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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/mm.h>
9 #include <linux/backing-dev.h>
10 #include <linux/hash.h>
11 #include <linux/swap.h>
12 #include <linux/security.h>
13 #include <linux/cdev.h>
14 #include <linux/memblock.h>
15 #include <linux/fsnotify.h>
16 #include <linux/mount.h>
17 #include <linux/posix_acl.h>
18 #include <linux/prefetch.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  * @kill_dirty: flag to guide handling of dirty inodes
757  *
758  * Attempts to free all inodes for a given superblock.  If there were any
759  * busy inodes return a non-zero value, else zero.
760  * If @kill_dirty is set, discard dirty inodes too, otherwise treat
761  * them as busy.
762  */
invalidate_inodes(struct super_block * sb,bool kill_dirty)763 int invalidate_inodes(struct super_block *sb, bool kill_dirty)
764 {
765 	int busy = 0;
766 	struct inode *inode, *next;
767 	LIST_HEAD(dispose);
768 
769 again:
770 	spin_lock(&sb->s_inode_list_lock);
771 	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
772 		spin_lock(&inode->i_lock);
773 		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
774 			spin_unlock(&inode->i_lock);
775 			continue;
776 		}
777 		if (inode->i_state & I_DIRTY_ALL && !kill_dirty) {
778 			spin_unlock(&inode->i_lock);
779 			busy = 1;
780 			continue;
781 		}
782 		if (atomic_read(&inode->i_count)) {
783 			spin_unlock(&inode->i_lock);
784 			busy = 1;
785 			continue;
786 		}
787 
788 		inode->i_state |= I_FREEING;
789 		inode_lru_list_del(inode);
790 		spin_unlock(&inode->i_lock);
791 		list_add(&inode->i_lru, &dispose);
792 		if (need_resched()) {
793 			spin_unlock(&sb->s_inode_list_lock);
794 			cond_resched();
795 			dispose_list(&dispose);
796 			goto again;
797 		}
798 	}
799 	spin_unlock(&sb->s_inode_list_lock);
800 
801 	dispose_list(&dispose);
802 
803 	return busy;
804 }
805 
806 /*
807  * Isolate the inode from the LRU in preparation for freeing it.
808  *
809  * If the inode has the I_REFERENCED flag set, then it means that it has been
810  * used recently - the flag is set in iput_final(). When we encounter such an
811  * inode, clear the flag and move it to the back of the LRU so it gets another
812  * pass through the LRU before it gets reclaimed. This is necessary because of
813  * the fact we are doing lazy LRU updates to minimise lock contention so the
814  * LRU does not have strict ordering. Hence we don't want to reclaim inodes
815  * with this flag set because they are the inodes that are out of order.
816  */
inode_lru_isolate(struct list_head * item,struct list_lru_one * lru,spinlock_t * lru_lock,void * arg)817 static enum lru_status inode_lru_isolate(struct list_head *item,
818 		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
819 {
820 	struct list_head *freeable = arg;
821 	struct inode	*inode = container_of(item, struct inode, i_lru);
822 
823 	/*
824 	 * We are inverting the lru lock/inode->i_lock here, so use a
825 	 * trylock. If we fail to get the lock, just skip it.
826 	 */
827 	if (!spin_trylock(&inode->i_lock))
828 		return LRU_SKIP;
829 
830 	/*
831 	 * Inodes can get referenced, redirtied, or repopulated while
832 	 * they're already on the LRU, and this can make them
833 	 * unreclaimable for a while. Remove them lazily here; iput,
834 	 * sync, or the last page cache deletion will requeue them.
835 	 */
836 	if (atomic_read(&inode->i_count) ||
837 	    (inode->i_state & ~I_REFERENCED) ||
838 	    !mapping_shrinkable(&inode->i_data)) {
839 		list_lru_isolate(lru, &inode->i_lru);
840 		spin_unlock(&inode->i_lock);
841 		this_cpu_dec(nr_unused);
842 		return LRU_REMOVED;
843 	}
844 
845 	/* Recently referenced inodes get one more pass */
846 	if (inode->i_state & I_REFERENCED) {
847 		inode->i_state &= ~I_REFERENCED;
848 		spin_unlock(&inode->i_lock);
849 		return LRU_ROTATE;
850 	}
851 
852 	/*
853 	 * On highmem systems, mapping_shrinkable() permits dropping
854 	 * page cache in order to free up struct inodes: lowmem might
855 	 * be under pressure before the cache inside the highmem zone.
856 	 */
857 	if (inode_has_buffers(inode) || !mapping_empty(&inode->i_data)) {
858 		__iget(inode);
859 		spin_unlock(&inode->i_lock);
860 		spin_unlock(lru_lock);
861 		if (remove_inode_buffers(inode)) {
862 			unsigned long reap;
863 			reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
864 			if (current_is_kswapd())
865 				__count_vm_events(KSWAPD_INODESTEAL, reap);
866 			else
867 				__count_vm_events(PGINODESTEAL, reap);
868 			if (current->reclaim_state)
869 				current->reclaim_state->reclaimed_slab += reap;
870 		}
871 		iput(inode);
872 		spin_lock(lru_lock);
873 		return LRU_RETRY;
874 	}
875 
876 	WARN_ON(inode->i_state & I_NEW);
877 	inode->i_state |= I_FREEING;
878 	list_lru_isolate_move(lru, &inode->i_lru, freeable);
879 	spin_unlock(&inode->i_lock);
880 
881 	this_cpu_dec(nr_unused);
882 	return LRU_REMOVED;
883 }
884 
885 /*
886  * Walk the superblock inode LRU for freeable inodes and attempt to free them.
887  * This is called from the superblock shrinker function with a number of inodes
888  * to trim from the LRU. Inodes to be freed are moved to a temporary list and
889  * then are freed outside inode_lock by dispose_list().
890  */
prune_icache_sb(struct super_block * sb,struct shrink_control * sc)891 long prune_icache_sb(struct super_block *sb, struct shrink_control *sc)
892 {
893 	LIST_HEAD(freeable);
894 	long freed;
895 
896 	freed = list_lru_shrink_walk(&sb->s_inode_lru, sc,
897 				     inode_lru_isolate, &freeable);
898 	dispose_list(&freeable);
899 	return freed;
900 }
901 
902 static void __wait_on_freeing_inode(struct inode *inode);
903 /*
904  * Called with the inode lock held.
905  */
find_inode(struct super_block * sb,struct hlist_head * head,int (* test)(struct inode *,void *),void * data)906 static struct inode *find_inode(struct super_block *sb,
907 				struct hlist_head *head,
908 				int (*test)(struct inode *, void *),
909 				void *data)
910 {
911 	struct inode *inode = NULL;
912 
913 repeat:
914 	hlist_for_each_entry(inode, head, i_hash) {
915 		if (inode->i_sb != sb)
916 			continue;
917 		if (!test(inode, data))
918 			continue;
919 		spin_lock(&inode->i_lock);
920 		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
921 			__wait_on_freeing_inode(inode);
922 			goto repeat;
923 		}
924 		if (unlikely(inode->i_state & I_CREATING)) {
925 			spin_unlock(&inode->i_lock);
926 			return ERR_PTR(-ESTALE);
927 		}
928 		__iget(inode);
929 		spin_unlock(&inode->i_lock);
930 		return inode;
931 	}
932 	return NULL;
933 }
934 
935 /*
936  * find_inode_fast is the fast path version of find_inode, see the comment at
937  * iget_locked for details.
938  */
find_inode_fast(struct super_block * sb,struct hlist_head * head,unsigned long ino)939 static struct inode *find_inode_fast(struct super_block *sb,
940 				struct hlist_head *head, unsigned long ino)
941 {
942 	struct inode *inode = NULL;
943 
944 repeat:
945 	hlist_for_each_entry(inode, head, i_hash) {
946 		if (inode->i_ino != ino)
947 			continue;
948 		if (inode->i_sb != sb)
949 			continue;
950 		spin_lock(&inode->i_lock);
951 		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
952 			__wait_on_freeing_inode(inode);
953 			goto repeat;
954 		}
955 		if (unlikely(inode->i_state & I_CREATING)) {
956 			spin_unlock(&inode->i_lock);
957 			return ERR_PTR(-ESTALE);
958 		}
959 		__iget(inode);
960 		spin_unlock(&inode->i_lock);
961 		return inode;
962 	}
963 	return NULL;
964 }
965 
966 /*
967  * Each cpu owns a range of LAST_INO_BATCH numbers.
968  * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
969  * to renew the exhausted range.
970  *
971  * This does not significantly increase overflow rate because every CPU can
972  * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
973  * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
974  * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
975  * overflow rate by 2x, which does not seem too significant.
976  *
977  * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
978  * error if st_ino won't fit in target struct field. Use 32bit counter
979  * here to attempt to avoid that.
980  */
981 #define LAST_INO_BATCH 1024
982 static DEFINE_PER_CPU(unsigned int, last_ino);
983 
get_next_ino(void)984 unsigned int get_next_ino(void)
985 {
986 	unsigned int *p = &get_cpu_var(last_ino);
987 	unsigned int res = *p;
988 
989 #ifdef CONFIG_SMP
990 	if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
991 		static atomic_t shared_last_ino;
992 		int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
993 
994 		res = next - LAST_INO_BATCH;
995 	}
996 #endif
997 
998 	res++;
999 	/* get_next_ino should not provide a 0 inode number */
1000 	if (unlikely(!res))
1001 		res++;
1002 	*p = res;
1003 	put_cpu_var(last_ino);
1004 	return res;
1005 }
1006 EXPORT_SYMBOL(get_next_ino);
1007 
1008 /**
1009  *	new_inode_pseudo 	- obtain an inode
1010  *	@sb: superblock
1011  *
1012  *	Allocates a new inode for given superblock.
1013  *	Inode wont be chained in superblock s_inodes list
1014  *	This means :
1015  *	- fs can't be unmount
1016  *	- quotas, fsnotify, writeback can't work
1017  */
new_inode_pseudo(struct super_block * sb)1018 struct inode *new_inode_pseudo(struct super_block *sb)
1019 {
1020 	struct inode *inode = alloc_inode(sb);
1021 
1022 	if (inode) {
1023 		spin_lock(&inode->i_lock);
1024 		inode->i_state = 0;
1025 		spin_unlock(&inode->i_lock);
1026 	}
1027 	return inode;
1028 }
1029 
1030 /**
1031  *	new_inode 	- obtain an inode
1032  *	@sb: superblock
1033  *
1034  *	Allocates a new inode for given superblock. The default gfp_mask
1035  *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
1036  *	If HIGHMEM pages are unsuitable or it is known that pages allocated
1037  *	for the page cache are not reclaimable or migratable,
1038  *	mapping_set_gfp_mask() must be called with suitable flags on the
1039  *	newly created inode's mapping
1040  *
1041  */
new_inode(struct super_block * sb)1042 struct inode *new_inode(struct super_block *sb)
1043 {
1044 	struct inode *inode;
1045 
1046 	spin_lock_prefetch(&sb->s_inode_list_lock);
1047 
1048 	inode = new_inode_pseudo(sb);
1049 	if (inode)
1050 		inode_sb_list_add(inode);
1051 	return inode;
1052 }
1053 EXPORT_SYMBOL(new_inode);
1054 
1055 #ifdef CONFIG_DEBUG_LOCK_ALLOC
lockdep_annotate_inode_mutex_key(struct inode * inode)1056 void lockdep_annotate_inode_mutex_key(struct inode *inode)
1057 {
1058 	if (S_ISDIR(inode->i_mode)) {
1059 		struct file_system_type *type = inode->i_sb->s_type;
1060 
1061 		/* Set new key only if filesystem hasn't already changed it */
1062 		if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) {
1063 			/*
1064 			 * ensure nobody is actually holding i_mutex
1065 			 */
1066 			// mutex_destroy(&inode->i_mutex);
1067 			init_rwsem(&inode->i_rwsem);
1068 			lockdep_set_class(&inode->i_rwsem,
1069 					  &type->i_mutex_dir_key);
1070 		}
1071 	}
1072 }
1073 EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
1074 #endif
1075 
1076 /**
1077  * unlock_new_inode - clear the I_NEW state and wake up any waiters
1078  * @inode:	new inode to unlock
1079  *
1080  * Called when the inode is fully initialised to clear the new state of the
1081  * inode and wake up anyone waiting for the inode to finish initialisation.
1082  */
unlock_new_inode(struct inode * inode)1083 void unlock_new_inode(struct inode *inode)
1084 {
1085 	lockdep_annotate_inode_mutex_key(inode);
1086 	spin_lock(&inode->i_lock);
1087 	WARN_ON(!(inode->i_state & I_NEW));
1088 	inode->i_state &= ~I_NEW & ~I_CREATING;
1089 	smp_mb();
1090 	wake_up_bit(&inode->i_state, __I_NEW);
1091 	spin_unlock(&inode->i_lock);
1092 }
1093 EXPORT_SYMBOL(unlock_new_inode);
1094 
discard_new_inode(struct inode * inode)1095 void discard_new_inode(struct inode *inode)
1096 {
1097 	lockdep_annotate_inode_mutex_key(inode);
1098 	spin_lock(&inode->i_lock);
1099 	WARN_ON(!(inode->i_state & I_NEW));
1100 	inode->i_state &= ~I_NEW;
1101 	smp_mb();
1102 	wake_up_bit(&inode->i_state, __I_NEW);
1103 	spin_unlock(&inode->i_lock);
1104 	iput(inode);
1105 }
1106 EXPORT_SYMBOL(discard_new_inode);
1107 
1108 /**
1109  * lock_two_inodes - lock two inodes (may be regular files but also dirs)
1110  *
1111  * Lock any non-NULL argument. The caller must make sure that if he is passing
1112  * in two directories, one is not ancestor of the other.  Zero, one or two
1113  * objects may be locked by this function.
1114  *
1115  * @inode1: first inode to lock
1116  * @inode2: second inode to lock
1117  * @subclass1: inode lock subclass for the first lock obtained
1118  * @subclass2: inode lock subclass for the second lock obtained
1119  */
lock_two_inodes(struct inode * inode1,struct inode * inode2,unsigned subclass1,unsigned subclass2)1120 void lock_two_inodes(struct inode *inode1, struct inode *inode2,
1121 		     unsigned subclass1, unsigned subclass2)
1122 {
1123 	if (!inode1 || !inode2) {
1124 		/*
1125 		 * Make sure @subclass1 will be used for the acquired lock.
1126 		 * This is not strictly necessary (no current caller cares) but
1127 		 * let's keep things consistent.
1128 		 */
1129 		if (!inode1)
1130 			swap(inode1, inode2);
1131 		goto lock;
1132 	}
1133 
1134 	/*
1135 	 * If one object is directory and the other is not, we must make sure
1136 	 * to lock directory first as the other object may be its child.
1137 	 */
1138 	if (S_ISDIR(inode2->i_mode) == S_ISDIR(inode1->i_mode)) {
1139 		if (inode1 > inode2)
1140 			swap(inode1, inode2);
1141 	} else if (!S_ISDIR(inode1->i_mode))
1142 		swap(inode1, inode2);
1143 lock:
1144 	if (inode1)
1145 		inode_lock_nested(inode1, subclass1);
1146 	if (inode2 && inode2 != inode1)
1147 		inode_lock_nested(inode2, subclass2);
1148 }
1149 
1150 /**
1151  * lock_two_nondirectories - take two i_mutexes on non-directory objects
1152  *
1153  * Lock any non-NULL argument that is not a directory.
1154  * Zero, one or two objects may be locked by this function.
1155  *
1156  * @inode1: first inode to lock
1157  * @inode2: second inode to lock
1158  */
lock_two_nondirectories(struct inode * inode1,struct inode * inode2)1159 void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1160 {
1161 	if (inode1 > inode2)
1162 		swap(inode1, inode2);
1163 
1164 	if (inode1 && !S_ISDIR(inode1->i_mode))
1165 		inode_lock(inode1);
1166 	if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
1167 		inode_lock_nested(inode2, I_MUTEX_NONDIR2);
1168 }
1169 EXPORT_SYMBOL(lock_two_nondirectories);
1170 
1171 /**
1172  * unlock_two_nondirectories - release locks from lock_two_nondirectories()
1173  * @inode1: first inode to unlock
1174  * @inode2: second inode to unlock
1175  */
unlock_two_nondirectories(struct inode * inode1,struct inode * inode2)1176 void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1177 {
1178 	if (inode1 && !S_ISDIR(inode1->i_mode))
1179 		inode_unlock(inode1);
1180 	if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
1181 		inode_unlock(inode2);
1182 }
1183 EXPORT_SYMBOL(unlock_two_nondirectories);
1184 
1185 /**
1186  * inode_insert5 - obtain an inode from a mounted file system
1187  * @inode:	pre-allocated inode to use for insert to cache
1188  * @hashval:	hash value (usually inode number) to get
1189  * @test:	callback used for comparisons between inodes
1190  * @set:	callback used to initialize a new struct inode
1191  * @data:	opaque data pointer to pass to @test and @set
1192  *
1193  * Search for the inode specified by @hashval and @data in the inode cache,
1194  * and if present it is return it with an increased reference count. This is
1195  * a variant of iget5_locked() for callers that don't want to fail on memory
1196  * allocation of inode.
1197  *
1198  * If the inode is not in cache, insert the pre-allocated inode to cache and
1199  * return it locked, hashed, and with the I_NEW flag set. The file system gets
1200  * to fill it in before unlocking it via unlock_new_inode().
1201  *
1202  * Note both @test and @set are called with the inode_hash_lock held, so can't
1203  * sleep.
1204  */
inode_insert5(struct inode * inode,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1205 struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
1206 			    int (*test)(struct inode *, void *),
1207 			    int (*set)(struct inode *, void *), void *data)
1208 {
1209 	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
1210 	struct inode *old;
1211 
1212 again:
1213 	spin_lock(&inode_hash_lock);
1214 	old = find_inode(inode->i_sb, head, test, data);
1215 	if (unlikely(old)) {
1216 		/*
1217 		 * Uhhuh, somebody else created the same inode under us.
1218 		 * Use the old inode instead of the preallocated one.
1219 		 */
1220 		spin_unlock(&inode_hash_lock);
1221 		if (IS_ERR(old))
1222 			return NULL;
1223 		wait_on_inode(old);
1224 		if (unlikely(inode_unhashed(old))) {
1225 			iput(old);
1226 			goto again;
1227 		}
1228 		return old;
1229 	}
1230 
1231 	if (set && unlikely(set(inode, data))) {
1232 		inode = NULL;
1233 		goto unlock;
1234 	}
1235 
1236 	/*
1237 	 * Return the locked inode with I_NEW set, the
1238 	 * caller is responsible for filling in the contents
1239 	 */
1240 	spin_lock(&inode->i_lock);
1241 	inode->i_state |= I_NEW;
1242 	hlist_add_head_rcu(&inode->i_hash, head);
1243 	spin_unlock(&inode->i_lock);
1244 
1245 	/*
1246 	 * Add inode to the sb list if it's not already. It has I_NEW at this
1247 	 * point, so it should be safe to test i_sb_list locklessly.
1248 	 */
1249 	if (list_empty(&inode->i_sb_list))
1250 		inode_sb_list_add(inode);
1251 unlock:
1252 	spin_unlock(&inode_hash_lock);
1253 
1254 	return inode;
1255 }
1256 EXPORT_SYMBOL(inode_insert5);
1257 
1258 /**
1259  * iget5_locked - obtain an inode from a mounted file system
1260  * @sb:		super block of file system
1261  * @hashval:	hash value (usually inode number) to get
1262  * @test:	callback used for comparisons between inodes
1263  * @set:	callback used to initialize a new struct inode
1264  * @data:	opaque data pointer to pass to @test and @set
1265  *
1266  * Search for the inode specified by @hashval and @data in the inode cache,
1267  * and if present it is return it with an increased reference count. This is
1268  * a generalized version of iget_locked() for file systems where the inode
1269  * number is not sufficient for unique identification of an inode.
1270  *
1271  * If the inode is not in cache, allocate a new inode and return it locked,
1272  * hashed, and with the I_NEW flag set. The file system gets to fill it in
1273  * before unlocking it via unlock_new_inode().
1274  *
1275  * Note both @test and @set are called with the inode_hash_lock held, so can't
1276  * sleep.
1277  */
iget5_locked(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1278 struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1279 		int (*test)(struct inode *, void *),
1280 		int (*set)(struct inode *, void *), void *data)
1281 {
1282 	struct inode *inode = ilookup5(sb, hashval, test, data);
1283 
1284 	if (!inode) {
1285 		struct inode *new = alloc_inode(sb);
1286 
1287 		if (new) {
1288 			new->i_state = 0;
1289 			inode = inode_insert5(new, hashval, test, set, data);
1290 			if (unlikely(inode != new))
1291 				destroy_inode(new);
1292 		}
1293 	}
1294 	return inode;
1295 }
1296 EXPORT_SYMBOL(iget5_locked);
1297 
1298 /**
1299  * iget_locked - obtain an inode from a mounted file system
1300  * @sb:		super block of file system
1301  * @ino:	inode number to get
1302  *
1303  * Search for the inode specified by @ino in the inode cache and if present
1304  * return it with an increased reference count. This is for file systems
1305  * where the inode number is sufficient for unique identification of an inode.
1306  *
1307  * If the inode is not in cache, allocate a new inode and return it locked,
1308  * hashed, and with the I_NEW flag set.  The file system gets to fill it in
1309  * before unlocking it via unlock_new_inode().
1310  */
iget_locked(struct super_block * sb,unsigned long ino)1311 struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1312 {
1313 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1314 	struct inode *inode;
1315 again:
1316 	spin_lock(&inode_hash_lock);
1317 	inode = find_inode_fast(sb, head, ino);
1318 	spin_unlock(&inode_hash_lock);
1319 	if (inode) {
1320 		if (IS_ERR(inode))
1321 			return NULL;
1322 		wait_on_inode(inode);
1323 		if (unlikely(inode_unhashed(inode))) {
1324 			iput(inode);
1325 			goto again;
1326 		}
1327 		return inode;
1328 	}
1329 
1330 	inode = alloc_inode(sb);
1331 	if (inode) {
1332 		struct inode *old;
1333 
1334 		spin_lock(&inode_hash_lock);
1335 		/* We released the lock, so.. */
1336 		old = find_inode_fast(sb, head, ino);
1337 		if (!old) {
1338 			inode->i_ino = ino;
1339 			spin_lock(&inode->i_lock);
1340 			inode->i_state = I_NEW;
1341 			hlist_add_head_rcu(&inode->i_hash, head);
1342 			spin_unlock(&inode->i_lock);
1343 			inode_sb_list_add(inode);
1344 			spin_unlock(&inode_hash_lock);
1345 
1346 			/* Return the locked inode with I_NEW set, the
1347 			 * caller is responsible for filling in the contents
1348 			 */
1349 			return inode;
1350 		}
1351 
1352 		/*
1353 		 * Uhhuh, somebody else created the same inode under
1354 		 * us. Use the old inode instead of the one we just
1355 		 * allocated.
1356 		 */
1357 		spin_unlock(&inode_hash_lock);
1358 		destroy_inode(inode);
1359 		if (IS_ERR(old))
1360 			return NULL;
1361 		inode = old;
1362 		wait_on_inode(inode);
1363 		if (unlikely(inode_unhashed(inode))) {
1364 			iput(inode);
1365 			goto again;
1366 		}
1367 	}
1368 	return inode;
1369 }
1370 EXPORT_SYMBOL(iget_locked);
1371 
1372 /*
1373  * search the inode cache for a matching inode number.
1374  * If we find one, then the inode number we are trying to
1375  * allocate is not unique and so we should not use it.
1376  *
1377  * Returns 1 if the inode number is unique, 0 if it is not.
1378  */
test_inode_iunique(struct super_block * sb,unsigned long ino)1379 static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1380 {
1381 	struct hlist_head *b = inode_hashtable + hash(sb, ino);
1382 	struct inode *inode;
1383 
1384 	hlist_for_each_entry_rcu(inode, b, i_hash) {
1385 		if (inode->i_ino == ino && inode->i_sb == sb)
1386 			return 0;
1387 	}
1388 	return 1;
1389 }
1390 
1391 /**
1392  *	iunique - get a unique inode number
1393  *	@sb: superblock
1394  *	@max_reserved: highest reserved inode number
1395  *
1396  *	Obtain an inode number that is unique on the system for a given
1397  *	superblock. This is used by file systems that have no natural
1398  *	permanent inode numbering system. An inode number is returned that
1399  *	is higher than the reserved limit but unique.
1400  *
1401  *	BUGS:
1402  *	With a large number of inodes live on the file system this function
1403  *	currently becomes quite slow.
1404  */
iunique(struct super_block * sb,ino_t max_reserved)1405 ino_t iunique(struct super_block *sb, ino_t max_reserved)
1406 {
1407 	/*
1408 	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1409 	 * error if st_ino won't fit in target struct field. Use 32bit counter
1410 	 * here to attempt to avoid that.
1411 	 */
1412 	static DEFINE_SPINLOCK(iunique_lock);
1413 	static unsigned int counter;
1414 	ino_t res;
1415 
1416 	rcu_read_lock();
1417 	spin_lock(&iunique_lock);
1418 	do {
1419 		if (counter <= max_reserved)
1420 			counter = max_reserved + 1;
1421 		res = counter++;
1422 	} while (!test_inode_iunique(sb, res));
1423 	spin_unlock(&iunique_lock);
1424 	rcu_read_unlock();
1425 
1426 	return res;
1427 }
1428 EXPORT_SYMBOL(iunique);
1429 
igrab(struct inode * inode)1430 struct inode *igrab(struct inode *inode)
1431 {
1432 	spin_lock(&inode->i_lock);
1433 	if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1434 		__iget(inode);
1435 		spin_unlock(&inode->i_lock);
1436 	} else {
1437 		spin_unlock(&inode->i_lock);
1438 		/*
1439 		 * Handle the case where s_op->clear_inode is not been
1440 		 * called yet, and somebody is calling igrab
1441 		 * while the inode is getting freed.
1442 		 */
1443 		inode = NULL;
1444 	}
1445 	return inode;
1446 }
1447 EXPORT_SYMBOL(igrab);
1448 
1449 /**
1450  * ilookup5_nowait - search for an inode in the inode cache
1451  * @sb:		super block of file system to search
1452  * @hashval:	hash value (usually inode number) to search for
1453  * @test:	callback used for comparisons between inodes
1454  * @data:	opaque data pointer to pass to @test
1455  *
1456  * Search for the inode specified by @hashval and @data in the inode cache.
1457  * If the inode is in the cache, the inode is returned with an incremented
1458  * reference count.
1459  *
1460  * Note: I_NEW is not waited upon so you have to be very careful what you do
1461  * with the returned inode.  You probably should be using ilookup5() instead.
1462  *
1463  * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1464  */
ilookup5_nowait(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1465 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1466 		int (*test)(struct inode *, void *), void *data)
1467 {
1468 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1469 	struct inode *inode;
1470 
1471 	spin_lock(&inode_hash_lock);
1472 	inode = find_inode(sb, head, test, data);
1473 	spin_unlock(&inode_hash_lock);
1474 
1475 	return IS_ERR(inode) ? NULL : inode;
1476 }
1477 EXPORT_SYMBOL(ilookup5_nowait);
1478 
1479 /**
1480  * ilookup5 - search for an inode in the inode cache
1481  * @sb:		super block of file system to search
1482  * @hashval:	hash value (usually inode number) to search for
1483  * @test:	callback used for comparisons between inodes
1484  * @data:	opaque data pointer to pass to @test
1485  *
1486  * Search for the inode specified by @hashval and @data in the inode cache,
1487  * and if the inode is in the cache, return the inode with an incremented
1488  * reference count.  Waits on I_NEW before returning the inode.
1489  * returned with an incremented reference count.
1490  *
1491  * This is a generalized version of ilookup() for file systems where the
1492  * inode number is not sufficient for unique identification of an inode.
1493  *
1494  * Note: @test is called with the inode_hash_lock held, so can't sleep.
1495  */
ilookup5(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1496 struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1497 		int (*test)(struct inode *, void *), void *data)
1498 {
1499 	struct inode *inode;
1500 again:
1501 	inode = ilookup5_nowait(sb, hashval, test, data);
1502 	if (inode) {
1503 		wait_on_inode(inode);
1504 		if (unlikely(inode_unhashed(inode))) {
1505 			iput(inode);
1506 			goto again;
1507 		}
1508 	}
1509 	return inode;
1510 }
1511 EXPORT_SYMBOL(ilookup5);
1512 
1513 /**
1514  * ilookup - search for an inode in the inode cache
1515  * @sb:		super block of file system to search
1516  * @ino:	inode number to search for
1517  *
1518  * Search for the inode @ino in the inode cache, and if the inode is in the
1519  * cache, the inode is returned with an incremented reference count.
1520  */
ilookup(struct super_block * sb,unsigned long ino)1521 struct inode *ilookup(struct super_block *sb, unsigned long ino)
1522 {
1523 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1524 	struct inode *inode;
1525 again:
1526 	spin_lock(&inode_hash_lock);
1527 	inode = find_inode_fast(sb, head, ino);
1528 	spin_unlock(&inode_hash_lock);
1529 
1530 	if (inode) {
1531 		if (IS_ERR(inode))
1532 			return NULL;
1533 		wait_on_inode(inode);
1534 		if (unlikely(inode_unhashed(inode))) {
1535 			iput(inode);
1536 			goto again;
1537 		}
1538 	}
1539 	return inode;
1540 }
1541 EXPORT_SYMBOL(ilookup);
1542 
1543 /**
1544  * find_inode_nowait - find an inode in the inode cache
1545  * @sb:		super block of file system to search
1546  * @hashval:	hash value (usually inode number) to search for
1547  * @match:	callback used for comparisons between inodes
1548  * @data:	opaque data pointer to pass to @match
1549  *
1550  * Search for the inode specified by @hashval and @data in the inode
1551  * cache, where the helper function @match will return 0 if the inode
1552  * does not match, 1 if the inode does match, and -1 if the search
1553  * should be stopped.  The @match function must be responsible for
1554  * taking the i_lock spin_lock and checking i_state for an inode being
1555  * freed or being initialized, and incrementing the reference count
1556  * before returning 1.  It also must not sleep, since it is called with
1557  * the inode_hash_lock spinlock held.
1558  *
1559  * This is a even more generalized version of ilookup5() when the
1560  * function must never block --- find_inode() can block in
1561  * __wait_on_freeing_inode() --- or when the caller can not increment
1562  * the reference count because the resulting iput() might cause an
1563  * inode eviction.  The tradeoff is that the @match funtion must be
1564  * very carefully implemented.
1565  */
find_inode_nowait(struct super_block * sb,unsigned long hashval,int (* match)(struct inode *,unsigned long,void *),void * data)1566 struct inode *find_inode_nowait(struct super_block *sb,
1567 				unsigned long hashval,
1568 				int (*match)(struct inode *, unsigned long,
1569 					     void *),
1570 				void *data)
1571 {
1572 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1573 	struct inode *inode, *ret_inode = NULL;
1574 	int mval;
1575 
1576 	spin_lock(&inode_hash_lock);
1577 	hlist_for_each_entry(inode, head, i_hash) {
1578 		if (inode->i_sb != sb)
1579 			continue;
1580 		mval = match(inode, hashval, data);
1581 		if (mval == 0)
1582 			continue;
1583 		if (mval == 1)
1584 			ret_inode = inode;
1585 		goto out;
1586 	}
1587 out:
1588 	spin_unlock(&inode_hash_lock);
1589 	return ret_inode;
1590 }
1591 EXPORT_SYMBOL(find_inode_nowait);
1592 
1593 /**
1594  * find_inode_rcu - find an inode in the inode cache
1595  * @sb:		Super block of file system to search
1596  * @hashval:	Key to hash
1597  * @test:	Function to test match on an inode
1598  * @data:	Data for test function
1599  *
1600  * Search for the inode specified by @hashval and @data in the inode cache,
1601  * where the helper function @test will return 0 if the inode does not match
1602  * and 1 if it does.  The @test function must be responsible for taking the
1603  * i_lock spin_lock and checking i_state for an inode being freed or being
1604  * initialized.
1605  *
1606  * If successful, this will return the inode for which the @test function
1607  * returned 1 and NULL otherwise.
1608  *
1609  * The @test function is not permitted to take a ref on any inode presented.
1610  * It is also not permitted to sleep.
1611  *
1612  * The caller must hold the RCU read lock.
1613  */
find_inode_rcu(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1614 struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval,
1615 			     int (*test)(struct inode *, void *), void *data)
1616 {
1617 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1618 	struct inode *inode;
1619 
1620 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1621 			 "suspicious find_inode_rcu() usage");
1622 
1623 	hlist_for_each_entry_rcu(inode, head, i_hash) {
1624 		if (inode->i_sb == sb &&
1625 		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)) &&
1626 		    test(inode, data))
1627 			return inode;
1628 	}
1629 	return NULL;
1630 }
1631 EXPORT_SYMBOL(find_inode_rcu);
1632 
1633 /**
1634  * find_inode_by_ino_rcu - Find an inode in the inode cache
1635  * @sb:		Super block of file system to search
1636  * @ino:	The inode number to match
1637  *
1638  * Search for the inode specified by @hashval and @data in the inode cache,
1639  * where the helper function @test will return 0 if the inode does not match
1640  * and 1 if it does.  The @test function must be responsible for taking the
1641  * i_lock spin_lock and checking i_state for an inode being freed or being
1642  * initialized.
1643  *
1644  * If successful, this will return the inode for which the @test function
1645  * returned 1 and NULL otherwise.
1646  *
1647  * The @test function is not permitted to take a ref on any inode presented.
1648  * It is also not permitted to sleep.
1649  *
1650  * The caller must hold the RCU read lock.
1651  */
find_inode_by_ino_rcu(struct super_block * sb,unsigned long ino)1652 struct inode *find_inode_by_ino_rcu(struct super_block *sb,
1653 				    unsigned long ino)
1654 {
1655 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1656 	struct inode *inode;
1657 
1658 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1659 			 "suspicious find_inode_by_ino_rcu() usage");
1660 
1661 	hlist_for_each_entry_rcu(inode, head, i_hash) {
1662 		if (inode->i_ino == ino &&
1663 		    inode->i_sb == sb &&
1664 		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)))
1665 		    return inode;
1666 	}
1667 	return NULL;
1668 }
1669 EXPORT_SYMBOL(find_inode_by_ino_rcu);
1670 
insert_inode_locked(struct inode * inode)1671 int insert_inode_locked(struct inode *inode)
1672 {
1673 	struct super_block *sb = inode->i_sb;
1674 	ino_t ino = inode->i_ino;
1675 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1676 
1677 	while (1) {
1678 		struct inode *old = NULL;
1679 		spin_lock(&inode_hash_lock);
1680 		hlist_for_each_entry(old, head, i_hash) {
1681 			if (old->i_ino != ino)
1682 				continue;
1683 			if (old->i_sb != sb)
1684 				continue;
1685 			spin_lock(&old->i_lock);
1686 			if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1687 				spin_unlock(&old->i_lock);
1688 				continue;
1689 			}
1690 			break;
1691 		}
1692 		if (likely(!old)) {
1693 			spin_lock(&inode->i_lock);
1694 			inode->i_state |= I_NEW | I_CREATING;
1695 			hlist_add_head_rcu(&inode->i_hash, head);
1696 			spin_unlock(&inode->i_lock);
1697 			spin_unlock(&inode_hash_lock);
1698 			return 0;
1699 		}
1700 		if (unlikely(old->i_state & I_CREATING)) {
1701 			spin_unlock(&old->i_lock);
1702 			spin_unlock(&inode_hash_lock);
1703 			return -EBUSY;
1704 		}
1705 		__iget(old);
1706 		spin_unlock(&old->i_lock);
1707 		spin_unlock(&inode_hash_lock);
1708 		wait_on_inode(old);
1709 		if (unlikely(!inode_unhashed(old))) {
1710 			iput(old);
1711 			return -EBUSY;
1712 		}
1713 		iput(old);
1714 	}
1715 }
1716 EXPORT_SYMBOL(insert_inode_locked);
1717 
insert_inode_locked4(struct inode * inode,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1718 int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1719 		int (*test)(struct inode *, void *), void *data)
1720 {
1721 	struct inode *old;
1722 
1723 	inode->i_state |= I_CREATING;
1724 	old = inode_insert5(inode, hashval, test, NULL, data);
1725 
1726 	if (old != inode) {
1727 		iput(old);
1728 		return -EBUSY;
1729 	}
1730 	return 0;
1731 }
1732 EXPORT_SYMBOL(insert_inode_locked4);
1733 
1734 
generic_delete_inode(struct inode * inode)1735 int generic_delete_inode(struct inode *inode)
1736 {
1737 	return 1;
1738 }
1739 EXPORT_SYMBOL(generic_delete_inode);
1740 
1741 /*
1742  * Called when we're dropping the last reference
1743  * to an inode.
1744  *
1745  * Call the FS "drop_inode()" function, defaulting to
1746  * the legacy UNIX filesystem behaviour.  If it tells
1747  * us to evict inode, do so.  Otherwise, retain inode
1748  * in cache if fs is alive, sync and evict if fs is
1749  * shutting down.
1750  */
iput_final(struct inode * inode)1751 static void iput_final(struct inode *inode)
1752 {
1753 	struct super_block *sb = inode->i_sb;
1754 	const struct super_operations *op = inode->i_sb->s_op;
1755 	unsigned long state;
1756 	int drop;
1757 
1758 	WARN_ON(inode->i_state & I_NEW);
1759 
1760 	if (op->drop_inode)
1761 		drop = op->drop_inode(inode);
1762 	else
1763 		drop = generic_drop_inode(inode);
1764 
1765 	if (!drop &&
1766 	    !(inode->i_state & I_DONTCACHE) &&
1767 	    (sb->s_flags & SB_ACTIVE)) {
1768 		__inode_add_lru(inode, true);
1769 		spin_unlock(&inode->i_lock);
1770 		return;
1771 	}
1772 
1773 	state = inode->i_state;
1774 	if (!drop) {
1775 		WRITE_ONCE(inode->i_state, state | I_WILL_FREE);
1776 		spin_unlock(&inode->i_lock);
1777 
1778 		write_inode_now(inode, 1);
1779 
1780 		spin_lock(&inode->i_lock);
1781 		state = inode->i_state;
1782 		WARN_ON(state & I_NEW);
1783 		state &= ~I_WILL_FREE;
1784 	}
1785 
1786 	WRITE_ONCE(inode->i_state, state | I_FREEING);
1787 	if (!list_empty(&inode->i_lru))
1788 		inode_lru_list_del(inode);
1789 	spin_unlock(&inode->i_lock);
1790 
1791 	evict(inode);
1792 }
1793 
1794 /**
1795  *	iput	- put an inode
1796  *	@inode: inode to put
1797  *
1798  *	Puts an inode, dropping its usage count. If the inode use count hits
1799  *	zero, the inode is then freed and may also be destroyed.
1800  *
1801  *	Consequently, iput() can sleep.
1802  */
iput(struct inode * inode)1803 void iput(struct inode *inode)
1804 {
1805 	if (!inode)
1806 		return;
1807 	BUG_ON(inode->i_state & I_CLEAR);
1808 retry:
1809 	if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
1810 		if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
1811 			atomic_inc(&inode->i_count);
1812 			spin_unlock(&inode->i_lock);
1813 			trace_writeback_lazytime_iput(inode);
1814 			mark_inode_dirty_sync(inode);
1815 			goto retry;
1816 		}
1817 		iput_final(inode);
1818 	}
1819 }
1820 EXPORT_SYMBOL(iput);
1821 
1822 #ifdef CONFIG_BLOCK
1823 /**
1824  *	bmap	- find a block number in a file
1825  *	@inode:  inode owning the block number being requested
1826  *	@block: pointer containing the block to find
1827  *
1828  *	Replaces the value in ``*block`` with the block number on the device holding
1829  *	corresponding to the requested block number in the file.
1830  *	That is, asked for block 4 of inode 1 the function will replace the
1831  *	4 in ``*block``, with disk block relative to the disk start that holds that
1832  *	block of the file.
1833  *
1834  *	Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
1835  *	hole, returns 0 and ``*block`` is also set to 0.
1836  */
bmap(struct inode * inode,sector_t * block)1837 int bmap(struct inode *inode, sector_t *block)
1838 {
1839 	if (!inode->i_mapping->a_ops->bmap)
1840 		return -EINVAL;
1841 
1842 	*block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
1843 	return 0;
1844 }
1845 EXPORT_SYMBOL(bmap);
1846 #endif
1847 
1848 /*
1849  * With relative atime, only update atime if the previous atime is
1850  * earlier than either the ctime or mtime or if at least a day has
1851  * passed since the last atime update.
1852  */
relatime_need_update(struct vfsmount * mnt,struct inode * inode,struct timespec64 now)1853 static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1854 			     struct timespec64 now)
1855 {
1856 
1857 	if (!(mnt->mnt_flags & MNT_RELATIME))
1858 		return 1;
1859 	/*
1860 	 * Is mtime younger than atime? If yes, update atime:
1861 	 */
1862 	if (timespec64_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1863 		return 1;
1864 	/*
1865 	 * Is ctime younger than atime? If yes, update atime:
1866 	 */
1867 	if (timespec64_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1868 		return 1;
1869 
1870 	/*
1871 	 * Is the previous atime value older than a day? If yes,
1872 	 * update atime:
1873 	 */
1874 	if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1875 		return 1;
1876 	/*
1877 	 * Good, we can skip the atime update:
1878 	 */
1879 	return 0;
1880 }
1881 
generic_update_time(struct inode * inode,struct timespec64 * time,int flags)1882 int generic_update_time(struct inode *inode, struct timespec64 *time, int flags)
1883 {
1884 	int dirty_flags = 0;
1885 
1886 	if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
1887 		if (flags & S_ATIME)
1888 			inode->i_atime = *time;
1889 		if (flags & S_CTIME)
1890 			inode->i_ctime = *time;
1891 		if (flags & S_MTIME)
1892 			inode->i_mtime = *time;
1893 
1894 		if (inode->i_sb->s_flags & SB_LAZYTIME)
1895 			dirty_flags |= I_DIRTY_TIME;
1896 		else
1897 			dirty_flags |= I_DIRTY_SYNC;
1898 	}
1899 
1900 	if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))
1901 		dirty_flags |= I_DIRTY_SYNC;
1902 
1903 	__mark_inode_dirty(inode, dirty_flags);
1904 	return 0;
1905 }
1906 EXPORT_SYMBOL(generic_update_time);
1907 
1908 /*
1909  * This does the actual work of updating an inodes time or version.  Must have
1910  * had called mnt_want_write() before calling this.
1911  */
inode_update_time(struct inode * inode,struct timespec64 * time,int flags)1912 int inode_update_time(struct inode *inode, struct timespec64 *time, int flags)
1913 {
1914 	if (inode->i_op->update_time)
1915 		return inode->i_op->update_time(inode, time, flags);
1916 	return generic_update_time(inode, time, flags);
1917 }
1918 EXPORT_SYMBOL(inode_update_time);
1919 
1920 /**
1921  *	atime_needs_update	-	update the access time
1922  *	@path: the &struct path to update
1923  *	@inode: inode to update
1924  *
1925  *	Update the accessed time on an inode and mark it for writeback.
1926  *	This function automatically handles read only file systems and media,
1927  *	as well as the "noatime" flag and inode specific "noatime" markers.
1928  */
atime_needs_update(const struct path * path,struct inode * inode)1929 bool atime_needs_update(const struct path *path, struct inode *inode)
1930 {
1931 	struct vfsmount *mnt = path->mnt;
1932 	struct timespec64 now;
1933 
1934 	if (inode->i_flags & S_NOATIME)
1935 		return false;
1936 
1937 	/* Atime updates will likely cause i_uid and i_gid to be written
1938 	 * back improprely if their true value is unknown to the vfs.
1939 	 */
1940 	if (HAS_UNMAPPED_ID(mnt_user_ns(mnt), inode))
1941 		return false;
1942 
1943 	if (IS_NOATIME(inode))
1944 		return false;
1945 	if ((inode->i_sb->s_flags & SB_NODIRATIME) && S_ISDIR(inode->i_mode))
1946 		return false;
1947 
1948 	if (mnt->mnt_flags & MNT_NOATIME)
1949 		return false;
1950 	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1951 		return false;
1952 
1953 	now = current_time(inode);
1954 
1955 	if (!relatime_need_update(mnt, inode, now))
1956 		return false;
1957 
1958 	if (timespec64_equal(&inode->i_atime, &now))
1959 		return false;
1960 
1961 	return true;
1962 }
1963 
touch_atime(const struct path * path)1964 void touch_atime(const struct path *path)
1965 {
1966 	struct vfsmount *mnt = path->mnt;
1967 	struct inode *inode = d_inode(path->dentry);
1968 	struct timespec64 now;
1969 
1970 	if (!atime_needs_update(path, inode))
1971 		return;
1972 
1973 	if (!sb_start_write_trylock(inode->i_sb))
1974 		return;
1975 
1976 	if (__mnt_want_write(mnt) != 0)
1977 		goto skip_update;
1978 	/*
1979 	 * File systems can error out when updating inodes if they need to
1980 	 * allocate new space to modify an inode (such is the case for
1981 	 * Btrfs), but since we touch atime while walking down the path we
1982 	 * really don't care if we failed to update the atime of the file,
1983 	 * so just ignore the return value.
1984 	 * We may also fail on filesystems that have the ability to make parts
1985 	 * of the fs read only, e.g. subvolumes in Btrfs.
1986 	 */
1987 	now = current_time(inode);
1988 	inode_update_time(inode, &now, S_ATIME);
1989 	__mnt_drop_write(mnt);
1990 skip_update:
1991 	sb_end_write(inode->i_sb);
1992 }
1993 EXPORT_SYMBOL(touch_atime);
1994 
1995 /*
1996  * Return mask of changes for notify_change() that need to be done as a
1997  * response to write or truncate. Return 0 if nothing has to be changed.
1998  * Negative value on error (change should be denied).
1999  */
dentry_needs_remove_privs(struct user_namespace * mnt_userns,struct dentry * dentry)2000 int dentry_needs_remove_privs(struct user_namespace *mnt_userns,
2001 			      struct dentry *dentry)
2002 {
2003 	struct inode *inode = d_inode(dentry);
2004 	int mask = 0;
2005 	int ret;
2006 
2007 	if (IS_NOSEC(inode))
2008 		return 0;
2009 
2010 	mask = setattr_should_drop_suidgid(mnt_userns, inode);
2011 	ret = security_inode_need_killpriv(dentry);
2012 	if (ret < 0)
2013 		return ret;
2014 	if (ret)
2015 		mask |= ATTR_KILL_PRIV;
2016 	return mask;
2017 }
2018 
__remove_privs(struct user_namespace * mnt_userns,struct dentry * dentry,int kill)2019 static int __remove_privs(struct user_namespace *mnt_userns,
2020 			  struct dentry *dentry, int kill)
2021 {
2022 	struct iattr newattrs;
2023 
2024 	newattrs.ia_valid = ATTR_FORCE | kill;
2025 	/*
2026 	 * Note we call this on write, so notify_change will not
2027 	 * encounter any conflicting delegations:
2028 	 */
2029 	return notify_change(mnt_userns, dentry, &newattrs, NULL);
2030 }
2031 
__file_remove_privs(struct file * file,unsigned int flags)2032 static int __file_remove_privs(struct file *file, unsigned int flags)
2033 {
2034 	struct dentry *dentry = file_dentry(file);
2035 	struct inode *inode = file_inode(file);
2036 	int error = 0;
2037 	int kill;
2038 
2039 	if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
2040 		return 0;
2041 
2042 	kill = dentry_needs_remove_privs(file_mnt_user_ns(file), dentry);
2043 	if (kill < 0)
2044 		return kill;
2045 
2046 	if (kill) {
2047 		if (flags & IOCB_NOWAIT)
2048 			return -EAGAIN;
2049 
2050 		error = __remove_privs(file_mnt_user_ns(file), dentry, kill);
2051 	}
2052 
2053 	if (!error)
2054 		inode_has_no_xattr(inode);
2055 	return error;
2056 }
2057 
2058 /**
2059  * file_remove_privs - remove special file privileges (suid, capabilities)
2060  * @file: file to remove privileges from
2061  *
2062  * When file is modified by a write or truncation ensure that special
2063  * file privileges are removed.
2064  *
2065  * Return: 0 on success, negative errno on failure.
2066  */
file_remove_privs(struct file * file)2067 int file_remove_privs(struct file *file)
2068 {
2069 	return __file_remove_privs(file, 0);
2070 }
2071 EXPORT_SYMBOL(file_remove_privs);
2072 
inode_needs_update_time(struct inode * inode,struct timespec64 * now)2073 static int inode_needs_update_time(struct inode *inode, struct timespec64 *now)
2074 {
2075 	int sync_it = 0;
2076 
2077 	/* First try to exhaust all avenues to not sync */
2078 	if (IS_NOCMTIME(inode))
2079 		return 0;
2080 
2081 	if (!timespec64_equal(&inode->i_mtime, now))
2082 		sync_it = S_MTIME;
2083 
2084 	if (!timespec64_equal(&inode->i_ctime, now))
2085 		sync_it |= S_CTIME;
2086 
2087 	if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
2088 		sync_it |= S_VERSION;
2089 
2090 	if (!sync_it)
2091 		return 0;
2092 
2093 	return sync_it;
2094 }
2095 
__file_update_time(struct file * file,struct timespec64 * now,int sync_mode)2096 static int __file_update_time(struct file *file, struct timespec64 *now,
2097 			int sync_mode)
2098 {
2099 	int ret = 0;
2100 	struct inode *inode = file_inode(file);
2101 
2102 	/* try to update time settings */
2103 	if (!__mnt_want_write_file(file)) {
2104 		ret = inode_update_time(inode, now, sync_mode);
2105 		__mnt_drop_write_file(file);
2106 	}
2107 
2108 	return ret;
2109 }
2110 
2111 /**
2112  * file_update_time - update mtime and ctime time
2113  * @file: file accessed
2114  *
2115  * Update the mtime and ctime members of an inode and mark the inode for
2116  * writeback. Note that this function is meant exclusively for usage in
2117  * the file write path of filesystems, and filesystems may choose to
2118  * explicitly ignore updates via this function with the _NOCMTIME inode
2119  * flag, e.g. for network filesystem where these imestamps are handled
2120  * by the server. This can return an error for file systems who need to
2121  * allocate space in order to update an inode.
2122  *
2123  * Return: 0 on success, negative errno on failure.
2124  */
file_update_time(struct file * file)2125 int file_update_time(struct file *file)
2126 {
2127 	int ret;
2128 	struct inode *inode = file_inode(file);
2129 	struct timespec64 now = current_time(inode);
2130 
2131 	ret = inode_needs_update_time(inode, &now);
2132 	if (ret <= 0)
2133 		return ret;
2134 
2135 	return __file_update_time(file, &now, ret);
2136 }
2137 EXPORT_SYMBOL(file_update_time);
2138 
2139 /**
2140  * file_modified_flags - handle mandated vfs changes when modifying a file
2141  * @file: file that was modified
2142  * @flags: kiocb flags
2143  *
2144  * When file has been modified ensure that special
2145  * file privileges are removed and time settings are updated.
2146  *
2147  * If IOCB_NOWAIT is set, special file privileges will not be removed and
2148  * time settings will not be updated. It will return -EAGAIN.
2149  *
2150  * Context: Caller must hold the file's inode lock.
2151  *
2152  * Return: 0 on success, negative errno on failure.
2153  */
file_modified_flags(struct file * file,int flags)2154 static int file_modified_flags(struct file *file, int flags)
2155 {
2156 	int ret;
2157 	struct inode *inode = file_inode(file);
2158 	struct timespec64 now = current_time(inode);
2159 
2160 	/*
2161 	 * Clear the security bits if the process is not being run by root.
2162 	 * This keeps people from modifying setuid and setgid binaries.
2163 	 */
2164 	ret = __file_remove_privs(file, flags);
2165 	if (ret)
2166 		return ret;
2167 
2168 	if (unlikely(file->f_mode & FMODE_NOCMTIME))
2169 		return 0;
2170 
2171 	ret = inode_needs_update_time(inode, &now);
2172 	if (ret <= 0)
2173 		return ret;
2174 	if (flags & IOCB_NOWAIT)
2175 		return -EAGAIN;
2176 
2177 	return __file_update_time(file, &now, ret);
2178 }
2179 
2180 /**
2181  * file_modified - handle mandated vfs changes when modifying a file
2182  * @file: file that was modified
2183  *
2184  * When file has been modified ensure that special
2185  * file privileges are removed and time settings are updated.
2186  *
2187  * Context: Caller must hold the file's inode lock.
2188  *
2189  * Return: 0 on success, negative errno on failure.
2190  */
file_modified(struct file * file)2191 int file_modified(struct file *file)
2192 {
2193 	return file_modified_flags(file, 0);
2194 }
2195 EXPORT_SYMBOL(file_modified);
2196 
2197 /**
2198  * kiocb_modified - handle mandated vfs changes when modifying a file
2199  * @iocb: iocb that was modified
2200  *
2201  * When file has been modified ensure that special
2202  * file privileges are removed and time settings are updated.
2203  *
2204  * Context: Caller must hold the file's inode lock.
2205  *
2206  * Return: 0 on success, negative errno on failure.
2207  */
kiocb_modified(struct kiocb * iocb)2208 int kiocb_modified(struct kiocb *iocb)
2209 {
2210 	return file_modified_flags(iocb->ki_filp, iocb->ki_flags);
2211 }
2212 EXPORT_SYMBOL_GPL(kiocb_modified);
2213 
inode_needs_sync(struct inode * inode)2214 int inode_needs_sync(struct inode *inode)
2215 {
2216 	if (IS_SYNC(inode))
2217 		return 1;
2218 	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
2219 		return 1;
2220 	return 0;
2221 }
2222 EXPORT_SYMBOL(inode_needs_sync);
2223 
2224 /*
2225  * If we try to find an inode in the inode hash while it is being
2226  * deleted, we have to wait until the filesystem completes its
2227  * deletion before reporting that it isn't found.  This function waits
2228  * until the deletion _might_ have completed.  Callers are responsible
2229  * to recheck inode state.
2230  *
2231  * It doesn't matter if I_NEW is not set initially, a call to
2232  * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
2233  * will DTRT.
2234  */
__wait_on_freeing_inode(struct inode * inode)2235 static void __wait_on_freeing_inode(struct inode *inode)
2236 {
2237 	wait_queue_head_t *wq;
2238 	DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
2239 	wq = bit_waitqueue(&inode->i_state, __I_NEW);
2240 	prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
2241 	spin_unlock(&inode->i_lock);
2242 	spin_unlock(&inode_hash_lock);
2243 	schedule();
2244 	finish_wait(wq, &wait.wq_entry);
2245 	spin_lock(&inode_hash_lock);
2246 }
2247 
2248 static __initdata unsigned long ihash_entries;
set_ihash_entries(char * str)2249 static int __init set_ihash_entries(char *str)
2250 {
2251 	if (!str)
2252 		return 0;
2253 	ihash_entries = simple_strtoul(str, &str, 0);
2254 	return 1;
2255 }
2256 __setup("ihash_entries=", set_ihash_entries);
2257 
2258 /*
2259  * Initialize the waitqueues and inode hash table.
2260  */
inode_init_early(void)2261 void __init inode_init_early(void)
2262 {
2263 	/* If hashes are distributed across NUMA nodes, defer
2264 	 * hash allocation until vmalloc space is available.
2265 	 */
2266 	if (hashdist)
2267 		return;
2268 
2269 	inode_hashtable =
2270 		alloc_large_system_hash("Inode-cache",
2271 					sizeof(struct hlist_head),
2272 					ihash_entries,
2273 					14,
2274 					HASH_EARLY | HASH_ZERO,
2275 					&i_hash_shift,
2276 					&i_hash_mask,
2277 					0,
2278 					0);
2279 }
2280 
inode_init(void)2281 void __init inode_init(void)
2282 {
2283 	/* inode slab cache */
2284 	inode_cachep = kmem_cache_create("inode_cache",
2285 					 sizeof(struct inode),
2286 					 0,
2287 					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
2288 					 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
2289 					 init_once);
2290 
2291 	/* Hash may have been set up in inode_init_early */
2292 	if (!hashdist)
2293 		return;
2294 
2295 	inode_hashtable =
2296 		alloc_large_system_hash("Inode-cache",
2297 					sizeof(struct hlist_head),
2298 					ihash_entries,
2299 					14,
2300 					HASH_ZERO,
2301 					&i_hash_shift,
2302 					&i_hash_mask,
2303 					0,
2304 					0);
2305 }
2306 
init_special_inode(struct inode * inode,umode_t mode,dev_t rdev)2307 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
2308 {
2309 	inode->i_mode = mode;
2310 	if (S_ISCHR(mode)) {
2311 		inode->i_fop = &def_chr_fops;
2312 		inode->i_rdev = rdev;
2313 	} else if (S_ISBLK(mode)) {
2314 		inode->i_fop = &def_blk_fops;
2315 		inode->i_rdev = rdev;
2316 	} else if (S_ISFIFO(mode))
2317 		inode->i_fop = &pipefifo_fops;
2318 	else if (S_ISSOCK(mode))
2319 		;	/* leave it no_open_fops */
2320 	else
2321 		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
2322 				  " inode %s:%lu\n", mode, inode->i_sb->s_id,
2323 				  inode->i_ino);
2324 }
2325 EXPORT_SYMBOL(init_special_inode);
2326 
2327 /**
2328  * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
2329  * @mnt_userns:	User namespace of the mount the inode was created from
2330  * @inode: New inode
2331  * @dir: Directory inode
2332  * @mode: mode of the new inode
2333  *
2334  * If the inode has been created through an idmapped mount the user namespace of
2335  * the vfsmount must be passed through @mnt_userns. This function will then take
2336  * care to map the inode according to @mnt_userns before checking permissions
2337  * and initializing i_uid and i_gid. On non-idmapped mounts or if permission
2338  * checking is to be performed on the raw inode simply passs init_user_ns.
2339  */
inode_init_owner(struct user_namespace * mnt_userns,struct inode * inode,const struct inode * dir,umode_t mode)2340 void inode_init_owner(struct user_namespace *mnt_userns, struct inode *inode,
2341 		      const struct inode *dir, umode_t mode)
2342 {
2343 	inode_fsuid_set(inode, mnt_userns);
2344 	if (dir && dir->i_mode & S_ISGID) {
2345 		inode->i_gid = dir->i_gid;
2346 
2347 		/* Directories are special, and always inherit S_ISGID */
2348 		if (S_ISDIR(mode))
2349 			mode |= S_ISGID;
2350 	} else
2351 		inode_fsgid_set(inode, mnt_userns);
2352 	inode->i_mode = mode;
2353 }
2354 EXPORT_SYMBOL(inode_init_owner);
2355 
2356 /**
2357  * inode_owner_or_capable - check current task permissions to inode
2358  * @mnt_userns:	user namespace of the mount the inode was found from
2359  * @inode: inode being checked
2360  *
2361  * Return true if current either has CAP_FOWNER in a namespace with the
2362  * inode owner uid mapped, or owns the file.
2363  *
2364  * If the inode has been found through an idmapped mount the user namespace of
2365  * the vfsmount must be passed through @mnt_userns. This function will then take
2366  * care to map the inode according to @mnt_userns before checking permissions.
2367  * On non-idmapped mounts or if permission checking is to be performed on the
2368  * raw inode simply passs init_user_ns.
2369  */
inode_owner_or_capable(struct user_namespace * mnt_userns,const struct inode * inode)2370 bool inode_owner_or_capable(struct user_namespace *mnt_userns,
2371 			    const struct inode *inode)
2372 {
2373 	kuid_t i_uid;
2374 	struct user_namespace *ns;
2375 
2376 	i_uid = i_uid_into_mnt(mnt_userns, inode);
2377 	if (uid_eq(current_fsuid(), i_uid))
2378 		return true;
2379 
2380 	ns = current_user_ns();
2381 	if (kuid_has_mapping(ns, i_uid) && ns_capable(ns, CAP_FOWNER))
2382 		return true;
2383 	return false;
2384 }
2385 EXPORT_SYMBOL(inode_owner_or_capable);
2386 
2387 /*
2388  * Direct i/o helper functions
2389  */
__inode_dio_wait(struct inode * inode)2390 static void __inode_dio_wait(struct inode *inode)
2391 {
2392 	wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP);
2393 	DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP);
2394 
2395 	do {
2396 		prepare_to_wait(wq, &q.wq_entry, TASK_UNINTERRUPTIBLE);
2397 		if (atomic_read(&inode->i_dio_count))
2398 			schedule();
2399 	} while (atomic_read(&inode->i_dio_count));
2400 	finish_wait(wq, &q.wq_entry);
2401 }
2402 
2403 /**
2404  * inode_dio_wait - wait for outstanding DIO requests to finish
2405  * @inode: inode to wait for
2406  *
2407  * Waits for all pending direct I/O requests to finish so that we can
2408  * proceed with a truncate or equivalent operation.
2409  *
2410  * Must be called under a lock that serializes taking new references
2411  * to i_dio_count, usually by inode->i_mutex.
2412  */
inode_dio_wait(struct inode * inode)2413 void inode_dio_wait(struct inode *inode)
2414 {
2415 	if (atomic_read(&inode->i_dio_count))
2416 		__inode_dio_wait(inode);
2417 }
2418 EXPORT_SYMBOL(inode_dio_wait);
2419 
2420 /*
2421  * inode_set_flags - atomically set some inode flags
2422  *
2423  * Note: the caller should be holding i_mutex, or else be sure that
2424  * they have exclusive access to the inode structure (i.e., while the
2425  * inode is being instantiated).  The reason for the cmpxchg() loop
2426  * --- which wouldn't be necessary if all code paths which modify
2427  * i_flags actually followed this rule, is that there is at least one
2428  * code path which doesn't today so we use cmpxchg() out of an abundance
2429  * of caution.
2430  *
2431  * In the long run, i_mutex is overkill, and we should probably look
2432  * at using the i_lock spinlock to protect i_flags, and then make sure
2433  * it is so documented in include/linux/fs.h and that all code follows
2434  * the locking convention!!
2435  */
inode_set_flags(struct inode * inode,unsigned int flags,unsigned int mask)2436 void inode_set_flags(struct inode *inode, unsigned int flags,
2437 		     unsigned int mask)
2438 {
2439 	WARN_ON_ONCE(flags & ~mask);
2440 	set_mask_bits(&inode->i_flags, mask, flags);
2441 }
2442 EXPORT_SYMBOL(inode_set_flags);
2443 
inode_nohighmem(struct inode * inode)2444 void inode_nohighmem(struct inode *inode)
2445 {
2446 	mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
2447 }
2448 EXPORT_SYMBOL(inode_nohighmem);
2449 
2450 /**
2451  * timestamp_truncate - Truncate timespec to a granularity
2452  * @t: Timespec
2453  * @inode: inode being updated
2454  *
2455  * Truncate a timespec to the granularity supported by the fs
2456  * containing the inode. Always rounds down. gran must
2457  * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
2458  */
timestamp_truncate(struct timespec64 t,struct inode * inode)2459 struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
2460 {
2461 	struct super_block *sb = inode->i_sb;
2462 	unsigned int gran = sb->s_time_gran;
2463 
2464 	t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);
2465 	if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))
2466 		t.tv_nsec = 0;
2467 
2468 	/* Avoid division in the common cases 1 ns and 1 s. */
2469 	if (gran == 1)
2470 		; /* nothing */
2471 	else if (gran == NSEC_PER_SEC)
2472 		t.tv_nsec = 0;
2473 	else if (gran > 1 && gran < NSEC_PER_SEC)
2474 		t.tv_nsec -= t.tv_nsec % gran;
2475 	else
2476 		WARN(1, "invalid file time granularity: %u", gran);
2477 	return t;
2478 }
2479 EXPORT_SYMBOL(timestamp_truncate);
2480 
2481 /**
2482  * current_time - Return FS time
2483  * @inode: inode.
2484  *
2485  * Return the current time truncated to the time granularity supported by
2486  * the fs.
2487  *
2488  * Note that inode and inode->sb cannot be NULL.
2489  * Otherwise, the function warns and returns time without truncation.
2490  */
current_time(struct inode * inode)2491 struct timespec64 current_time(struct inode *inode)
2492 {
2493 	struct timespec64 now;
2494 
2495 	ktime_get_coarse_real_ts64(&now);
2496 
2497 	if (unlikely(!inode->i_sb)) {
2498 		WARN(1, "current_time() called with uninitialized super_block in the inode");
2499 		return now;
2500 	}
2501 
2502 	return timestamp_truncate(now, inode);
2503 }
2504 EXPORT_SYMBOL(current_time);
2505 
2506 /**
2507  * inode_set_ctime_current - set the ctime to current_time
2508  * @inode: inode
2509  *
2510  * Set the inode->i_ctime to the current value for the inode. Returns
2511  * the current value that was assigned to i_ctime.
2512  */
inode_set_ctime_current(struct inode * inode)2513 struct timespec64 inode_set_ctime_current(struct inode *inode)
2514 {
2515 	struct timespec64 now = current_time(inode);
2516 
2517 	inode_set_ctime(inode, now.tv_sec, now.tv_nsec);
2518 	return now;
2519 }
2520 EXPORT_SYMBOL(inode_set_ctime_current);
2521 
2522 /**
2523  * in_group_or_capable - check whether caller is CAP_FSETID privileged
2524  * @mnt_userns: user namespace of the mount @inode was found from
2525  * @inode:	inode to check
2526  * @vfsgid:	the new/current vfsgid of @inode
2527  *
2528  * Check wether @vfsgid is in the caller's group list or if the caller is
2529  * privileged with CAP_FSETID over @inode. This can be used to determine
2530  * whether the setgid bit can be kept or must be dropped.
2531  *
2532  * Return: true if the caller is sufficiently privileged, false if not.
2533  */
in_group_or_capable(struct user_namespace * mnt_userns,const struct inode * inode,vfsgid_t vfsgid)2534 bool in_group_or_capable(struct user_namespace *mnt_userns,
2535 			 const struct inode *inode, vfsgid_t vfsgid)
2536 {
2537 	if (vfsgid_in_group_p(vfsgid))
2538 		return true;
2539 	if (capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
2540 		return true;
2541 	return false;
2542 }
2543 
2544 /**
2545  * mode_strip_sgid - handle the sgid bit for non-directories
2546  * @mnt_userns: User namespace of the mount the inode was created from
2547  * @dir: parent directory inode
2548  * @mode: mode of the file to be created in @dir
2549  *
2550  * If the @mode of the new file has both the S_ISGID and S_IXGRP bit
2551  * raised and @dir has the S_ISGID bit raised ensure that the caller is
2552  * either in the group of the parent directory or they have CAP_FSETID
2553  * in their user namespace and are privileged over the parent directory.
2554  * In all other cases, strip the S_ISGID bit from @mode.
2555  *
2556  * Return: the new mode to use for the file
2557  */
mode_strip_sgid(struct user_namespace * mnt_userns,const struct inode * dir,umode_t mode)2558 umode_t mode_strip_sgid(struct user_namespace *mnt_userns,
2559 			const struct inode *dir, umode_t mode)
2560 {
2561 	if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP))
2562 		return mode;
2563 	if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID))
2564 		return mode;
2565 	if (in_group_or_capable(mnt_userns, dir,
2566 				i_gid_into_vfsgid(mnt_userns, dir)))
2567 		return mode;
2568 	return mode & ~S_ISGID;
2569 }
2570 EXPORT_SYMBOL(mode_strip_sgid);
2571