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  
get_nr_inodes(void)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  
get_nr_inodes_unused(void)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  
get_nr_dirty_inodes(void)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  
proc_nr_inodes(const struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)110  static int proc_nr_inodes(const 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  
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_gfp - perform inode structure initialisation
150   * @sb: superblock inode belongs to
151   * @inode: inode to initialise
152   * @gfp: allocation flags
153   *
154   * These are initializations that need to be done on every inode
155   * allocation as the fields are not initialised by slab allocation.
156   * If there are additional allocations required @gfp is used.
157   */
inode_init_always_gfp(struct super_block * sb,struct inode * inode,gfp_t gfp)158  int inode_init_always_gfp(struct super_block *sb, struct inode *inode, gfp_t gfp)
159  {
160  	static const struct inode_operations empty_iops;
161  	static const struct file_operations no_open_fops = {.open = no_open};
162  	struct address_space *const mapping = &inode->i_data;
163  
164  	inode->i_sb = sb;
165  	inode->i_blkbits = sb->s_blocksize_bits;
166  	inode->i_flags = 0;
167  	inode->i_state = 0;
168  	atomic64_set(&inode->i_sequence, 0);
169  	atomic_set(&inode->i_count, 1);
170  	inode->i_op = &empty_iops;
171  	inode->i_fop = &no_open_fops;
172  	inode->i_ino = 0;
173  	inode->__i_nlink = 1;
174  	inode->i_opflags = 0;
175  	if (sb->s_xattr)
176  		inode->i_opflags |= IOP_XATTR;
177  	i_uid_write(inode, 0);
178  	i_gid_write(inode, 0);
179  	atomic_set(&inode->i_writecount, 0);
180  	inode->i_size = 0;
181  	inode->i_write_hint = WRITE_LIFE_NOT_SET;
182  	inode->i_blocks = 0;
183  	inode->i_bytes = 0;
184  	inode->i_generation = 0;
185  	inode->i_pipe = NULL;
186  	inode->i_cdev = NULL;
187  	inode->i_link = NULL;
188  	inode->i_dir_seq = 0;
189  	inode->i_rdev = 0;
190  	inode->dirtied_when = 0;
191  
192  #ifdef CONFIG_CGROUP_WRITEBACK
193  	inode->i_wb_frn_winner = 0;
194  	inode->i_wb_frn_avg_time = 0;
195  	inode->i_wb_frn_history = 0;
196  #endif
197  
198  	spin_lock_init(&inode->i_lock);
199  	lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
200  
201  	init_rwsem(&inode->i_rwsem);
202  	lockdep_set_class(&inode->i_rwsem, &sb->s_type->i_mutex_key);
203  
204  	atomic_set(&inode->i_dio_count, 0);
205  
206  	mapping->a_ops = &empty_aops;
207  	mapping->host = inode;
208  	mapping->flags = 0;
209  	mapping->wb_err = 0;
210  	atomic_set(&mapping->i_mmap_writable, 0);
211  #ifdef CONFIG_READ_ONLY_THP_FOR_FS
212  	atomic_set(&mapping->nr_thps, 0);
213  #endif
214  	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
215  	mapping->i_private_data = NULL;
216  	mapping->writeback_index = 0;
217  	init_rwsem(&mapping->invalidate_lock);
218  	lockdep_set_class_and_name(&mapping->invalidate_lock,
219  				   &sb->s_type->invalidate_lock_key,
220  				   "mapping.invalidate_lock");
221  	if (sb->s_iflags & SB_I_STABLE_WRITES)
222  		mapping_set_stable_writes(mapping);
223  	inode->i_private = NULL;
224  	inode->i_mapping = mapping;
225  	INIT_HLIST_HEAD(&inode->i_dentry);	/* buggered by rcu freeing */
226  #ifdef CONFIG_FS_POSIX_ACL
227  	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
228  #endif
229  
230  #ifdef CONFIG_FSNOTIFY
231  	inode->i_fsnotify_mask = 0;
232  #endif
233  	inode->i_flctx = NULL;
234  
235  	if (unlikely(security_inode_alloc(inode, gfp)))
236  		return -ENOMEM;
237  
238  	this_cpu_inc(nr_inodes);
239  
240  	return 0;
241  }
242  EXPORT_SYMBOL(inode_init_always_gfp);
243  
free_inode_nonrcu(struct inode * inode)244  void free_inode_nonrcu(struct inode *inode)
245  {
246  	kmem_cache_free(inode_cachep, inode);
247  }
248  EXPORT_SYMBOL(free_inode_nonrcu);
249  
i_callback(struct rcu_head * head)250  static void i_callback(struct rcu_head *head)
251  {
252  	struct inode *inode = container_of(head, struct inode, i_rcu);
253  	if (inode->free_inode)
254  		inode->free_inode(inode);
255  	else
256  		free_inode_nonrcu(inode);
257  }
258  
alloc_inode(struct super_block * sb)259  static struct inode *alloc_inode(struct super_block *sb)
260  {
261  	const struct super_operations *ops = sb->s_op;
262  	struct inode *inode;
263  
264  	if (ops->alloc_inode)
265  		inode = ops->alloc_inode(sb);
266  	else
267  		inode = alloc_inode_sb(sb, inode_cachep, GFP_KERNEL);
268  
269  	if (!inode)
270  		return NULL;
271  
272  	if (unlikely(inode_init_always(sb, inode))) {
273  		if (ops->destroy_inode) {
274  			ops->destroy_inode(inode);
275  			if (!ops->free_inode)
276  				return NULL;
277  		}
278  		inode->free_inode = ops->free_inode;
279  		i_callback(&inode->i_rcu);
280  		return NULL;
281  	}
282  
283  	return inode;
284  }
285  
__destroy_inode(struct inode * inode)286  void __destroy_inode(struct inode *inode)
287  {
288  	BUG_ON(inode_has_buffers(inode));
289  	inode_detach_wb(inode);
290  	security_inode_free(inode);
291  	fsnotify_inode_delete(inode);
292  	locks_free_lock_context(inode);
293  	if (!inode->i_nlink) {
294  		WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);
295  		atomic_long_dec(&inode->i_sb->s_remove_count);
296  	}
297  
298  #ifdef CONFIG_FS_POSIX_ACL
299  	if (inode->i_acl && !is_uncached_acl(inode->i_acl))
300  		posix_acl_release(inode->i_acl);
301  	if (inode->i_default_acl && !is_uncached_acl(inode->i_default_acl))
302  		posix_acl_release(inode->i_default_acl);
303  #endif
304  	this_cpu_dec(nr_inodes);
305  }
306  EXPORT_SYMBOL(__destroy_inode);
307  
destroy_inode(struct inode * inode)308  static void destroy_inode(struct inode *inode)
309  {
310  	const struct super_operations *ops = inode->i_sb->s_op;
311  
312  	BUG_ON(!list_empty(&inode->i_lru));
313  	__destroy_inode(inode);
314  	if (ops->destroy_inode) {
315  		ops->destroy_inode(inode);
316  		if (!ops->free_inode)
317  			return;
318  	}
319  	inode->free_inode = ops->free_inode;
320  	call_rcu(&inode->i_rcu, i_callback);
321  }
322  
323  /**
324   * drop_nlink - directly drop an inode's link count
325   * @inode: inode
326   *
327   * This is a low-level filesystem helper to replace any
328   * direct filesystem manipulation of i_nlink.  In cases
329   * where we are attempting to track writes to the
330   * filesystem, a decrement to zero means an imminent
331   * write when the file is truncated and actually unlinked
332   * on the filesystem.
333   */
drop_nlink(struct inode * inode)334  void drop_nlink(struct inode *inode)
335  {
336  	WARN_ON(inode->i_nlink == 0);
337  	inode->__i_nlink--;
338  	if (!inode->i_nlink)
339  		atomic_long_inc(&inode->i_sb->s_remove_count);
340  }
341  EXPORT_SYMBOL(drop_nlink);
342  
343  /**
344   * clear_nlink - directly zero an inode's link count
345   * @inode: inode
346   *
347   * This is a low-level filesystem helper to replace any
348   * direct filesystem manipulation of i_nlink.  See
349   * drop_nlink() for why we care about i_nlink hitting zero.
350   */
clear_nlink(struct inode * inode)351  void clear_nlink(struct inode *inode)
352  {
353  	if (inode->i_nlink) {
354  		inode->__i_nlink = 0;
355  		atomic_long_inc(&inode->i_sb->s_remove_count);
356  	}
357  }
358  EXPORT_SYMBOL(clear_nlink);
359  
360  /**
361   * set_nlink - directly set an inode's link count
362   * @inode: inode
363   * @nlink: new nlink (should be non-zero)
364   *
365   * This is a low-level filesystem helper to replace any
366   * direct filesystem manipulation of i_nlink.
367   */
set_nlink(struct inode * inode,unsigned int nlink)368  void set_nlink(struct inode *inode, unsigned int nlink)
369  {
370  	if (!nlink) {
371  		clear_nlink(inode);
372  	} else {
373  		/* Yes, some filesystems do change nlink from zero to one */
374  		if (inode->i_nlink == 0)
375  			atomic_long_dec(&inode->i_sb->s_remove_count);
376  
377  		inode->__i_nlink = nlink;
378  	}
379  }
380  EXPORT_SYMBOL(set_nlink);
381  
382  /**
383   * inc_nlink - directly increment an inode's link count
384   * @inode: inode
385   *
386   * This is a low-level filesystem helper to replace any
387   * direct filesystem manipulation of i_nlink.  Currently,
388   * it is only here for parity with dec_nlink().
389   */
inc_nlink(struct inode * inode)390  void inc_nlink(struct inode *inode)
391  {
392  	if (unlikely(inode->i_nlink == 0)) {
393  		WARN_ON(!(inode->i_state & I_LINKABLE));
394  		atomic_long_dec(&inode->i_sb->s_remove_count);
395  	}
396  
397  	inode->__i_nlink++;
398  }
399  EXPORT_SYMBOL(inc_nlink);
400  
__address_space_init_once(struct address_space * mapping)401  static void __address_space_init_once(struct address_space *mapping)
402  {
403  	xa_init_flags(&mapping->i_pages, XA_FLAGS_LOCK_IRQ | XA_FLAGS_ACCOUNT);
404  	init_rwsem(&mapping->i_mmap_rwsem);
405  	INIT_LIST_HEAD(&mapping->i_private_list);
406  	spin_lock_init(&mapping->i_private_lock);
407  	mapping->i_mmap = RB_ROOT_CACHED;
408  }
409  
address_space_init_once(struct address_space * mapping)410  void address_space_init_once(struct address_space *mapping)
411  {
412  	memset(mapping, 0, sizeof(*mapping));
413  	__address_space_init_once(mapping);
414  }
415  EXPORT_SYMBOL(address_space_init_once);
416  
417  /*
418   * These are initializations that only need to be done
419   * once, because the fields are idempotent across use
420   * of the inode, so let the slab aware of that.
421   */
inode_init_once(struct inode * inode)422  void inode_init_once(struct inode *inode)
423  {
424  	memset(inode, 0, sizeof(*inode));
425  	INIT_HLIST_NODE(&inode->i_hash);
426  	INIT_LIST_HEAD(&inode->i_devices);
427  	INIT_LIST_HEAD(&inode->i_io_list);
428  	INIT_LIST_HEAD(&inode->i_wb_list);
429  	INIT_LIST_HEAD(&inode->i_lru);
430  	INIT_LIST_HEAD(&inode->i_sb_list);
431  	__address_space_init_once(&inode->i_data);
432  	i_size_ordered_init(inode);
433  }
434  EXPORT_SYMBOL(inode_init_once);
435  
init_once(void * foo)436  static void init_once(void *foo)
437  {
438  	struct inode *inode = (struct inode *) foo;
439  
440  	inode_init_once(inode);
441  }
442  
443  /*
444   * get additional reference to inode; caller must already hold one.
445   */
ihold(struct inode * inode)446  void ihold(struct inode *inode)
447  {
448  	WARN_ON(atomic_inc_return(&inode->i_count) < 2);
449  }
450  EXPORT_SYMBOL(ihold);
451  
__inode_add_lru(struct inode * inode,bool rotate)452  static void __inode_add_lru(struct inode *inode, bool rotate)
453  {
454  	if (inode->i_state & (I_DIRTY_ALL | I_SYNC | I_FREEING | I_WILL_FREE))
455  		return;
456  	if (atomic_read(&inode->i_count))
457  		return;
458  	if (!(inode->i_sb->s_flags & SB_ACTIVE))
459  		return;
460  	if (!mapping_shrinkable(&inode->i_data))
461  		return;
462  
463  	if (list_lru_add_obj(&inode->i_sb->s_inode_lru, &inode->i_lru))
464  		this_cpu_inc(nr_unused);
465  	else if (rotate)
466  		inode->i_state |= I_REFERENCED;
467  }
468  
inode_bit_waitqueue(struct wait_bit_queue_entry * wqe,struct inode * inode,u32 bit)469  struct wait_queue_head *inode_bit_waitqueue(struct wait_bit_queue_entry *wqe,
470  					    struct inode *inode, u32 bit)
471  {
472          void *bit_address;
473  
474          bit_address = inode_state_wait_address(inode, bit);
475          init_wait_var_entry(wqe, bit_address, 0);
476          return __var_waitqueue(bit_address);
477  }
478  EXPORT_SYMBOL(inode_bit_waitqueue);
479  
480  /*
481   * Add inode to LRU if needed (inode is unused and clean).
482   *
483   * Needs inode->i_lock held.
484   */
inode_add_lru(struct inode * inode)485  void inode_add_lru(struct inode *inode)
486  {
487  	__inode_add_lru(inode, false);
488  }
489  
inode_lru_list_del(struct inode * inode)490  static void inode_lru_list_del(struct inode *inode)
491  {
492  	if (list_lru_del_obj(&inode->i_sb->s_inode_lru, &inode->i_lru))
493  		this_cpu_dec(nr_unused);
494  }
495  
inode_pin_lru_isolating(struct inode * inode)496  static void inode_pin_lru_isolating(struct inode *inode)
497  {
498  	lockdep_assert_held(&inode->i_lock);
499  	WARN_ON(inode->i_state & (I_LRU_ISOLATING | I_FREEING | I_WILL_FREE));
500  	inode->i_state |= I_LRU_ISOLATING;
501  }
502  
inode_unpin_lru_isolating(struct inode * inode)503  static void inode_unpin_lru_isolating(struct inode *inode)
504  {
505  	spin_lock(&inode->i_lock);
506  	WARN_ON(!(inode->i_state & I_LRU_ISOLATING));
507  	inode->i_state &= ~I_LRU_ISOLATING;
508  	/* Called with inode->i_lock which ensures memory ordering. */
509  	inode_wake_up_bit(inode, __I_LRU_ISOLATING);
510  	spin_unlock(&inode->i_lock);
511  }
512  
inode_wait_for_lru_isolating(struct inode * inode)513  static void inode_wait_for_lru_isolating(struct inode *inode)
514  {
515  	struct wait_bit_queue_entry wqe;
516  	struct wait_queue_head *wq_head;
517  
518  	lockdep_assert_held(&inode->i_lock);
519  	if (!(inode->i_state & I_LRU_ISOLATING))
520  		return;
521  
522  	wq_head = inode_bit_waitqueue(&wqe, inode, __I_LRU_ISOLATING);
523  	for (;;) {
524  		prepare_to_wait_event(wq_head, &wqe.wq_entry, TASK_UNINTERRUPTIBLE);
525  		/*
526  		 * Checking I_LRU_ISOLATING with inode->i_lock guarantees
527  		 * memory ordering.
528  		 */
529  		if (!(inode->i_state & I_LRU_ISOLATING))
530  			break;
531  		spin_unlock(&inode->i_lock);
532  		schedule();
533  		spin_lock(&inode->i_lock);
534  	}
535  	finish_wait(wq_head, &wqe.wq_entry);
536  	WARN_ON(inode->i_state & I_LRU_ISOLATING);
537  }
538  
539  /**
540   * inode_sb_list_add - add inode to the superblock list of inodes
541   * @inode: inode to add
542   */
inode_sb_list_add(struct inode * inode)543  void inode_sb_list_add(struct inode *inode)
544  {
545  	spin_lock(&inode->i_sb->s_inode_list_lock);
546  	list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
547  	spin_unlock(&inode->i_sb->s_inode_list_lock);
548  }
549  EXPORT_SYMBOL_GPL(inode_sb_list_add);
550  
inode_sb_list_del(struct inode * inode)551  static inline void inode_sb_list_del(struct inode *inode)
552  {
553  	if (!list_empty(&inode->i_sb_list)) {
554  		spin_lock(&inode->i_sb->s_inode_list_lock);
555  		list_del_init(&inode->i_sb_list);
556  		spin_unlock(&inode->i_sb->s_inode_list_lock);
557  	}
558  }
559  
hash(struct super_block * sb,unsigned long hashval)560  static unsigned long hash(struct super_block *sb, unsigned long hashval)
561  {
562  	unsigned long tmp;
563  
564  	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
565  			L1_CACHE_BYTES;
566  	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
567  	return tmp & i_hash_mask;
568  }
569  
570  /**
571   *	__insert_inode_hash - hash an inode
572   *	@inode: unhashed inode
573   *	@hashval: unsigned long value used to locate this object in the
574   *		inode_hashtable.
575   *
576   *	Add an inode to the inode hash for this superblock.
577   */
__insert_inode_hash(struct inode * inode,unsigned long hashval)578  void __insert_inode_hash(struct inode *inode, unsigned long hashval)
579  {
580  	struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
581  
582  	spin_lock(&inode_hash_lock);
583  	spin_lock(&inode->i_lock);
584  	hlist_add_head_rcu(&inode->i_hash, b);
585  	spin_unlock(&inode->i_lock);
586  	spin_unlock(&inode_hash_lock);
587  }
588  EXPORT_SYMBOL(__insert_inode_hash);
589  
590  /**
591   *	__remove_inode_hash - remove an inode from the hash
592   *	@inode: inode to unhash
593   *
594   *	Remove an inode from the superblock.
595   */
__remove_inode_hash(struct inode * inode)596  void __remove_inode_hash(struct inode *inode)
597  {
598  	spin_lock(&inode_hash_lock);
599  	spin_lock(&inode->i_lock);
600  	hlist_del_init_rcu(&inode->i_hash);
601  	spin_unlock(&inode->i_lock);
602  	spin_unlock(&inode_hash_lock);
603  }
604  EXPORT_SYMBOL(__remove_inode_hash);
605  
dump_mapping(const struct address_space * mapping)606  void dump_mapping(const struct address_space *mapping)
607  {
608  	struct inode *host;
609  	const struct address_space_operations *a_ops;
610  	struct hlist_node *dentry_first;
611  	struct dentry *dentry_ptr;
612  	struct dentry dentry;
613  	char fname[64] = {};
614  	unsigned long ino;
615  
616  	/*
617  	 * If mapping is an invalid pointer, we don't want to crash
618  	 * accessing it, so probe everything depending on it carefully.
619  	 */
620  	if (get_kernel_nofault(host, &mapping->host) ||
621  	    get_kernel_nofault(a_ops, &mapping->a_ops)) {
622  		pr_warn("invalid mapping:%px\n", mapping);
623  		return;
624  	}
625  
626  	if (!host) {
627  		pr_warn("aops:%ps\n", a_ops);
628  		return;
629  	}
630  
631  	if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
632  	    get_kernel_nofault(ino, &host->i_ino)) {
633  		pr_warn("aops:%ps invalid inode:%px\n", a_ops, host);
634  		return;
635  	}
636  
637  	if (!dentry_first) {
638  		pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
639  		return;
640  	}
641  
642  	dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
643  	if (get_kernel_nofault(dentry, dentry_ptr) ||
644  	    !dentry.d_parent || !dentry.d_name.name) {
645  		pr_warn("aops:%ps ino:%lx invalid dentry:%px\n",
646  				a_ops, ino, dentry_ptr);
647  		return;
648  	}
649  
650  	if (strncpy_from_kernel_nofault(fname, dentry.d_name.name, 63) < 0)
651  		strscpy(fname, "<invalid>");
652  	/*
653  	 * Even if strncpy_from_kernel_nofault() succeeded,
654  	 * the fname could be unreliable
655  	 */
656  	pr_warn("aops:%ps ino:%lx dentry name(?):\"%s\"\n",
657  		a_ops, ino, fname);
658  }
659  
clear_inode(struct inode * inode)660  void clear_inode(struct inode *inode)
661  {
662  	/*
663  	 * We have to cycle the i_pages lock here because reclaim can be in the
664  	 * process of removing the last page (in __filemap_remove_folio())
665  	 * and we must not free the mapping under it.
666  	 */
667  	xa_lock_irq(&inode->i_data.i_pages);
668  	BUG_ON(inode->i_data.nrpages);
669  	/*
670  	 * Almost always, mapping_empty(&inode->i_data) here; but there are
671  	 * two known and long-standing ways in which nodes may get left behind
672  	 * (when deep radix-tree node allocation failed partway; or when THP
673  	 * collapse_file() failed). Until those two known cases are cleaned up,
674  	 * or a cleanup function is called here, do not BUG_ON(!mapping_empty),
675  	 * nor even WARN_ON(!mapping_empty).
676  	 */
677  	xa_unlock_irq(&inode->i_data.i_pages);
678  	BUG_ON(!list_empty(&inode->i_data.i_private_list));
679  	BUG_ON(!(inode->i_state & I_FREEING));
680  	BUG_ON(inode->i_state & I_CLEAR);
681  	BUG_ON(!list_empty(&inode->i_wb_list));
682  	/* don't need i_lock here, no concurrent mods to i_state */
683  	inode->i_state = I_FREEING | I_CLEAR;
684  }
685  EXPORT_SYMBOL(clear_inode);
686  
687  /*
688   * Free the inode passed in, removing it from the lists it is still connected
689   * to. We remove any pages still attached to the inode and wait for any IO that
690   * is still in progress before finally destroying the inode.
691   *
692   * An inode must already be marked I_FREEING so that we avoid the inode being
693   * moved back onto lists if we race with other code that manipulates the lists
694   * (e.g. writeback_single_inode). The caller is responsible for setting this.
695   *
696   * An inode must already be removed from the LRU list before being evicted from
697   * the cache. This should occur atomically with setting the I_FREEING state
698   * flag, so no inodes here should ever be on the LRU when being evicted.
699   */
evict(struct inode * inode)700  static void evict(struct inode *inode)
701  {
702  	const struct super_operations *op = inode->i_sb->s_op;
703  
704  	BUG_ON(!(inode->i_state & I_FREEING));
705  	BUG_ON(!list_empty(&inode->i_lru));
706  
707  	if (!list_empty(&inode->i_io_list))
708  		inode_io_list_del(inode);
709  
710  	inode_sb_list_del(inode);
711  
712  	spin_lock(&inode->i_lock);
713  	inode_wait_for_lru_isolating(inode);
714  
715  	/*
716  	 * Wait for flusher thread to be done with the inode so that filesystem
717  	 * does not start destroying it while writeback is still running. Since
718  	 * the inode has I_FREEING set, flusher thread won't start new work on
719  	 * the inode.  We just have to wait for running writeback to finish.
720  	 */
721  	inode_wait_for_writeback(inode);
722  	spin_unlock(&inode->i_lock);
723  
724  	if (op->evict_inode) {
725  		op->evict_inode(inode);
726  	} else {
727  		truncate_inode_pages_final(&inode->i_data);
728  		clear_inode(inode);
729  	}
730  	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
731  		cd_forget(inode);
732  
733  	remove_inode_hash(inode);
734  
735  	/*
736  	 * Wake up waiters in __wait_on_freeing_inode().
737  	 *
738  	 * Lockless hash lookup may end up finding the inode before we removed
739  	 * it above, but only lock it *after* we are done with the wakeup below.
740  	 * In this case the potential waiter cannot safely block.
741  	 *
742  	 * The inode being unhashed after the call to remove_inode_hash() is
743  	 * used as an indicator whether blocking on it is safe.
744  	 */
745  	spin_lock(&inode->i_lock);
746  	/*
747  	 * Pairs with the barrier in prepare_to_wait_event() to make sure
748  	 * ___wait_var_event() either sees the bit cleared or
749  	 * waitqueue_active() check in wake_up_var() sees the waiter.
750  	 */
751  	smp_mb();
752  	inode_wake_up_bit(inode, __I_NEW);
753  	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
754  	spin_unlock(&inode->i_lock);
755  
756  	destroy_inode(inode);
757  }
758  
759  /*
760   * dispose_list - dispose of the contents of a local list
761   * @head: the head of the list to free
762   *
763   * Dispose-list gets a local list with local inodes in it, so it doesn't
764   * need to worry about list corruption and SMP locks.
765   */
dispose_list(struct list_head * head)766  static void dispose_list(struct list_head *head)
767  {
768  	while (!list_empty(head)) {
769  		struct inode *inode;
770  
771  		inode = list_first_entry(head, struct inode, i_lru);
772  		list_del_init(&inode->i_lru);
773  
774  		evict(inode);
775  		cond_resched();
776  	}
777  }
778  
779  /**
780   * evict_inodes	- evict all evictable inodes for a superblock
781   * @sb:		superblock to operate on
782   *
783   * Make sure that no inodes with zero refcount are retained.  This is
784   * called by superblock shutdown after having SB_ACTIVE flag removed,
785   * so any inode reaching zero refcount during or after that call will
786   * be immediately evicted.
787   */
evict_inodes(struct super_block * sb)788  void evict_inodes(struct super_block *sb)
789  {
790  	struct inode *inode, *next;
791  	LIST_HEAD(dispose);
792  
793  again:
794  	spin_lock(&sb->s_inode_list_lock);
795  	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
796  		if (atomic_read(&inode->i_count))
797  			continue;
798  
799  		spin_lock(&inode->i_lock);
800  		if (atomic_read(&inode->i_count)) {
801  			spin_unlock(&inode->i_lock);
802  			continue;
803  		}
804  		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
805  			spin_unlock(&inode->i_lock);
806  			continue;
807  		}
808  
809  		inode->i_state |= I_FREEING;
810  		inode_lru_list_del(inode);
811  		spin_unlock(&inode->i_lock);
812  		list_add(&inode->i_lru, &dispose);
813  
814  		/*
815  		 * We can have a ton of inodes to evict at unmount time given
816  		 * enough memory, check to see if we need to go to sleep for a
817  		 * bit so we don't livelock.
818  		 */
819  		if (need_resched()) {
820  			spin_unlock(&sb->s_inode_list_lock);
821  			cond_resched();
822  			dispose_list(&dispose);
823  			goto again;
824  		}
825  	}
826  	spin_unlock(&sb->s_inode_list_lock);
827  
828  	dispose_list(&dispose);
829  }
830  EXPORT_SYMBOL_GPL(evict_inodes);
831  
832  /**
833   * invalidate_inodes	- attempt to free all inodes on a superblock
834   * @sb:		superblock to operate on
835   *
836   * Attempts to free all inodes (including dirty inodes) for a given superblock.
837   */
invalidate_inodes(struct super_block * sb)838  void invalidate_inodes(struct super_block *sb)
839  {
840  	struct inode *inode, *next;
841  	LIST_HEAD(dispose);
842  
843  again:
844  	spin_lock(&sb->s_inode_list_lock);
845  	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
846  		spin_lock(&inode->i_lock);
847  		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
848  			spin_unlock(&inode->i_lock);
849  			continue;
850  		}
851  		if (atomic_read(&inode->i_count)) {
852  			spin_unlock(&inode->i_lock);
853  			continue;
854  		}
855  
856  		inode->i_state |= I_FREEING;
857  		inode_lru_list_del(inode);
858  		spin_unlock(&inode->i_lock);
859  		list_add(&inode->i_lru, &dispose);
860  		if (need_resched()) {
861  			spin_unlock(&sb->s_inode_list_lock);
862  			cond_resched();
863  			dispose_list(&dispose);
864  			goto again;
865  		}
866  	}
867  	spin_unlock(&sb->s_inode_list_lock);
868  
869  	dispose_list(&dispose);
870  }
871  
872  /*
873   * Isolate the inode from the LRU in preparation for freeing it.
874   *
875   * If the inode has the I_REFERENCED flag set, then it means that it has been
876   * used recently - the flag is set in iput_final(). When we encounter such an
877   * inode, clear the flag and move it to the back of the LRU so it gets another
878   * pass through the LRU before it gets reclaimed. This is necessary because of
879   * the fact we are doing lazy LRU updates to minimise lock contention so the
880   * LRU does not have strict ordering. Hence we don't want to reclaim inodes
881   * with this flag set because they are the inodes that are out of order.
882   */
inode_lru_isolate(struct list_head * item,struct list_lru_one * lru,spinlock_t * lru_lock,void * arg)883  static enum lru_status inode_lru_isolate(struct list_head *item,
884  		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
885  {
886  	struct list_head *freeable = arg;
887  	struct inode	*inode = container_of(item, struct inode, i_lru);
888  
889  	/*
890  	 * We are inverting the lru lock/inode->i_lock here, so use a
891  	 * trylock. If we fail to get the lock, just skip it.
892  	 */
893  	if (!spin_trylock(&inode->i_lock))
894  		return LRU_SKIP;
895  
896  	/*
897  	 * Inodes can get referenced, redirtied, or repopulated while
898  	 * they're already on the LRU, and this can make them
899  	 * unreclaimable for a while. Remove them lazily here; iput,
900  	 * sync, or the last page cache deletion will requeue them.
901  	 */
902  	if (atomic_read(&inode->i_count) ||
903  	    (inode->i_state & ~I_REFERENCED) ||
904  	    !mapping_shrinkable(&inode->i_data)) {
905  		list_lru_isolate(lru, &inode->i_lru);
906  		spin_unlock(&inode->i_lock);
907  		this_cpu_dec(nr_unused);
908  		return LRU_REMOVED;
909  	}
910  
911  	/* Recently referenced inodes get one more pass */
912  	if (inode->i_state & I_REFERENCED) {
913  		inode->i_state &= ~I_REFERENCED;
914  		spin_unlock(&inode->i_lock);
915  		return LRU_ROTATE;
916  	}
917  
918  	/*
919  	 * On highmem systems, mapping_shrinkable() permits dropping
920  	 * page cache in order to free up struct inodes: lowmem might
921  	 * be under pressure before the cache inside the highmem zone.
922  	 */
923  	if (inode_has_buffers(inode) || !mapping_empty(&inode->i_data)) {
924  		inode_pin_lru_isolating(inode);
925  		spin_unlock(&inode->i_lock);
926  		spin_unlock(lru_lock);
927  		if (remove_inode_buffers(inode)) {
928  			unsigned long reap;
929  			reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
930  			if (current_is_kswapd())
931  				__count_vm_events(KSWAPD_INODESTEAL, reap);
932  			else
933  				__count_vm_events(PGINODESTEAL, reap);
934  			mm_account_reclaimed_pages(reap);
935  		}
936  		inode_unpin_lru_isolating(inode);
937  		spin_lock(lru_lock);
938  		return LRU_RETRY;
939  	}
940  
941  	WARN_ON(inode->i_state & I_NEW);
942  	inode->i_state |= I_FREEING;
943  	list_lru_isolate_move(lru, &inode->i_lru, freeable);
944  	spin_unlock(&inode->i_lock);
945  
946  	this_cpu_dec(nr_unused);
947  	return LRU_REMOVED;
948  }
949  
950  /*
951   * Walk the superblock inode LRU for freeable inodes and attempt to free them.
952   * This is called from the superblock shrinker function with a number of inodes
953   * to trim from the LRU. Inodes to be freed are moved to a temporary list and
954   * then are freed outside inode_lock by dispose_list().
955   */
prune_icache_sb(struct super_block * sb,struct shrink_control * sc)956  long prune_icache_sb(struct super_block *sb, struct shrink_control *sc)
957  {
958  	LIST_HEAD(freeable);
959  	long freed;
960  
961  	freed = list_lru_shrink_walk(&sb->s_inode_lru, sc,
962  				     inode_lru_isolate, &freeable);
963  	dispose_list(&freeable);
964  	return freed;
965  }
966  
967  static void __wait_on_freeing_inode(struct inode *inode, bool is_inode_hash_locked);
968  /*
969   * Called with the inode lock held.
970   */
find_inode(struct super_block * sb,struct hlist_head * head,int (* test)(struct inode *,void *),void * data,bool is_inode_hash_locked)971  static struct inode *find_inode(struct super_block *sb,
972  				struct hlist_head *head,
973  				int (*test)(struct inode *, void *),
974  				void *data, bool is_inode_hash_locked)
975  {
976  	struct inode *inode = NULL;
977  
978  	if (is_inode_hash_locked)
979  		lockdep_assert_held(&inode_hash_lock);
980  	else
981  		lockdep_assert_not_held(&inode_hash_lock);
982  
983  	rcu_read_lock();
984  repeat:
985  	hlist_for_each_entry_rcu(inode, head, i_hash) {
986  		if (inode->i_sb != sb)
987  			continue;
988  		if (!test(inode, data))
989  			continue;
990  		spin_lock(&inode->i_lock);
991  		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
992  			__wait_on_freeing_inode(inode, is_inode_hash_locked);
993  			goto repeat;
994  		}
995  		if (unlikely(inode->i_state & I_CREATING)) {
996  			spin_unlock(&inode->i_lock);
997  			rcu_read_unlock();
998  			return ERR_PTR(-ESTALE);
999  		}
1000  		__iget(inode);
1001  		spin_unlock(&inode->i_lock);
1002  		rcu_read_unlock();
1003  		return inode;
1004  	}
1005  	rcu_read_unlock();
1006  	return NULL;
1007  }
1008  
1009  /*
1010   * find_inode_fast is the fast path version of find_inode, see the comment at
1011   * iget_locked for details.
1012   */
find_inode_fast(struct super_block * sb,struct hlist_head * head,unsigned long ino,bool is_inode_hash_locked)1013  static struct inode *find_inode_fast(struct super_block *sb,
1014  				struct hlist_head *head, unsigned long ino,
1015  				bool is_inode_hash_locked)
1016  {
1017  	struct inode *inode = NULL;
1018  
1019  	if (is_inode_hash_locked)
1020  		lockdep_assert_held(&inode_hash_lock);
1021  	else
1022  		lockdep_assert_not_held(&inode_hash_lock);
1023  
1024  	rcu_read_lock();
1025  repeat:
1026  	hlist_for_each_entry_rcu(inode, head, i_hash) {
1027  		if (inode->i_ino != ino)
1028  			continue;
1029  		if (inode->i_sb != sb)
1030  			continue;
1031  		spin_lock(&inode->i_lock);
1032  		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
1033  			__wait_on_freeing_inode(inode, is_inode_hash_locked);
1034  			goto repeat;
1035  		}
1036  		if (unlikely(inode->i_state & I_CREATING)) {
1037  			spin_unlock(&inode->i_lock);
1038  			rcu_read_unlock();
1039  			return ERR_PTR(-ESTALE);
1040  		}
1041  		__iget(inode);
1042  		spin_unlock(&inode->i_lock);
1043  		rcu_read_unlock();
1044  		return inode;
1045  	}
1046  	rcu_read_unlock();
1047  	return NULL;
1048  }
1049  
1050  /*
1051   * Each cpu owns a range of LAST_INO_BATCH numbers.
1052   * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
1053   * to renew the exhausted range.
1054   *
1055   * This does not significantly increase overflow rate because every CPU can
1056   * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
1057   * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
1058   * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
1059   * overflow rate by 2x, which does not seem too significant.
1060   *
1061   * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1062   * error if st_ino won't fit in target struct field. Use 32bit counter
1063   * here to attempt to avoid that.
1064   */
1065  #define LAST_INO_BATCH 1024
1066  static DEFINE_PER_CPU(unsigned int, last_ino);
1067  
get_next_ino(void)1068  unsigned int get_next_ino(void)
1069  {
1070  	unsigned int *p = &get_cpu_var(last_ino);
1071  	unsigned int res = *p;
1072  
1073  #ifdef CONFIG_SMP
1074  	if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
1075  		static atomic_t shared_last_ino;
1076  		int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
1077  
1078  		res = next - LAST_INO_BATCH;
1079  	}
1080  #endif
1081  
1082  	res++;
1083  	/* get_next_ino should not provide a 0 inode number */
1084  	if (unlikely(!res))
1085  		res++;
1086  	*p = res;
1087  	put_cpu_var(last_ino);
1088  	return res;
1089  }
1090  EXPORT_SYMBOL(get_next_ino);
1091  
1092  /**
1093   *	new_inode_pseudo 	- obtain an inode
1094   *	@sb: superblock
1095   *
1096   *	Allocates a new inode for given superblock.
1097   *	Inode wont be chained in superblock s_inodes list
1098   *	This means :
1099   *	- fs can't be unmount
1100   *	- quotas, fsnotify, writeback can't work
1101   */
new_inode_pseudo(struct super_block * sb)1102  struct inode *new_inode_pseudo(struct super_block *sb)
1103  {
1104  	return alloc_inode(sb);
1105  }
1106  
1107  /**
1108   *	new_inode 	- obtain an inode
1109   *	@sb: superblock
1110   *
1111   *	Allocates a new inode for given superblock. The default gfp_mask
1112   *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
1113   *	If HIGHMEM pages are unsuitable or it is known that pages allocated
1114   *	for the page cache are not reclaimable or migratable,
1115   *	mapping_set_gfp_mask() must be called with suitable flags on the
1116   *	newly created inode's mapping
1117   *
1118   */
new_inode(struct super_block * sb)1119  struct inode *new_inode(struct super_block *sb)
1120  {
1121  	struct inode *inode;
1122  
1123  	inode = new_inode_pseudo(sb);
1124  	if (inode)
1125  		inode_sb_list_add(inode);
1126  	return inode;
1127  }
1128  EXPORT_SYMBOL(new_inode);
1129  
1130  #ifdef CONFIG_DEBUG_LOCK_ALLOC
lockdep_annotate_inode_mutex_key(struct inode * inode)1131  void lockdep_annotate_inode_mutex_key(struct inode *inode)
1132  {
1133  	if (S_ISDIR(inode->i_mode)) {
1134  		struct file_system_type *type = inode->i_sb->s_type;
1135  
1136  		/* Set new key only if filesystem hasn't already changed it */
1137  		if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) {
1138  			/*
1139  			 * ensure nobody is actually holding i_mutex
1140  			 */
1141  			// mutex_destroy(&inode->i_mutex);
1142  			init_rwsem(&inode->i_rwsem);
1143  			lockdep_set_class(&inode->i_rwsem,
1144  					  &type->i_mutex_dir_key);
1145  		}
1146  	}
1147  }
1148  EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
1149  #endif
1150  
1151  /**
1152   * unlock_new_inode - clear the I_NEW state and wake up any waiters
1153   * @inode:	new inode to unlock
1154   *
1155   * Called when the inode is fully initialised to clear the new state of the
1156   * inode and wake up anyone waiting for the inode to finish initialisation.
1157   */
unlock_new_inode(struct inode * inode)1158  void unlock_new_inode(struct inode *inode)
1159  {
1160  	lockdep_annotate_inode_mutex_key(inode);
1161  	spin_lock(&inode->i_lock);
1162  	WARN_ON(!(inode->i_state & I_NEW));
1163  	inode->i_state &= ~I_NEW & ~I_CREATING;
1164  	/*
1165  	 * Pairs with the barrier in prepare_to_wait_event() to make sure
1166  	 * ___wait_var_event() either sees the bit cleared or
1167  	 * waitqueue_active() check in wake_up_var() sees the waiter.
1168  	 */
1169  	smp_mb();
1170  	inode_wake_up_bit(inode, __I_NEW);
1171  	spin_unlock(&inode->i_lock);
1172  }
1173  EXPORT_SYMBOL(unlock_new_inode);
1174  
discard_new_inode(struct inode * inode)1175  void discard_new_inode(struct inode *inode)
1176  {
1177  	lockdep_annotate_inode_mutex_key(inode);
1178  	spin_lock(&inode->i_lock);
1179  	WARN_ON(!(inode->i_state & I_NEW));
1180  	inode->i_state &= ~I_NEW;
1181  	/*
1182  	 * Pairs with the barrier in prepare_to_wait_event() to make sure
1183  	 * ___wait_var_event() either sees the bit cleared or
1184  	 * waitqueue_active() check in wake_up_var() sees the waiter.
1185  	 */
1186  	smp_mb();
1187  	inode_wake_up_bit(inode, __I_NEW);
1188  	spin_unlock(&inode->i_lock);
1189  	iput(inode);
1190  }
1191  EXPORT_SYMBOL(discard_new_inode);
1192  
1193  /**
1194   * lock_two_nondirectories - take two i_mutexes on non-directory objects
1195   *
1196   * Lock any non-NULL argument. Passed objects must not be directories.
1197   * Zero, one or two objects may be locked by this function.
1198   *
1199   * @inode1: first inode to lock
1200   * @inode2: second inode to lock
1201   */
lock_two_nondirectories(struct inode * inode1,struct inode * inode2)1202  void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1203  {
1204  	if (inode1)
1205  		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
1206  	if (inode2)
1207  		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
1208  	if (inode1 > inode2)
1209  		swap(inode1, inode2);
1210  	if (inode1)
1211  		inode_lock(inode1);
1212  	if (inode2 && inode2 != inode1)
1213  		inode_lock_nested(inode2, I_MUTEX_NONDIR2);
1214  }
1215  EXPORT_SYMBOL(lock_two_nondirectories);
1216  
1217  /**
1218   * unlock_two_nondirectories - release locks from lock_two_nondirectories()
1219   * @inode1: first inode to unlock
1220   * @inode2: second inode to unlock
1221   */
unlock_two_nondirectories(struct inode * inode1,struct inode * inode2)1222  void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1223  {
1224  	if (inode1) {
1225  		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
1226  		inode_unlock(inode1);
1227  	}
1228  	if (inode2 && inode2 != inode1) {
1229  		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
1230  		inode_unlock(inode2);
1231  	}
1232  }
1233  EXPORT_SYMBOL(unlock_two_nondirectories);
1234  
1235  /**
1236   * inode_insert5 - obtain an inode from a mounted file system
1237   * @inode:	pre-allocated inode to use for insert to cache
1238   * @hashval:	hash value (usually inode number) to get
1239   * @test:	callback used for comparisons between inodes
1240   * @set:	callback used to initialize a new struct inode
1241   * @data:	opaque data pointer to pass to @test and @set
1242   *
1243   * Search for the inode specified by @hashval and @data in the inode cache,
1244   * and if present it is return it with an increased reference count. This is
1245   * a variant of iget5_locked() for callers that don't want to fail on memory
1246   * allocation of inode.
1247   *
1248   * If the inode is not in cache, insert the pre-allocated inode to cache and
1249   * return it locked, hashed, and with the I_NEW flag set. The file system gets
1250   * to fill it in before unlocking it via unlock_new_inode().
1251   *
1252   * Note both @test and @set are called with the inode_hash_lock held, so can't
1253   * sleep.
1254   */
inode_insert5(struct inode * inode,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1255  struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
1256  			    int (*test)(struct inode *, void *),
1257  			    int (*set)(struct inode *, void *), void *data)
1258  {
1259  	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
1260  	struct inode *old;
1261  
1262  again:
1263  	spin_lock(&inode_hash_lock);
1264  	old = find_inode(inode->i_sb, head, test, data, true);
1265  	if (unlikely(old)) {
1266  		/*
1267  		 * Uhhuh, somebody else created the same inode under us.
1268  		 * Use the old inode instead of the preallocated one.
1269  		 */
1270  		spin_unlock(&inode_hash_lock);
1271  		if (IS_ERR(old))
1272  			return NULL;
1273  		wait_on_inode(old);
1274  		if (unlikely(inode_unhashed(old))) {
1275  			iput(old);
1276  			goto again;
1277  		}
1278  		return old;
1279  	}
1280  
1281  	if (set && unlikely(set(inode, data))) {
1282  		inode = NULL;
1283  		goto unlock;
1284  	}
1285  
1286  	/*
1287  	 * Return the locked inode with I_NEW set, the
1288  	 * caller is responsible for filling in the contents
1289  	 */
1290  	spin_lock(&inode->i_lock);
1291  	inode->i_state |= I_NEW;
1292  	hlist_add_head_rcu(&inode->i_hash, head);
1293  	spin_unlock(&inode->i_lock);
1294  
1295  	/*
1296  	 * Add inode to the sb list if it's not already. It has I_NEW at this
1297  	 * point, so it should be safe to test i_sb_list locklessly.
1298  	 */
1299  	if (list_empty(&inode->i_sb_list))
1300  		inode_sb_list_add(inode);
1301  unlock:
1302  	spin_unlock(&inode_hash_lock);
1303  
1304  	return inode;
1305  }
1306  EXPORT_SYMBOL(inode_insert5);
1307  
1308  /**
1309   * iget5_locked - obtain an inode from a mounted file system
1310   * @sb:		super block of file system
1311   * @hashval:	hash value (usually inode number) to get
1312   * @test:	callback used for comparisons between inodes
1313   * @set:	callback used to initialize a new struct inode
1314   * @data:	opaque data pointer to pass to @test and @set
1315   *
1316   * Search for the inode specified by @hashval and @data in the inode cache,
1317   * and if present it is return it with an increased reference count. This is
1318   * a generalized version of iget_locked() for file systems where the inode
1319   * number is not sufficient for unique identification of an inode.
1320   *
1321   * If the inode is not in cache, allocate a new inode and return it locked,
1322   * hashed, and with the I_NEW flag set. The file system gets to fill it in
1323   * before unlocking it via unlock_new_inode().
1324   *
1325   * Note both @test and @set are called with the inode_hash_lock held, so can't
1326   * sleep.
1327   */
iget5_locked(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1328  struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1329  		int (*test)(struct inode *, void *),
1330  		int (*set)(struct inode *, void *), void *data)
1331  {
1332  	struct inode *inode = ilookup5(sb, hashval, test, data);
1333  
1334  	if (!inode) {
1335  		struct inode *new = alloc_inode(sb);
1336  
1337  		if (new) {
1338  			inode = inode_insert5(new, hashval, test, set, data);
1339  			if (unlikely(inode != new))
1340  				destroy_inode(new);
1341  		}
1342  	}
1343  	return inode;
1344  }
1345  EXPORT_SYMBOL(iget5_locked);
1346  
1347  /**
1348   * iget5_locked_rcu - obtain an inode from a mounted file system
1349   * @sb:		super block of file system
1350   * @hashval:	hash value (usually inode number) to get
1351   * @test:	callback used for comparisons between inodes
1352   * @set:	callback used to initialize a new struct inode
1353   * @data:	opaque data pointer to pass to @test and @set
1354   *
1355   * This is equivalent to iget5_locked, except the @test callback must
1356   * tolerate the inode not being stable, including being mid-teardown.
1357   */
iget5_locked_rcu(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1358  struct inode *iget5_locked_rcu(struct super_block *sb, unsigned long hashval,
1359  		int (*test)(struct inode *, void *),
1360  		int (*set)(struct inode *, void *), void *data)
1361  {
1362  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1363  	struct inode *inode, *new;
1364  
1365  again:
1366  	inode = find_inode(sb, head, test, data, false);
1367  	if (inode) {
1368  		if (IS_ERR(inode))
1369  			return NULL;
1370  		wait_on_inode(inode);
1371  		if (unlikely(inode_unhashed(inode))) {
1372  			iput(inode);
1373  			goto again;
1374  		}
1375  		return inode;
1376  	}
1377  
1378  	new = alloc_inode(sb);
1379  	if (new) {
1380  		inode = inode_insert5(new, hashval, test, set, data);
1381  		if (unlikely(inode != new))
1382  			destroy_inode(new);
1383  	}
1384  	return inode;
1385  }
1386  EXPORT_SYMBOL_GPL(iget5_locked_rcu);
1387  
1388  /**
1389   * iget_locked - obtain an inode from a mounted file system
1390   * @sb:		super block of file system
1391   * @ino:	inode number to get
1392   *
1393   * Search for the inode specified by @ino in the inode cache and if present
1394   * return it with an increased reference count. This is for file systems
1395   * where the inode number is sufficient for unique identification of an inode.
1396   *
1397   * If the inode is not in cache, allocate a new inode and return it locked,
1398   * hashed, and with the I_NEW flag set.  The file system gets to fill it in
1399   * before unlocking it via unlock_new_inode().
1400   */
iget_locked(struct super_block * sb,unsigned long ino)1401  struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1402  {
1403  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1404  	struct inode *inode;
1405  again:
1406  	inode = find_inode_fast(sb, head, ino, false);
1407  	if (inode) {
1408  		if (IS_ERR(inode))
1409  			return NULL;
1410  		wait_on_inode(inode);
1411  		if (unlikely(inode_unhashed(inode))) {
1412  			iput(inode);
1413  			goto again;
1414  		}
1415  		return inode;
1416  	}
1417  
1418  	inode = alloc_inode(sb);
1419  	if (inode) {
1420  		struct inode *old;
1421  
1422  		spin_lock(&inode_hash_lock);
1423  		/* We released the lock, so.. */
1424  		old = find_inode_fast(sb, head, ino, true);
1425  		if (!old) {
1426  			inode->i_ino = ino;
1427  			spin_lock(&inode->i_lock);
1428  			inode->i_state = I_NEW;
1429  			hlist_add_head_rcu(&inode->i_hash, head);
1430  			spin_unlock(&inode->i_lock);
1431  			inode_sb_list_add(inode);
1432  			spin_unlock(&inode_hash_lock);
1433  
1434  			/* Return the locked inode with I_NEW set, the
1435  			 * caller is responsible for filling in the contents
1436  			 */
1437  			return inode;
1438  		}
1439  
1440  		/*
1441  		 * Uhhuh, somebody else created the same inode under
1442  		 * us. Use the old inode instead of the one we just
1443  		 * allocated.
1444  		 */
1445  		spin_unlock(&inode_hash_lock);
1446  		destroy_inode(inode);
1447  		if (IS_ERR(old))
1448  			return NULL;
1449  		inode = old;
1450  		wait_on_inode(inode);
1451  		if (unlikely(inode_unhashed(inode))) {
1452  			iput(inode);
1453  			goto again;
1454  		}
1455  	}
1456  	return inode;
1457  }
1458  EXPORT_SYMBOL(iget_locked);
1459  
1460  /*
1461   * search the inode cache for a matching inode number.
1462   * If we find one, then the inode number we are trying to
1463   * allocate is not unique and so we should not use it.
1464   *
1465   * Returns 1 if the inode number is unique, 0 if it is not.
1466   */
test_inode_iunique(struct super_block * sb,unsigned long ino)1467  static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1468  {
1469  	struct hlist_head *b = inode_hashtable + hash(sb, ino);
1470  	struct inode *inode;
1471  
1472  	hlist_for_each_entry_rcu(inode, b, i_hash) {
1473  		if (inode->i_ino == ino && inode->i_sb == sb)
1474  			return 0;
1475  	}
1476  	return 1;
1477  }
1478  
1479  /**
1480   *	iunique - get a unique inode number
1481   *	@sb: superblock
1482   *	@max_reserved: highest reserved inode number
1483   *
1484   *	Obtain an inode number that is unique on the system for a given
1485   *	superblock. This is used by file systems that have no natural
1486   *	permanent inode numbering system. An inode number is returned that
1487   *	is higher than the reserved limit but unique.
1488   *
1489   *	BUGS:
1490   *	With a large number of inodes live on the file system this function
1491   *	currently becomes quite slow.
1492   */
iunique(struct super_block * sb,ino_t max_reserved)1493  ino_t iunique(struct super_block *sb, ino_t max_reserved)
1494  {
1495  	/*
1496  	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1497  	 * error if st_ino won't fit in target struct field. Use 32bit counter
1498  	 * here to attempt to avoid that.
1499  	 */
1500  	static DEFINE_SPINLOCK(iunique_lock);
1501  	static unsigned int counter;
1502  	ino_t res;
1503  
1504  	rcu_read_lock();
1505  	spin_lock(&iunique_lock);
1506  	do {
1507  		if (counter <= max_reserved)
1508  			counter = max_reserved + 1;
1509  		res = counter++;
1510  	} while (!test_inode_iunique(sb, res));
1511  	spin_unlock(&iunique_lock);
1512  	rcu_read_unlock();
1513  
1514  	return res;
1515  }
1516  EXPORT_SYMBOL(iunique);
1517  
igrab(struct inode * inode)1518  struct inode *igrab(struct inode *inode)
1519  {
1520  	spin_lock(&inode->i_lock);
1521  	if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1522  		__iget(inode);
1523  		spin_unlock(&inode->i_lock);
1524  	} else {
1525  		spin_unlock(&inode->i_lock);
1526  		/*
1527  		 * Handle the case where s_op->clear_inode is not been
1528  		 * called yet, and somebody is calling igrab
1529  		 * while the inode is getting freed.
1530  		 */
1531  		inode = NULL;
1532  	}
1533  	return inode;
1534  }
1535  EXPORT_SYMBOL(igrab);
1536  
1537  /**
1538   * ilookup5_nowait - search for an inode in the inode cache
1539   * @sb:		super block of file system to search
1540   * @hashval:	hash value (usually inode number) to search for
1541   * @test:	callback used for comparisons between inodes
1542   * @data:	opaque data pointer to pass to @test
1543   *
1544   * Search for the inode specified by @hashval and @data in the inode cache.
1545   * If the inode is in the cache, the inode is returned with an incremented
1546   * reference count.
1547   *
1548   * Note: I_NEW is not waited upon so you have to be very careful what you do
1549   * with the returned inode.  You probably should be using ilookup5() instead.
1550   *
1551   * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1552   */
ilookup5_nowait(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1553  struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1554  		int (*test)(struct inode *, void *), void *data)
1555  {
1556  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1557  	struct inode *inode;
1558  
1559  	spin_lock(&inode_hash_lock);
1560  	inode = find_inode(sb, head, test, data, true);
1561  	spin_unlock(&inode_hash_lock);
1562  
1563  	return IS_ERR(inode) ? NULL : inode;
1564  }
1565  EXPORT_SYMBOL(ilookup5_nowait);
1566  
1567  /**
1568   * ilookup5 - search for an inode in the inode cache
1569   * @sb:		super block of file system to search
1570   * @hashval:	hash value (usually inode number) to search for
1571   * @test:	callback used for comparisons between inodes
1572   * @data:	opaque data pointer to pass to @test
1573   *
1574   * Search for the inode specified by @hashval and @data in the inode cache,
1575   * and if the inode is in the cache, return the inode with an incremented
1576   * reference count.  Waits on I_NEW before returning the inode.
1577   * returned with an incremented reference count.
1578   *
1579   * This is a generalized version of ilookup() for file systems where the
1580   * inode number is not sufficient for unique identification of an inode.
1581   *
1582   * Note: @test is called with the inode_hash_lock held, so can't sleep.
1583   */
ilookup5(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1584  struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1585  		int (*test)(struct inode *, void *), void *data)
1586  {
1587  	struct inode *inode;
1588  again:
1589  	inode = ilookup5_nowait(sb, hashval, test, data);
1590  	if (inode) {
1591  		wait_on_inode(inode);
1592  		if (unlikely(inode_unhashed(inode))) {
1593  			iput(inode);
1594  			goto again;
1595  		}
1596  	}
1597  	return inode;
1598  }
1599  EXPORT_SYMBOL(ilookup5);
1600  
1601  /**
1602   * ilookup - search for an inode in the inode cache
1603   * @sb:		super block of file system to search
1604   * @ino:	inode number to search for
1605   *
1606   * Search for the inode @ino in the inode cache, and if the inode is in the
1607   * cache, the inode is returned with an incremented reference count.
1608   */
ilookup(struct super_block * sb,unsigned long ino)1609  struct inode *ilookup(struct super_block *sb, unsigned long ino)
1610  {
1611  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1612  	struct inode *inode;
1613  again:
1614  	inode = find_inode_fast(sb, head, ino, false);
1615  
1616  	if (inode) {
1617  		if (IS_ERR(inode))
1618  			return NULL;
1619  		wait_on_inode(inode);
1620  		if (unlikely(inode_unhashed(inode))) {
1621  			iput(inode);
1622  			goto again;
1623  		}
1624  	}
1625  	return inode;
1626  }
1627  EXPORT_SYMBOL(ilookup);
1628  
1629  /**
1630   * find_inode_nowait - find an inode in the inode cache
1631   * @sb:		super block of file system to search
1632   * @hashval:	hash value (usually inode number) to search for
1633   * @match:	callback used for comparisons between inodes
1634   * @data:	opaque data pointer to pass to @match
1635   *
1636   * Search for the inode specified by @hashval and @data in the inode
1637   * cache, where the helper function @match will return 0 if the inode
1638   * does not match, 1 if the inode does match, and -1 if the search
1639   * should be stopped.  The @match function must be responsible for
1640   * taking the i_lock spin_lock and checking i_state for an inode being
1641   * freed or being initialized, and incrementing the reference count
1642   * before returning 1.  It also must not sleep, since it is called with
1643   * the inode_hash_lock spinlock held.
1644   *
1645   * This is a even more generalized version of ilookup5() when the
1646   * function must never block --- find_inode() can block in
1647   * __wait_on_freeing_inode() --- or when the caller can not increment
1648   * the reference count because the resulting iput() might cause an
1649   * inode eviction.  The tradeoff is that the @match funtion must be
1650   * very carefully implemented.
1651   */
find_inode_nowait(struct super_block * sb,unsigned long hashval,int (* match)(struct inode *,unsigned long,void *),void * data)1652  struct inode *find_inode_nowait(struct super_block *sb,
1653  				unsigned long hashval,
1654  				int (*match)(struct inode *, unsigned long,
1655  					     void *),
1656  				void *data)
1657  {
1658  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1659  	struct inode *inode, *ret_inode = NULL;
1660  	int mval;
1661  
1662  	spin_lock(&inode_hash_lock);
1663  	hlist_for_each_entry(inode, head, i_hash) {
1664  		if (inode->i_sb != sb)
1665  			continue;
1666  		mval = match(inode, hashval, data);
1667  		if (mval == 0)
1668  			continue;
1669  		if (mval == 1)
1670  			ret_inode = inode;
1671  		goto out;
1672  	}
1673  out:
1674  	spin_unlock(&inode_hash_lock);
1675  	return ret_inode;
1676  }
1677  EXPORT_SYMBOL(find_inode_nowait);
1678  
1679  /**
1680   * find_inode_rcu - find an inode in the inode cache
1681   * @sb:		Super block of file system to search
1682   * @hashval:	Key to hash
1683   * @test:	Function to test match on an inode
1684   * @data:	Data for test function
1685   *
1686   * Search for the inode specified by @hashval and @data in the inode cache,
1687   * where the helper function @test will return 0 if the inode does not match
1688   * and 1 if it does.  The @test function must be responsible for taking the
1689   * i_lock spin_lock and checking i_state for an inode being freed or being
1690   * initialized.
1691   *
1692   * If successful, this will return the inode for which the @test function
1693   * returned 1 and NULL otherwise.
1694   *
1695   * The @test function is not permitted to take a ref on any inode presented.
1696   * It is also not permitted to sleep.
1697   *
1698   * The caller must hold the RCU read lock.
1699   */
find_inode_rcu(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1700  struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval,
1701  			     int (*test)(struct inode *, void *), void *data)
1702  {
1703  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1704  	struct inode *inode;
1705  
1706  	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1707  			 "suspicious find_inode_rcu() usage");
1708  
1709  	hlist_for_each_entry_rcu(inode, head, i_hash) {
1710  		if (inode->i_sb == sb &&
1711  		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)) &&
1712  		    test(inode, data))
1713  			return inode;
1714  	}
1715  	return NULL;
1716  }
1717  EXPORT_SYMBOL(find_inode_rcu);
1718  
1719  /**
1720   * find_inode_by_ino_rcu - Find an inode in the inode cache
1721   * @sb:		Super block of file system to search
1722   * @ino:	The inode number to match
1723   *
1724   * Search for the inode specified by @hashval and @data in the inode cache,
1725   * where the helper function @test will return 0 if the inode does not match
1726   * and 1 if it does.  The @test function must be responsible for taking the
1727   * i_lock spin_lock and checking i_state for an inode being freed or being
1728   * initialized.
1729   *
1730   * If successful, this will return the inode for which the @test function
1731   * returned 1 and NULL otherwise.
1732   *
1733   * The @test function is not permitted to take a ref on any inode presented.
1734   * It is also not permitted to sleep.
1735   *
1736   * The caller must hold the RCU read lock.
1737   */
find_inode_by_ino_rcu(struct super_block * sb,unsigned long ino)1738  struct inode *find_inode_by_ino_rcu(struct super_block *sb,
1739  				    unsigned long ino)
1740  {
1741  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1742  	struct inode *inode;
1743  
1744  	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1745  			 "suspicious find_inode_by_ino_rcu() usage");
1746  
1747  	hlist_for_each_entry_rcu(inode, head, i_hash) {
1748  		if (inode->i_ino == ino &&
1749  		    inode->i_sb == sb &&
1750  		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)))
1751  		    return inode;
1752  	}
1753  	return NULL;
1754  }
1755  EXPORT_SYMBOL(find_inode_by_ino_rcu);
1756  
insert_inode_locked(struct inode * inode)1757  int insert_inode_locked(struct inode *inode)
1758  {
1759  	struct super_block *sb = inode->i_sb;
1760  	ino_t ino = inode->i_ino;
1761  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1762  
1763  	while (1) {
1764  		struct inode *old = NULL;
1765  		spin_lock(&inode_hash_lock);
1766  		hlist_for_each_entry(old, head, i_hash) {
1767  			if (old->i_ino != ino)
1768  				continue;
1769  			if (old->i_sb != sb)
1770  				continue;
1771  			spin_lock(&old->i_lock);
1772  			if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1773  				spin_unlock(&old->i_lock);
1774  				continue;
1775  			}
1776  			break;
1777  		}
1778  		if (likely(!old)) {
1779  			spin_lock(&inode->i_lock);
1780  			inode->i_state |= I_NEW | I_CREATING;
1781  			hlist_add_head_rcu(&inode->i_hash, head);
1782  			spin_unlock(&inode->i_lock);
1783  			spin_unlock(&inode_hash_lock);
1784  			return 0;
1785  		}
1786  		if (unlikely(old->i_state & I_CREATING)) {
1787  			spin_unlock(&old->i_lock);
1788  			spin_unlock(&inode_hash_lock);
1789  			return -EBUSY;
1790  		}
1791  		__iget(old);
1792  		spin_unlock(&old->i_lock);
1793  		spin_unlock(&inode_hash_lock);
1794  		wait_on_inode(old);
1795  		if (unlikely(!inode_unhashed(old))) {
1796  			iput(old);
1797  			return -EBUSY;
1798  		}
1799  		iput(old);
1800  	}
1801  }
1802  EXPORT_SYMBOL(insert_inode_locked);
1803  
insert_inode_locked4(struct inode * inode,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1804  int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1805  		int (*test)(struct inode *, void *), void *data)
1806  {
1807  	struct inode *old;
1808  
1809  	inode->i_state |= I_CREATING;
1810  	old = inode_insert5(inode, hashval, test, NULL, data);
1811  
1812  	if (old != inode) {
1813  		iput(old);
1814  		return -EBUSY;
1815  	}
1816  	return 0;
1817  }
1818  EXPORT_SYMBOL(insert_inode_locked4);
1819  
1820  
generic_delete_inode(struct inode * inode)1821  int generic_delete_inode(struct inode *inode)
1822  {
1823  	return 1;
1824  }
1825  EXPORT_SYMBOL(generic_delete_inode);
1826  
1827  /*
1828   * Called when we're dropping the last reference
1829   * to an inode.
1830   *
1831   * Call the FS "drop_inode()" function, defaulting to
1832   * the legacy UNIX filesystem behaviour.  If it tells
1833   * us to evict inode, do so.  Otherwise, retain inode
1834   * in cache if fs is alive, sync and evict if fs is
1835   * shutting down.
1836   */
iput_final(struct inode * inode)1837  static void iput_final(struct inode *inode)
1838  {
1839  	struct super_block *sb = inode->i_sb;
1840  	const struct super_operations *op = inode->i_sb->s_op;
1841  	unsigned long state;
1842  	int drop;
1843  
1844  	WARN_ON(inode->i_state & I_NEW);
1845  
1846  	if (op->drop_inode)
1847  		drop = op->drop_inode(inode);
1848  	else
1849  		drop = generic_drop_inode(inode);
1850  
1851  	if (!drop &&
1852  	    !(inode->i_state & I_DONTCACHE) &&
1853  	    (sb->s_flags & SB_ACTIVE)) {
1854  		__inode_add_lru(inode, true);
1855  		spin_unlock(&inode->i_lock);
1856  		return;
1857  	}
1858  
1859  	state = inode->i_state;
1860  	if (!drop) {
1861  		WRITE_ONCE(inode->i_state, state | I_WILL_FREE);
1862  		spin_unlock(&inode->i_lock);
1863  
1864  		write_inode_now(inode, 1);
1865  
1866  		spin_lock(&inode->i_lock);
1867  		state = inode->i_state;
1868  		WARN_ON(state & I_NEW);
1869  		state &= ~I_WILL_FREE;
1870  	}
1871  
1872  	WRITE_ONCE(inode->i_state, state | I_FREEING);
1873  	if (!list_empty(&inode->i_lru))
1874  		inode_lru_list_del(inode);
1875  	spin_unlock(&inode->i_lock);
1876  
1877  	evict(inode);
1878  }
1879  
1880  /**
1881   *	iput	- put an inode
1882   *	@inode: inode to put
1883   *
1884   *	Puts an inode, dropping its usage count. If the inode use count hits
1885   *	zero, the inode is then freed and may also be destroyed.
1886   *
1887   *	Consequently, iput() can sleep.
1888   */
iput(struct inode * inode)1889  void iput(struct inode *inode)
1890  {
1891  	if (!inode)
1892  		return;
1893  	BUG_ON(inode->i_state & I_CLEAR);
1894  retry:
1895  	if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
1896  		if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
1897  			atomic_inc(&inode->i_count);
1898  			spin_unlock(&inode->i_lock);
1899  			trace_writeback_lazytime_iput(inode);
1900  			mark_inode_dirty_sync(inode);
1901  			goto retry;
1902  		}
1903  		iput_final(inode);
1904  	}
1905  }
1906  EXPORT_SYMBOL(iput);
1907  
1908  #ifdef CONFIG_BLOCK
1909  /**
1910   *	bmap	- find a block number in a file
1911   *	@inode:  inode owning the block number being requested
1912   *	@block: pointer containing the block to find
1913   *
1914   *	Replaces the value in ``*block`` with the block number on the device holding
1915   *	corresponding to the requested block number in the file.
1916   *	That is, asked for block 4 of inode 1 the function will replace the
1917   *	4 in ``*block``, with disk block relative to the disk start that holds that
1918   *	block of the file.
1919   *
1920   *	Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
1921   *	hole, returns 0 and ``*block`` is also set to 0.
1922   */
bmap(struct inode * inode,sector_t * block)1923  int bmap(struct inode *inode, sector_t *block)
1924  {
1925  	if (!inode->i_mapping->a_ops->bmap)
1926  		return -EINVAL;
1927  
1928  	*block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
1929  	return 0;
1930  }
1931  EXPORT_SYMBOL(bmap);
1932  #endif
1933  
1934  /*
1935   * With relative atime, only update atime if the previous atime is
1936   * earlier than or equal to either the ctime or mtime,
1937   * or if at least a day has passed since the last atime update.
1938   */
relatime_need_update(struct vfsmount * mnt,struct inode * inode,struct timespec64 now)1939  static bool relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1940  			     struct timespec64 now)
1941  {
1942  	struct timespec64 atime, mtime, ctime;
1943  
1944  	if (!(mnt->mnt_flags & MNT_RELATIME))
1945  		return true;
1946  	/*
1947  	 * Is mtime younger than or equal to atime? If yes, update atime:
1948  	 */
1949  	atime = inode_get_atime(inode);
1950  	mtime = inode_get_mtime(inode);
1951  	if (timespec64_compare(&mtime, &atime) >= 0)
1952  		return true;
1953  	/*
1954  	 * Is ctime younger than or equal to atime? If yes, update atime:
1955  	 */
1956  	ctime = inode_get_ctime(inode);
1957  	if (timespec64_compare(&ctime, &atime) >= 0)
1958  		return true;
1959  
1960  	/*
1961  	 * Is the previous atime value older than a day? If yes,
1962  	 * update atime:
1963  	 */
1964  	if ((long)(now.tv_sec - atime.tv_sec) >= 24*60*60)
1965  		return true;
1966  	/*
1967  	 * Good, we can skip the atime update:
1968  	 */
1969  	return false;
1970  }
1971  
1972  /**
1973   * inode_update_timestamps - update the timestamps on the inode
1974   * @inode: inode to be updated
1975   * @flags: S_* flags that needed to be updated
1976   *
1977   * The update_time function is called when an inode's timestamps need to be
1978   * updated for a read or write operation. This function handles updating the
1979   * actual timestamps. It's up to the caller to ensure that the inode is marked
1980   * dirty appropriately.
1981   *
1982   * In the case where any of S_MTIME, S_CTIME, or S_VERSION need to be updated,
1983   * attempt to update all three of them. S_ATIME updates can be handled
1984   * independently of the rest.
1985   *
1986   * Returns a set of S_* flags indicating which values changed.
1987   */
inode_update_timestamps(struct inode * inode,int flags)1988  int inode_update_timestamps(struct inode *inode, int flags)
1989  {
1990  	int updated = 0;
1991  	struct timespec64 now;
1992  
1993  	if (flags & (S_MTIME|S_CTIME|S_VERSION)) {
1994  		struct timespec64 ctime = inode_get_ctime(inode);
1995  		struct timespec64 mtime = inode_get_mtime(inode);
1996  
1997  		now = inode_set_ctime_current(inode);
1998  		if (!timespec64_equal(&now, &ctime))
1999  			updated |= S_CTIME;
2000  		if (!timespec64_equal(&now, &mtime)) {
2001  			inode_set_mtime_to_ts(inode, now);
2002  			updated |= S_MTIME;
2003  		}
2004  		if (IS_I_VERSION(inode) && inode_maybe_inc_iversion(inode, updated))
2005  			updated |= S_VERSION;
2006  	} else {
2007  		now = current_time(inode);
2008  	}
2009  
2010  	if (flags & S_ATIME) {
2011  		struct timespec64 atime = inode_get_atime(inode);
2012  
2013  		if (!timespec64_equal(&now, &atime)) {
2014  			inode_set_atime_to_ts(inode, now);
2015  			updated |= S_ATIME;
2016  		}
2017  	}
2018  	return updated;
2019  }
2020  EXPORT_SYMBOL(inode_update_timestamps);
2021  
2022  /**
2023   * generic_update_time - update the timestamps on the inode
2024   * @inode: inode to be updated
2025   * @flags: S_* flags that needed to be updated
2026   *
2027   * The update_time function is called when an inode's timestamps need to be
2028   * updated for a read or write operation. In the case where any of S_MTIME, S_CTIME,
2029   * or S_VERSION need to be updated we attempt to update all three of them. S_ATIME
2030   * updates can be handled done independently of the rest.
2031   *
2032   * Returns a S_* mask indicating which fields were updated.
2033   */
generic_update_time(struct inode * inode,int flags)2034  int generic_update_time(struct inode *inode, int flags)
2035  {
2036  	int updated = inode_update_timestamps(inode, flags);
2037  	int dirty_flags = 0;
2038  
2039  	if (updated & (S_ATIME|S_MTIME|S_CTIME))
2040  		dirty_flags = inode->i_sb->s_flags & SB_LAZYTIME ? I_DIRTY_TIME : I_DIRTY_SYNC;
2041  	if (updated & S_VERSION)
2042  		dirty_flags |= I_DIRTY_SYNC;
2043  	__mark_inode_dirty(inode, dirty_flags);
2044  	return updated;
2045  }
2046  EXPORT_SYMBOL(generic_update_time);
2047  
2048  /*
2049   * This does the actual work of updating an inodes time or version.  Must have
2050   * had called mnt_want_write() before calling this.
2051   */
inode_update_time(struct inode * inode,int flags)2052  int inode_update_time(struct inode *inode, int flags)
2053  {
2054  	if (inode->i_op->update_time)
2055  		return inode->i_op->update_time(inode, flags);
2056  	generic_update_time(inode, flags);
2057  	return 0;
2058  }
2059  EXPORT_SYMBOL(inode_update_time);
2060  
2061  /**
2062   *	atime_needs_update	-	update the access time
2063   *	@path: the &struct path to update
2064   *	@inode: inode to update
2065   *
2066   *	Update the accessed time on an inode and mark it for writeback.
2067   *	This function automatically handles read only file systems and media,
2068   *	as well as the "noatime" flag and inode specific "noatime" markers.
2069   */
atime_needs_update(const struct path * path,struct inode * inode)2070  bool atime_needs_update(const struct path *path, struct inode *inode)
2071  {
2072  	struct vfsmount *mnt = path->mnt;
2073  	struct timespec64 now, atime;
2074  
2075  	if (inode->i_flags & S_NOATIME)
2076  		return false;
2077  
2078  	/* Atime updates will likely cause i_uid and i_gid to be written
2079  	 * back improprely if their true value is unknown to the vfs.
2080  	 */
2081  	if (HAS_UNMAPPED_ID(mnt_idmap(mnt), inode))
2082  		return false;
2083  
2084  	if (IS_NOATIME(inode))
2085  		return false;
2086  	if ((inode->i_sb->s_flags & SB_NODIRATIME) && S_ISDIR(inode->i_mode))
2087  		return false;
2088  
2089  	if (mnt->mnt_flags & MNT_NOATIME)
2090  		return false;
2091  	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
2092  		return false;
2093  
2094  	now = current_time(inode);
2095  
2096  	if (!relatime_need_update(mnt, inode, now))
2097  		return false;
2098  
2099  	atime = inode_get_atime(inode);
2100  	if (timespec64_equal(&atime, &now))
2101  		return false;
2102  
2103  	return true;
2104  }
2105  
touch_atime(const struct path * path)2106  void touch_atime(const struct path *path)
2107  {
2108  	struct vfsmount *mnt = path->mnt;
2109  	struct inode *inode = d_inode(path->dentry);
2110  
2111  	if (!atime_needs_update(path, inode))
2112  		return;
2113  
2114  	if (!sb_start_write_trylock(inode->i_sb))
2115  		return;
2116  
2117  	if (mnt_get_write_access(mnt) != 0)
2118  		goto skip_update;
2119  	/*
2120  	 * File systems can error out when updating inodes if they need to
2121  	 * allocate new space to modify an inode (such is the case for
2122  	 * Btrfs), but since we touch atime while walking down the path we
2123  	 * really don't care if we failed to update the atime of the file,
2124  	 * so just ignore the return value.
2125  	 * We may also fail on filesystems that have the ability to make parts
2126  	 * of the fs read only, e.g. subvolumes in Btrfs.
2127  	 */
2128  	inode_update_time(inode, S_ATIME);
2129  	mnt_put_write_access(mnt);
2130  skip_update:
2131  	sb_end_write(inode->i_sb);
2132  }
2133  EXPORT_SYMBOL(touch_atime);
2134  
2135  /*
2136   * Return mask of changes for notify_change() that need to be done as a
2137   * response to write or truncate. Return 0 if nothing has to be changed.
2138   * Negative value on error (change should be denied).
2139   */
dentry_needs_remove_privs(struct mnt_idmap * idmap,struct dentry * dentry)2140  int dentry_needs_remove_privs(struct mnt_idmap *idmap,
2141  			      struct dentry *dentry)
2142  {
2143  	struct inode *inode = d_inode(dentry);
2144  	int mask = 0;
2145  	int ret;
2146  
2147  	if (IS_NOSEC(inode))
2148  		return 0;
2149  
2150  	mask = setattr_should_drop_suidgid(idmap, inode);
2151  	ret = security_inode_need_killpriv(dentry);
2152  	if (ret < 0)
2153  		return ret;
2154  	if (ret)
2155  		mask |= ATTR_KILL_PRIV;
2156  	return mask;
2157  }
2158  
__remove_privs(struct mnt_idmap * idmap,struct dentry * dentry,int kill)2159  static int __remove_privs(struct mnt_idmap *idmap,
2160  			  struct dentry *dentry, int kill)
2161  {
2162  	struct iattr newattrs;
2163  
2164  	newattrs.ia_valid = ATTR_FORCE | kill;
2165  	/*
2166  	 * Note we call this on write, so notify_change will not
2167  	 * encounter any conflicting delegations:
2168  	 */
2169  	return notify_change(idmap, dentry, &newattrs, NULL);
2170  }
2171  
file_remove_privs_flags(struct file * file,unsigned int flags)2172  int file_remove_privs_flags(struct file *file, unsigned int flags)
2173  {
2174  	struct dentry *dentry = file_dentry(file);
2175  	struct inode *inode = file_inode(file);
2176  	int error = 0;
2177  	int kill;
2178  
2179  	if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
2180  		return 0;
2181  
2182  	kill = dentry_needs_remove_privs(file_mnt_idmap(file), dentry);
2183  	if (kill < 0)
2184  		return kill;
2185  
2186  	if (kill) {
2187  		if (flags & IOCB_NOWAIT)
2188  			return -EAGAIN;
2189  
2190  		error = __remove_privs(file_mnt_idmap(file), dentry, kill);
2191  	}
2192  
2193  	if (!error)
2194  		inode_has_no_xattr(inode);
2195  	return error;
2196  }
2197  EXPORT_SYMBOL_GPL(file_remove_privs_flags);
2198  
2199  /**
2200   * file_remove_privs - remove special file privileges (suid, capabilities)
2201   * @file: file to remove privileges from
2202   *
2203   * When file is modified by a write or truncation ensure that special
2204   * file privileges are removed.
2205   *
2206   * Return: 0 on success, negative errno on failure.
2207   */
file_remove_privs(struct file * file)2208  int file_remove_privs(struct file *file)
2209  {
2210  	return file_remove_privs_flags(file, 0);
2211  }
2212  EXPORT_SYMBOL(file_remove_privs);
2213  
inode_needs_update_time(struct inode * inode)2214  static int inode_needs_update_time(struct inode *inode)
2215  {
2216  	int sync_it = 0;
2217  	struct timespec64 now = current_time(inode);
2218  	struct timespec64 ts;
2219  
2220  	/* First try to exhaust all avenues to not sync */
2221  	if (IS_NOCMTIME(inode))
2222  		return 0;
2223  
2224  	ts = inode_get_mtime(inode);
2225  	if (!timespec64_equal(&ts, &now))
2226  		sync_it = S_MTIME;
2227  
2228  	ts = inode_get_ctime(inode);
2229  	if (!timespec64_equal(&ts, &now))
2230  		sync_it |= S_CTIME;
2231  
2232  	if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
2233  		sync_it |= S_VERSION;
2234  
2235  	return sync_it;
2236  }
2237  
__file_update_time(struct file * file,int sync_mode)2238  static int __file_update_time(struct file *file, int sync_mode)
2239  {
2240  	int ret = 0;
2241  	struct inode *inode = file_inode(file);
2242  
2243  	/* try to update time settings */
2244  	if (!mnt_get_write_access_file(file)) {
2245  		ret = inode_update_time(inode, sync_mode);
2246  		mnt_put_write_access_file(file);
2247  	}
2248  
2249  	return ret;
2250  }
2251  
2252  /**
2253   * file_update_time - update mtime and ctime time
2254   * @file: file accessed
2255   *
2256   * Update the mtime and ctime members of an inode and mark the inode for
2257   * writeback. Note that this function is meant exclusively for usage in
2258   * the file write path of filesystems, and filesystems may choose to
2259   * explicitly ignore updates via this function with the _NOCMTIME inode
2260   * flag, e.g. for network filesystem where these imestamps are handled
2261   * by the server. This can return an error for file systems who need to
2262   * allocate space in order to update an inode.
2263   *
2264   * Return: 0 on success, negative errno on failure.
2265   */
file_update_time(struct file * file)2266  int file_update_time(struct file *file)
2267  {
2268  	int ret;
2269  	struct inode *inode = file_inode(file);
2270  
2271  	ret = inode_needs_update_time(inode);
2272  	if (ret <= 0)
2273  		return ret;
2274  
2275  	return __file_update_time(file, ret);
2276  }
2277  EXPORT_SYMBOL(file_update_time);
2278  
2279  /**
2280   * file_modified_flags - handle mandated vfs changes when modifying a file
2281   * @file: file that was modified
2282   * @flags: kiocb flags
2283   *
2284   * When file has been modified ensure that special
2285   * file privileges are removed and time settings are updated.
2286   *
2287   * If IOCB_NOWAIT is set, special file privileges will not be removed and
2288   * time settings will not be updated. It will return -EAGAIN.
2289   *
2290   * Context: Caller must hold the file's inode lock.
2291   *
2292   * Return: 0 on success, negative errno on failure.
2293   */
file_modified_flags(struct file * file,int flags)2294  static int file_modified_flags(struct file *file, int flags)
2295  {
2296  	int ret;
2297  	struct inode *inode = file_inode(file);
2298  
2299  	/*
2300  	 * Clear the security bits if the process is not being run by root.
2301  	 * This keeps people from modifying setuid and setgid binaries.
2302  	 */
2303  	ret = file_remove_privs_flags(file, flags);
2304  	if (ret)
2305  		return ret;
2306  
2307  	if (unlikely(file->f_mode & FMODE_NOCMTIME))
2308  		return 0;
2309  
2310  	ret = inode_needs_update_time(inode);
2311  	if (ret <= 0)
2312  		return ret;
2313  	if (flags & IOCB_NOWAIT)
2314  		return -EAGAIN;
2315  
2316  	return __file_update_time(file, ret);
2317  }
2318  
2319  /**
2320   * file_modified - handle mandated vfs changes when modifying a file
2321   * @file: file that was modified
2322   *
2323   * When file has been modified ensure that special
2324   * file privileges are removed and time settings are updated.
2325   *
2326   * Context: Caller must hold the file's inode lock.
2327   *
2328   * Return: 0 on success, negative errno on failure.
2329   */
file_modified(struct file * file)2330  int file_modified(struct file *file)
2331  {
2332  	return file_modified_flags(file, 0);
2333  }
2334  EXPORT_SYMBOL(file_modified);
2335  
2336  /**
2337   * kiocb_modified - handle mandated vfs changes when modifying a file
2338   * @iocb: iocb that was modified
2339   *
2340   * When file has been modified ensure that special
2341   * file privileges are removed and time settings are updated.
2342   *
2343   * Context: Caller must hold the file's inode lock.
2344   *
2345   * Return: 0 on success, negative errno on failure.
2346   */
kiocb_modified(struct kiocb * iocb)2347  int kiocb_modified(struct kiocb *iocb)
2348  {
2349  	return file_modified_flags(iocb->ki_filp, iocb->ki_flags);
2350  }
2351  EXPORT_SYMBOL_GPL(kiocb_modified);
2352  
inode_needs_sync(struct inode * inode)2353  int inode_needs_sync(struct inode *inode)
2354  {
2355  	if (IS_SYNC(inode))
2356  		return 1;
2357  	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
2358  		return 1;
2359  	return 0;
2360  }
2361  EXPORT_SYMBOL(inode_needs_sync);
2362  
2363  /*
2364   * If we try to find an inode in the inode hash while it is being
2365   * deleted, we have to wait until the filesystem completes its
2366   * deletion before reporting that it isn't found.  This function waits
2367   * until the deletion _might_ have completed.  Callers are responsible
2368   * to recheck inode state.
2369   *
2370   * It doesn't matter if I_NEW is not set initially, a call to
2371   * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
2372   * will DTRT.
2373   */
__wait_on_freeing_inode(struct inode * inode,bool is_inode_hash_locked)2374  static void __wait_on_freeing_inode(struct inode *inode, bool is_inode_hash_locked)
2375  {
2376  	struct wait_bit_queue_entry wqe;
2377  	struct wait_queue_head *wq_head;
2378  
2379  	/*
2380  	 * Handle racing against evict(), see that routine for more details.
2381  	 */
2382  	if (unlikely(inode_unhashed(inode))) {
2383  		WARN_ON(is_inode_hash_locked);
2384  		spin_unlock(&inode->i_lock);
2385  		return;
2386  	}
2387  
2388  	wq_head = inode_bit_waitqueue(&wqe, inode, __I_NEW);
2389  	prepare_to_wait_event(wq_head, &wqe.wq_entry, TASK_UNINTERRUPTIBLE);
2390  	spin_unlock(&inode->i_lock);
2391  	rcu_read_unlock();
2392  	if (is_inode_hash_locked)
2393  		spin_unlock(&inode_hash_lock);
2394  	schedule();
2395  	finish_wait(wq_head, &wqe.wq_entry);
2396  	if (is_inode_hash_locked)
2397  		spin_lock(&inode_hash_lock);
2398  	rcu_read_lock();
2399  }
2400  
2401  static __initdata unsigned long ihash_entries;
set_ihash_entries(char * str)2402  static int __init set_ihash_entries(char *str)
2403  {
2404  	if (!str)
2405  		return 0;
2406  	ihash_entries = simple_strtoul(str, &str, 0);
2407  	return 1;
2408  }
2409  __setup("ihash_entries=", set_ihash_entries);
2410  
2411  /*
2412   * Initialize the waitqueues and inode hash table.
2413   */
inode_init_early(void)2414  void __init inode_init_early(void)
2415  {
2416  	/* If hashes are distributed across NUMA nodes, defer
2417  	 * hash allocation until vmalloc space is available.
2418  	 */
2419  	if (hashdist)
2420  		return;
2421  
2422  	inode_hashtable =
2423  		alloc_large_system_hash("Inode-cache",
2424  					sizeof(struct hlist_head),
2425  					ihash_entries,
2426  					14,
2427  					HASH_EARLY | HASH_ZERO,
2428  					&i_hash_shift,
2429  					&i_hash_mask,
2430  					0,
2431  					0);
2432  }
2433  
inode_init(void)2434  void __init inode_init(void)
2435  {
2436  	/* inode slab cache */
2437  	inode_cachep = kmem_cache_create("inode_cache",
2438  					 sizeof(struct inode),
2439  					 0,
2440  					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
2441  					 SLAB_ACCOUNT),
2442  					 init_once);
2443  
2444  	/* Hash may have been set up in inode_init_early */
2445  	if (!hashdist)
2446  		return;
2447  
2448  	inode_hashtable =
2449  		alloc_large_system_hash("Inode-cache",
2450  					sizeof(struct hlist_head),
2451  					ihash_entries,
2452  					14,
2453  					HASH_ZERO,
2454  					&i_hash_shift,
2455  					&i_hash_mask,
2456  					0,
2457  					0);
2458  }
2459  
init_special_inode(struct inode * inode,umode_t mode,dev_t rdev)2460  void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
2461  {
2462  	inode->i_mode = mode;
2463  	if (S_ISCHR(mode)) {
2464  		inode->i_fop = &def_chr_fops;
2465  		inode->i_rdev = rdev;
2466  	} else if (S_ISBLK(mode)) {
2467  		if (IS_ENABLED(CONFIG_BLOCK))
2468  			inode->i_fop = &def_blk_fops;
2469  		inode->i_rdev = rdev;
2470  	} else if (S_ISFIFO(mode))
2471  		inode->i_fop = &pipefifo_fops;
2472  	else if (S_ISSOCK(mode))
2473  		;	/* leave it no_open_fops */
2474  	else
2475  		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
2476  				  " inode %s:%lu\n", mode, inode->i_sb->s_id,
2477  				  inode->i_ino);
2478  }
2479  EXPORT_SYMBOL(init_special_inode);
2480  
2481  /**
2482   * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
2483   * @idmap: idmap of the mount the inode was created from
2484   * @inode: New inode
2485   * @dir: Directory inode
2486   * @mode: mode of the new inode
2487   *
2488   * If the inode has been created through an idmapped mount the idmap of
2489   * the vfsmount must be passed through @idmap. This function will then take
2490   * care to map the inode according to @idmap before checking permissions
2491   * and initializing i_uid and i_gid. On non-idmapped mounts or if permission
2492   * checking is to be performed on the raw inode simply pass @nop_mnt_idmap.
2493   */
inode_init_owner(struct mnt_idmap * idmap,struct inode * inode,const struct inode * dir,umode_t mode)2494  void inode_init_owner(struct mnt_idmap *idmap, struct inode *inode,
2495  		      const struct inode *dir, umode_t mode)
2496  {
2497  	inode_fsuid_set(inode, idmap);
2498  	if (dir && dir->i_mode & S_ISGID) {
2499  		inode->i_gid = dir->i_gid;
2500  
2501  		/* Directories are special, and always inherit S_ISGID */
2502  		if (S_ISDIR(mode))
2503  			mode |= S_ISGID;
2504  	} else
2505  		inode_fsgid_set(inode, idmap);
2506  	inode->i_mode = mode;
2507  }
2508  EXPORT_SYMBOL(inode_init_owner);
2509  
2510  /**
2511   * inode_owner_or_capable - check current task permissions to inode
2512   * @idmap: idmap of the mount the inode was found from
2513   * @inode: inode being checked
2514   *
2515   * Return true if current either has CAP_FOWNER in a namespace with the
2516   * inode owner uid mapped, or owns the file.
2517   *
2518   * If the inode has been found through an idmapped mount the idmap of
2519   * the vfsmount must be passed through @idmap. This function will then take
2520   * care to map the inode according to @idmap before checking permissions.
2521   * On non-idmapped mounts or if permission checking is to be performed on the
2522   * raw inode simply pass @nop_mnt_idmap.
2523   */
inode_owner_or_capable(struct mnt_idmap * idmap,const struct inode * inode)2524  bool inode_owner_or_capable(struct mnt_idmap *idmap,
2525  			    const struct inode *inode)
2526  {
2527  	vfsuid_t vfsuid;
2528  	struct user_namespace *ns;
2529  
2530  	vfsuid = i_uid_into_vfsuid(idmap, inode);
2531  	if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
2532  		return true;
2533  
2534  	ns = current_user_ns();
2535  	if (vfsuid_has_mapping(ns, vfsuid) && ns_capable(ns, CAP_FOWNER))
2536  		return true;
2537  	return false;
2538  }
2539  EXPORT_SYMBOL(inode_owner_or_capable);
2540  
2541  /*
2542   * Direct i/o helper functions
2543   */
inode_dio_finished(const struct inode * inode)2544  bool inode_dio_finished(const struct inode *inode)
2545  {
2546  	return atomic_read(&inode->i_dio_count) == 0;
2547  }
2548  EXPORT_SYMBOL(inode_dio_finished);
2549  
2550  /**
2551   * inode_dio_wait - wait for outstanding DIO requests to finish
2552   * @inode: inode to wait for
2553   *
2554   * Waits for all pending direct I/O requests to finish so that we can
2555   * proceed with a truncate or equivalent operation.
2556   *
2557   * Must be called under a lock that serializes taking new references
2558   * to i_dio_count, usually by inode->i_mutex.
2559   */
inode_dio_wait(struct inode * inode)2560  void inode_dio_wait(struct inode *inode)
2561  {
2562  	wait_var_event(&inode->i_dio_count, inode_dio_finished(inode));
2563  }
2564  EXPORT_SYMBOL(inode_dio_wait);
2565  
inode_dio_wait_interruptible(struct inode * inode)2566  void inode_dio_wait_interruptible(struct inode *inode)
2567  {
2568  	wait_var_event_interruptible(&inode->i_dio_count,
2569  				     inode_dio_finished(inode));
2570  }
2571  EXPORT_SYMBOL(inode_dio_wait_interruptible);
2572  
2573  /*
2574   * inode_set_flags - atomically set some inode flags
2575   *
2576   * Note: the caller should be holding i_mutex, or else be sure that
2577   * they have exclusive access to the inode structure (i.e., while the
2578   * inode is being instantiated).  The reason for the cmpxchg() loop
2579   * --- which wouldn't be necessary if all code paths which modify
2580   * i_flags actually followed this rule, is that there is at least one
2581   * code path which doesn't today so we use cmpxchg() out of an abundance
2582   * of caution.
2583   *
2584   * In the long run, i_mutex is overkill, and we should probably look
2585   * at using the i_lock spinlock to protect i_flags, and then make sure
2586   * it is so documented in include/linux/fs.h and that all code follows
2587   * the locking convention!!
2588   */
inode_set_flags(struct inode * inode,unsigned int flags,unsigned int mask)2589  void inode_set_flags(struct inode *inode, unsigned int flags,
2590  		     unsigned int mask)
2591  {
2592  	WARN_ON_ONCE(flags & ~mask);
2593  	set_mask_bits(&inode->i_flags, mask, flags);
2594  }
2595  EXPORT_SYMBOL(inode_set_flags);
2596  
inode_nohighmem(struct inode * inode)2597  void inode_nohighmem(struct inode *inode)
2598  {
2599  	mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
2600  }
2601  EXPORT_SYMBOL(inode_nohighmem);
2602  
2603  /**
2604   * timestamp_truncate - Truncate timespec to a granularity
2605   * @t: Timespec
2606   * @inode: inode being updated
2607   *
2608   * Truncate a timespec to the granularity supported by the fs
2609   * containing the inode. Always rounds down. gran must
2610   * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
2611   */
timestamp_truncate(struct timespec64 t,struct inode * inode)2612  struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
2613  {
2614  	struct super_block *sb = inode->i_sb;
2615  	unsigned int gran = sb->s_time_gran;
2616  
2617  	t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);
2618  	if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))
2619  		t.tv_nsec = 0;
2620  
2621  	/* Avoid division in the common cases 1 ns and 1 s. */
2622  	if (gran == 1)
2623  		; /* nothing */
2624  	else if (gran == NSEC_PER_SEC)
2625  		t.tv_nsec = 0;
2626  	else if (gran > 1 && gran < NSEC_PER_SEC)
2627  		t.tv_nsec -= t.tv_nsec % gran;
2628  	else
2629  		WARN(1, "invalid file time granularity: %u", gran);
2630  	return t;
2631  }
2632  EXPORT_SYMBOL(timestamp_truncate);
2633  
2634  /**
2635   * current_time - Return FS time
2636   * @inode: inode.
2637   *
2638   * Return the current time truncated to the time granularity supported by
2639   * the fs.
2640   *
2641   * Note that inode and inode->sb cannot be NULL.
2642   * Otherwise, the function warns and returns time without truncation.
2643   */
current_time(struct inode * inode)2644  struct timespec64 current_time(struct inode *inode)
2645  {
2646  	struct timespec64 now;
2647  
2648  	ktime_get_coarse_real_ts64(&now);
2649  	return timestamp_truncate(now, inode);
2650  }
2651  EXPORT_SYMBOL(current_time);
2652  
2653  /**
2654   * inode_set_ctime_current - set the ctime to current_time
2655   * @inode: inode
2656   *
2657   * Set the inode->i_ctime to the current value for the inode. Returns
2658   * the current value that was assigned to i_ctime.
2659   */
inode_set_ctime_current(struct inode * inode)2660  struct timespec64 inode_set_ctime_current(struct inode *inode)
2661  {
2662  	struct timespec64 now = current_time(inode);
2663  
2664  	inode_set_ctime_to_ts(inode, now);
2665  	return now;
2666  }
2667  EXPORT_SYMBOL(inode_set_ctime_current);
2668  
2669  /**
2670   * in_group_or_capable - check whether caller is CAP_FSETID privileged
2671   * @idmap:	idmap of the mount @inode was found from
2672   * @inode:	inode to check
2673   * @vfsgid:	the new/current vfsgid of @inode
2674   *
2675   * Check wether @vfsgid is in the caller's group list or if the caller is
2676   * privileged with CAP_FSETID over @inode. This can be used to determine
2677   * whether the setgid bit can be kept or must be dropped.
2678   *
2679   * Return: true if the caller is sufficiently privileged, false if not.
2680   */
in_group_or_capable(struct mnt_idmap * idmap,const struct inode * inode,vfsgid_t vfsgid)2681  bool in_group_or_capable(struct mnt_idmap *idmap,
2682  			 const struct inode *inode, vfsgid_t vfsgid)
2683  {
2684  	if (vfsgid_in_group_p(vfsgid))
2685  		return true;
2686  	if (capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
2687  		return true;
2688  	return false;
2689  }
2690  EXPORT_SYMBOL(in_group_or_capable);
2691  
2692  /**
2693   * mode_strip_sgid - handle the sgid bit for non-directories
2694   * @idmap: idmap of the mount the inode was created from
2695   * @dir: parent directory inode
2696   * @mode: mode of the file to be created in @dir
2697   *
2698   * If the @mode of the new file has both the S_ISGID and S_IXGRP bit
2699   * raised and @dir has the S_ISGID bit raised ensure that the caller is
2700   * either in the group of the parent directory or they have CAP_FSETID
2701   * in their user namespace and are privileged over the parent directory.
2702   * In all other cases, strip the S_ISGID bit from @mode.
2703   *
2704   * Return: the new mode to use for the file
2705   */
mode_strip_sgid(struct mnt_idmap * idmap,const struct inode * dir,umode_t mode)2706  umode_t mode_strip_sgid(struct mnt_idmap *idmap,
2707  			const struct inode *dir, umode_t mode)
2708  {
2709  	if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP))
2710  		return mode;
2711  	if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID))
2712  		return mode;
2713  	if (in_group_or_capable(idmap, dir, i_gid_into_vfsgid(idmap, dir)))
2714  		return mode;
2715  	return mode & ~S_ISGID;
2716  }
2717  EXPORT_SYMBOL(mode_strip_sgid);
2718