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