xref: /openbmc/linux/fs/inode.c (revision 0e01d176d5788f66dc64a7e61119edb56eb08339)
1  // SPDX-License-Identifier: GPL-2.0-only
2  /*
3   * (C) 1997 Linus Torvalds
4   * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation)
5   */
6  #include <linux/export.h>
7  #include <linux/fs.h>
8  #include <linux/mm.h>
9  #include <linux/backing-dev.h>
10  #include <linux/hash.h>
11  #include <linux/swap.h>
12  #include <linux/security.h>
13  #include <linux/cdev.h>
14  #include <linux/memblock.h>
15  #include <linux/fsnotify.h>
16  #include <linux/mount.h>
17  #include <linux/posix_acl.h>
18  #include <linux/prefetch.h>
19  #include <linux/buffer_head.h> /* for inode_has_buffers */
20  #include <linux/ratelimit.h>
21  #include <linux/list_lru.h>
22  #include <linux/iversion.h>
23  #include <trace/events/writeback.h>
24  #include "internal.h"
25  
26  /*
27   * Inode locking rules:
28   *
29   * inode->i_lock protects:
30   *   inode->i_state, inode->i_hash, __iget()
31   * Inode LRU list locks protect:
32   *   inode->i_sb->s_inode_lru, inode->i_lru
33   * inode->i_sb->s_inode_list_lock protects:
34   *   inode->i_sb->s_inodes, inode->i_sb_list
35   * bdi->wb.list_lock protects:
36   *   bdi->wb.b_{dirty,io,more_io,dirty_time}, inode->i_io_list
37   * inode_hash_lock protects:
38   *   inode_hashtable, inode->i_hash
39   *
40   * Lock ordering:
41   *
42   * inode->i_sb->s_inode_list_lock
43   *   inode->i_lock
44   *     Inode LRU list locks
45   *
46   * bdi->wb.list_lock
47   *   inode->i_lock
48   *
49   * inode_hash_lock
50   *   inode->i_sb->s_inode_list_lock
51   *   inode->i_lock
52   *
53   * iunique_lock
54   *   inode_hash_lock
55   */
56  
57  static unsigned int i_hash_mask __read_mostly;
58  static unsigned int i_hash_shift __read_mostly;
59  static struct hlist_head *inode_hashtable __read_mostly;
60  static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
61  
62  /*
63   * Empty aops. Can be used for the cases where the user does not
64   * define any of the address_space operations.
65   */
66  const struct address_space_operations empty_aops = {
67  };
68  EXPORT_SYMBOL(empty_aops);
69  
70  static DEFINE_PER_CPU(unsigned long, nr_inodes);
71  static DEFINE_PER_CPU(unsigned long, nr_unused);
72  
73  static struct kmem_cache *inode_cachep __read_mostly;
74  
75  static long get_nr_inodes(void)
76  {
77  	int i;
78  	long sum = 0;
79  	for_each_possible_cpu(i)
80  		sum += per_cpu(nr_inodes, i);
81  	return sum < 0 ? 0 : sum;
82  }
83  
84  static inline long get_nr_inodes_unused(void)
85  {
86  	int i;
87  	long sum = 0;
88  	for_each_possible_cpu(i)
89  		sum += per_cpu(nr_unused, i);
90  	return sum < 0 ? 0 : sum;
91  }
92  
93  long get_nr_dirty_inodes(void)
94  {
95  	/* not actually dirty inodes, but a wild approximation */
96  	long nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
97  	return nr_dirty > 0 ? nr_dirty : 0;
98  }
99  
100  /*
101   * Handle nr_inode sysctl
102   */
103  #ifdef CONFIG_SYSCTL
104  /*
105   * Statistics gathering..
106   */
107  static struct inodes_stat_t inodes_stat;
108  
109  static int proc_nr_inodes(struct ctl_table *table, int write, void *buffer,
110  			  size_t *lenp, loff_t *ppos)
111  {
112  	inodes_stat.nr_inodes = get_nr_inodes();
113  	inodes_stat.nr_unused = get_nr_inodes_unused();
114  	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
115  }
116  
117  static struct ctl_table inodes_sysctls[] = {
118  	{
119  		.procname	= "inode-nr",
120  		.data		= &inodes_stat,
121  		.maxlen		= 2*sizeof(long),
122  		.mode		= 0444,
123  		.proc_handler	= proc_nr_inodes,
124  	},
125  	{
126  		.procname	= "inode-state",
127  		.data		= &inodes_stat,
128  		.maxlen		= 7*sizeof(long),
129  		.mode		= 0444,
130  		.proc_handler	= proc_nr_inodes,
131  	},
132  	{ }
133  };
134  
135  static int __init init_fs_inode_sysctls(void)
136  {
137  	register_sysctl_init("fs", inodes_sysctls);
138  	return 0;
139  }
140  early_initcall(init_fs_inode_sysctls);
141  #endif
142  
143  static int no_open(struct inode *inode, struct file *file)
144  {
145  	return -ENXIO;
146  }
147  
148  /**
149   * inode_init_always - perform inode structure initialisation
150   * @sb: superblock inode belongs to
151   * @inode: inode to initialise
152   *
153   * These are initializations that need to be done on every inode
154   * allocation as the fields are not initialised by slab allocation.
155   */
156  int inode_init_always(struct super_block *sb, struct inode *inode)
157  {
158  	static const struct inode_operations empty_iops;
159  	static const struct file_operations no_open_fops = {.open = no_open};
160  	struct address_space *const mapping = &inode->i_data;
161  
162  	inode->i_sb = sb;
163  	inode->i_blkbits = sb->s_blocksize_bits;
164  	inode->i_flags = 0;
165  	atomic64_set(&inode->i_sequence, 0);
166  	atomic_set(&inode->i_count, 1);
167  	inode->i_op = &empty_iops;
168  	inode->i_fop = &no_open_fops;
169  	inode->i_ino = 0;
170  	inode->__i_nlink = 1;
171  	inode->i_opflags = 0;
172  	if (sb->s_xattr)
173  		inode->i_opflags |= IOP_XATTR;
174  	i_uid_write(inode, 0);
175  	i_gid_write(inode, 0);
176  	atomic_set(&inode->i_writecount, 0);
177  	inode->i_size = 0;
178  	inode->i_write_hint = WRITE_LIFE_NOT_SET;
179  	inode->i_blocks = 0;
180  	inode->i_bytes = 0;
181  	inode->i_generation = 0;
182  	inode->i_pipe = NULL;
183  	inode->i_cdev = NULL;
184  	inode->i_link = NULL;
185  	inode->i_dir_seq = 0;
186  	inode->i_rdev = 0;
187  	inode->dirtied_when = 0;
188  
189  #ifdef CONFIG_CGROUP_WRITEBACK
190  	inode->i_wb_frn_winner = 0;
191  	inode->i_wb_frn_avg_time = 0;
192  	inode->i_wb_frn_history = 0;
193  #endif
194  
195  	if (security_inode_alloc(inode))
196  		goto out;
197  	spin_lock_init(&inode->i_lock);
198  	lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
199  
200  	init_rwsem(&inode->i_rwsem);
201  	lockdep_set_class(&inode->i_rwsem, &sb->s_type->i_mutex_key);
202  
203  	atomic_set(&inode->i_dio_count, 0);
204  
205  	mapping->a_ops = &empty_aops;
206  	mapping->host = inode;
207  	mapping->flags = 0;
208  	mapping->wb_err = 0;
209  	atomic_set(&mapping->i_mmap_writable, 0);
210  #ifdef CONFIG_READ_ONLY_THP_FOR_FS
211  	atomic_set(&mapping->nr_thps, 0);
212  #endif
213  	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
214  	mapping->private_data = NULL;
215  	mapping->writeback_index = 0;
216  	init_rwsem(&mapping->invalidate_lock);
217  	lockdep_set_class_and_name(&mapping->invalidate_lock,
218  				   &sb->s_type->invalidate_lock_key,
219  				   "mapping.invalidate_lock");
220  	inode->i_private = NULL;
221  	inode->i_mapping = mapping;
222  	INIT_HLIST_HEAD(&inode->i_dentry);	/* buggered by rcu freeing */
223  #ifdef CONFIG_FS_POSIX_ACL
224  	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
225  #endif
226  
227  #ifdef CONFIG_FSNOTIFY
228  	inode->i_fsnotify_mask = 0;
229  #endif
230  	inode->i_flctx = NULL;
231  	this_cpu_inc(nr_inodes);
232  
233  	return 0;
234  out:
235  	return -ENOMEM;
236  }
237  EXPORT_SYMBOL(inode_init_always);
238  
239  void free_inode_nonrcu(struct inode *inode)
240  {
241  	kmem_cache_free(inode_cachep, inode);
242  }
243  EXPORT_SYMBOL(free_inode_nonrcu);
244  
245  static void i_callback(struct rcu_head *head)
246  {
247  	struct inode *inode = container_of(head, struct inode, i_rcu);
248  	if (inode->free_inode)
249  		inode->free_inode(inode);
250  	else
251  		free_inode_nonrcu(inode);
252  }
253  
254  static struct inode *alloc_inode(struct super_block *sb)
255  {
256  	const struct super_operations *ops = sb->s_op;
257  	struct inode *inode;
258  
259  	if (ops->alloc_inode)
260  		inode = ops->alloc_inode(sb);
261  	else
262  		inode = alloc_inode_sb(sb, inode_cachep, GFP_KERNEL);
263  
264  	if (!inode)
265  		return NULL;
266  
267  	if (unlikely(inode_init_always(sb, inode))) {
268  		if (ops->destroy_inode) {
269  			ops->destroy_inode(inode);
270  			if (!ops->free_inode)
271  				return NULL;
272  		}
273  		inode->free_inode = ops->free_inode;
274  		i_callback(&inode->i_rcu);
275  		return NULL;
276  	}
277  
278  	return inode;
279  }
280  
281  void __destroy_inode(struct inode *inode)
282  {
283  	BUG_ON(inode_has_buffers(inode));
284  	inode_detach_wb(inode);
285  	security_inode_free(inode);
286  	fsnotify_inode_delete(inode);
287  	locks_free_lock_context(inode);
288  	if (!inode->i_nlink) {
289  		WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);
290  		atomic_long_dec(&inode->i_sb->s_remove_count);
291  	}
292  
293  #ifdef CONFIG_FS_POSIX_ACL
294  	if (inode->i_acl && !is_uncached_acl(inode->i_acl))
295  		posix_acl_release(inode->i_acl);
296  	if (inode->i_default_acl && !is_uncached_acl(inode->i_default_acl))
297  		posix_acl_release(inode->i_default_acl);
298  #endif
299  	this_cpu_dec(nr_inodes);
300  }
301  EXPORT_SYMBOL(__destroy_inode);
302  
303  static void destroy_inode(struct inode *inode)
304  {
305  	const struct super_operations *ops = inode->i_sb->s_op;
306  
307  	BUG_ON(!list_empty(&inode->i_lru));
308  	__destroy_inode(inode);
309  	if (ops->destroy_inode) {
310  		ops->destroy_inode(inode);
311  		if (!ops->free_inode)
312  			return;
313  	}
314  	inode->free_inode = ops->free_inode;
315  	call_rcu(&inode->i_rcu, i_callback);
316  }
317  
318  /**
319   * drop_nlink - directly drop an inode's link count
320   * @inode: inode
321   *
322   * This is a low-level filesystem helper to replace any
323   * direct filesystem manipulation of i_nlink.  In cases
324   * where we are attempting to track writes to the
325   * filesystem, a decrement to zero means an imminent
326   * write when the file is truncated and actually unlinked
327   * on the filesystem.
328   */
329  void drop_nlink(struct inode *inode)
330  {
331  	WARN_ON(inode->i_nlink == 0);
332  	inode->__i_nlink--;
333  	if (!inode->i_nlink)
334  		atomic_long_inc(&inode->i_sb->s_remove_count);
335  }
336  EXPORT_SYMBOL(drop_nlink);
337  
338  /**
339   * clear_nlink - directly zero an inode's link count
340   * @inode: inode
341   *
342   * This is a low-level filesystem helper to replace any
343   * direct filesystem manipulation of i_nlink.  See
344   * drop_nlink() for why we care about i_nlink hitting zero.
345   */
346  void clear_nlink(struct inode *inode)
347  {
348  	if (inode->i_nlink) {
349  		inode->__i_nlink = 0;
350  		atomic_long_inc(&inode->i_sb->s_remove_count);
351  	}
352  }
353  EXPORT_SYMBOL(clear_nlink);
354  
355  /**
356   * set_nlink - directly set an inode's link count
357   * @inode: inode
358   * @nlink: new nlink (should be non-zero)
359   *
360   * This is a low-level filesystem helper to replace any
361   * direct filesystem manipulation of i_nlink.
362   */
363  void set_nlink(struct inode *inode, unsigned int nlink)
364  {
365  	if (!nlink) {
366  		clear_nlink(inode);
367  	} else {
368  		/* Yes, some filesystems do change nlink from zero to one */
369  		if (inode->i_nlink == 0)
370  			atomic_long_dec(&inode->i_sb->s_remove_count);
371  
372  		inode->__i_nlink = nlink;
373  	}
374  }
375  EXPORT_SYMBOL(set_nlink);
376  
377  /**
378   * inc_nlink - directly increment an inode's link count
379   * @inode: inode
380   *
381   * This is a low-level filesystem helper to replace any
382   * direct filesystem manipulation of i_nlink.  Currently,
383   * it is only here for parity with dec_nlink().
384   */
385  void inc_nlink(struct inode *inode)
386  {
387  	if (unlikely(inode->i_nlink == 0)) {
388  		WARN_ON(!(inode->i_state & I_LINKABLE));
389  		atomic_long_dec(&inode->i_sb->s_remove_count);
390  	}
391  
392  	inode->__i_nlink++;
393  }
394  EXPORT_SYMBOL(inc_nlink);
395  
396  static void __address_space_init_once(struct address_space *mapping)
397  {
398  	xa_init_flags(&mapping->i_pages, XA_FLAGS_LOCK_IRQ | XA_FLAGS_ACCOUNT);
399  	init_rwsem(&mapping->i_mmap_rwsem);
400  	INIT_LIST_HEAD(&mapping->private_list);
401  	spin_lock_init(&mapping->private_lock);
402  	mapping->i_mmap = RB_ROOT_CACHED;
403  }
404  
405  void address_space_init_once(struct address_space *mapping)
406  {
407  	memset(mapping, 0, sizeof(*mapping));
408  	__address_space_init_once(mapping);
409  }
410  EXPORT_SYMBOL(address_space_init_once);
411  
412  /*
413   * These are initializations that only need to be done
414   * once, because the fields are idempotent across use
415   * of the inode, so let the slab aware of that.
416   */
417  void inode_init_once(struct inode *inode)
418  {
419  	memset(inode, 0, sizeof(*inode));
420  	INIT_HLIST_NODE(&inode->i_hash);
421  	INIT_LIST_HEAD(&inode->i_devices);
422  	INIT_LIST_HEAD(&inode->i_io_list);
423  	INIT_LIST_HEAD(&inode->i_wb_list);
424  	INIT_LIST_HEAD(&inode->i_lru);
425  	__address_space_init_once(&inode->i_data);
426  	i_size_ordered_init(inode);
427  }
428  EXPORT_SYMBOL(inode_init_once);
429  
430  static void init_once(void *foo)
431  {
432  	struct inode *inode = (struct inode *) foo;
433  
434  	inode_init_once(inode);
435  }
436  
437  /*
438   * inode->i_lock must be held
439   */
440  void __iget(struct inode *inode)
441  {
442  	atomic_inc(&inode->i_count);
443  }
444  
445  /*
446   * get additional reference to inode; caller must already hold one.
447   */
448  void ihold(struct inode *inode)
449  {
450  	WARN_ON(atomic_inc_return(&inode->i_count) < 2);
451  }
452  EXPORT_SYMBOL(ihold);
453  
454  static void __inode_add_lru(struct inode *inode, bool rotate)
455  {
456  	if (inode->i_state & (I_DIRTY_ALL | I_SYNC | I_FREEING | I_WILL_FREE))
457  		return;
458  	if (atomic_read(&inode->i_count))
459  		return;
460  	if (!(inode->i_sb->s_flags & SB_ACTIVE))
461  		return;
462  	if (!mapping_shrinkable(&inode->i_data))
463  		return;
464  
465  	if (list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru))
466  		this_cpu_inc(nr_unused);
467  	else if (rotate)
468  		inode->i_state |= I_REFERENCED;
469  }
470  
471  /*
472   * Add inode to LRU if needed (inode is unused and clean).
473   *
474   * Needs inode->i_lock held.
475   */
476  void inode_add_lru(struct inode *inode)
477  {
478  	__inode_add_lru(inode, false);
479  }
480  
481  static void inode_lru_list_del(struct inode *inode)
482  {
483  	if (list_lru_del(&inode->i_sb->s_inode_lru, &inode->i_lru))
484  		this_cpu_dec(nr_unused);
485  }
486  
487  /**
488   * inode_sb_list_add - add inode to the superblock list of inodes
489   * @inode: inode to add
490   */
491  void inode_sb_list_add(struct inode *inode)
492  {
493  	spin_lock(&inode->i_sb->s_inode_list_lock);
494  	list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
495  	spin_unlock(&inode->i_sb->s_inode_list_lock);
496  }
497  EXPORT_SYMBOL_GPL(inode_sb_list_add);
498  
499  static inline void inode_sb_list_del(struct inode *inode)
500  {
501  	if (!list_empty(&inode->i_sb_list)) {
502  		spin_lock(&inode->i_sb->s_inode_list_lock);
503  		list_del_init(&inode->i_sb_list);
504  		spin_unlock(&inode->i_sb->s_inode_list_lock);
505  	}
506  }
507  
508  static unsigned long hash(struct super_block *sb, unsigned long hashval)
509  {
510  	unsigned long tmp;
511  
512  	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
513  			L1_CACHE_BYTES;
514  	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
515  	return tmp & i_hash_mask;
516  }
517  
518  /**
519   *	__insert_inode_hash - hash an inode
520   *	@inode: unhashed inode
521   *	@hashval: unsigned long value used to locate this object in the
522   *		inode_hashtable.
523   *
524   *	Add an inode to the inode hash for this superblock.
525   */
526  void __insert_inode_hash(struct inode *inode, unsigned long hashval)
527  {
528  	struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
529  
530  	spin_lock(&inode_hash_lock);
531  	spin_lock(&inode->i_lock);
532  	hlist_add_head_rcu(&inode->i_hash, b);
533  	spin_unlock(&inode->i_lock);
534  	spin_unlock(&inode_hash_lock);
535  }
536  EXPORT_SYMBOL(__insert_inode_hash);
537  
538  /**
539   *	__remove_inode_hash - remove an inode from the hash
540   *	@inode: inode to unhash
541   *
542   *	Remove an inode from the superblock.
543   */
544  void __remove_inode_hash(struct inode *inode)
545  {
546  	spin_lock(&inode_hash_lock);
547  	spin_lock(&inode->i_lock);
548  	hlist_del_init_rcu(&inode->i_hash);
549  	spin_unlock(&inode->i_lock);
550  	spin_unlock(&inode_hash_lock);
551  }
552  EXPORT_SYMBOL(__remove_inode_hash);
553  
554  void dump_mapping(const struct address_space *mapping)
555  {
556  	struct inode *host;
557  	const struct address_space_operations *a_ops;
558  	struct hlist_node *dentry_first;
559  	struct dentry *dentry_ptr;
560  	struct dentry dentry;
561  	unsigned long ino;
562  
563  	/*
564  	 * If mapping is an invalid pointer, we don't want to crash
565  	 * accessing it, so probe everything depending on it carefully.
566  	 */
567  	if (get_kernel_nofault(host, &mapping->host) ||
568  	    get_kernel_nofault(a_ops, &mapping->a_ops)) {
569  		pr_warn("invalid mapping:%px\n", mapping);
570  		return;
571  	}
572  
573  	if (!host) {
574  		pr_warn("aops:%ps\n", a_ops);
575  		return;
576  	}
577  
578  	if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
579  	    get_kernel_nofault(ino, &host->i_ino)) {
580  		pr_warn("aops:%ps invalid inode:%px\n", a_ops, host);
581  		return;
582  	}
583  
584  	if (!dentry_first) {
585  		pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
586  		return;
587  	}
588  
589  	dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
590  	if (get_kernel_nofault(dentry, dentry_ptr)) {
591  		pr_warn("aops:%ps ino:%lx invalid dentry:%px\n",
592  				a_ops, ino, dentry_ptr);
593  		return;
594  	}
595  
596  	/*
597  	 * if dentry is corrupted, the %pd handler may still crash,
598  	 * but it's unlikely that we reach here with a corrupt mapping
599  	 */
600  	pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n", a_ops, ino, &dentry);
601  }
602  
603  void clear_inode(struct inode *inode)
604  {
605  	/*
606  	 * We have to cycle the i_pages lock here because reclaim can be in the
607  	 * process of removing the last page (in __delete_from_page_cache())
608  	 * and we must not free the mapping under it.
609  	 */
610  	xa_lock_irq(&inode->i_data.i_pages);
611  	BUG_ON(inode->i_data.nrpages);
612  	/*
613  	 * Almost always, mapping_empty(&inode->i_data) here; but there are
614  	 * two known and long-standing ways in which nodes may get left behind
615  	 * (when deep radix-tree node allocation failed partway; or when THP
616  	 * collapse_file() failed). Until those two known cases are cleaned up,
617  	 * or a cleanup function is called here, do not BUG_ON(!mapping_empty),
618  	 * nor even WARN_ON(!mapping_empty).
619  	 */
620  	xa_unlock_irq(&inode->i_data.i_pages);
621  	BUG_ON(!list_empty(&inode->i_data.private_list));
622  	BUG_ON(!(inode->i_state & I_FREEING));
623  	BUG_ON(inode->i_state & I_CLEAR);
624  	BUG_ON(!list_empty(&inode->i_wb_list));
625  	/* don't need i_lock here, no concurrent mods to i_state */
626  	inode->i_state = I_FREEING | I_CLEAR;
627  }
628  EXPORT_SYMBOL(clear_inode);
629  
630  /*
631   * Free the inode passed in, removing it from the lists it is still connected
632   * to. We remove any pages still attached to the inode and wait for any IO that
633   * is still in progress before finally destroying the inode.
634   *
635   * An inode must already be marked I_FREEING so that we avoid the inode being
636   * moved back onto lists if we race with other code that manipulates the lists
637   * (e.g. writeback_single_inode). The caller is responsible for setting this.
638   *
639   * An inode must already be removed from the LRU list before being evicted from
640   * the cache. This should occur atomically with setting the I_FREEING state
641   * flag, so no inodes here should ever be on the LRU when being evicted.
642   */
643  static void evict(struct inode *inode)
644  {
645  	const struct super_operations *op = inode->i_sb->s_op;
646  
647  	BUG_ON(!(inode->i_state & I_FREEING));
648  	BUG_ON(!list_empty(&inode->i_lru));
649  
650  	if (!list_empty(&inode->i_io_list))
651  		inode_io_list_del(inode);
652  
653  	inode_sb_list_del(inode);
654  
655  	/*
656  	 * Wait for flusher thread to be done with the inode so that filesystem
657  	 * does not start destroying it while writeback is still running. Since
658  	 * the inode has I_FREEING set, flusher thread won't start new work on
659  	 * the inode.  We just have to wait for running writeback to finish.
660  	 */
661  	inode_wait_for_writeback(inode);
662  
663  	if (op->evict_inode) {
664  		op->evict_inode(inode);
665  	} else {
666  		truncate_inode_pages_final(&inode->i_data);
667  		clear_inode(inode);
668  	}
669  	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
670  		cd_forget(inode);
671  
672  	remove_inode_hash(inode);
673  
674  	spin_lock(&inode->i_lock);
675  	wake_up_bit(&inode->i_state, __I_NEW);
676  	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
677  	spin_unlock(&inode->i_lock);
678  
679  	destroy_inode(inode);
680  }
681  
682  /*
683   * dispose_list - dispose of the contents of a local list
684   * @head: the head of the list to free
685   *
686   * Dispose-list gets a local list with local inodes in it, so it doesn't
687   * need to worry about list corruption and SMP locks.
688   */
689  static void dispose_list(struct list_head *head)
690  {
691  	while (!list_empty(head)) {
692  		struct inode *inode;
693  
694  		inode = list_first_entry(head, struct inode, i_lru);
695  		list_del_init(&inode->i_lru);
696  
697  		evict(inode);
698  		cond_resched();
699  	}
700  }
701  
702  /**
703   * evict_inodes	- evict all evictable inodes for a superblock
704   * @sb:		superblock to operate on
705   *
706   * Make sure that no inodes with zero refcount are retained.  This is
707   * called by superblock shutdown after having SB_ACTIVE flag removed,
708   * so any inode reaching zero refcount during or after that call will
709   * be immediately evicted.
710   */
711  void evict_inodes(struct super_block *sb)
712  {
713  	struct inode *inode, *next;
714  	LIST_HEAD(dispose);
715  
716  again:
717  	spin_lock(&sb->s_inode_list_lock);
718  	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
719  		if (atomic_read(&inode->i_count))
720  			continue;
721  
722  		spin_lock(&inode->i_lock);
723  		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
724  			spin_unlock(&inode->i_lock);
725  			continue;
726  		}
727  
728  		inode->i_state |= I_FREEING;
729  		inode_lru_list_del(inode);
730  		spin_unlock(&inode->i_lock);
731  		list_add(&inode->i_lru, &dispose);
732  
733  		/*
734  		 * We can have a ton of inodes to evict at unmount time given
735  		 * enough memory, check to see if we need to go to sleep for a
736  		 * bit so we don't livelock.
737  		 */
738  		if (need_resched()) {
739  			spin_unlock(&sb->s_inode_list_lock);
740  			cond_resched();
741  			dispose_list(&dispose);
742  			goto again;
743  		}
744  	}
745  	spin_unlock(&sb->s_inode_list_lock);
746  
747  	dispose_list(&dispose);
748  }
749  EXPORT_SYMBOL_GPL(evict_inodes);
750  
751  /**
752   * invalidate_inodes	- attempt to free all inodes on a superblock
753   * @sb:		superblock to operate on
754   * @kill_dirty: flag to guide handling of dirty inodes
755   *
756   * Attempts to free all inodes for a given superblock.  If there were any
757   * busy inodes return a non-zero value, else zero.
758   * If @kill_dirty is set, discard dirty inodes too, otherwise treat
759   * them as busy.
760   */
761  int invalidate_inodes(struct super_block *sb, bool kill_dirty)
762  {
763  	int busy = 0;
764  	struct inode *inode, *next;
765  	LIST_HEAD(dispose);
766  
767  again:
768  	spin_lock(&sb->s_inode_list_lock);
769  	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
770  		spin_lock(&inode->i_lock);
771  		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
772  			spin_unlock(&inode->i_lock);
773  			continue;
774  		}
775  		if (inode->i_state & I_DIRTY_ALL && !kill_dirty) {
776  			spin_unlock(&inode->i_lock);
777  			busy = 1;
778  			continue;
779  		}
780  		if (atomic_read(&inode->i_count)) {
781  			spin_unlock(&inode->i_lock);
782  			busy = 1;
783  			continue;
784  		}
785  
786  		inode->i_state |= I_FREEING;
787  		inode_lru_list_del(inode);
788  		spin_unlock(&inode->i_lock);
789  		list_add(&inode->i_lru, &dispose);
790  		if (need_resched()) {
791  			spin_unlock(&sb->s_inode_list_lock);
792  			cond_resched();
793  			dispose_list(&dispose);
794  			goto again;
795  		}
796  	}
797  	spin_unlock(&sb->s_inode_list_lock);
798  
799  	dispose_list(&dispose);
800  
801  	return busy;
802  }
803  
804  /*
805   * Isolate the inode from the LRU in preparation for freeing it.
806   *
807   * If the inode has the I_REFERENCED flag set, then it means that it has been
808   * used recently - the flag is set in iput_final(). When we encounter such an
809   * inode, clear the flag and move it to the back of the LRU so it gets another
810   * pass through the LRU before it gets reclaimed. This is necessary because of
811   * the fact we are doing lazy LRU updates to minimise lock contention so the
812   * LRU does not have strict ordering. Hence we don't want to reclaim inodes
813   * with this flag set because they are the inodes that are out of order.
814   */
815  static enum lru_status inode_lru_isolate(struct list_head *item,
816  		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
817  {
818  	struct list_head *freeable = arg;
819  	struct inode	*inode = container_of(item, struct inode, i_lru);
820  
821  	/*
822  	 * We are inverting the lru lock/inode->i_lock here, so use a
823  	 * trylock. If we fail to get the lock, just skip it.
824  	 */
825  	if (!spin_trylock(&inode->i_lock))
826  		return LRU_SKIP;
827  
828  	/*
829  	 * Inodes can get referenced, redirtied, or repopulated while
830  	 * they're already on the LRU, and this can make them
831  	 * unreclaimable for a while. Remove them lazily here; iput,
832  	 * sync, or the last page cache deletion will requeue them.
833  	 */
834  	if (atomic_read(&inode->i_count) ||
835  	    (inode->i_state & ~I_REFERENCED) ||
836  	    !mapping_shrinkable(&inode->i_data)) {
837  		list_lru_isolate(lru, &inode->i_lru);
838  		spin_unlock(&inode->i_lock);
839  		this_cpu_dec(nr_unused);
840  		return LRU_REMOVED;
841  	}
842  
843  	/* Recently referenced inodes get one more pass */
844  	if (inode->i_state & I_REFERENCED) {
845  		inode->i_state &= ~I_REFERENCED;
846  		spin_unlock(&inode->i_lock);
847  		return LRU_ROTATE;
848  	}
849  
850  	/*
851  	 * On highmem systems, mapping_shrinkable() permits dropping
852  	 * page cache in order to free up struct inodes: lowmem might
853  	 * be under pressure before the cache inside the highmem zone.
854  	 */
855  	if (inode_has_buffers(inode) || !mapping_empty(&inode->i_data)) {
856  		__iget(inode);
857  		spin_unlock(&inode->i_lock);
858  		spin_unlock(lru_lock);
859  		if (remove_inode_buffers(inode)) {
860  			unsigned long reap;
861  			reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
862  			if (current_is_kswapd())
863  				__count_vm_events(KSWAPD_INODESTEAL, reap);
864  			else
865  				__count_vm_events(PGINODESTEAL, reap);
866  			if (current->reclaim_state)
867  				current->reclaim_state->reclaimed_slab += reap;
868  		}
869  		iput(inode);
870  		spin_lock(lru_lock);
871  		return LRU_RETRY;
872  	}
873  
874  	WARN_ON(inode->i_state & I_NEW);
875  	inode->i_state |= I_FREEING;
876  	list_lru_isolate_move(lru, &inode->i_lru, freeable);
877  	spin_unlock(&inode->i_lock);
878  
879  	this_cpu_dec(nr_unused);
880  	return LRU_REMOVED;
881  }
882  
883  /*
884   * Walk the superblock inode LRU for freeable inodes and attempt to free them.
885   * This is called from the superblock shrinker function with a number of inodes
886   * to trim from the LRU. Inodes to be freed are moved to a temporary list and
887   * then are freed outside inode_lock by dispose_list().
888   */
889  long prune_icache_sb(struct super_block *sb, struct shrink_control *sc)
890  {
891  	LIST_HEAD(freeable);
892  	long freed;
893  
894  	freed = list_lru_shrink_walk(&sb->s_inode_lru, sc,
895  				     inode_lru_isolate, &freeable);
896  	dispose_list(&freeable);
897  	return freed;
898  }
899  
900  static void __wait_on_freeing_inode(struct inode *inode);
901  /*
902   * Called with the inode lock held.
903   */
904  static struct inode *find_inode(struct super_block *sb,
905  				struct hlist_head *head,
906  				int (*test)(struct inode *, void *),
907  				void *data)
908  {
909  	struct inode *inode = NULL;
910  
911  repeat:
912  	hlist_for_each_entry(inode, head, i_hash) {
913  		if (inode->i_sb != sb)
914  			continue;
915  		if (!test(inode, data))
916  			continue;
917  		spin_lock(&inode->i_lock);
918  		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
919  			__wait_on_freeing_inode(inode);
920  			goto repeat;
921  		}
922  		if (unlikely(inode->i_state & I_CREATING)) {
923  			spin_unlock(&inode->i_lock);
924  			return ERR_PTR(-ESTALE);
925  		}
926  		__iget(inode);
927  		spin_unlock(&inode->i_lock);
928  		return inode;
929  	}
930  	return NULL;
931  }
932  
933  /*
934   * find_inode_fast is the fast path version of find_inode, see the comment at
935   * iget_locked for details.
936   */
937  static struct inode *find_inode_fast(struct super_block *sb,
938  				struct hlist_head *head, unsigned long ino)
939  {
940  	struct inode *inode = NULL;
941  
942  repeat:
943  	hlist_for_each_entry(inode, head, i_hash) {
944  		if (inode->i_ino != ino)
945  			continue;
946  		if (inode->i_sb != sb)
947  			continue;
948  		spin_lock(&inode->i_lock);
949  		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
950  			__wait_on_freeing_inode(inode);
951  			goto repeat;
952  		}
953  		if (unlikely(inode->i_state & I_CREATING)) {
954  			spin_unlock(&inode->i_lock);
955  			return ERR_PTR(-ESTALE);
956  		}
957  		__iget(inode);
958  		spin_unlock(&inode->i_lock);
959  		return inode;
960  	}
961  	return NULL;
962  }
963  
964  /*
965   * Each cpu owns a range of LAST_INO_BATCH numbers.
966   * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
967   * to renew the exhausted range.
968   *
969   * This does not significantly increase overflow rate because every CPU can
970   * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
971   * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
972   * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
973   * overflow rate by 2x, which does not seem too significant.
974   *
975   * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
976   * error if st_ino won't fit in target struct field. Use 32bit counter
977   * here to attempt to avoid that.
978   */
979  #define LAST_INO_BATCH 1024
980  static DEFINE_PER_CPU(unsigned int, last_ino);
981  
982  unsigned int get_next_ino(void)
983  {
984  	unsigned int *p = &get_cpu_var(last_ino);
985  	unsigned int res = *p;
986  
987  #ifdef CONFIG_SMP
988  	if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
989  		static atomic_t shared_last_ino;
990  		int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
991  
992  		res = next - LAST_INO_BATCH;
993  	}
994  #endif
995  
996  	res++;
997  	/* get_next_ino should not provide a 0 inode number */
998  	if (unlikely(!res))
999  		res++;
1000  	*p = res;
1001  	put_cpu_var(last_ino);
1002  	return res;
1003  }
1004  EXPORT_SYMBOL(get_next_ino);
1005  
1006  /**
1007   *	new_inode_pseudo 	- obtain an inode
1008   *	@sb: superblock
1009   *
1010   *	Allocates a new inode for given superblock.
1011   *	Inode wont be chained in superblock s_inodes list
1012   *	This means :
1013   *	- fs can't be unmount
1014   *	- quotas, fsnotify, writeback can't work
1015   */
1016  struct inode *new_inode_pseudo(struct super_block *sb)
1017  {
1018  	struct inode *inode = alloc_inode(sb);
1019  
1020  	if (inode) {
1021  		spin_lock(&inode->i_lock);
1022  		inode->i_state = 0;
1023  		spin_unlock(&inode->i_lock);
1024  		INIT_LIST_HEAD(&inode->i_sb_list);
1025  	}
1026  	return inode;
1027  }
1028  
1029  /**
1030   *	new_inode 	- obtain an inode
1031   *	@sb: superblock
1032   *
1033   *	Allocates a new inode for given superblock. The default gfp_mask
1034   *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
1035   *	If HIGHMEM pages are unsuitable or it is known that pages allocated
1036   *	for the page cache are not reclaimable or migratable,
1037   *	mapping_set_gfp_mask() must be called with suitable flags on the
1038   *	newly created inode's mapping
1039   *
1040   */
1041  struct inode *new_inode(struct super_block *sb)
1042  {
1043  	struct inode *inode;
1044  
1045  	spin_lock_prefetch(&sb->s_inode_list_lock);
1046  
1047  	inode = new_inode_pseudo(sb);
1048  	if (inode)
1049  		inode_sb_list_add(inode);
1050  	return inode;
1051  }
1052  EXPORT_SYMBOL(new_inode);
1053  
1054  #ifdef CONFIG_DEBUG_LOCK_ALLOC
1055  void lockdep_annotate_inode_mutex_key(struct inode *inode)
1056  {
1057  	if (S_ISDIR(inode->i_mode)) {
1058  		struct file_system_type *type = inode->i_sb->s_type;
1059  
1060  		/* Set new key only if filesystem hasn't already changed it */
1061  		if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) {
1062  			/*
1063  			 * ensure nobody is actually holding i_mutex
1064  			 */
1065  			// mutex_destroy(&inode->i_mutex);
1066  			init_rwsem(&inode->i_rwsem);
1067  			lockdep_set_class(&inode->i_rwsem,
1068  					  &type->i_mutex_dir_key);
1069  		}
1070  	}
1071  }
1072  EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
1073  #endif
1074  
1075  /**
1076   * unlock_new_inode - clear the I_NEW state and wake up any waiters
1077   * @inode:	new inode to unlock
1078   *
1079   * Called when the inode is fully initialised to clear the new state of the
1080   * inode and wake up anyone waiting for the inode to finish initialisation.
1081   */
1082  void unlock_new_inode(struct inode *inode)
1083  {
1084  	lockdep_annotate_inode_mutex_key(inode);
1085  	spin_lock(&inode->i_lock);
1086  	WARN_ON(!(inode->i_state & I_NEW));
1087  	inode->i_state &= ~I_NEW & ~I_CREATING;
1088  	smp_mb();
1089  	wake_up_bit(&inode->i_state, __I_NEW);
1090  	spin_unlock(&inode->i_lock);
1091  }
1092  EXPORT_SYMBOL(unlock_new_inode);
1093  
1094  void discard_new_inode(struct inode *inode)
1095  {
1096  	lockdep_annotate_inode_mutex_key(inode);
1097  	spin_lock(&inode->i_lock);
1098  	WARN_ON(!(inode->i_state & I_NEW));
1099  	inode->i_state &= ~I_NEW;
1100  	smp_mb();
1101  	wake_up_bit(&inode->i_state, __I_NEW);
1102  	spin_unlock(&inode->i_lock);
1103  	iput(inode);
1104  }
1105  EXPORT_SYMBOL(discard_new_inode);
1106  
1107  /**
1108   * lock_two_nondirectories - take two i_mutexes on non-directory objects
1109   *
1110   * Lock any non-NULL argument that is not a directory.
1111   * Zero, one or two objects may be locked by this function.
1112   *
1113   * @inode1: first inode to lock
1114   * @inode2: second inode to lock
1115   */
1116  void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1117  {
1118  	if (inode1 > inode2)
1119  		swap(inode1, inode2);
1120  
1121  	if (inode1 && !S_ISDIR(inode1->i_mode))
1122  		inode_lock(inode1);
1123  	if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
1124  		inode_lock_nested(inode2, I_MUTEX_NONDIR2);
1125  }
1126  EXPORT_SYMBOL(lock_two_nondirectories);
1127  
1128  /**
1129   * unlock_two_nondirectories - release locks from lock_two_nondirectories()
1130   * @inode1: first inode to unlock
1131   * @inode2: second inode to unlock
1132   */
1133  void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1134  {
1135  	if (inode1 && !S_ISDIR(inode1->i_mode))
1136  		inode_unlock(inode1);
1137  	if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
1138  		inode_unlock(inode2);
1139  }
1140  EXPORT_SYMBOL(unlock_two_nondirectories);
1141  
1142  /**
1143   * inode_insert5 - obtain an inode from a mounted file system
1144   * @inode:	pre-allocated inode to use for insert to cache
1145   * @hashval:	hash value (usually inode number) to get
1146   * @test:	callback used for comparisons between inodes
1147   * @set:	callback used to initialize a new struct inode
1148   * @data:	opaque data pointer to pass to @test and @set
1149   *
1150   * Search for the inode specified by @hashval and @data in the inode cache,
1151   * and if present it is return it with an increased reference count. This is
1152   * a variant of iget5_locked() for callers that don't want to fail on memory
1153   * allocation of inode.
1154   *
1155   * If the inode is not in cache, insert the pre-allocated inode to cache and
1156   * return it locked, hashed, and with the I_NEW flag set. The file system gets
1157   * to fill it in before unlocking it via unlock_new_inode().
1158   *
1159   * Note both @test and @set are called with the inode_hash_lock held, so can't
1160   * sleep.
1161   */
1162  struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
1163  			    int (*test)(struct inode *, void *),
1164  			    int (*set)(struct inode *, void *), void *data)
1165  {
1166  	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
1167  	struct inode *old;
1168  	bool creating = inode->i_state & I_CREATING;
1169  
1170  again:
1171  	spin_lock(&inode_hash_lock);
1172  	old = find_inode(inode->i_sb, head, test, data);
1173  	if (unlikely(old)) {
1174  		/*
1175  		 * Uhhuh, somebody else created the same inode under us.
1176  		 * Use the old inode instead of the preallocated one.
1177  		 */
1178  		spin_unlock(&inode_hash_lock);
1179  		if (IS_ERR(old))
1180  			return NULL;
1181  		wait_on_inode(old);
1182  		if (unlikely(inode_unhashed(old))) {
1183  			iput(old);
1184  			goto again;
1185  		}
1186  		return old;
1187  	}
1188  
1189  	if (set && unlikely(set(inode, data))) {
1190  		inode = NULL;
1191  		goto unlock;
1192  	}
1193  
1194  	/*
1195  	 * Return the locked inode with I_NEW set, the
1196  	 * caller is responsible for filling in the contents
1197  	 */
1198  	spin_lock(&inode->i_lock);
1199  	inode->i_state |= I_NEW;
1200  	hlist_add_head_rcu(&inode->i_hash, head);
1201  	spin_unlock(&inode->i_lock);
1202  	if (!creating)
1203  		inode_sb_list_add(inode);
1204  unlock:
1205  	spin_unlock(&inode_hash_lock);
1206  
1207  	return inode;
1208  }
1209  EXPORT_SYMBOL(inode_insert5);
1210  
1211  /**
1212   * iget5_locked - obtain an inode from a mounted file system
1213   * @sb:		super block of file system
1214   * @hashval:	hash value (usually inode number) to get
1215   * @test:	callback used for comparisons between inodes
1216   * @set:	callback used to initialize a new struct inode
1217   * @data:	opaque data pointer to pass to @test and @set
1218   *
1219   * Search for the inode specified by @hashval and @data in the inode cache,
1220   * and if present it is return it with an increased reference count. This is
1221   * a generalized version of iget_locked() for file systems where the inode
1222   * number is not sufficient for unique identification of an inode.
1223   *
1224   * If the inode is not in cache, allocate a new inode and return it locked,
1225   * hashed, and with the I_NEW flag set. The file system gets to fill it in
1226   * before unlocking it via unlock_new_inode().
1227   *
1228   * Note both @test and @set are called with the inode_hash_lock held, so can't
1229   * sleep.
1230   */
1231  struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1232  		int (*test)(struct inode *, void *),
1233  		int (*set)(struct inode *, void *), void *data)
1234  {
1235  	struct inode *inode = ilookup5(sb, hashval, test, data);
1236  
1237  	if (!inode) {
1238  		struct inode *new = alloc_inode(sb);
1239  
1240  		if (new) {
1241  			new->i_state = 0;
1242  			inode = inode_insert5(new, hashval, test, set, data);
1243  			if (unlikely(inode != new))
1244  				destroy_inode(new);
1245  		}
1246  	}
1247  	return inode;
1248  }
1249  EXPORT_SYMBOL(iget5_locked);
1250  
1251  /**
1252   * iget_locked - obtain an inode from a mounted file system
1253   * @sb:		super block of file system
1254   * @ino:	inode number to get
1255   *
1256   * Search for the inode specified by @ino in the inode cache and if present
1257   * return it with an increased reference count. This is for file systems
1258   * where the inode number is sufficient for unique identification of an inode.
1259   *
1260   * If the inode is not in cache, allocate a new inode and return it locked,
1261   * hashed, and with the I_NEW flag set.  The file system gets to fill it in
1262   * before unlocking it via unlock_new_inode().
1263   */
1264  struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1265  {
1266  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1267  	struct inode *inode;
1268  again:
1269  	spin_lock(&inode_hash_lock);
1270  	inode = find_inode_fast(sb, head, ino);
1271  	spin_unlock(&inode_hash_lock);
1272  	if (inode) {
1273  		if (IS_ERR(inode))
1274  			return NULL;
1275  		wait_on_inode(inode);
1276  		if (unlikely(inode_unhashed(inode))) {
1277  			iput(inode);
1278  			goto again;
1279  		}
1280  		return inode;
1281  	}
1282  
1283  	inode = alloc_inode(sb);
1284  	if (inode) {
1285  		struct inode *old;
1286  
1287  		spin_lock(&inode_hash_lock);
1288  		/* We released the lock, so.. */
1289  		old = find_inode_fast(sb, head, ino);
1290  		if (!old) {
1291  			inode->i_ino = ino;
1292  			spin_lock(&inode->i_lock);
1293  			inode->i_state = I_NEW;
1294  			hlist_add_head_rcu(&inode->i_hash, head);
1295  			spin_unlock(&inode->i_lock);
1296  			inode_sb_list_add(inode);
1297  			spin_unlock(&inode_hash_lock);
1298  
1299  			/* Return the locked inode with I_NEW set, the
1300  			 * caller is responsible for filling in the contents
1301  			 */
1302  			return inode;
1303  		}
1304  
1305  		/*
1306  		 * Uhhuh, somebody else created the same inode under
1307  		 * us. Use the old inode instead of the one we just
1308  		 * allocated.
1309  		 */
1310  		spin_unlock(&inode_hash_lock);
1311  		destroy_inode(inode);
1312  		if (IS_ERR(old))
1313  			return NULL;
1314  		inode = old;
1315  		wait_on_inode(inode);
1316  		if (unlikely(inode_unhashed(inode))) {
1317  			iput(inode);
1318  			goto again;
1319  		}
1320  	}
1321  	return inode;
1322  }
1323  EXPORT_SYMBOL(iget_locked);
1324  
1325  /*
1326   * search the inode cache for a matching inode number.
1327   * If we find one, then the inode number we are trying to
1328   * allocate is not unique and so we should not use it.
1329   *
1330   * Returns 1 if the inode number is unique, 0 if it is not.
1331   */
1332  static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1333  {
1334  	struct hlist_head *b = inode_hashtable + hash(sb, ino);
1335  	struct inode *inode;
1336  
1337  	hlist_for_each_entry_rcu(inode, b, i_hash) {
1338  		if (inode->i_ino == ino && inode->i_sb == sb)
1339  			return 0;
1340  	}
1341  	return 1;
1342  }
1343  
1344  /**
1345   *	iunique - get a unique inode number
1346   *	@sb: superblock
1347   *	@max_reserved: highest reserved inode number
1348   *
1349   *	Obtain an inode number that is unique on the system for a given
1350   *	superblock. This is used by file systems that have no natural
1351   *	permanent inode numbering system. An inode number is returned that
1352   *	is higher than the reserved limit but unique.
1353   *
1354   *	BUGS:
1355   *	With a large number of inodes live on the file system this function
1356   *	currently becomes quite slow.
1357   */
1358  ino_t iunique(struct super_block *sb, ino_t max_reserved)
1359  {
1360  	/*
1361  	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1362  	 * error if st_ino won't fit in target struct field. Use 32bit counter
1363  	 * here to attempt to avoid that.
1364  	 */
1365  	static DEFINE_SPINLOCK(iunique_lock);
1366  	static unsigned int counter;
1367  	ino_t res;
1368  
1369  	rcu_read_lock();
1370  	spin_lock(&iunique_lock);
1371  	do {
1372  		if (counter <= max_reserved)
1373  			counter = max_reserved + 1;
1374  		res = counter++;
1375  	} while (!test_inode_iunique(sb, res));
1376  	spin_unlock(&iunique_lock);
1377  	rcu_read_unlock();
1378  
1379  	return res;
1380  }
1381  EXPORT_SYMBOL(iunique);
1382  
1383  struct inode *igrab(struct inode *inode)
1384  {
1385  	spin_lock(&inode->i_lock);
1386  	if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1387  		__iget(inode);
1388  		spin_unlock(&inode->i_lock);
1389  	} else {
1390  		spin_unlock(&inode->i_lock);
1391  		/*
1392  		 * Handle the case where s_op->clear_inode is not been
1393  		 * called yet, and somebody is calling igrab
1394  		 * while the inode is getting freed.
1395  		 */
1396  		inode = NULL;
1397  	}
1398  	return inode;
1399  }
1400  EXPORT_SYMBOL(igrab);
1401  
1402  /**
1403   * ilookup5_nowait - search for an inode in the inode cache
1404   * @sb:		super block of file system to search
1405   * @hashval:	hash value (usually inode number) to search for
1406   * @test:	callback used for comparisons between inodes
1407   * @data:	opaque data pointer to pass to @test
1408   *
1409   * Search for the inode specified by @hashval and @data in the inode cache.
1410   * If the inode is in the cache, the inode is returned with an incremented
1411   * reference count.
1412   *
1413   * Note: I_NEW is not waited upon so you have to be very careful what you do
1414   * with the returned inode.  You probably should be using ilookup5() instead.
1415   *
1416   * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1417   */
1418  struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1419  		int (*test)(struct inode *, void *), void *data)
1420  {
1421  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1422  	struct inode *inode;
1423  
1424  	spin_lock(&inode_hash_lock);
1425  	inode = find_inode(sb, head, test, data);
1426  	spin_unlock(&inode_hash_lock);
1427  
1428  	return IS_ERR(inode) ? NULL : inode;
1429  }
1430  EXPORT_SYMBOL(ilookup5_nowait);
1431  
1432  /**
1433   * ilookup5 - search for an inode in the inode cache
1434   * @sb:		super block of file system to search
1435   * @hashval:	hash value (usually inode number) to search for
1436   * @test:	callback used for comparisons between inodes
1437   * @data:	opaque data pointer to pass to @test
1438   *
1439   * Search for the inode specified by @hashval and @data in the inode cache,
1440   * and if the inode is in the cache, return the inode with an incremented
1441   * reference count.  Waits on I_NEW before returning the inode.
1442   * returned with an incremented reference count.
1443   *
1444   * This is a generalized version of ilookup() for file systems where the
1445   * inode number is not sufficient for unique identification of an inode.
1446   *
1447   * Note: @test is called with the inode_hash_lock held, so can't sleep.
1448   */
1449  struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1450  		int (*test)(struct inode *, void *), void *data)
1451  {
1452  	struct inode *inode;
1453  again:
1454  	inode = ilookup5_nowait(sb, hashval, test, data);
1455  	if (inode) {
1456  		wait_on_inode(inode);
1457  		if (unlikely(inode_unhashed(inode))) {
1458  			iput(inode);
1459  			goto again;
1460  		}
1461  	}
1462  	return inode;
1463  }
1464  EXPORT_SYMBOL(ilookup5);
1465  
1466  /**
1467   * ilookup - search for an inode in the inode cache
1468   * @sb:		super block of file system to search
1469   * @ino:	inode number to search for
1470   *
1471   * Search for the inode @ino in the inode cache, and if the inode is in the
1472   * cache, the inode is returned with an incremented reference count.
1473   */
1474  struct inode *ilookup(struct super_block *sb, unsigned long ino)
1475  {
1476  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1477  	struct inode *inode;
1478  again:
1479  	spin_lock(&inode_hash_lock);
1480  	inode = find_inode_fast(sb, head, ino);
1481  	spin_unlock(&inode_hash_lock);
1482  
1483  	if (inode) {
1484  		if (IS_ERR(inode))
1485  			return NULL;
1486  		wait_on_inode(inode);
1487  		if (unlikely(inode_unhashed(inode))) {
1488  			iput(inode);
1489  			goto again;
1490  		}
1491  	}
1492  	return inode;
1493  }
1494  EXPORT_SYMBOL(ilookup);
1495  
1496  /**
1497   * find_inode_nowait - find an inode in the inode cache
1498   * @sb:		super block of file system to search
1499   * @hashval:	hash value (usually inode number) to search for
1500   * @match:	callback used for comparisons between inodes
1501   * @data:	opaque data pointer to pass to @match
1502   *
1503   * Search for the inode specified by @hashval and @data in the inode
1504   * cache, where the helper function @match will return 0 if the inode
1505   * does not match, 1 if the inode does match, and -1 if the search
1506   * should be stopped.  The @match function must be responsible for
1507   * taking the i_lock spin_lock and checking i_state for an inode being
1508   * freed or being initialized, and incrementing the reference count
1509   * before returning 1.  It also must not sleep, since it is called with
1510   * the inode_hash_lock spinlock held.
1511   *
1512   * This is a even more generalized version of ilookup5() when the
1513   * function must never block --- find_inode() can block in
1514   * __wait_on_freeing_inode() --- or when the caller can not increment
1515   * the reference count because the resulting iput() might cause an
1516   * inode eviction.  The tradeoff is that the @match funtion must be
1517   * very carefully implemented.
1518   */
1519  struct inode *find_inode_nowait(struct super_block *sb,
1520  				unsigned long hashval,
1521  				int (*match)(struct inode *, unsigned long,
1522  					     void *),
1523  				void *data)
1524  {
1525  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1526  	struct inode *inode, *ret_inode = NULL;
1527  	int mval;
1528  
1529  	spin_lock(&inode_hash_lock);
1530  	hlist_for_each_entry(inode, head, i_hash) {
1531  		if (inode->i_sb != sb)
1532  			continue;
1533  		mval = match(inode, hashval, data);
1534  		if (mval == 0)
1535  			continue;
1536  		if (mval == 1)
1537  			ret_inode = inode;
1538  		goto out;
1539  	}
1540  out:
1541  	spin_unlock(&inode_hash_lock);
1542  	return ret_inode;
1543  }
1544  EXPORT_SYMBOL(find_inode_nowait);
1545  
1546  /**
1547   * find_inode_rcu - find an inode in the inode cache
1548   * @sb:		Super block of file system to search
1549   * @hashval:	Key to hash
1550   * @test:	Function to test match on an inode
1551   * @data:	Data for test function
1552   *
1553   * Search for the inode specified by @hashval and @data in the inode cache,
1554   * where the helper function @test will return 0 if the inode does not match
1555   * and 1 if it does.  The @test function must be responsible for taking the
1556   * i_lock spin_lock and checking i_state for an inode being freed or being
1557   * initialized.
1558   *
1559   * If successful, this will return the inode for which the @test function
1560   * returned 1 and NULL otherwise.
1561   *
1562   * The @test function is not permitted to take a ref on any inode presented.
1563   * It is also not permitted to sleep.
1564   *
1565   * The caller must hold the RCU read lock.
1566   */
1567  struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval,
1568  			     int (*test)(struct inode *, void *), void *data)
1569  {
1570  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1571  	struct inode *inode;
1572  
1573  	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1574  			 "suspicious find_inode_rcu() usage");
1575  
1576  	hlist_for_each_entry_rcu(inode, head, i_hash) {
1577  		if (inode->i_sb == sb &&
1578  		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)) &&
1579  		    test(inode, data))
1580  			return inode;
1581  	}
1582  	return NULL;
1583  }
1584  EXPORT_SYMBOL(find_inode_rcu);
1585  
1586  /**
1587   * find_inode_by_ino_rcu - Find an inode in the inode cache
1588   * @sb:		Super block of file system to search
1589   * @ino:	The inode number to match
1590   *
1591   * Search for the inode specified by @hashval and @data in the inode cache,
1592   * where the helper function @test will return 0 if the inode does not match
1593   * and 1 if it does.  The @test function must be responsible for taking the
1594   * i_lock spin_lock and checking i_state for an inode being freed or being
1595   * initialized.
1596   *
1597   * If successful, this will return the inode for which the @test function
1598   * returned 1 and NULL otherwise.
1599   *
1600   * The @test function is not permitted to take a ref on any inode presented.
1601   * It is also not permitted to sleep.
1602   *
1603   * The caller must hold the RCU read lock.
1604   */
1605  struct inode *find_inode_by_ino_rcu(struct super_block *sb,
1606  				    unsigned long ino)
1607  {
1608  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1609  	struct inode *inode;
1610  
1611  	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1612  			 "suspicious find_inode_by_ino_rcu() usage");
1613  
1614  	hlist_for_each_entry_rcu(inode, head, i_hash) {
1615  		if (inode->i_ino == ino &&
1616  		    inode->i_sb == sb &&
1617  		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)))
1618  		    return inode;
1619  	}
1620  	return NULL;
1621  }
1622  EXPORT_SYMBOL(find_inode_by_ino_rcu);
1623  
1624  int insert_inode_locked(struct inode *inode)
1625  {
1626  	struct super_block *sb = inode->i_sb;
1627  	ino_t ino = inode->i_ino;
1628  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1629  
1630  	while (1) {
1631  		struct inode *old = NULL;
1632  		spin_lock(&inode_hash_lock);
1633  		hlist_for_each_entry(old, head, i_hash) {
1634  			if (old->i_ino != ino)
1635  				continue;
1636  			if (old->i_sb != sb)
1637  				continue;
1638  			spin_lock(&old->i_lock);
1639  			if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1640  				spin_unlock(&old->i_lock);
1641  				continue;
1642  			}
1643  			break;
1644  		}
1645  		if (likely(!old)) {
1646  			spin_lock(&inode->i_lock);
1647  			inode->i_state |= I_NEW | I_CREATING;
1648  			hlist_add_head_rcu(&inode->i_hash, head);
1649  			spin_unlock(&inode->i_lock);
1650  			spin_unlock(&inode_hash_lock);
1651  			return 0;
1652  		}
1653  		if (unlikely(old->i_state & I_CREATING)) {
1654  			spin_unlock(&old->i_lock);
1655  			spin_unlock(&inode_hash_lock);
1656  			return -EBUSY;
1657  		}
1658  		__iget(old);
1659  		spin_unlock(&old->i_lock);
1660  		spin_unlock(&inode_hash_lock);
1661  		wait_on_inode(old);
1662  		if (unlikely(!inode_unhashed(old))) {
1663  			iput(old);
1664  			return -EBUSY;
1665  		}
1666  		iput(old);
1667  	}
1668  }
1669  EXPORT_SYMBOL(insert_inode_locked);
1670  
1671  int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1672  		int (*test)(struct inode *, void *), void *data)
1673  {
1674  	struct inode *old;
1675  
1676  	inode->i_state |= I_CREATING;
1677  	old = inode_insert5(inode, hashval, test, NULL, data);
1678  
1679  	if (old != inode) {
1680  		iput(old);
1681  		return -EBUSY;
1682  	}
1683  	return 0;
1684  }
1685  EXPORT_SYMBOL(insert_inode_locked4);
1686  
1687  
1688  int generic_delete_inode(struct inode *inode)
1689  {
1690  	return 1;
1691  }
1692  EXPORT_SYMBOL(generic_delete_inode);
1693  
1694  /*
1695   * Called when we're dropping the last reference
1696   * to an inode.
1697   *
1698   * Call the FS "drop_inode()" function, defaulting to
1699   * the legacy UNIX filesystem behaviour.  If it tells
1700   * us to evict inode, do so.  Otherwise, retain inode
1701   * in cache if fs is alive, sync and evict if fs is
1702   * shutting down.
1703   */
1704  static void iput_final(struct inode *inode)
1705  {
1706  	struct super_block *sb = inode->i_sb;
1707  	const struct super_operations *op = inode->i_sb->s_op;
1708  	unsigned long state;
1709  	int drop;
1710  
1711  	WARN_ON(inode->i_state & I_NEW);
1712  
1713  	if (op->drop_inode)
1714  		drop = op->drop_inode(inode);
1715  	else
1716  		drop = generic_drop_inode(inode);
1717  
1718  	if (!drop &&
1719  	    !(inode->i_state & I_DONTCACHE) &&
1720  	    (sb->s_flags & SB_ACTIVE)) {
1721  		__inode_add_lru(inode, true);
1722  		spin_unlock(&inode->i_lock);
1723  		return;
1724  	}
1725  
1726  	state = inode->i_state;
1727  	if (!drop) {
1728  		WRITE_ONCE(inode->i_state, state | I_WILL_FREE);
1729  		spin_unlock(&inode->i_lock);
1730  
1731  		write_inode_now(inode, 1);
1732  
1733  		spin_lock(&inode->i_lock);
1734  		state = inode->i_state;
1735  		WARN_ON(state & I_NEW);
1736  		state &= ~I_WILL_FREE;
1737  	}
1738  
1739  	WRITE_ONCE(inode->i_state, state | I_FREEING);
1740  	if (!list_empty(&inode->i_lru))
1741  		inode_lru_list_del(inode);
1742  	spin_unlock(&inode->i_lock);
1743  
1744  	evict(inode);
1745  }
1746  
1747  /**
1748   *	iput	- put an inode
1749   *	@inode: inode to put
1750   *
1751   *	Puts an inode, dropping its usage count. If the inode use count hits
1752   *	zero, the inode is then freed and may also be destroyed.
1753   *
1754   *	Consequently, iput() can sleep.
1755   */
1756  void iput(struct inode *inode)
1757  {
1758  	if (!inode)
1759  		return;
1760  	BUG_ON(inode->i_state & I_CLEAR);
1761  retry:
1762  	if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
1763  		if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
1764  			atomic_inc(&inode->i_count);
1765  			spin_unlock(&inode->i_lock);
1766  			trace_writeback_lazytime_iput(inode);
1767  			mark_inode_dirty_sync(inode);
1768  			goto retry;
1769  		}
1770  		iput_final(inode);
1771  	}
1772  }
1773  EXPORT_SYMBOL(iput);
1774  
1775  #ifdef CONFIG_BLOCK
1776  /**
1777   *	bmap	- find a block number in a file
1778   *	@inode:  inode owning the block number being requested
1779   *	@block: pointer containing the block to find
1780   *
1781   *	Replaces the value in ``*block`` with the block number on the device holding
1782   *	corresponding to the requested block number in the file.
1783   *	That is, asked for block 4 of inode 1 the function will replace the
1784   *	4 in ``*block``, with disk block relative to the disk start that holds that
1785   *	block of the file.
1786   *
1787   *	Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
1788   *	hole, returns 0 and ``*block`` is also set to 0.
1789   */
1790  int bmap(struct inode *inode, sector_t *block)
1791  {
1792  	if (!inode->i_mapping->a_ops->bmap)
1793  		return -EINVAL;
1794  
1795  	*block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
1796  	return 0;
1797  }
1798  EXPORT_SYMBOL(bmap);
1799  #endif
1800  
1801  /*
1802   * With relative atime, only update atime if the previous atime is
1803   * earlier than either the ctime or mtime or if at least a day has
1804   * passed since the last atime update.
1805   */
1806  static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1807  			     struct timespec64 now)
1808  {
1809  
1810  	if (!(mnt->mnt_flags & MNT_RELATIME))
1811  		return 1;
1812  	/*
1813  	 * Is mtime younger than atime? If yes, update atime:
1814  	 */
1815  	if (timespec64_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1816  		return 1;
1817  	/*
1818  	 * Is ctime younger than atime? If yes, update atime:
1819  	 */
1820  	if (timespec64_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1821  		return 1;
1822  
1823  	/*
1824  	 * Is the previous atime value older than a day? If yes,
1825  	 * update atime:
1826  	 */
1827  	if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1828  		return 1;
1829  	/*
1830  	 * Good, we can skip the atime update:
1831  	 */
1832  	return 0;
1833  }
1834  
1835  int generic_update_time(struct inode *inode, struct timespec64 *time, int flags)
1836  {
1837  	int dirty_flags = 0;
1838  
1839  	if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
1840  		if (flags & S_ATIME)
1841  			inode->i_atime = *time;
1842  		if (flags & S_CTIME)
1843  			inode->i_ctime = *time;
1844  		if (flags & S_MTIME)
1845  			inode->i_mtime = *time;
1846  
1847  		if (inode->i_sb->s_flags & SB_LAZYTIME)
1848  			dirty_flags |= I_DIRTY_TIME;
1849  		else
1850  			dirty_flags |= I_DIRTY_SYNC;
1851  	}
1852  
1853  	if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))
1854  		dirty_flags |= I_DIRTY_SYNC;
1855  
1856  	__mark_inode_dirty(inode, dirty_flags);
1857  	return 0;
1858  }
1859  EXPORT_SYMBOL(generic_update_time);
1860  
1861  /*
1862   * This does the actual work of updating an inodes time or version.  Must have
1863   * had called mnt_want_write() before calling this.
1864   */
1865  int inode_update_time(struct inode *inode, struct timespec64 *time, int flags)
1866  {
1867  	if (inode->i_op->update_time)
1868  		return inode->i_op->update_time(inode, time, flags);
1869  	return generic_update_time(inode, time, flags);
1870  }
1871  EXPORT_SYMBOL(inode_update_time);
1872  
1873  /**
1874   *	atime_needs_update	-	update the access time
1875   *	@path: the &struct path to update
1876   *	@inode: inode to update
1877   *
1878   *	Update the accessed time on an inode and mark it for writeback.
1879   *	This function automatically handles read only file systems and media,
1880   *	as well as the "noatime" flag and inode specific "noatime" markers.
1881   */
1882  bool atime_needs_update(const struct path *path, struct inode *inode)
1883  {
1884  	struct vfsmount *mnt = path->mnt;
1885  	struct timespec64 now;
1886  
1887  	if (inode->i_flags & S_NOATIME)
1888  		return false;
1889  
1890  	/* Atime updates will likely cause i_uid and i_gid to be written
1891  	 * back improprely if their true value is unknown to the vfs.
1892  	 */
1893  	if (HAS_UNMAPPED_ID(mnt_user_ns(mnt), inode))
1894  		return false;
1895  
1896  	if (IS_NOATIME(inode))
1897  		return false;
1898  	if ((inode->i_sb->s_flags & SB_NODIRATIME) && S_ISDIR(inode->i_mode))
1899  		return false;
1900  
1901  	if (mnt->mnt_flags & MNT_NOATIME)
1902  		return false;
1903  	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1904  		return false;
1905  
1906  	now = current_time(inode);
1907  
1908  	if (!relatime_need_update(mnt, inode, now))
1909  		return false;
1910  
1911  	if (timespec64_equal(&inode->i_atime, &now))
1912  		return false;
1913  
1914  	return true;
1915  }
1916  
1917  void touch_atime(const struct path *path)
1918  {
1919  	struct vfsmount *mnt = path->mnt;
1920  	struct inode *inode = d_inode(path->dentry);
1921  	struct timespec64 now;
1922  
1923  	if (!atime_needs_update(path, inode))
1924  		return;
1925  
1926  	if (!sb_start_write_trylock(inode->i_sb))
1927  		return;
1928  
1929  	if (__mnt_want_write(mnt) != 0)
1930  		goto skip_update;
1931  	/*
1932  	 * File systems can error out when updating inodes if they need to
1933  	 * allocate new space to modify an inode (such is the case for
1934  	 * Btrfs), but since we touch atime while walking down the path we
1935  	 * really don't care if we failed to update the atime of the file,
1936  	 * so just ignore the return value.
1937  	 * We may also fail on filesystems that have the ability to make parts
1938  	 * of the fs read only, e.g. subvolumes in Btrfs.
1939  	 */
1940  	now = current_time(inode);
1941  	inode_update_time(inode, &now, S_ATIME);
1942  	__mnt_drop_write(mnt);
1943  skip_update:
1944  	sb_end_write(inode->i_sb);
1945  }
1946  EXPORT_SYMBOL(touch_atime);
1947  
1948  /*
1949   * The logic we want is
1950   *
1951   *	if suid or (sgid and xgrp)
1952   *		remove privs
1953   */
1954  int should_remove_suid(struct dentry *dentry)
1955  {
1956  	umode_t mode = d_inode(dentry)->i_mode;
1957  	int kill = 0;
1958  
1959  	/* suid always must be killed */
1960  	if (unlikely(mode & S_ISUID))
1961  		kill = ATTR_KILL_SUID;
1962  
1963  	/*
1964  	 * sgid without any exec bits is just a mandatory locking mark; leave
1965  	 * it alone.  If some exec bits are set, it's a real sgid; kill it.
1966  	 */
1967  	if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1968  		kill |= ATTR_KILL_SGID;
1969  
1970  	if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
1971  		return kill;
1972  
1973  	return 0;
1974  }
1975  EXPORT_SYMBOL(should_remove_suid);
1976  
1977  /*
1978   * Return mask of changes for notify_change() that need to be done as a
1979   * response to write or truncate. Return 0 if nothing has to be changed.
1980   * Negative value on error (change should be denied).
1981   */
1982  int dentry_needs_remove_privs(struct dentry *dentry)
1983  {
1984  	struct inode *inode = d_inode(dentry);
1985  	int mask = 0;
1986  	int ret;
1987  
1988  	if (IS_NOSEC(inode))
1989  		return 0;
1990  
1991  	mask = should_remove_suid(dentry);
1992  	ret = security_inode_need_killpriv(dentry);
1993  	if (ret < 0)
1994  		return ret;
1995  	if (ret)
1996  		mask |= ATTR_KILL_PRIV;
1997  	return mask;
1998  }
1999  
2000  static int __remove_privs(struct user_namespace *mnt_userns,
2001  			  struct dentry *dentry, int kill)
2002  {
2003  	struct iattr newattrs;
2004  
2005  	newattrs.ia_valid = ATTR_FORCE | kill;
2006  	/*
2007  	 * Note we call this on write, so notify_change will not
2008  	 * encounter any conflicting delegations:
2009  	 */
2010  	return notify_change(mnt_userns, dentry, &newattrs, NULL);
2011  }
2012  
2013  /*
2014   * Remove special file priviledges (suid, capabilities) when file is written
2015   * to or truncated.
2016   */
2017  int file_remove_privs(struct file *file)
2018  {
2019  	struct dentry *dentry = file_dentry(file);
2020  	struct inode *inode = file_inode(file);
2021  	int kill;
2022  	int error = 0;
2023  
2024  	/*
2025  	 * Fast path for nothing security related.
2026  	 * As well for non-regular files, e.g. blkdev inodes.
2027  	 * For example, blkdev_write_iter() might get here
2028  	 * trying to remove privs which it is not allowed to.
2029  	 */
2030  	if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
2031  		return 0;
2032  
2033  	kill = dentry_needs_remove_privs(dentry);
2034  	if (kill < 0)
2035  		return kill;
2036  	if (kill)
2037  		error = __remove_privs(file_mnt_user_ns(file), dentry, kill);
2038  	if (!error)
2039  		inode_has_no_xattr(inode);
2040  
2041  	return error;
2042  }
2043  EXPORT_SYMBOL(file_remove_privs);
2044  
2045  /**
2046   *	file_update_time	-	update mtime and ctime time
2047   *	@file: file accessed
2048   *
2049   *	Update the mtime and ctime members of an inode and mark the inode
2050   *	for writeback.  Note that this function is meant exclusively for
2051   *	usage in the file write path of filesystems, and filesystems may
2052   *	choose to explicitly ignore update via this function with the
2053   *	S_NOCMTIME inode flag, e.g. for network filesystem where these
2054   *	timestamps are handled by the server.  This can return an error for
2055   *	file systems who need to allocate space in order to update an inode.
2056   */
2057  
2058  int file_update_time(struct file *file)
2059  {
2060  	struct inode *inode = file_inode(file);
2061  	struct timespec64 now;
2062  	int sync_it = 0;
2063  	int ret;
2064  
2065  	/* First try to exhaust all avenues to not sync */
2066  	if (IS_NOCMTIME(inode))
2067  		return 0;
2068  
2069  	now = current_time(inode);
2070  	if (!timespec64_equal(&inode->i_mtime, &now))
2071  		sync_it = S_MTIME;
2072  
2073  	if (!timespec64_equal(&inode->i_ctime, &now))
2074  		sync_it |= S_CTIME;
2075  
2076  	if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
2077  		sync_it |= S_VERSION;
2078  
2079  	if (!sync_it)
2080  		return 0;
2081  
2082  	/* Finally allowed to write? Takes lock. */
2083  	if (__mnt_want_write_file(file))
2084  		return 0;
2085  
2086  	ret = inode_update_time(inode, &now, sync_it);
2087  	__mnt_drop_write_file(file);
2088  
2089  	return ret;
2090  }
2091  EXPORT_SYMBOL(file_update_time);
2092  
2093  /* Caller must hold the file's inode lock */
2094  int file_modified(struct file *file)
2095  {
2096  	int err;
2097  
2098  	/*
2099  	 * Clear the security bits if the process is not being run by root.
2100  	 * This keeps people from modifying setuid and setgid binaries.
2101  	 */
2102  	err = file_remove_privs(file);
2103  	if (err)
2104  		return err;
2105  
2106  	if (unlikely(file->f_mode & FMODE_NOCMTIME))
2107  		return 0;
2108  
2109  	return file_update_time(file);
2110  }
2111  EXPORT_SYMBOL(file_modified);
2112  
2113  int inode_needs_sync(struct inode *inode)
2114  {
2115  	if (IS_SYNC(inode))
2116  		return 1;
2117  	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
2118  		return 1;
2119  	return 0;
2120  }
2121  EXPORT_SYMBOL(inode_needs_sync);
2122  
2123  /*
2124   * If we try to find an inode in the inode hash while it is being
2125   * deleted, we have to wait until the filesystem completes its
2126   * deletion before reporting that it isn't found.  This function waits
2127   * until the deletion _might_ have completed.  Callers are responsible
2128   * to recheck inode state.
2129   *
2130   * It doesn't matter if I_NEW is not set initially, a call to
2131   * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
2132   * will DTRT.
2133   */
2134  static void __wait_on_freeing_inode(struct inode *inode)
2135  {
2136  	wait_queue_head_t *wq;
2137  	DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
2138  	wq = bit_waitqueue(&inode->i_state, __I_NEW);
2139  	prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
2140  	spin_unlock(&inode->i_lock);
2141  	spin_unlock(&inode_hash_lock);
2142  	schedule();
2143  	finish_wait(wq, &wait.wq_entry);
2144  	spin_lock(&inode_hash_lock);
2145  }
2146  
2147  static __initdata unsigned long ihash_entries;
2148  static int __init set_ihash_entries(char *str)
2149  {
2150  	if (!str)
2151  		return 0;
2152  	ihash_entries = simple_strtoul(str, &str, 0);
2153  	return 1;
2154  }
2155  __setup("ihash_entries=", set_ihash_entries);
2156  
2157  /*
2158   * Initialize the waitqueues and inode hash table.
2159   */
2160  void __init inode_init_early(void)
2161  {
2162  	/* If hashes are distributed across NUMA nodes, defer
2163  	 * hash allocation until vmalloc space is available.
2164  	 */
2165  	if (hashdist)
2166  		return;
2167  
2168  	inode_hashtable =
2169  		alloc_large_system_hash("Inode-cache",
2170  					sizeof(struct hlist_head),
2171  					ihash_entries,
2172  					14,
2173  					HASH_EARLY | HASH_ZERO,
2174  					&i_hash_shift,
2175  					&i_hash_mask,
2176  					0,
2177  					0);
2178  }
2179  
2180  void __init inode_init(void)
2181  {
2182  	/* inode slab cache */
2183  	inode_cachep = kmem_cache_create("inode_cache",
2184  					 sizeof(struct inode),
2185  					 0,
2186  					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
2187  					 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
2188  					 init_once);
2189  
2190  	/* Hash may have been set up in inode_init_early */
2191  	if (!hashdist)
2192  		return;
2193  
2194  	inode_hashtable =
2195  		alloc_large_system_hash("Inode-cache",
2196  					sizeof(struct hlist_head),
2197  					ihash_entries,
2198  					14,
2199  					HASH_ZERO,
2200  					&i_hash_shift,
2201  					&i_hash_mask,
2202  					0,
2203  					0);
2204  }
2205  
2206  void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
2207  {
2208  	inode->i_mode = mode;
2209  	if (S_ISCHR(mode)) {
2210  		inode->i_fop = &def_chr_fops;
2211  		inode->i_rdev = rdev;
2212  	} else if (S_ISBLK(mode)) {
2213  		inode->i_fop = &def_blk_fops;
2214  		inode->i_rdev = rdev;
2215  	} else if (S_ISFIFO(mode))
2216  		inode->i_fop = &pipefifo_fops;
2217  	else if (S_ISSOCK(mode))
2218  		;	/* leave it no_open_fops */
2219  	else
2220  		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
2221  				  " inode %s:%lu\n", mode, inode->i_sb->s_id,
2222  				  inode->i_ino);
2223  }
2224  EXPORT_SYMBOL(init_special_inode);
2225  
2226  /**
2227   * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
2228   * @mnt_userns:	User namespace of the mount the inode was created from
2229   * @inode: New inode
2230   * @dir: Directory inode
2231   * @mode: mode of the new inode
2232   *
2233   * If the inode has been created through an idmapped mount the user namespace of
2234   * the vfsmount must be passed through @mnt_userns. This function will then take
2235   * care to map the inode according to @mnt_userns before checking permissions
2236   * and initializing i_uid and i_gid. On non-idmapped mounts or if permission
2237   * checking is to be performed on the raw inode simply passs init_user_ns.
2238   */
2239  void inode_init_owner(struct user_namespace *mnt_userns, struct inode *inode,
2240  		      const struct inode *dir, umode_t mode)
2241  {
2242  	inode_fsuid_set(inode, mnt_userns);
2243  	if (dir && dir->i_mode & S_ISGID) {
2244  		inode->i_gid = dir->i_gid;
2245  
2246  		/* Directories are special, and always inherit S_ISGID */
2247  		if (S_ISDIR(mode))
2248  			mode |= S_ISGID;
2249  		else if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP) &&
2250  			 !in_group_p(i_gid_into_mnt(mnt_userns, dir)) &&
2251  			 !capable_wrt_inode_uidgid(mnt_userns, dir, CAP_FSETID))
2252  			mode &= ~S_ISGID;
2253  	} else
2254  		inode_fsgid_set(inode, mnt_userns);
2255  	inode->i_mode = mode;
2256  }
2257  EXPORT_SYMBOL(inode_init_owner);
2258  
2259  /**
2260   * inode_owner_or_capable - check current task permissions to inode
2261   * @mnt_userns:	user namespace of the mount the inode was found from
2262   * @inode: inode being checked
2263   *
2264   * Return true if current either has CAP_FOWNER in a namespace with the
2265   * inode owner uid mapped, or owns the file.
2266   *
2267   * If the inode has been found through an idmapped mount the user namespace of
2268   * the vfsmount must be passed through @mnt_userns. This function will then take
2269   * care to map the inode according to @mnt_userns before checking permissions.
2270   * On non-idmapped mounts or if permission checking is to be performed on the
2271   * raw inode simply passs init_user_ns.
2272   */
2273  bool inode_owner_or_capable(struct user_namespace *mnt_userns,
2274  			    const struct inode *inode)
2275  {
2276  	kuid_t i_uid;
2277  	struct user_namespace *ns;
2278  
2279  	i_uid = i_uid_into_mnt(mnt_userns, inode);
2280  	if (uid_eq(current_fsuid(), i_uid))
2281  		return true;
2282  
2283  	ns = current_user_ns();
2284  	if (kuid_has_mapping(ns, i_uid) && ns_capable(ns, CAP_FOWNER))
2285  		return true;
2286  	return false;
2287  }
2288  EXPORT_SYMBOL(inode_owner_or_capable);
2289  
2290  /*
2291   * Direct i/o helper functions
2292   */
2293  static void __inode_dio_wait(struct inode *inode)
2294  {
2295  	wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP);
2296  	DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP);
2297  
2298  	do {
2299  		prepare_to_wait(wq, &q.wq_entry, TASK_UNINTERRUPTIBLE);
2300  		if (atomic_read(&inode->i_dio_count))
2301  			schedule();
2302  	} while (atomic_read(&inode->i_dio_count));
2303  	finish_wait(wq, &q.wq_entry);
2304  }
2305  
2306  /**
2307   * inode_dio_wait - wait for outstanding DIO requests to finish
2308   * @inode: inode to wait for
2309   *
2310   * Waits for all pending direct I/O requests to finish so that we can
2311   * proceed with a truncate or equivalent operation.
2312   *
2313   * Must be called under a lock that serializes taking new references
2314   * to i_dio_count, usually by inode->i_mutex.
2315   */
2316  void inode_dio_wait(struct inode *inode)
2317  {
2318  	if (atomic_read(&inode->i_dio_count))
2319  		__inode_dio_wait(inode);
2320  }
2321  EXPORT_SYMBOL(inode_dio_wait);
2322  
2323  /*
2324   * inode_set_flags - atomically set some inode flags
2325   *
2326   * Note: the caller should be holding i_mutex, or else be sure that
2327   * they have exclusive access to the inode structure (i.e., while the
2328   * inode is being instantiated).  The reason for the cmpxchg() loop
2329   * --- which wouldn't be necessary if all code paths which modify
2330   * i_flags actually followed this rule, is that there is at least one
2331   * code path which doesn't today so we use cmpxchg() out of an abundance
2332   * of caution.
2333   *
2334   * In the long run, i_mutex is overkill, and we should probably look
2335   * at using the i_lock spinlock to protect i_flags, and then make sure
2336   * it is so documented in include/linux/fs.h and that all code follows
2337   * the locking convention!!
2338   */
2339  void inode_set_flags(struct inode *inode, unsigned int flags,
2340  		     unsigned int mask)
2341  {
2342  	WARN_ON_ONCE(flags & ~mask);
2343  	set_mask_bits(&inode->i_flags, mask, flags);
2344  }
2345  EXPORT_SYMBOL(inode_set_flags);
2346  
2347  void inode_nohighmem(struct inode *inode)
2348  {
2349  	mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
2350  }
2351  EXPORT_SYMBOL(inode_nohighmem);
2352  
2353  /**
2354   * timestamp_truncate - Truncate timespec to a granularity
2355   * @t: Timespec
2356   * @inode: inode being updated
2357   *
2358   * Truncate a timespec to the granularity supported by the fs
2359   * containing the inode. Always rounds down. gran must
2360   * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
2361   */
2362  struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
2363  {
2364  	struct super_block *sb = inode->i_sb;
2365  	unsigned int gran = sb->s_time_gran;
2366  
2367  	t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);
2368  	if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))
2369  		t.tv_nsec = 0;
2370  
2371  	/* Avoid division in the common cases 1 ns and 1 s. */
2372  	if (gran == 1)
2373  		; /* nothing */
2374  	else if (gran == NSEC_PER_SEC)
2375  		t.tv_nsec = 0;
2376  	else if (gran > 1 && gran < NSEC_PER_SEC)
2377  		t.tv_nsec -= t.tv_nsec % gran;
2378  	else
2379  		WARN(1, "invalid file time granularity: %u", gran);
2380  	return t;
2381  }
2382  EXPORT_SYMBOL(timestamp_truncate);
2383  
2384  /**
2385   * current_time - Return FS time
2386   * @inode: inode.
2387   *
2388   * Return the current time truncated to the time granularity supported by
2389   * the fs.
2390   *
2391   * Note that inode and inode->sb cannot be NULL.
2392   * Otherwise, the function warns and returns time without truncation.
2393   */
2394  struct timespec64 current_time(struct inode *inode)
2395  {
2396  	struct timespec64 now;
2397  
2398  	ktime_get_coarse_real_ts64(&now);
2399  
2400  	if (unlikely(!inode->i_sb)) {
2401  		WARN(1, "current_time() called with uninitialized super_block in the inode");
2402  		return now;
2403  	}
2404  
2405  	return timestamp_truncate(now, inode);
2406  }
2407  EXPORT_SYMBOL(current_time);
2408