396 	 * here to attempt to avoid that.
1397 	 */
1398 	static DEFINE_SPINLOCK(iunique_lock);
1399 	static unsigned int counter;
1400 	ino_t res;
1401 
1402 	rcu_read_lock();
1403 	spin_lock(&iunique_lock);
1404 	do {
1405 		if (counter <= max_reserved)
1406 			counter = max_reserved + 1;
1407 		res = counter++;
1408 	} while (!test_inode_iunique(sb, res));
1409 	spin_unlock(&iunique_lock);
1410 	rcu_read_unlock();
1411 
1412 	return res;
1413 }
1414 EXPORT_SYMBOL(iunique);
1415 
igrab(struct inode * inode)1416 struct inode *igrab(struct inode *inode)
1417 {
1418 	spin_lock(&inode->i_lock);
1419 	if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1420 		__iget(inode);
1421 		spin_unlock(&inode->i_lock);
1422 	} else {
1423 		spin_unlock(&inode->i_lock);
1424 		/*
1425 		 * Handle the case where s_op->clear_inode is not been
1426 		 * called yet, and somebody is calling igrab
1427 		 * while the inode is getting freed.
1428 		 */
1429 		inode = NULL;
1430 	}
1431 	return inode;
1432 }
1433 EXPORT_SYMBOL(igrab);
1434 
1435 /**
1436  * ilookup5_nowait - search for an inode in the inode cache
1437  * @sb:		super block of file system to search
1438  * @hashval:	hash value (usually inode number) to search for
1439  * @test:	callback used for comparisons between inodes
1440  * @data:	opaque data pointer to pass to @test
1441  *
1442  * Search for the inode specified by @hashval and @data in the inode cache.
1443  * If the inode is in the cache, the inode is returned with an incremented
1444  * reference count.
1445  *
1446  * Note: I_NEW is not waited upon so you have to be very careful what you do
1447  * with the returned inode.  You probably should be using ilookup5() instead.
1448  *
1449  * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1450  */
ilookup5_nowait(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1451 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1452 		int (*test)(struct inode *, void *), void *data)
1453 {
1454 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1455 	struct inode *inode;
1456 
1457 	spin_lock(&inode_hash_lock);
1458 	inode = find_inode(sb, head, test, data);
1459 	spin_unlock(&inode_hash_lock);
1460 
1461 	return IS_ERR(inode) ? NULL : inode;
1462 }
1463 EXPORT_SYMBOL(ilookup5_nowait);
1464 
1465 /**
1466  * ilookup5 - search for an inode in the inode cache
1467  * @sb:		super block of file system to search
1468  * @hashval:	hash value (usually inode number) to search for
1469  * @test:	callback used for comparisons between inodes
1470  * @data:	opaque data pointer to pass to @test
1471  *
1472  * Search for the inode specified by @hashval and @data in the inode cache,
1473  * and if the inode is in the cache, return the inode with an incremented
1474  * reference count.  Waits on I_NEW before returning the inode.
1475  * returned with an incremented reference count.
1476  *
1477  * This is a generalized version of ilookup() for file systems where the
1478  * inode number is not sufficient for unique identification of an inode.
1479  *
1480  * Note: @test is called with the inode_hash_lock held, so can't sleep.
1481  */
ilookup5(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1482 struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1483 		int (*test)(struct inode *, void *), void *data)
1484 {
1485 	struct inode *inode;
1486 again:
1487 	inode = ilookup5_nowait(sb, hashval, test, data);
1488 	if (inode) {
1489 		wait_on_inode(inode);
1490 		if (unlikely(inode_unhashed(inode))) {
1491 			iput(inode);
1492 			goto again;
1493 		}
1494 	}
1495 	return inode;
1496 }
1497 EXPORT_SYMBOL(ilookup5);
1498 
1499 /**
1500  * ilookup - search for an inode in the inode cache
1501  * @sb:		super block of file system to search
1502  * @ino:	inode number to search for
1503  *
1504  * Search for the inode @ino in the inode cache, and if the inode is in the
1505  * cache, the inode is returned with an incremented reference count.
1506  */
ilookup(struct super_block * sb,unsigned long ino)1507 struct inode *ilookup(struct super_block *sb, unsigned long ino)
1508 {
1509 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1510 	struct inode *inode;
1511 again:
1512 	spin_lock(&inode_hash_lock);
1513 	inode = find_inode_fast(sb, head, ino);
1514 	spin_unlock(&inode_hash_lock);
1515 
1516 	if (inode) {
1517 		if (IS_ERR(inode))
1518 			return NULL;
1519 		wait_on_inode(inode);
1520 		if (unlikely(inode_unhashed(inode))) {
1521 			iput(inode);
1522 			goto again;
1523 		}
1524 	}
1525 	return inode;
1526 }
1527 EXPORT_SYMBOL(ilookup);
1528 
1529 /**
1530  * find_inode_nowait - find an inode in the inode cache
1531  * @sb:		super block of file system to search
1532  * @hashval:	hash value (usually inode number) to search for
1533  * @match:	callback used for comparisons between inodes
1534  * @data:	opaque data pointer to pass to @match
1535  *
1536  * Search for the inode specified by @hashval and @data in the inode
1537  * cache, where the helper function @match will return 0 if the inode
1538  * does not match, 1 if the inode does match, and -1 if the search
1539  * should be stopped.  The @match function must be responsible for
1540  * taking the i_lock spin_lock and checking i_state for an inode being
1541  * freed or being initialized, and incrementing the reference count
1542  * before returning 1.  It also must not sleep, since it is called with
1543  * the inode_hash_lock spinlock held.
1544  *
1545  * This is a even more generalized version of ilookup5() when the
1546  * function must never block --- find_inode() can block in
1547  * __wait_on_freeing_inode() --- or when the caller can not increment
1548  * the reference count because the resulting iput() might cause an
1549  * inode eviction.  The tradeoff is that the @match funtion must be
1550  * very carefully implemented.
1551  */
find_inode_nowait(struct super_block * sb,unsigned long hashval,int (* match)(struct inode *,unsigned long,void *),void * data)1552 struct inode *find_inode_nowait(struct super_block *sb,
1553 				unsigned long hashval,
1554 				int (*match)(struct inode *, unsigned long,
1555 					     void *),
1556 				void *data)
1557 {
1558 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1559 	struct inode *inode, *ret_inode = NULL;
1560 	int mval;
1561 
1562 	spin_lock(&inode_hash_lock);
1563 	hlist_for_each_entry(inode, head, i_hash) {
1564 		if (inode->i_sb != sb)
1565 			continue;
1566 		mval = match(inode, hashval, data);
1567 		if (mval == 0)
1568 			continue;
1569 		if (mval == 1)
1570 			ret_inode = inode;
1571 		goto out;
1572 	}
1573 out:
1574 	spin_unlock(&inode_hash_lock);
1575 	return ret_inode;
1576 }
1577 EXPORT_SYMBOL(find_inode_nowait);
1578 
1579 /**
1580  * find_inode_rcu - find an inode in the inode cache
1581  * @sb:		Super block of file system to search
1582  * @hashval:	Key to hash
1583  * @test:	Function to test match on an inode
1584  * @data:	Data for test function
1585  *
1586  * Search for the inode specified by @hashval and @data in the inode cache,
1587  * where the helper function @test will return 0 if the inode does not match
1588  * and 1 if it does.  The @test function must be responsible for taking the
1589  * i_lock spin_lock and checking i_state for an inode being freed or being
1590  * initialized.
1591  *
1592  * If successful, this will return the inode for which the @test function
1593  * returned 1 and NULL otherwise.
1594  *
1595  * The @test function is not permitted to take a ref on any inode presented.
1596  * It is also not permitted to sleep.
1597  *
1598  * The caller must hold the RCU read lock.
1599  */
find_inode_rcu(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1600 struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval,
1601 			     int (*test)(struct inode *, void *), void *data)
1602 {
1603 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1604 	struct inode *inode;
1605 
1606 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1607 			 "suspicious find_inode_rcu() usage");
1608 
1609 	hlist_for_each_entry_rcu(inode, head, i_hash) {
1610 		if (inode->i_sb == sb &&
1611 		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)) &&
1612 		    test(inode, data))
1613 			return inode;
1614 	}
1615 	return NULL;
1616 }
1617 EXPORT_SYMBOL(find_inode_rcu);
1618 
1619 /**
1620  * find_inode_by_ino_rcu - Find an inode in the inode cache
1621  * @sb:		Super block of file system to search
1622  * @ino:	The inode number to match
1623  *
1624  * Search for the inode specified by @hashval and @data in the inode cache,
1625  * where the helper function @test will return 0 if the inode does not match
1626  * and 1 if it does.  The @test function must be responsible for taking the
1627  * i_lock spin_lock and checking i_state for an inode being freed or being
1628  * initialized.
1629  *
1630  * If successful, this will return the inode for which the @test function
1631  * returned 1 and NULL otherwise.
1632  *
1633  * The @test function is not permitted to take a ref on any inode presented.
1634  * It is also not permitted to sleep.
1635  *
1636  * The caller must hold the RCU read lock.
1637  */
find_inode_by_ino_rcu(struct super_block * sb,unsigned long ino)1638 struct inode *find_inode_by_ino_rcu(struct super_block *sb,
1639 				    unsigned long ino)
1640 {
1641 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1642 	struct inode *inode;
1643 
1644 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1645 			 "suspicious find_inode_by_ino_rcu() usage");
1646 
1647 	hlist_for_each_entry_rcu(inode, head, i_hash) {
1648 		if (inode->i_ino == ino &&
1649 		    inode->i_sb == sb &&
1650 		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)))
1651 		    return inode;
1652 	}
1653 	return NULL;
1654 }
1655 EXPORT_SYMBOL(find_inode_by_ino_rcu);
1656 
insert_inode_locked(struct inode * inode)1657 int insert_inode_locked(struct inode *inode)
1658 {
1659 	struct super_block *sb = inode->i_sb;
1660 	ino_t ino = inode->i_ino;
1661 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1662 
1663 	while (1) {
1664 		struct inode *old = NULL;
1665 		spin_lock(&inode_hash_lock);
1666 		hlist_for_each_entry(old, head, i_hash) {
1667 			if (old->i_ino != ino)
1668 				continue;
1669 			if (old->i_sb != sb)
1670 				continue;
1671 			spin_lock(&old->i_lock);
1672 			if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1673 				spin_unlock(&old->i_lock);
1674 				continue;
1675 			}
1676 			break;
1677 		}
1678 		if (likely(!old)) {
1679 			spin_lock(&inode->i_lock);
1680 			inode->i_state |= I_NEW | I_CREATING;
1681 			hlist_add_head_rcu(&inode->i_hash, head);
1682 			spin_unlock(&inode->i_lock);
1683 			spin_unlock(&inode_hash_lock);
1684 			return 0;
1685 		}
1686 		if (unlikely(old->i_state & I_CREATING)) {
1687 			spin_unlock(&old->i_lock);
1688 			spin_unlock(&inode_hash_lock);
1689 			return -EBUSY;
1690 		}
1691 		__iget(old);
1692 		spin_unlock(&old->i_lock);
1693 		spin_unlock(&inode_hash_lock);
1694 		wait_on_inode(old);
1695 		if (unlikely(!inode_unhashed(old))) {
1696 			iput(old);
1697 			return -EBUSY;
1698 		}
1699 		iput(old);
1700 	}
1701 }
1702 EXPORT_SYMBOL(insert_inode_locked);
1703 
insert_inode_locked4(struct inode * inode,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1704 int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1705 		int (*test)(struct inode *, void *), void *data)
1706 {
1707 	struct inode *old;
1708 
1709 	inode->i_state |= I_CREATING;
1710 	old = inode_insert5(inode, hashval, test, NULL, data);
1711 
1712 	if (old != inode) {
1713 		iput(old);
1714 		return -EBUSY;
1715 	}
1716 	return 0;
1717 }
1718 EXPORT_SYMBOL(insert_inode_locked4);
1719 
1720 
generic_delete_inode(struct inode * inode)1721 int generic_delete_inode(struct inode *inode)
1722 {
1723 	return 1;
1724 }
1725 EXPORT_SYMBOL(generic_delete_inode);
1726 
1727 /*
1728  * Called when we're dropping the last reference
1729  * to an inode.
1730  *
1731  * Call the FS "drop_inode()" function, defaulting to
1732  * the legacy UNIX filesystem behaviour.  If it tells
1733  * us to evict inode, do so.  Otherwise, retain inode
1734  * in cache if fs is alive, sync and evict if fs is
1735  * shutting down.
1736  */
iput_final(struct inode * inode)1737 static void iput_final(struct inode *inode)
1738 {
1739 	struct super_block *sb = inode->i_sb;
1740 	const struct super_operations *op = inode->i_sb->s_op;
1741 	unsigned long state;
1742 	int drop;
1743 
1744 	WARN_ON(inode->i_state & I_NEW);
1745 
1746 	if (op->drop_inode)
1747 		drop = op->drop_inode(inode);
1748 	else
1749 		drop = generic_drop_inode(inode);
1750 
1751 	if (!drop &&
1752 	    !(inode->i_state & I_DONTCACHE) &&
1753 	    (sb->s_flags & SB_ACTIVE)) {
1754 		__inode_add_lru(inode, true);
1755 		spin_unlock(&inode->i_lock);
1756 		return;
1757 	}
1758 
1759 	state = inode->i_state;
1760 	if (!drop) {
1761 		WRITE_ONCE(inode->i_state, state | I_WILL_FREE);
1762 		spin_unlock(&inode->i_lock);
1763 
1764 		write_inode_now(inode, 1);
1765 
1766 		spin_lock(&inode->i_lock);
1767 		state = inode->i_state;
1768 		WARN_ON(state & I_NEW);
1769 		state &= ~I_WILL_FREE;
1770 	}
1771 
1772 	WRITE_ONCE(inode->i_state, state | I_FREEING);
1773 	if (!list_empty(&inode->i_lru))
1774 		inode_lru_list_del(inode);
1775 	spin_unlock(&inode->i_lock);
1776 
1777 	evict(inode);
1778 }
1779 
1780 /**
1781  *	iput	- put an inode
1782  *	@inode: inode to put
1783  *
1784  *	Puts an inode, dropping its usage count. If the inode use count hits
1785  *	zero, the inode is then freed and may also be destroyed.
1786  *
1787  *	Consequently, iput() can sleep.
1788  */
iput(struct inode * inode)1789 void iput(struct inode *inode)
1790 {
1791 	if (!inode)
1792 		return;
1793 	BUG_ON(inode->i_state & I_CLEAR);
1794 retry:
1795 	if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
1796 		if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
1797 			atomic_inc(&inode->i_count);
1798 			spin_unlock(&inode->i_lock);
1799 			trace_writeback_lazytime_iput(inode);
1800 			mark_inode_dirty_sync(inode);
1801 			goto retry;
1802 		}
1803 		iput_final(inode);
1804 	}
1805 }
1806 EXPORT_SYMBOL(iput);
1807 
1808 #ifdef CONFIG_BLOCK
1809 /**
1810  *	bmap	- find a block number in a file
1811  *	@inode:  inode owning the block number being requested
1812  *	@block: pointer containing the block to find
1813  *
1814  *	Replaces the value in ``*block`` with the block number on the device holding
1815  *	corresponding to the requested block number in the file.
1816  *	That is, asked for block 4 of inode 1 the function will replace the
1817  *	4 in ``*block``, with disk block relative to the disk start that holds that
1818  *	block of the file.
1819  *
1820  *	Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
1821  *	hole, returns 0 and ``*block`` is also set to 0.
1822  */
bmap(struct inode * inode,sector_t * block)1823 int bmap(struct inode *inode, sector_t *block)
1824 {
1825 	if (!inode->i_mapping->a_ops->bmap)
1826 		return -EINVAL;
1827 
1828 	*block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
1829 	return 0;
1830 }
1831 EXPORT_SYMBOL(bmap);
1832 #endif
1833 
1834 /*
1835  * With relative atime, only update atime if the previous atime is
1836  * earlier than or equal to either the ctime or mtime,
1837  * or if at least a day has passed since the last atime update.
1838  */
relatime_need_update(struct vfsmount * mnt,struct inode * inode,struct timespec64 now)1839 static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1840 			     struct timespec64 now)
1841 {
1842 	struct timespec64 ctime;
1843 
1844 	if (!(mnt->mnt_flags & MNT_RELATIME))
1845 		return 1;
1846 	/*
1847 	 * Is mtime younger than or equal to atime? If yes, update atime:
1848 	 */
1849 	if (timespec64_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1850 		return 1;
1851 	/*
1852 	 * Is ctime younger than or equal to atime? If yes, update atime:
1853 	 */
1854 	ctime = inode_get_ctime(inode);
1855 	if (timespec64_compare(&ctime, &inode->i_atime) >= 0)
1856 		return 1;
1857 
1858 	/*
1859 	 * Is the previous atime value older than a day? If yes,
1860 	 * update atime:
1861 	 */
1862 	if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1863 		return 1;
1864 	/*
1865 	 * Good, we can skip the atime update:
1866 	 */
1867 	return 0;
1868 }
1869 
1870 /**
1871  * inode_update_timestamps - update the timestamps on the inode
1872  * @inode: inode to be updated
1873  * @flags: S_* flags that needed to be updated
1874  *
1875  * The update_time function is called when an inode's timestamps need to be
1876  * updated for a read or write operation. This function handles updating the
1877  * actual timestamps. It's up to the caller to ensure that the inode is marked
1878  * dirty appropriately.
1879  *
1880  * In the case where any of S_MTIME, S_CTIME, or S_VERSION need to be updated,
1881  * attempt to update all three of them. S_ATIME updates can be handled
1882  * independently of the rest.
1883  *
1884  * Returns a set of S_* flags indicating which values changed.
1885  */
inode_update_timestamps(struct inode * inode,int flags)1886 int inode_update_timestamps(struct inode *inode, int flags)
1887 {
1888 	int updated = 0;
1889 	struct timespec64 now;
1890 
1891 	if (flags & (S_MTIME|S_CTIME|S_VERSION)) {
1892 		struct timespec64 ctime = inode_get_ctime(inode);
1893 
1894 		now = inode_set_ctime_current(inode);
1895 		if (!timespec64_equal(&now, &ctime))
1896 			updated |= S_CTIME;
1897 		if (!timespec64_equal(&now, &inode->i_mtime)) {
1898 			inode->i_mtime = now;
1899 			updated |= S_MTIME;
1900 		}
1901 		if (IS_I_VERSION(inode) && inode_maybe_inc_iversion(inode, updated))
1902 			updated |= S_VERSION;
1903 	} else {
1904 		now = current_time(inode);
1905 	}
1906 
1907 	if (flags & S_ATIME) {
1908 		if (!timespec64_equal(&now, &inode->i_atime)) {
1909 			inode->i_atime = now;
1910 			updated |= S_ATIME;
1911 		}
1912 	}
1913 	return updated;
1914 }
1915 EXPORT_SYMBOL(inode_update_timestamps);
1916 
1917 /**
1918  * generic_update_time - update the timestamps on the inode
1919  * @inode: inode to be updated
1920  * @flags: S_* flags that needed to be updated
1921  *
1922  * The update_time function is called when an inode's timestamps need to be
1923  * updated for a read or write operation. In the case where any of S_MTIME, S_CTIME,
1924  * or S_VERSION need to be updated we attempt to update all three of them. S_ATIME
1925  * updates can be handled done independently of the rest.
1926  *
1927  * Returns a S_* mask indicating which fields were updated.
1928  */
generic_update_time(struct inode * inode,int flags)1929 int generic_update_time(struct inode *inode, int flags)
1930 {
1931 	int updated = inode_update_timestamps(inode, flags);
1932 	int dirty_flags = 0;
1933 
1934 	if (updated & (S_ATIME|S_MTIME|S_CTIME))
1935 		dirty_flags = inode->i_sb->s_flags & SB_LAZYTIME ? I_DIRTY_TIME : I_DIRTY_SYNC;
1936 	if (updated & S_VERSION)
1937 		dirty_flags |= I_DIRTY_SYNC;
1938 	__mark_inode_dirty(inode, dirty_flags);
1939 	return updated;
1940 }
1941 EXPORT_SYMBOL(generic_update_time);
1942 
1943 /*
1944  * This does the actual work of updating an inodes time or version.  Must have
1945  * had called mnt_want_write() before calling this.
1946  */
inode_update_time(struct inode * inode,int flags)1947 int inode_update_time(struct inode *inode, int flags)
1948 {
1949 	if (inode->i_op->update_time)
1950 		return inode->i_op->update_time(inode, flags);
1951 	generic_update_time(inode, flags);
1952 	return 0;
1953 }
1954 EXPORT_SYMBOL(inode_update_time);
1955 
1956 /**
1957  *	atime_needs_update	-	update the access time
1958  *	@path: the &struct path to update
1959  *	@inode: inode to update
1960  *
1961  *	Update the accessed time on an inode and mark it for writeback.
1962  *	This function automatically handles read only file systems and media,
1963  *	as well as the "noatime" flag and inode specific "noatime" markers.
1964  */
atime_needs_update(const struct path * path,struct inode * inode)1965 bool atime_needs_update(const struct path *path, struct inode *inode)
1966 {
1967 	struct vfsmount *mnt = path->mnt;
1968 	struct timespec64 now;
1969 
1970 	if (inode->i_flags & S_NOATIME)
1971 		return false;
1972 
1973 	/* Atime updates will likely cause i_uid and i_gid to be written
1974 	 * back improprely if their true value is unknown to the vfs.
1975 	 */
1976 	if (HAS_UNMAPPED_ID(mnt_idmap(mnt), inode))
1977 		return false;
1978 
1979 	if (IS_NOATIME(inode))
1980 		return false;
1981 	if ((inode->i_sb->s_flags & SB_NODIRATIME) && S_ISDIR(inode->i_mode))
1982 		return false;
1983 
1984 	if (mnt->mnt_flags & MNT_NOATIME)
1985 		return false;
1986 	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1987 		return false;
1988 
1989 	now = current_time(inode);
1990 
1991 	if (!relatime_need_update(mnt, inode, now))
1992 		return false;
1993 
1994 	if (timespec64_equal(&inode->i_atime, &now))
1995 		return false;
1996 
1997 	return true;
1998 }
1999 
touch_atime(const struct path * path)2000 void touch_atime(const struct path *path)
2001 {
2002 	struct vfsmount *mnt = path->mnt;
2003 	struct inode *inode = d_inode(path->dentry);
2004 
2005 	if (!atime_needs_update(path, inode))
2006 		return;
2007 
2008 	if (!sb_start_write_trylock(inode->i_sb))
2009 		return;
2010 
2011 	if (__mnt_want_write(mnt) != 0)
2012 		goto skip_update;
2013 	/*
2014 	 * File systems can error out when updating inodes if they need to
2015 	 * allocate new space to modify an inode (such is the case for
2016 	 * Btrfs), but since we touch atime while walking down the path we
2017 	 * really don't care if we failed to update the atime of the file,
2018 	 * so just ignore the return value.
2019 	 * We may also fail on filesystems that have the ability to make parts
2020 	 * of the fs read only, e.g. subvolumes in Btrfs.
2021 	 */
2022 	inode_update_time(inode, S_ATIME);
2023 	__mnt_drop_write(mnt);
2024 skip_update:
2025 	sb_end_write(inode->i_sb);
2026 }
2027 EXPORT_SYMBOL(touch_atime);
2028 
2029 /*
2030  * Return mask of changes for notify_change() that need to be done as a
2031  * response to write or truncate. Return 0 if nothing has to be changed.
2032  * Negative value on error (change should be denied).
2033  */
dentry_needs_remove_privs(struct mnt_idmap * idmap,struct dentry * dentry)2034 int dentry_needs_remove_privs(struct mnt_idmap *idmap,
2035 			      struct dentry *dentry)
2036 {
2037 	struct inode *inode = d_inode(dentry);
2038 	int mask = 0;
2039 	int ret;
2040 
2041 	if (IS_NOSEC(inode))
2042 		return 0;
2043 
2044 	mask = setattr_should_drop_suidgid(idmap, inode);
2045 	ret = security_inode_need_killpriv(dentry);
2046 	if (ret < 0)
2047 		return ret;
2048 	if (ret)
2049 		mask |= ATTR_KILL_PRIV;
2050 	return mask;
2051 }
2052 
__remove_privs(struct mnt_idmap * idmap,struct dentry * dentry,int kill)2053 static int __remove_privs(struct mnt_idmap *idmap,
2054 			  struct dentry *dentry, int kill)
2055 {
2056 	struct iattr newattrs;
2057 
2058 	newattrs.ia_valid = ATTR_FORCE | kill;
2059 	/*
2060 	 * Note we call this on write, so notify_change will not
2061 	 * encounter any conflicting delegations:
2062 	 */
2063 	return notify_change(idmap, dentry, &newattrs, NULL);
2064 }
2065 
__file_remove_privs(struct file * file,unsigned int flags)2066 static int __file_remove_privs(struct file *file, unsigned int flags)
2067 {
2068 	struct dentry *dentry = file_dentry(file);
2069 	struct inode *inode = file_inode(file);
2070 	int error = 0;
2071 	int kill;
2072 
2073 	if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
2074 		return 0;
2075 
2076 	kill = dentry_needs_remove_privs(file_mnt_idmap(file), dentry);
2077 	if (kill < 0)
2078 		return kill;
2079 
2080 	if (kill) {
2081 		if (flags & IOCB_NOWAIT)
2082 			return -EAGAIN;
2083 
2084 		error = __remove_privs(file_mnt_idmap(file), dentry, kill);
2085 	}
2086 
2087 	if (!error)
2088 		inode_has_no_xattr(inode);
2089 	return error;
2090 }
2091 
2092 /**
2093  * file_remove_privs - remove special file privileges (suid, capabilities)
2094  * @file: file to remove privileges from
2095  *
2096  * When file is modified by a write or truncation ensure that special
2097  * file privileges are removed.
2098  *
2099  * Return: 0 on success, negative errno on failure.
2100  */
file_remove_privs(struct file * file)2101 int file_remove_privs(struct file *file)
2102 {
2103 	return __file_remove_privs(file, 0);
2104 }
2105 EXPORT_SYMBOL(file_remove_privs);
2106 
inode_needs_update_time(struct inode * inode)2107 static int inode_needs_update_time(struct inode *inode)
2108 {
2109 	int sync_it = 0;
2110 	struct timespec64 now = current_time(inode);
2111 	struct timespec64 ctime;
2112 
2113 	/* First try to exhaust all avenues to not sync */
2114 	if (IS_NOCMTIME(inode))
2115 		return 0;
2116 
2117 	if (!timespec64_equal(&inode->i_mtime, &now))
2118 		sync_it = S_MTIME;
2119 
2120 	ctime = inode_get_ctime(inode);
2121 	if (!timespec64_equal(&ctime, &now))
2122 		sync_it |= S_CTIME;
2123 
2124 	if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
2125 		sync_it |= S_VERSION;
2126 
2127 	return sync_it;
2128 }
2129 
__file_update_time(struct file * file,int sync_mode)2130 static int __file_update_time(struct file *file, int sync_mode)
2131 {
2132 	int ret = 0;
2133 	struct inode *inode = file_inode(file);
2134 
2135 	/* try to update time settings */
2136 	if (!__mnt_want_write_file(file)) {
2137 		ret = inode_update_time(inode, sync_mode);
2138 		__mnt_drop_write_file(file);
2139 	}
2140 
2141 	return ret;
2142 }
2143 
2144 /**
2145  * file_update_time - update mtime and ctime time
2146  * @file: file accessed
2147  *
2148  * Update the mtime and ctime members of an inode and mark the inode for
2149  * writeback. Note that this function is meant exclusively for usage in
2150  * the file write path of filesystems, and filesystems may choose to
2151  * explicitly ignore updates via this function with the _NOCMTIME inode
2152  * flag, e.g. for network filesystem where these imestamps are handled
2153  * by the server. This can return an error for file systems who need to
2154  * allocate space in order to update an inode.
2155  *
2156  * Return: 0 on success, negative errno on failure.
2157  */
file_update_time(struct file * file)2158 int file_update_time(struct file *file)
2159 {
2160 	int ret;
2161 	struct inode *inode = file_inode(file);
2162 
2163 	ret = inode_needs_update_time(inode);
2164 	if (ret <= 0)
2165 		return ret;
2166 
2167 	return __file_update_time(file, ret);
2168 }
2169 EXPORT_SYMBOL(file_update_time);
2170 
2171 /**
2172  * file_modified_flags - handle mandated vfs changes when modifying a file
2173  * @file: file that was modified
2174  * @flags: kiocb flags
2175  *
2176  * When file has been modified ensure that special
2177  * file privileges are removed and time settings are updated.
2178  *
2179  * If IOCB_NOWAIT is set, special file privileges will not be removed and
2180  * time settings will not be updated. It will return -EAGAIN.
2181  *
2182  * Context: Caller must hold the file's inode lock.
2183  *
2184  * Return: 0 on success, negative errno on failure.
2185  */
file_modified_flags(struct file * file,int flags)2186 static int file_modified_flags(struct file *file, int flags)
2187 {
2188 	int ret;
2189 	struct inode *inode = file_inode(file);
2190 
2191 	/*
2192 	 * Clear the security bits if the process is not being run by root.
2193 	 * This keeps people from modifying setuid and setgid binaries.
2194 	 */
2195 	ret = __file_remove_privs(file, flags);
2196 	if (ret)
2197 		return ret;
2198 
2199 	if (unlikely(file->f_mode & FMODE_NOCMTIME))
2200 		return 0;
2201 
2202 	ret = inode_needs_update_time(inode);
2203 	if (ret <= 0)
2204 		return ret;
2205 	if (flags & IOCB_NOWAIT)
2206 		return -EAGAIN;
2207 
2208 	return __file_update_time(file, ret);
2209 }
2210 
2211 /**
2212  * file_modified - handle mandated vfs changes when modifying a file
2213  * @file: file that was modified
2214  *
2215  * When file has been modified ensure that special
2216  * file privileges are removed and time settings are updated.
2217  *
2218  * Context: Caller must hold the file's inode lock.
2219  *
2220  * Return: 0 on success, negative errno on failure.
2221  */
file_modified(struct file * file)2222 int file_modified(struct file *file)
2223 {
2224 	return file_modified_flags(file, 0);
2225 }
2226 EXPORT_SYMBOL(file_modified);
2227 
2228 /**
2229  * kiocb_modified - handle mandated vfs changes when modifying a file
2230  * @iocb: iocb that was modified
2231  *
2232  * When file has been modified ensure that special
2233  * file privileges are removed and time settings are updated.
2234  *
2235  * Context: Caller must hold the file's inode lock.
2236  *
2237  * Return: 0 on success, negative errno on failure.
2238  */
kiocb_modified(struct kiocb * iocb)2239 int kiocb_modified(struct kiocb *iocb)
2240 {
2241 	return file_modified_flags(iocb->ki_filp, iocb->ki_flags);
2242 }
2243 EXPORT_SYMBOL_GPL(kiocb_modified);
2244 
inode_needs_sync(struct inode * inode)2245 int inode_needs_sync(struct inode *inode)
2246 {
2247 	if (IS_SYNC(inode))
2248 		return 1;
2249 	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
2250 		return 1;
2251 	return 0;
2252 }
2253 EXPORT_SYMBOL(inode_needs_sync);
2254 
2255 /*
2256  * If we try to find an inode in the inode hash while it is being
2257  * deleted, we have to wait until the filesystem completes its
2258  * deletion before reporting that it isn't found.  This function waits
2259  * until the deletion _might_ have completed.  Callers are responsible
2260  * to recheck inode state.
2261  *
2262  * It doesn't matter if I_NEW is not set initially, a call to
2263  * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
2264  * will DTRT.
2265  */
__wait_on_freeing_inode(struct inode * inode)2266 static void __wait_on_freeing_inode(struct inode *inode)
2267 {
2268 	wait_queue_head_t *wq;
2269 	DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
2270 	wq = bit_waitqueue(&inode->i_state, __I_NEW);
2271 	prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
2272 	spin_unlock(&inode->i_lock);
2273 	spin_unlock(&inode_hash_lock);
2274 	schedule();
2275 	finish_wait(wq, &wait.wq_entry);
2276 	spin_lock(&inode_hash_lock);
2277 }
2278 
2279 static __initdata unsigned long ihash_entries;
set_ihash_entries(char * str)2280 static int __init set_ihash_entries(char *str)
2281 {
2282 	if (!str)
2283 		return 0;
2284 	ihash_entries = simple_strtoul(str, &str, 0);
2285 	return 1;
2286 }
2287 __setup("ihash_entries=", set_ihash_entries);
2288 
2289 /*
2290  * Initialize the waitqueues and inode hash table.
2291  */
inode_init_early(void)2292 void __init inode_init_early(void)
2293 {
2294 	/* If hashes are distributed across NUMA nodes, defer
2295 	 * hash allocation until vmalloc space is available.
2296 	 */
2297 	if (hashdist)
2298 		return;
2299 
2300 	inode_hashtable =
2301 		alloc_large_system_hash("Inode-cache",
2302 					sizeof(struct hlist_head),
2303 					ihash_entries,
2304 					14,
2305 					HASH_EARLY | HASH_ZERO,
2306 					&i_hash_shift,
2307 					&i_hash_mask,
2308 					0,
2309 					0);
2310 }
2311 
inode_init(void)2312 void __init inode_init(void)
2313 {
2314 	/* inode slab cache */
2315 	inode_cachep = kmem_cache_create("inode_cache",
2316 					 sizeof(struct inode),
2317 					 0,
2318 					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
2319 					 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
2320 					 init_once);
2321 
2322 	/* Hash may have been set up in inode_init_early */
2323 	if (!hashdist)
2324 		return;
2325 
2326 	inode_hashtable =
2327 		alloc_large_system_hash("Inode-cache",
2328 					sizeof(struct hlist_head),
2329 					ihash_entries,
2330 					14,
2331 					HASH_ZERO,
2332 					&i_hash_shift,
2333 					&i_hash_mask,
2334 					0,
2335 					0);
2336 }
2337 
init_special_inode(struct inode * inode,umode_t mode,dev_t rdev)2338 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
2339 {
2340 	inode->i_mode = mode;
2341 	if (S_ISCHR(mode)) {
2342 		inode->i_fop = &def_chr_fops;
2343 		inode->i_rdev = rdev;
2344 	} else if (S_ISBLK(mode)) {
2345 		if (IS_ENABLED(CONFIG_BLOCK))
2346 			inode->i_fop = &def_blk_fops;
2347 		inode->i_rdev = rdev;
2348 	} else if (S_ISFIFO(mode))
2349 		inode->i_fop = &pipefifo_fops;
2350 	else if (S_ISSOCK(mode))
2351 		;	/* leave it no_open_fops */
2352 	else
2353 		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
2354 				  " inode %s:%lu\n", mode, inode->i_sb->s_id,
2355 				  inode->i_ino);
2356 }
2357 EXPORT_SYMBOL(init_special_inode);
2358 
2359 /**
2360  * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
2361  * @idmap: idmap of the mount the inode was created from
2362  * @inode: New inode
2363  * @dir: Directory inode
2364  * @mode: mode of the new inode
2365  *
2366  * If the inode has been created through an idmapped mount the idmap of
2367  * the vfsmount must be passed through @idmap. This function will then take
2368  * care to map the inode according to @idmap before checking permissions
2369  * and initializing i_uid and i_gid. On non-idmapped mounts or if permission
2370  * checking is to be performed on the raw inode simply pass @nop_mnt_idmap.
2371  */
inode_init_owner(struct mnt_idmap * idmap,struct inode * inode,const struct inode * dir,umode_t mode)2372 void inode_init_owner(struct mnt_idmap *idmap, struct inode *inode,
2373 		      const struct inode *dir, umode_t mode)
2374 {
2375 	inode_fsuid_set(inode, idmap);
2376 	if (dir && dir->i_mode & S_ISGID) {
2377 		inode->i_gid = dir->i_gid;
2378 
2379 		/* Directories are special, and always inherit S_ISGID */
2380 		if (S_ISDIR(mode))
2381 			mode |= S_ISGID;
2382 	} else
2383 		inode_fsgid_set(inode, idmap);
2384 	inode->i_mode = mode;
2385 }
2386 EXPORT_SYMBOL(inode_init_owner);
2387 
2388 /**
2389  * inode_owner_or_capable - check current task permissions to inode
2390  * @idmap: idmap of the mount the inode was found from
2391  * @inode: inode being checked
2392  *
2393  * Return true if current either has CAP_FOWNER in a namespace with the
2394  * inode owner uid mapped, or owns the file.
2395  *
2396  * If the inode has been found through an idmapped mount the idmap of
2397  * the vfsmount must be passed through @idmap. This function will then take
2398  * care to map the inode according to @idmap before checking permissions.
2399  * On non-idmapped mounts or if permission checking is to be performed on the
2400  * raw inode simply passs @nop_mnt_idmap.
2401  */
inode_owner_or_capable(struct mnt_idmap * idmap,const struct inode * inode)2402 bool inode_owner_or_capable(struct mnt_idmap *idmap,
2403 			    const struct inode *inode)
2404 {
2405 	vfsuid_t vfsuid;
2406 	struct user_namespace *ns;
2407 
2408 	vfsuid = i_uid_into_vfsuid(idmap, inode);
2409 	if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
2410 		return true;
2411 
2412 	ns = current_user_ns();
2413 	if (vfsuid_has_mapping(ns, vfsuid) && ns_capable(ns, CAP_FOWNER))
2414 		return true;
2415 	return false;
2416 }
2417 EXPORT_SYMBOL(inode_owner_or_capable);
2418 
2419 /*
2420  * Direct i/o helper functions
2421  */
__inode_dio_wait(struct inode * inode)2422 static void __inode_dio_wait(struct inode *inode)
2423 {
2424 	wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP);
2425 	DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP);
2426 
2427 	do {
2428 		prepare_to_wait(wq, &q.wq_entry, TASK_UNINTERRUPTIBLE);
2429 		if (atomic_read(&inode->i_dio_count))
2430 			schedule();
2431 	} while (atomic_read(&inode->i_dio_count));
2432 	finish_wait(wq, &q.wq_entry);
2433 }
2434 
2435 /**
2436  * inode_dio_wait - wait for outstanding DIO requests to finish
2437  * @inode: inode to wait for
2438  *
2439  * Waits for all pending direct I/O requests to finish so that we can
2440  * proceed with a truncate or equivalent operation.
2441  *
2442  * Must be called under a lock that serializes taking new references
2443  * to i_dio_count, usually by inode->i_mutex.
2444  */
inode_dio_wait(struct inode * inode)2445 void inode_dio_wait(struct inode *inode)
2446 {
2447 	if (atomic_read(&inode->i_dio_count))
2448 		__inode_dio_wait(inode);
2449 }
2450 EXPORT_SYMBOL(inode_dio_wait);
2451 
2452 /*
2453  * inode_set_flags - atomically set some inode flags
2454  *
2455  * Note: the caller should be holding i_mutex, or else be sure that
2456  * they have exclusive access to the inode structure (i.e., while the
2457  * inode is being instantiated).  The reason for the cmpxchg() loop
2458  * --- which wouldn't be necessary if all code paths which modify
2459  * i_flags actually followed this rule, is that there is at least one
2460  * code path which doesn't today so we use cmpxchg() out of an abundance
2461  * of caution.
2462  *
2463  * In the long run, i_mutex is overkill, and we should probably look
2464  * at using the i_lock spinlock to protect i_flags, and then make sure
2465  * it is so documented in include/linux/fs.h and that all code follows
2466  * the locking convention!!
2467  */
inode_set_flags(struct inode * inode,unsigned int flags,unsigned int mask)2468 void inode_set_flags(struct inode *inode, unsigned int flags,
2469 		     unsigned int mask)
2470 {
2471 	WARN_ON_ONCE(flags & ~mask);
2472 	set_mask_bits(&inode->i_flags, mask, flags);
2473 }
2474 EXPORT_SYMBOL(inode_set_flags);
2475 
inode_nohighmem(struct inode * inode)2476 void inode_nohighmem(struct inode *inode)
2477 {
2478 	mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
2479 }
2480 EXPORT_SYMBOL(inode_nohighmem);
2481 
2482 /**
2483  * timestamp_truncate - Truncate timespec to a granularity
2484  * @t: Timespec
2485  * @inode: inode being updated
2486  *
2487  * Truncate a timespec to the granularity supported by the fs
2488  * containing the inode. Always rounds down. gran must
2489  * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
2490  */
timestamp_truncate(struct timespec64 t,struct inode * inode)2491 struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
2492 {
2493 	struct super_block *sb = inode->i_sb;
2494 	unsigned int gran = sb->s_time_gran;
2495 
2496 	t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);
2497 	if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))
2498 		t.tv_nsec = 0;
2499 
2500 	/* Avoid division in the common cases 1 ns and 1 s. */
2501 	if (gran == 1)
2502 		; /* nothing */
2503 	else if (gran == NSEC_PER_SEC)
2504 		t.tv_nsec = 0;
2505 	else if (gran > 1 && gran < NSEC_PER_SEC)
2506 		t.tv_nsec -= t.tv_nsec % gran;
2507 	else
2508 		WARN(1, "invalid file time granularity: %u", gran);
2509 	return t;
2510 }
2511 EXPORT_SYMBOL(timestamp_truncate);
2512 
2513 /**
2514  * current_time - Return FS time
2515  * @inode: inode.
2516  *
2517  * Return the current time truncated to the time granularity supported by
2518  * the fs.
2519  *
2520  * Note that inode and inode->sb cannot be NULL.
2521  * Otherwise, the function warns and returns time without truncation.
2522  */
current_time(struct inode * inode)2523 struct timespec64 current_time(struct inode *inode)
2524 {
2525 	struct timespec64 now;
2526 
2527 	ktime_get_coarse_real_ts64(&now);
2528 	return timestamp_truncate(now, inode);
2529 }
2530 EXPORT_SYMBOL(current_time);
2531 
2532 /**
2533  * inode_set_ctime_current - set the ctime to current_time
2534  * @inode: inode
2535  *
2536  * Set the inode->i_ctime to the current value for the inode. Returns
2537  * the current value that was assigned to i_ctime.
2538  */
inode_set_ctime_current(struct inode * inode)2539 struct timespec64 inode_set_ctime_current(struct inode *inode)
2540 {
2541 	struct timespec64 now = current_time(inode);
2542 
2543 	inode_set_ctime(inode, now.tv_sec, now.tv_nsec);
2544 	return now;
2545 }
2546 EXPORT_SYMBOL(inode_set_ctime_current);
2547 
2548 /**
2549  * in_group_or_capable - check whether caller is CAP_FSETID privileged
2550  * @idmap:	idmap of the mount @inode was found from
2551  * @inode:	inode to check
2552  * @vfsgid:	the new/current vfsgid of @inode
2553  *
2554  * Check wether @vfsgid is in the caller's group list or if the caller is
2555  * privileged with CAP_FSETID over @inode. This can be used to determine
2556  * whether the setgid bit can be kept or must be dropped.
2557  *
2558  * Return: true if the caller is sufficiently privileged, false if not.
2559  */
in_group_or_capable(struct mnt_idmap * idmap,const struct inode * inode,vfsgid_t vfsgid)2560 bool in_group_or_capable(struct mnt_idmap *idmap,
2561 			 const struct inode *inode, vfsgid_t vfsgid)
2562 {
2563 	if (vfsgid_in_group_p(vfsgid))
2564 		return true;
2565 	if (capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
2566 		return true;
2567 	return false;
2568 }
2569 
2570 /**
2571  * mode_strip_sgid - handle the sgid bit for non-directories
2572  * @idmap: idmap of the mount the inode was created from
2573  * @dir: parent directory inode
2574  * @mode: mode of the file to be created in @dir
2575  *
2576  * If the @mode of the new file has both the S_ISGID and S_IXGRP bit
2577  * raised and @dir has the S_ISGID bit raised ensure that the caller is
2578  * either in the group of the parent directory or they have CAP_FSETID
2579  * in their user namespace and are privileged over the parent directory.
2580  * In all other cases, strip the S_ISGID bit from @mode.
2581  *
2582  * Return: the new mode to use for the file
2583  */
mode_strip_sgid(struct mnt_idmap * idmap,const struct inode * dir,umode_t mode)2584 umode_t mode_strip_sgid(struct mnt_idmap *idmap,
2585 			const struct inode *dir, umode_t mode)
2586 {
2587 	if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP))
2588 		return mode;
2589 	if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID))
2590 		return mode;
2591 	if (in_group_or_capable(idmap, dir, i_gid_into_vfsgid(idmap, dir)))
2592 		return mode;
2593 	return mode & ~S_ISGID;
2594 }
2595 EXPORT_SYMBOL(mode_strip_sgid);
2596