xref: /openbmc/linux/fs/inode.c (revision 1b39e7607144337d752f36c2068ed79447462f99)
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/prefetch.h>
20  #include <linux/buffer_head.h> /* for inode_has_buffers */
21  #include <linux/ratelimit.h>
22  #include <linux/list_lru.h>
23  #include <linux/iversion.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 __read_mostly;
59  static unsigned int i_hash_shift __read_mostly;
60  static struct hlist_head *inode_hashtable __read_mostly;
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 __read_mostly;
75  
76  static long get_nr_inodes(void)
77  {
78  	int i;
79  	long sum = 0;
80  	for_each_possible_cpu(i)
81  		sum += per_cpu(nr_inodes, i);
82  	return sum < 0 ? 0 : sum;
83  }
84  
85  static inline long get_nr_inodes_unused(void)
86  {
87  	int i;
88  	long sum = 0;
89  	for_each_possible_cpu(i)
90  		sum += per_cpu(nr_unused, i);
91  	return sum < 0 ? 0 : sum;
92  }
93  
94  long get_nr_dirty_inodes(void)
95  {
96  	/* not actually dirty inodes, but a wild approximation */
97  	long nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
98  	return nr_dirty > 0 ? nr_dirty : 0;
99  }
100  
101  /*
102   * Handle nr_inode sysctl
103   */
104  #ifdef CONFIG_SYSCTL
105  /*
106   * Statistics gathering..
107   */
108  static struct inodes_stat_t inodes_stat;
109  
110  static int proc_nr_inodes(struct ctl_table *table, int write, void *buffer,
111  			  size_t *lenp, loff_t *ppos)
112  {
113  	inodes_stat.nr_inodes = get_nr_inodes();
114  	inodes_stat.nr_unused = get_nr_inodes_unused();
115  	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
116  }
117  
118  static struct ctl_table inodes_sysctls[] = {
119  	{
120  		.procname	= "inode-nr",
121  		.data		= &inodes_stat,
122  		.maxlen		= 2*sizeof(long),
123  		.mode		= 0444,
124  		.proc_handler	= proc_nr_inodes,
125  	},
126  	{
127  		.procname	= "inode-state",
128  		.data		= &inodes_stat,
129  		.maxlen		= 7*sizeof(long),
130  		.mode		= 0444,
131  		.proc_handler	= proc_nr_inodes,
132  	},
133  	{ }
134  };
135  
136  static int __init init_fs_inode_sysctls(void)
137  {
138  	register_sysctl_init("fs", inodes_sysctls);
139  	return 0;
140  }
141  early_initcall(init_fs_inode_sysctls);
142  #endif
143  
144  static int no_open(struct inode *inode, struct file *file)
145  {
146  	return -ENXIO;
147  }
148  
149  /**
150   * inode_init_always - perform inode structure initialisation
151   * @sb: superblock inode belongs to
152   * @inode: inode to initialise
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   */
157  int inode_init_always(struct super_block *sb, struct inode *inode)
158  {
159  	static const struct inode_operations empty_iops;
160  	static const struct file_operations no_open_fops = {.open = no_open};
161  	struct address_space *const mapping = &inode->i_data;
162  
163  	inode->i_sb = sb;
164  	inode->i_blkbits = sb->s_blocksize_bits;
165  	inode->i_flags = 0;
166  	atomic64_set(&inode->i_sequence, 0);
167  	atomic_set(&inode->i_count, 1);
168  	inode->i_op = &empty_iops;
169  	inode->i_fop = &no_open_fops;
170  	inode->i_ino = 0;
171  	inode->__i_nlink = 1;
172  	inode->i_opflags = 0;
173  	if (sb->s_xattr)
174  		inode->i_opflags |= IOP_XATTR;
175  	i_uid_write(inode, 0);
176  	i_gid_write(inode, 0);
177  	atomic_set(&inode->i_writecount, 0);
178  	inode->i_size = 0;
179  	inode->i_write_hint = WRITE_LIFE_NOT_SET;
180  	inode->i_blocks = 0;
181  	inode->i_bytes = 0;
182  	inode->i_generation = 0;
183  	inode->i_pipe = NULL;
184  	inode->i_cdev = NULL;
185  	inode->i_link = NULL;
186  	inode->i_dir_seq = 0;
187  	inode->i_rdev = 0;
188  	inode->dirtied_when = 0;
189  
190  #ifdef CONFIG_CGROUP_WRITEBACK
191  	inode->i_wb_frn_winner = 0;
192  	inode->i_wb_frn_avg_time = 0;
193  	inode->i_wb_frn_history = 0;
194  #endif
195  
196  	spin_lock_init(&inode->i_lock);
197  	lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
198  
199  	init_rwsem(&inode->i_rwsem);
200  	lockdep_set_class(&inode->i_rwsem, &sb->s_type->i_mutex_key);
201  
202  	atomic_set(&inode->i_dio_count, 0);
203  
204  	mapping->a_ops = &empty_aops;
205  	mapping->host = inode;
206  	mapping->flags = 0;
207  	mapping->wb_err = 0;
208  	atomic_set(&mapping->i_mmap_writable, 0);
209  #ifdef CONFIG_READ_ONLY_THP_FOR_FS
210  	atomic_set(&mapping->nr_thps, 0);
211  #endif
212  	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
213  	mapping->private_data = NULL;
214  	mapping->writeback_index = 0;
215  	init_rwsem(&mapping->invalidate_lock);
216  	lockdep_set_class_and_name(&mapping->invalidate_lock,
217  				   &sb->s_type->invalidate_lock_key,
218  				   "mapping.invalidate_lock");
219  	inode->i_private = NULL;
220  	inode->i_mapping = mapping;
221  	INIT_HLIST_HEAD(&inode->i_dentry);	/* buggered by rcu freeing */
222  #ifdef CONFIG_FS_POSIX_ACL
223  	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
224  #endif
225  
226  #ifdef CONFIG_FSNOTIFY
227  	inode->i_fsnotify_mask = 0;
228  #endif
229  	inode->i_flctx = NULL;
230  
231  	if (unlikely(security_inode_alloc(inode)))
232  		return -ENOMEM;
233  	this_cpu_inc(nr_inodes);
234  
235  	return 0;
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  	INIT_LIST_HEAD(&inode->i_sb_list);
426  	__address_space_init_once(&inode->i_data);
427  	i_size_ordered_init(inode);
428  }
429  EXPORT_SYMBOL(inode_init_once);
430  
431  static void init_once(void *foo)
432  {
433  	struct inode *inode = (struct inode *) foo;
434  
435  	inode_init_once(inode);
436  }
437  
438  /*
439   * inode->i_lock must be held
440   */
441  void __iget(struct inode *inode)
442  {
443  	atomic_inc(&inode->i_count);
444  }
445  
446  /*
447   * get additional reference to inode; caller must already hold one.
448   */
449  void ihold(struct inode *inode)
450  {
451  	WARN_ON(atomic_inc_return(&inode->i_count) < 2);
452  }
453  EXPORT_SYMBOL(ihold);
454  
455  static void __inode_add_lru(struct inode *inode, bool rotate)
456  {
457  	if (inode->i_state & (I_DIRTY_ALL | I_SYNC | I_FREEING | I_WILL_FREE))
458  		return;
459  	if (atomic_read(&inode->i_count))
460  		return;
461  	if (!(inode->i_sb->s_flags & SB_ACTIVE))
462  		return;
463  	if (!mapping_shrinkable(&inode->i_data))
464  		return;
465  
466  	if (list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru))
467  		this_cpu_inc(nr_unused);
468  	else if (rotate)
469  		inode->i_state |= I_REFERENCED;
470  }
471  
472  /*
473   * Add inode to LRU if needed (inode is unused and clean).
474   *
475   * Needs inode->i_lock held.
476   */
477  void inode_add_lru(struct inode *inode)
478  {
479  	__inode_add_lru(inode, false);
480  }
481  
482  static void inode_lru_list_del(struct inode *inode)
483  {
484  	if (list_lru_del(&inode->i_sb->s_inode_lru, &inode->i_lru))
485  		this_cpu_dec(nr_unused);
486  }
487  
488  /**
489   * inode_sb_list_add - add inode to the superblock list of inodes
490   * @inode: inode to add
491   */
492  void inode_sb_list_add(struct inode *inode)
493  {
494  	spin_lock(&inode->i_sb->s_inode_list_lock);
495  	list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
496  	spin_unlock(&inode->i_sb->s_inode_list_lock);
497  }
498  EXPORT_SYMBOL_GPL(inode_sb_list_add);
499  
500  static inline void inode_sb_list_del(struct inode *inode)
501  {
502  	if (!list_empty(&inode->i_sb_list)) {
503  		spin_lock(&inode->i_sb->s_inode_list_lock);
504  		list_del_init(&inode->i_sb_list);
505  		spin_unlock(&inode->i_sb->s_inode_list_lock);
506  	}
507  }
508  
509  static unsigned long hash(struct super_block *sb, unsigned long hashval)
510  {
511  	unsigned long tmp;
512  
513  	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
514  			L1_CACHE_BYTES;
515  	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
516  	return tmp & i_hash_mask;
517  }
518  
519  /**
520   *	__insert_inode_hash - hash an inode
521   *	@inode: unhashed inode
522   *	@hashval: unsigned long value used to locate this object in the
523   *		inode_hashtable.
524   *
525   *	Add an inode to the inode hash for this superblock.
526   */
527  void __insert_inode_hash(struct inode *inode, unsigned long hashval)
528  {
529  	struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
530  
531  	spin_lock(&inode_hash_lock);
532  	spin_lock(&inode->i_lock);
533  	hlist_add_head_rcu(&inode->i_hash, b);
534  	spin_unlock(&inode->i_lock);
535  	spin_unlock(&inode_hash_lock);
536  }
537  EXPORT_SYMBOL(__insert_inode_hash);
538  
539  /**
540   *	__remove_inode_hash - remove an inode from the hash
541   *	@inode: inode to unhash
542   *
543   *	Remove an inode from the superblock.
544   */
545  void __remove_inode_hash(struct inode *inode)
546  {
547  	spin_lock(&inode_hash_lock);
548  	spin_lock(&inode->i_lock);
549  	hlist_del_init_rcu(&inode->i_hash);
550  	spin_unlock(&inode->i_lock);
551  	spin_unlock(&inode_hash_lock);
552  }
553  EXPORT_SYMBOL(__remove_inode_hash);
554  
555  void dump_mapping(const struct address_space *mapping)
556  {
557  	struct inode *host;
558  	const struct address_space_operations *a_ops;
559  	struct hlist_node *dentry_first;
560  	struct dentry *dentry_ptr;
561  	struct dentry dentry;
562  	unsigned long ino;
563  
564  	/*
565  	 * If mapping is an invalid pointer, we don't want to crash
566  	 * accessing it, so probe everything depending on it carefully.
567  	 */
568  	if (get_kernel_nofault(host, &mapping->host) ||
569  	    get_kernel_nofault(a_ops, &mapping->a_ops)) {
570  		pr_warn("invalid mapping:%px\n", mapping);
571  		return;
572  	}
573  
574  	if (!host) {
575  		pr_warn("aops:%ps\n", a_ops);
576  		return;
577  	}
578  
579  	if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
580  	    get_kernel_nofault(ino, &host->i_ino)) {
581  		pr_warn("aops:%ps invalid inode:%px\n", a_ops, host);
582  		return;
583  	}
584  
585  	if (!dentry_first) {
586  		pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
587  		return;
588  	}
589  
590  	dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
591  	if (get_kernel_nofault(dentry, dentry_ptr)) {
592  		pr_warn("aops:%ps ino:%lx invalid dentry:%px\n",
593  				a_ops, ino, dentry_ptr);
594  		return;
595  	}
596  
597  	/*
598  	 * if dentry is corrupted, the %pd handler may still crash,
599  	 * but it's unlikely that we reach here with a corrupt mapping
600  	 */
601  	pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n", a_ops, ino, &dentry);
602  }
603  
604  void clear_inode(struct inode *inode)
605  {
606  	/*
607  	 * We have to cycle the i_pages lock here because reclaim can be in the
608  	 * process of removing the last page (in __filemap_remove_folio())
609  	 * and we must not free the mapping under it.
610  	 */
611  	xa_lock_irq(&inode->i_data.i_pages);
612  	BUG_ON(inode->i_data.nrpages);
613  	/*
614  	 * Almost always, mapping_empty(&inode->i_data) here; but there are
615  	 * two known and long-standing ways in which nodes may get left behind
616  	 * (when deep radix-tree node allocation failed partway; or when THP
617  	 * collapse_file() failed). Until those two known cases are cleaned up,
618  	 * or a cleanup function is called here, do not BUG_ON(!mapping_empty),
619  	 * nor even WARN_ON(!mapping_empty).
620  	 */
621  	xa_unlock_irq(&inode->i_data.i_pages);
622  	BUG_ON(!list_empty(&inode->i_data.private_list));
623  	BUG_ON(!(inode->i_state & I_FREEING));
624  	BUG_ON(inode->i_state & I_CLEAR);
625  	BUG_ON(!list_empty(&inode->i_wb_list));
626  	/* don't need i_lock here, no concurrent mods to i_state */
627  	inode->i_state = I_FREEING | I_CLEAR;
628  }
629  EXPORT_SYMBOL(clear_inode);
630  
631  /*
632   * Free the inode passed in, removing it from the lists it is still connected
633   * to. We remove any pages still attached to the inode and wait for any IO that
634   * is still in progress before finally destroying the inode.
635   *
636   * An inode must already be marked I_FREEING so that we avoid the inode being
637   * moved back onto lists if we race with other code that manipulates the lists
638   * (e.g. writeback_single_inode). The caller is responsible for setting this.
639   *
640   * An inode must already be removed from the LRU list before being evicted from
641   * the cache. This should occur atomically with setting the I_FREEING state
642   * flag, so no inodes here should ever be on the LRU when being evicted.
643   */
644  static void evict(struct inode *inode)
645  {
646  	const struct super_operations *op = inode->i_sb->s_op;
647  
648  	BUG_ON(!(inode->i_state & I_FREEING));
649  	BUG_ON(!list_empty(&inode->i_lru));
650  
651  	if (!list_empty(&inode->i_io_list))
652  		inode_io_list_del(inode);
653  
654  	inode_sb_list_del(inode);
655  
656  	/*
657  	 * Wait for flusher thread to be done with the inode so that filesystem
658  	 * does not start destroying it while writeback is still running. Since
659  	 * the inode has I_FREEING set, flusher thread won't start new work on
660  	 * the inode.  We just have to wait for running writeback to finish.
661  	 */
662  	inode_wait_for_writeback(inode);
663  
664  	if (op->evict_inode) {
665  		op->evict_inode(inode);
666  	} else {
667  		truncate_inode_pages_final(&inode->i_data);
668  		clear_inode(inode);
669  	}
670  	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
671  		cd_forget(inode);
672  
673  	remove_inode_hash(inode);
674  
675  	spin_lock(&inode->i_lock);
676  	wake_up_bit(&inode->i_state, __I_NEW);
677  	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
678  	spin_unlock(&inode->i_lock);
679  
680  	destroy_inode(inode);
681  }
682  
683  /*
684   * dispose_list - dispose of the contents of a local list
685   * @head: the head of the list to free
686   *
687   * Dispose-list gets a local list with local inodes in it, so it doesn't
688   * need to worry about list corruption and SMP locks.
689   */
690  static void dispose_list(struct list_head *head)
691  {
692  	while (!list_empty(head)) {
693  		struct inode *inode;
694  
695  		inode = list_first_entry(head, struct inode, i_lru);
696  		list_del_init(&inode->i_lru);
697  
698  		evict(inode);
699  		cond_resched();
700  	}
701  }
702  
703  /**
704   * evict_inodes	- evict all evictable inodes for a superblock
705   * @sb:		superblock to operate on
706   *
707   * Make sure that no inodes with zero refcount are retained.  This is
708   * called by superblock shutdown after having SB_ACTIVE flag removed,
709   * so any inode reaching zero refcount during or after that call will
710   * be immediately evicted.
711   */
712  void evict_inodes(struct super_block *sb)
713  {
714  	struct inode *inode, *next;
715  	LIST_HEAD(dispose);
716  
717  again:
718  	spin_lock(&sb->s_inode_list_lock);
719  	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
720  		if (atomic_read(&inode->i_count))
721  			continue;
722  
723  		spin_lock(&inode->i_lock);
724  		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
725  			spin_unlock(&inode->i_lock);
726  			continue;
727  		}
728  
729  		inode->i_state |= I_FREEING;
730  		inode_lru_list_del(inode);
731  		spin_unlock(&inode->i_lock);
732  		list_add(&inode->i_lru, &dispose);
733  
734  		/*
735  		 * We can have a ton of inodes to evict at unmount time given
736  		 * enough memory, check to see if we need to go to sleep for a
737  		 * bit so we don't livelock.
738  		 */
739  		if (need_resched()) {
740  			spin_unlock(&sb->s_inode_list_lock);
741  			cond_resched();
742  			dispose_list(&dispose);
743  			goto again;
744  		}
745  	}
746  	spin_unlock(&sb->s_inode_list_lock);
747  
748  	dispose_list(&dispose);
749  }
750  EXPORT_SYMBOL_GPL(evict_inodes);
751  
752  /**
753   * invalidate_inodes	- attempt to free all inodes on a superblock
754   * @sb:		superblock to operate on
755   * @kill_dirty: flag to guide handling of dirty inodes
756   *
757   * Attempts to free all inodes for a given superblock.  If there were any
758   * busy inodes return a non-zero value, else zero.
759   * If @kill_dirty is set, discard dirty inodes too, otherwise treat
760   * them as busy.
761   */
762  int invalidate_inodes(struct super_block *sb, bool kill_dirty)
763  {
764  	int busy = 0;
765  	struct inode *inode, *next;
766  	LIST_HEAD(dispose);
767  
768  again:
769  	spin_lock(&sb->s_inode_list_lock);
770  	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
771  		spin_lock(&inode->i_lock);
772  		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
773  			spin_unlock(&inode->i_lock);
774  			continue;
775  		}
776  		if (inode->i_state & I_DIRTY_ALL && !kill_dirty) {
777  			spin_unlock(&inode->i_lock);
778  			busy = 1;
779  			continue;
780  		}
781  		if (atomic_read(&inode->i_count)) {
782  			spin_unlock(&inode->i_lock);
783  			busy = 1;
784  			continue;
785  		}
786  
787  		inode->i_state |= I_FREEING;
788  		inode_lru_list_del(inode);
789  		spin_unlock(&inode->i_lock);
790  		list_add(&inode->i_lru, &dispose);
791  		if (need_resched()) {
792  			spin_unlock(&sb->s_inode_list_lock);
793  			cond_resched();
794  			dispose_list(&dispose);
795  			goto again;
796  		}
797  	}
798  	spin_unlock(&sb->s_inode_list_lock);
799  
800  	dispose_list(&dispose);
801  
802  	return busy;
803  }
804  
805  /*
806   * Isolate the inode from the LRU in preparation for freeing it.
807   *
808   * If the inode has the I_REFERENCED flag set, then it means that it has been
809   * used recently - the flag is set in iput_final(). When we encounter such an
810   * inode, clear the flag and move it to the back of the LRU so it gets another
811   * pass through the LRU before it gets reclaimed. This is necessary because of
812   * the fact we are doing lazy LRU updates to minimise lock contention so the
813   * LRU does not have strict ordering. Hence we don't want to reclaim inodes
814   * with this flag set because they are the inodes that are out of order.
815   */
816  static enum lru_status inode_lru_isolate(struct list_head *item,
817  		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
818  {
819  	struct list_head *freeable = arg;
820  	struct inode	*inode = container_of(item, struct inode, i_lru);
821  
822  	/*
823  	 * We are inverting the lru lock/inode->i_lock here, so use a
824  	 * trylock. If we fail to get the lock, just skip it.
825  	 */
826  	if (!spin_trylock(&inode->i_lock))
827  		return LRU_SKIP;
828  
829  	/*
830  	 * Inodes can get referenced, redirtied, or repopulated while
831  	 * they're already on the LRU, and this can make them
832  	 * unreclaimable for a while. Remove them lazily here; iput,
833  	 * sync, or the last page cache deletion will requeue them.
834  	 */
835  	if (atomic_read(&inode->i_count) ||
836  	    (inode->i_state & ~I_REFERENCED) ||
837  	    !mapping_shrinkable(&inode->i_data)) {
838  		list_lru_isolate(lru, &inode->i_lru);
839  		spin_unlock(&inode->i_lock);
840  		this_cpu_dec(nr_unused);
841  		return LRU_REMOVED;
842  	}
843  
844  	/* Recently referenced inodes get one more pass */
845  	if (inode->i_state & I_REFERENCED) {
846  		inode->i_state &= ~I_REFERENCED;
847  		spin_unlock(&inode->i_lock);
848  		return LRU_ROTATE;
849  	}
850  
851  	/*
852  	 * On highmem systems, mapping_shrinkable() permits dropping
853  	 * page cache in order to free up struct inodes: lowmem might
854  	 * be under pressure before the cache inside the highmem zone.
855  	 */
856  	if (inode_has_buffers(inode) || !mapping_empty(&inode->i_data)) {
857  		__iget(inode);
858  		spin_unlock(&inode->i_lock);
859  		spin_unlock(lru_lock);
860  		if (remove_inode_buffers(inode)) {
861  			unsigned long reap;
862  			reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
863  			if (current_is_kswapd())
864  				__count_vm_events(KSWAPD_INODESTEAL, reap);
865  			else
866  				__count_vm_events(PGINODESTEAL, reap);
867  			mm_account_reclaimed_pages(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  	}
1025  	return inode;
1026  }
1027  
1028  /**
1029   *	new_inode 	- obtain an inode
1030   *	@sb: superblock
1031   *
1032   *	Allocates a new inode for given superblock. The default gfp_mask
1033   *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
1034   *	If HIGHMEM pages are unsuitable or it is known that pages allocated
1035   *	for the page cache are not reclaimable or migratable,
1036   *	mapping_set_gfp_mask() must be called with suitable flags on the
1037   *	newly created inode's mapping
1038   *
1039   */
1040  struct inode *new_inode(struct super_block *sb)
1041  {
1042  	struct inode *inode;
1043  
1044  	spin_lock_prefetch(&sb->s_inode_list_lock);
1045  
1046  	inode = new_inode_pseudo(sb);
1047  	if (inode)
1048  		inode_sb_list_add(inode);
1049  	return inode;
1050  }
1051  EXPORT_SYMBOL(new_inode);
1052  
1053  #ifdef CONFIG_DEBUG_LOCK_ALLOC
1054  void lockdep_annotate_inode_mutex_key(struct inode *inode)
1055  {
1056  	if (S_ISDIR(inode->i_mode)) {
1057  		struct file_system_type *type = inode->i_sb->s_type;
1058  
1059  		/* Set new key only if filesystem hasn't already changed it */
1060  		if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) {
1061  			/*
1062  			 * ensure nobody is actually holding i_mutex
1063  			 */
1064  			// mutex_destroy(&inode->i_mutex);
1065  			init_rwsem(&inode->i_rwsem);
1066  			lockdep_set_class(&inode->i_rwsem,
1067  					  &type->i_mutex_dir_key);
1068  		}
1069  	}
1070  }
1071  EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
1072  #endif
1073  
1074  /**
1075   * unlock_new_inode - clear the I_NEW state and wake up any waiters
1076   * @inode:	new inode to unlock
1077   *
1078   * Called when the inode is fully initialised to clear the new state of the
1079   * inode and wake up anyone waiting for the inode to finish initialisation.
1080   */
1081  void unlock_new_inode(struct inode *inode)
1082  {
1083  	lockdep_annotate_inode_mutex_key(inode);
1084  	spin_lock(&inode->i_lock);
1085  	WARN_ON(!(inode->i_state & I_NEW));
1086  	inode->i_state &= ~I_NEW & ~I_CREATING;
1087  	smp_mb();
1088  	wake_up_bit(&inode->i_state, __I_NEW);
1089  	spin_unlock(&inode->i_lock);
1090  }
1091  EXPORT_SYMBOL(unlock_new_inode);
1092  
1093  void discard_new_inode(struct inode *inode)
1094  {
1095  	lockdep_annotate_inode_mutex_key(inode);
1096  	spin_lock(&inode->i_lock);
1097  	WARN_ON(!(inode->i_state & I_NEW));
1098  	inode->i_state &= ~I_NEW;
1099  	smp_mb();
1100  	wake_up_bit(&inode->i_state, __I_NEW);
1101  	spin_unlock(&inode->i_lock);
1102  	iput(inode);
1103  }
1104  EXPORT_SYMBOL(discard_new_inode);
1105  
1106  /**
1107   * lock_two_nondirectories - take two i_mutexes on non-directory objects
1108   *
1109   * Lock any non-NULL argument that is not a directory.
1110   * Zero, one or two objects may be locked by this function.
1111   *
1112   * @inode1: first inode to lock
1113   * @inode2: second inode to lock
1114   */
1115  void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1116  {
1117  	if (inode1 > inode2)
1118  		swap(inode1, inode2);
1119  
1120  	if (inode1 && !S_ISDIR(inode1->i_mode))
1121  		inode_lock(inode1);
1122  	if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
1123  		inode_lock_nested(inode2, I_MUTEX_NONDIR2);
1124  }
1125  EXPORT_SYMBOL(lock_two_nondirectories);
1126  
1127  /**
1128   * unlock_two_nondirectories - release locks from lock_two_nondirectories()
1129   * @inode1: first inode to unlock
1130   * @inode2: second inode to unlock
1131   */
1132  void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1133  {
1134  	if (inode1 && !S_ISDIR(inode1->i_mode))
1135  		inode_unlock(inode1);
1136  	if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
1137  		inode_unlock(inode2);
1138  }
1139  EXPORT_SYMBOL(unlock_two_nondirectories);
1140  
1141  /**
1142   * inode_insert5 - obtain an inode from a mounted file system
1143   * @inode:	pre-allocated inode to use for insert to cache
1144   * @hashval:	hash value (usually inode number) to get
1145   * @test:	callback used for comparisons between inodes
1146   * @set:	callback used to initialize a new struct inode
1147   * @data:	opaque data pointer to pass to @test and @set
1148   *
1149   * Search for the inode specified by @hashval and @data in the inode cache,
1150   * and if present it is return it with an increased reference count. This is
1151   * a variant of iget5_locked() for callers that don't want to fail on memory
1152   * allocation of inode.
1153   *
1154   * If the inode is not in cache, insert the pre-allocated inode to cache and
1155   * return it locked, hashed, and with the I_NEW flag set. The file system gets
1156   * to fill it in before unlocking it via unlock_new_inode().
1157   *
1158   * Note both @test and @set are called with the inode_hash_lock held, so can't
1159   * sleep.
1160   */
1161  struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
1162  			    int (*test)(struct inode *, void *),
1163  			    int (*set)(struct inode *, void *), void *data)
1164  {
1165  	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
1166  	struct inode *old;
1167  
1168  again:
1169  	spin_lock(&inode_hash_lock);
1170  	old = find_inode(inode->i_sb, head, test, data);
1171  	if (unlikely(old)) {
1172  		/*
1173  		 * Uhhuh, somebody else created the same inode under us.
1174  		 * Use the old inode instead of the preallocated one.
1175  		 */
1176  		spin_unlock(&inode_hash_lock);
1177  		if (IS_ERR(old))
1178  			return NULL;
1179  		wait_on_inode(old);
1180  		if (unlikely(inode_unhashed(old))) {
1181  			iput(old);
1182  			goto again;
1183  		}
1184  		return old;
1185  	}
1186  
1187  	if (set && unlikely(set(inode, data))) {
1188  		inode = NULL;
1189  		goto unlock;
1190  	}
1191  
1192  	/*
1193  	 * Return the locked inode with I_NEW set, the
1194  	 * caller is responsible for filling in the contents
1195  	 */
1196  	spin_lock(&inode->i_lock);
1197  	inode->i_state |= I_NEW;
1198  	hlist_add_head_rcu(&inode->i_hash, head);
1199  	spin_unlock(&inode->i_lock);
1200  
1201  	/*
1202  	 * Add inode to the sb list if it's not already. It has I_NEW at this
1203  	 * point, so it should be safe to test i_sb_list locklessly.
1204  	 */
1205  	if (list_empty(&inode->i_sb_list))
1206  		inode_sb_list_add(inode);
1207  unlock:
1208  	spin_unlock(&inode_hash_lock);
1209  
1210  	return inode;
1211  }
1212  EXPORT_SYMBOL(inode_insert5);
1213  
1214  /**
1215   * iget5_locked - obtain an inode from a mounted file system
1216   * @sb:		super block of file system
1217   * @hashval:	hash value (usually inode number) to get
1218   * @test:	callback used for comparisons between inodes
1219   * @set:	callback used to initialize a new struct inode
1220   * @data:	opaque data pointer to pass to @test and @set
1221   *
1222   * Search for the inode specified by @hashval and @data in the inode cache,
1223   * and if present it is return it with an increased reference count. This is
1224   * a generalized version of iget_locked() for file systems where the inode
1225   * number is not sufficient for unique identification of an inode.
1226   *
1227   * If the inode is not in cache, allocate a new inode and return it locked,
1228   * hashed, and with the I_NEW flag set. The file system gets to fill it in
1229   * before unlocking it via unlock_new_inode().
1230   *
1231   * Note both @test and @set are called with the inode_hash_lock held, so can't
1232   * sleep.
1233   */
1234  struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1235  		int (*test)(struct inode *, void *),
1236  		int (*set)(struct inode *, void *), void *data)
1237  {
1238  	struct inode *inode = ilookup5(sb, hashval, test, data);
1239  
1240  	if (!inode) {
1241  		struct inode *new = alloc_inode(sb);
1242  
1243  		if (new) {
1244  			new->i_state = 0;
1245  			inode = inode_insert5(new, hashval, test, set, data);
1246  			if (unlikely(inode != new))
1247  				destroy_inode(new);
1248  		}
1249  	}
1250  	return inode;
1251  }
1252  EXPORT_SYMBOL(iget5_locked);
1253  
1254  /**
1255   * iget_locked - obtain an inode from a mounted file system
1256   * @sb:		super block of file system
1257   * @ino:	inode number to get
1258   *
1259   * Search for the inode specified by @ino in the inode cache and if present
1260   * return it with an increased reference count. This is for file systems
1261   * where the inode number is sufficient for unique identification of an inode.
1262   *
1263   * If the inode is not in cache, allocate a new inode and return it locked,
1264   * hashed, and with the I_NEW flag set.  The file system gets to fill it in
1265   * before unlocking it via unlock_new_inode().
1266   */
1267  struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1268  {
1269  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1270  	struct inode *inode;
1271  again:
1272  	spin_lock(&inode_hash_lock);
1273  	inode = find_inode_fast(sb, head, ino);
1274  	spin_unlock(&inode_hash_lock);
1275  	if (inode) {
1276  		if (IS_ERR(inode))
1277  			return NULL;
1278  		wait_on_inode(inode);
1279  		if (unlikely(inode_unhashed(inode))) {
1280  			iput(inode);
1281  			goto again;
1282  		}
1283  		return inode;
1284  	}
1285  
1286  	inode = alloc_inode(sb);
1287  	if (inode) {
1288  		struct inode *old;
1289  
1290  		spin_lock(&inode_hash_lock);
1291  		/* We released the lock, so.. */
1292  		old = find_inode_fast(sb, head, ino);
1293  		if (!old) {
1294  			inode->i_ino = ino;
1295  			spin_lock(&inode->i_lock);
1296  			inode->i_state = I_NEW;
1297  			hlist_add_head_rcu(&inode->i_hash, head);
1298  			spin_unlock(&inode->i_lock);
1299  			inode_sb_list_add(inode);
1300  			spin_unlock(&inode_hash_lock);
1301  
1302  			/* Return the locked inode with I_NEW set, the
1303  			 * caller is responsible for filling in the contents
1304  			 */
1305  			return inode;
1306  		}
1307  
1308  		/*
1309  		 * Uhhuh, somebody else created the same inode under
1310  		 * us. Use the old inode instead of the one we just
1311  		 * allocated.
1312  		 */
1313  		spin_unlock(&inode_hash_lock);
1314  		destroy_inode(inode);
1315  		if (IS_ERR(old))
1316  			return NULL;
1317  		inode = old;
1318  		wait_on_inode(inode);
1319  		if (unlikely(inode_unhashed(inode))) {
1320  			iput(inode);
1321  			goto again;
1322  		}
1323  	}
1324  	return inode;
1325  }
1326  EXPORT_SYMBOL(iget_locked);
1327  
1328  /*
1329   * search the inode cache for a matching inode number.
1330   * If we find one, then the inode number we are trying to
1331   * allocate is not unique and so we should not use it.
1332   *
1333   * Returns 1 if the inode number is unique, 0 if it is not.
1334   */
1335  static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1336  {
1337  	struct hlist_head *b = inode_hashtable + hash(sb, ino);
1338  	struct inode *inode;
1339  
1340  	hlist_for_each_entry_rcu(inode, b, i_hash) {
1341  		if (inode->i_ino == ino && inode->i_sb == sb)
1342  			return 0;
1343  	}
1344  	return 1;
1345  }
1346  
1347  /**
1348   *	iunique - get a unique inode number
1349   *	@sb: superblock
1350   *	@max_reserved: highest reserved inode number
1351   *
1352   *	Obtain an inode number that is unique on the system for a given
1353   *	superblock. This is used by file systems that have no natural
1354   *	permanent inode numbering system. An inode number is returned that
1355   *	is higher than the reserved limit but unique.
1356   *
1357   *	BUGS:
1358   *	With a large number of inodes live on the file system this function
1359   *	currently becomes quite slow.
1360   */
1361  ino_t iunique(struct super_block *sb, ino_t max_reserved)
1362  {
1363  	/*
1364  	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1365  	 * error if st_ino won't fit in target struct field. Use 32bit counter
1366  	 * here to attempt to avoid that.
1367  	 */
1368  	static DEFINE_SPINLOCK(iunique_lock);
1369  	static unsigned int counter;
1370  	ino_t res;
1371  
1372  	rcu_read_lock();
1373  	spin_lock(&iunique_lock);
1374  	do {
1375  		if (counter <= max_reserved)
1376  			counter = max_reserved + 1;
1377  		res = counter++;
1378  	} while (!test_inode_iunique(sb, res));
1379  	spin_unlock(&iunique_lock);
1380  	rcu_read_unlock();
1381  
1382  	return res;
1383  }
1384  EXPORT_SYMBOL(iunique);
1385  
1386  struct inode *igrab(struct inode *inode)
1387  {
1388  	spin_lock(&inode->i_lock);
1389  	if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1390  		__iget(inode);
1391  		spin_unlock(&inode->i_lock);
1392  	} else {
1393  		spin_unlock(&inode->i_lock);
1394  		/*
1395  		 * Handle the case where s_op->clear_inode is not been
1396  		 * called yet, and somebody is calling igrab
1397  		 * while the inode is getting freed.
1398  		 */
1399  		inode = NULL;
1400  	}
1401  	return inode;
1402  }
1403  EXPORT_SYMBOL(igrab);
1404  
1405  /**
1406   * ilookup5_nowait - search for an inode in the inode cache
1407   * @sb:		super block of file system to search
1408   * @hashval:	hash value (usually inode number) to search for
1409   * @test:	callback used for comparisons between inodes
1410   * @data:	opaque data pointer to pass to @test
1411   *
1412   * Search for the inode specified by @hashval and @data in the inode cache.
1413   * If the inode is in the cache, the inode is returned with an incremented
1414   * reference count.
1415   *
1416   * Note: I_NEW is not waited upon so you have to be very careful what you do
1417   * with the returned inode.  You probably should be using ilookup5() instead.
1418   *
1419   * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1420   */
1421  struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1422  		int (*test)(struct inode *, void *), void *data)
1423  {
1424  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1425  	struct inode *inode;
1426  
1427  	spin_lock(&inode_hash_lock);
1428  	inode = find_inode(sb, head, test, data);
1429  	spin_unlock(&inode_hash_lock);
1430  
1431  	return IS_ERR(inode) ? NULL : inode;
1432  }
1433  EXPORT_SYMBOL(ilookup5_nowait);
1434  
1435  /**
1436   * ilookup5 - search for an inode in the inode cache
1437   * @sb:		super block of file system to search
1438   * @hashval:	hash value (usually inode number) to search for
1439   * @test:	callback used for comparisons between inodes
1440   * @data:	opaque data pointer to pass to @test
1441   *
1442   * Search for the inode specified by @hashval and @data in the inode cache,
1443   * and if the inode is in the cache, return the inode with an incremented
1444   * reference count.  Waits on I_NEW before returning the inode.
1445   * returned with an incremented reference count.
1446   *
1447   * This is a generalized version of ilookup() for file systems where the
1448   * inode number is not sufficient for unique identification of an inode.
1449   *
1450   * Note: @test is called with the inode_hash_lock held, so can't sleep.
1451   */
1452  struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1453  		int (*test)(struct inode *, void *), void *data)
1454  {
1455  	struct inode *inode;
1456  again:
1457  	inode = ilookup5_nowait(sb, hashval, test, data);
1458  	if (inode) {
1459  		wait_on_inode(inode);
1460  		if (unlikely(inode_unhashed(inode))) {
1461  			iput(inode);
1462  			goto again;
1463  		}
1464  	}
1465  	return inode;
1466  }
1467  EXPORT_SYMBOL(ilookup5);
1468  
1469  /**
1470   * ilookup - search for an inode in the inode cache
1471   * @sb:		super block of file system to search
1472   * @ino:	inode number to search for
1473   *
1474   * Search for the inode @ino in the inode cache, and if the inode is in the
1475   * cache, the inode is returned with an incremented reference count.
1476   */
1477  struct inode *ilookup(struct super_block *sb, unsigned long ino)
1478  {
1479  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1480  	struct inode *inode;
1481  again:
1482  	spin_lock(&inode_hash_lock);
1483  	inode = find_inode_fast(sb, head, ino);
1484  	spin_unlock(&inode_hash_lock);
1485  
1486  	if (inode) {
1487  		if (IS_ERR(inode))
1488  			return NULL;
1489  		wait_on_inode(inode);
1490  		if (unlikely(inode_unhashed(inode))) {
1491  			iput(inode);
1492  			goto again;
1493  		}
1494  	}
1495  	return inode;
1496  }
1497  EXPORT_SYMBOL(ilookup);
1498  
1499  /**
1500   * find_inode_nowait - find an inode in the inode cache
1501   * @sb:		super block of file system to search
1502   * @hashval:	hash value (usually inode number) to search for
1503   * @match:	callback used for comparisons between inodes
1504   * @data:	opaque data pointer to pass to @match
1505   *
1506   * Search for the inode specified by @hashval and @data in the inode
1507   * cache, where the helper function @match will return 0 if the inode
1508   * does not match, 1 if the inode does match, and -1 if the search
1509   * should be stopped.  The @match function must be responsible for
1510   * taking the i_lock spin_lock and checking i_state for an inode being
1511   * freed or being initialized, and incrementing the reference count
1512   * before returning 1.  It also must not sleep, since it is called with
1513   * the inode_hash_lock spinlock held.
1514   *
1515   * This is a even more generalized version of ilookup5() when the
1516   * function must never block --- find_inode() can block in
1517   * __wait_on_freeing_inode() --- or when the caller can not increment
1518   * the reference count because the resulting iput() might cause an
1519   * inode eviction.  The tradeoff is that the @match funtion must be
1520   * very carefully implemented.
1521   */
1522  struct inode *find_inode_nowait(struct super_block *sb,
1523  				unsigned long hashval,
1524  				int (*match)(struct inode *, unsigned long,
1525  					     void *),
1526  				void *data)
1527  {
1528  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1529  	struct inode *inode, *ret_inode = NULL;
1530  	int mval;
1531  
1532  	spin_lock(&inode_hash_lock);
1533  	hlist_for_each_entry(inode, head, i_hash) {
1534  		if (inode->i_sb != sb)
1535  			continue;
1536  		mval = match(inode, hashval, data);
1537  		if (mval == 0)
1538  			continue;
1539  		if (mval == 1)
1540  			ret_inode = inode;
1541  		goto out;
1542  	}
1543  out:
1544  	spin_unlock(&inode_hash_lock);
1545  	return ret_inode;
1546  }
1547  EXPORT_SYMBOL(find_inode_nowait);
1548  
1549  /**
1550   * find_inode_rcu - find an inode in the inode cache
1551   * @sb:		Super block of file system to search
1552   * @hashval:	Key to hash
1553   * @test:	Function to test match on an inode
1554   * @data:	Data for test function
1555   *
1556   * Search for the inode specified by @hashval and @data in the inode cache,
1557   * where the helper function @test will return 0 if the inode does not match
1558   * and 1 if it does.  The @test function must be responsible for taking the
1559   * i_lock spin_lock and checking i_state for an inode being freed or being
1560   * initialized.
1561   *
1562   * If successful, this will return the inode for which the @test function
1563   * returned 1 and NULL otherwise.
1564   *
1565   * The @test function is not permitted to take a ref on any inode presented.
1566   * It is also not permitted to sleep.
1567   *
1568   * The caller must hold the RCU read lock.
1569   */
1570  struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval,
1571  			     int (*test)(struct inode *, void *), void *data)
1572  {
1573  	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1574  	struct inode *inode;
1575  
1576  	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1577  			 "suspicious find_inode_rcu() usage");
1578  
1579  	hlist_for_each_entry_rcu(inode, head, i_hash) {
1580  		if (inode->i_sb == sb &&
1581  		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)) &&
1582  		    test(inode, data))
1583  			return inode;
1584  	}
1585  	return NULL;
1586  }
1587  EXPORT_SYMBOL(find_inode_rcu);
1588  
1589  /**
1590   * find_inode_by_ino_rcu - Find an inode in the inode cache
1591   * @sb:		Super block of file system to search
1592   * @ino:	The inode number to match
1593   *
1594   * Search for the inode specified by @hashval and @data in the inode cache,
1595   * where the helper function @test will return 0 if the inode does not match
1596   * and 1 if it does.  The @test function must be responsible for taking the
1597   * i_lock spin_lock and checking i_state for an inode being freed or being
1598   * initialized.
1599   *
1600   * If successful, this will return the inode for which the @test function
1601   * returned 1 and NULL otherwise.
1602   *
1603   * The @test function is not permitted to take a ref on any inode presented.
1604   * It is also not permitted to sleep.
1605   *
1606   * The caller must hold the RCU read lock.
1607   */
1608  struct inode *find_inode_by_ino_rcu(struct super_block *sb,
1609  				    unsigned long ino)
1610  {
1611  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1612  	struct inode *inode;
1613  
1614  	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1615  			 "suspicious find_inode_by_ino_rcu() usage");
1616  
1617  	hlist_for_each_entry_rcu(inode, head, i_hash) {
1618  		if (inode->i_ino == ino &&
1619  		    inode->i_sb == sb &&
1620  		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)))
1621  		    return inode;
1622  	}
1623  	return NULL;
1624  }
1625  EXPORT_SYMBOL(find_inode_by_ino_rcu);
1626  
1627  int insert_inode_locked(struct inode *inode)
1628  {
1629  	struct super_block *sb = inode->i_sb;
1630  	ino_t ino = inode->i_ino;
1631  	struct hlist_head *head = inode_hashtable + hash(sb, ino);
1632  
1633  	while (1) {
1634  		struct inode *old = NULL;
1635  		spin_lock(&inode_hash_lock);
1636  		hlist_for_each_entry(old, head, i_hash) {
1637  			if (old->i_ino != ino)
1638  				continue;
1639  			if (old->i_sb != sb)
1640  				continue;
1641  			spin_lock(&old->i_lock);
1642  			if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1643  				spin_unlock(&old->i_lock);
1644  				continue;
1645  			}
1646  			break;
1647  		}
1648  		if (likely(!old)) {
1649  			spin_lock(&inode->i_lock);
1650  			inode->i_state |= I_NEW | I_CREATING;
1651  			hlist_add_head_rcu(&inode->i_hash, head);
1652  			spin_unlock(&inode->i_lock);
1653  			spin_unlock(&inode_hash_lock);
1654  			return 0;
1655  		}
1656  		if (unlikely(old->i_state & I_CREATING)) {
1657  			spin_unlock(&old->i_lock);
1658  			spin_unlock(&inode_hash_lock);
1659  			return -EBUSY;
1660  		}
1661  		__iget(old);
1662  		spin_unlock(&old->i_lock);
1663  		spin_unlock(&inode_hash_lock);
1664  		wait_on_inode(old);
1665  		if (unlikely(!inode_unhashed(old))) {
1666  			iput(old);
1667  			return -EBUSY;
1668  		}
1669  		iput(old);
1670  	}
1671  }
1672  EXPORT_SYMBOL(insert_inode_locked);
1673  
1674  int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1675  		int (*test)(struct inode *, void *), void *data)
1676  {
1677  	struct inode *old;
1678  
1679  	inode->i_state |= I_CREATING;
1680  	old = inode_insert5(inode, hashval, test, NULL, data);
1681  
1682  	if (old != inode) {
1683  		iput(old);
1684  		return -EBUSY;
1685  	}
1686  	return 0;
1687  }
1688  EXPORT_SYMBOL(insert_inode_locked4);
1689  
1690  
1691  int generic_delete_inode(struct inode *inode)
1692  {
1693  	return 1;
1694  }
1695  EXPORT_SYMBOL(generic_delete_inode);
1696  
1697  /*
1698   * Called when we're dropping the last reference
1699   * to an inode.
1700   *
1701   * Call the FS "drop_inode()" function, defaulting to
1702   * the legacy UNIX filesystem behaviour.  If it tells
1703   * us to evict inode, do so.  Otherwise, retain inode
1704   * in cache if fs is alive, sync and evict if fs is
1705   * shutting down.
1706   */
1707  static void iput_final(struct inode *inode)
1708  {
1709  	struct super_block *sb = inode->i_sb;
1710  	const struct super_operations *op = inode->i_sb->s_op;
1711  	unsigned long state;
1712  	int drop;
1713  
1714  	WARN_ON(inode->i_state & I_NEW);
1715  
1716  	if (op->drop_inode)
1717  		drop = op->drop_inode(inode);
1718  	else
1719  		drop = generic_drop_inode(inode);
1720  
1721  	if (!drop &&
1722  	    !(inode->i_state & I_DONTCACHE) &&
1723  	    (sb->s_flags & SB_ACTIVE)) {
1724  		__inode_add_lru(inode, true);
1725  		spin_unlock(&inode->i_lock);
1726  		return;
1727  	}
1728  
1729  	state = inode->i_state;
1730  	if (!drop) {
1731  		WRITE_ONCE(inode->i_state, state | I_WILL_FREE);
1732  		spin_unlock(&inode->i_lock);
1733  
1734  		write_inode_now(inode, 1);
1735  
1736  		spin_lock(&inode->i_lock);
1737  		state = inode->i_state;
1738  		WARN_ON(state & I_NEW);
1739  		state &= ~I_WILL_FREE;
1740  	}
1741  
1742  	WRITE_ONCE(inode->i_state, state | I_FREEING);
1743  	if (!list_empty(&inode->i_lru))
1744  		inode_lru_list_del(inode);
1745  	spin_unlock(&inode->i_lock);
1746  
1747  	evict(inode);
1748  }
1749  
1750  /**
1751   *	iput	- put an inode
1752   *	@inode: inode to put
1753   *
1754   *	Puts an inode, dropping its usage count. If the inode use count hits
1755   *	zero, the inode is then freed and may also be destroyed.
1756   *
1757   *	Consequently, iput() can sleep.
1758   */
1759  void iput(struct inode *inode)
1760  {
1761  	if (!inode)
1762  		return;
1763  	BUG_ON(inode->i_state & I_CLEAR);
1764  retry:
1765  	if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
1766  		if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
1767  			atomic_inc(&inode->i_count);
1768  			spin_unlock(&inode->i_lock);
1769  			trace_writeback_lazytime_iput(inode);
1770  			mark_inode_dirty_sync(inode);
1771  			goto retry;
1772  		}
1773  		iput_final(inode);
1774  	}
1775  }
1776  EXPORT_SYMBOL(iput);
1777  
1778  #ifdef CONFIG_BLOCK
1779  /**
1780   *	bmap	- find a block number in a file
1781   *	@inode:  inode owning the block number being requested
1782   *	@block: pointer containing the block to find
1783   *
1784   *	Replaces the value in ``*block`` with the block number on the device holding
1785   *	corresponding to the requested block number in the file.
1786   *	That is, asked for block 4 of inode 1 the function will replace the
1787   *	4 in ``*block``, with disk block relative to the disk start that holds that
1788   *	block of the file.
1789   *
1790   *	Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
1791   *	hole, returns 0 and ``*block`` is also set to 0.
1792   */
1793  int bmap(struct inode *inode, sector_t *block)
1794  {
1795  	if (!inode->i_mapping->a_ops->bmap)
1796  		return -EINVAL;
1797  
1798  	*block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
1799  	return 0;
1800  }
1801  EXPORT_SYMBOL(bmap);
1802  #endif
1803  
1804  /*
1805   * With relative atime, only update atime if the previous atime is
1806   * earlier than or equal to either the ctime or mtime,
1807   * or if at least a day has passed since the last atime update.
1808   */
1809  static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1810  			     struct timespec64 now)
1811  {
1812  
1813  	if (!(mnt->mnt_flags & MNT_RELATIME))
1814  		return 1;
1815  	/*
1816  	 * Is mtime younger than or equal to atime? If yes, update atime:
1817  	 */
1818  	if (timespec64_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1819  		return 1;
1820  	/*
1821  	 * Is ctime younger than or equal to atime? If yes, update atime:
1822  	 */
1823  	if (timespec64_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1824  		return 1;
1825  
1826  	/*
1827  	 * Is the previous atime value older than a day? If yes,
1828  	 * update atime:
1829  	 */
1830  	if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1831  		return 1;
1832  	/*
1833  	 * Good, we can skip the atime update:
1834  	 */
1835  	return 0;
1836  }
1837  
1838  int generic_update_time(struct inode *inode, struct timespec64 *time, int flags)
1839  {
1840  	int dirty_flags = 0;
1841  
1842  	if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
1843  		if (flags & S_ATIME)
1844  			inode->i_atime = *time;
1845  		if (flags & S_CTIME)
1846  			inode->i_ctime = *time;
1847  		if (flags & S_MTIME)
1848  			inode->i_mtime = *time;
1849  
1850  		if (inode->i_sb->s_flags & SB_LAZYTIME)
1851  			dirty_flags |= I_DIRTY_TIME;
1852  		else
1853  			dirty_flags |= I_DIRTY_SYNC;
1854  	}
1855  
1856  	if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))
1857  		dirty_flags |= I_DIRTY_SYNC;
1858  
1859  	__mark_inode_dirty(inode, dirty_flags);
1860  	return 0;
1861  }
1862  EXPORT_SYMBOL(generic_update_time);
1863  
1864  /*
1865   * This does the actual work of updating an inodes time or version.  Must have
1866   * had called mnt_want_write() before calling this.
1867   */
1868  int inode_update_time(struct inode *inode, struct timespec64 *time, int flags)
1869  {
1870  	if (inode->i_op->update_time)
1871  		return inode->i_op->update_time(inode, time, flags);
1872  	return generic_update_time(inode, time, flags);
1873  }
1874  EXPORT_SYMBOL(inode_update_time);
1875  
1876  /**
1877   *	atime_needs_update	-	update the access time
1878   *	@path: the &struct path to update
1879   *	@inode: inode to update
1880   *
1881   *	Update the accessed time on an inode and mark it for writeback.
1882   *	This function automatically handles read only file systems and media,
1883   *	as well as the "noatime" flag and inode specific "noatime" markers.
1884   */
1885  bool atime_needs_update(const struct path *path, struct inode *inode)
1886  {
1887  	struct vfsmount *mnt = path->mnt;
1888  	struct timespec64 now;
1889  
1890  	if (inode->i_flags & S_NOATIME)
1891  		return false;
1892  
1893  	/* Atime updates will likely cause i_uid and i_gid to be written
1894  	 * back improprely if their true value is unknown to the vfs.
1895  	 */
1896  	if (HAS_UNMAPPED_ID(mnt_idmap(mnt), inode))
1897  		return false;
1898  
1899  	if (IS_NOATIME(inode))
1900  		return false;
1901  	if ((inode->i_sb->s_flags & SB_NODIRATIME) && S_ISDIR(inode->i_mode))
1902  		return false;
1903  
1904  	if (mnt->mnt_flags & MNT_NOATIME)
1905  		return false;
1906  	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1907  		return false;
1908  
1909  	now = current_time(inode);
1910  
1911  	if (!relatime_need_update(mnt, inode, now))
1912  		return false;
1913  
1914  	if (timespec64_equal(&inode->i_atime, &now))
1915  		return false;
1916  
1917  	return true;
1918  }
1919  
1920  void touch_atime(const struct path *path)
1921  {
1922  	struct vfsmount *mnt = path->mnt;
1923  	struct inode *inode = d_inode(path->dentry);
1924  	struct timespec64 now;
1925  
1926  	if (!atime_needs_update(path, inode))
1927  		return;
1928  
1929  	if (!sb_start_write_trylock(inode->i_sb))
1930  		return;
1931  
1932  	if (__mnt_want_write(mnt) != 0)
1933  		goto skip_update;
1934  	/*
1935  	 * File systems can error out when updating inodes if they need to
1936  	 * allocate new space to modify an inode (such is the case for
1937  	 * Btrfs), but since we touch atime while walking down the path we
1938  	 * really don't care if we failed to update the atime of the file,
1939  	 * so just ignore the return value.
1940  	 * We may also fail on filesystems that have the ability to make parts
1941  	 * of the fs read only, e.g. subvolumes in Btrfs.
1942  	 */
1943  	now = current_time(inode);
1944  	inode_update_time(inode, &now, S_ATIME);
1945  	__mnt_drop_write(mnt);
1946  skip_update:
1947  	sb_end_write(inode->i_sb);
1948  }
1949  EXPORT_SYMBOL(touch_atime);
1950  
1951  /*
1952   * Return mask of changes for notify_change() that need to be done as a
1953   * response to write or truncate. Return 0 if nothing has to be changed.
1954   * Negative value on error (change should be denied).
1955   */
1956  int dentry_needs_remove_privs(struct mnt_idmap *idmap,
1957  			      struct dentry *dentry)
1958  {
1959  	struct inode *inode = d_inode(dentry);
1960  	int mask = 0;
1961  	int ret;
1962  
1963  	if (IS_NOSEC(inode))
1964  		return 0;
1965  
1966  	mask = setattr_should_drop_suidgid(idmap, inode);
1967  	ret = security_inode_need_killpriv(dentry);
1968  	if (ret < 0)
1969  		return ret;
1970  	if (ret)
1971  		mask |= ATTR_KILL_PRIV;
1972  	return mask;
1973  }
1974  
1975  static int __remove_privs(struct mnt_idmap *idmap,
1976  			  struct dentry *dentry, int kill)
1977  {
1978  	struct iattr newattrs;
1979  
1980  	newattrs.ia_valid = ATTR_FORCE | kill;
1981  	/*
1982  	 * Note we call this on write, so notify_change will not
1983  	 * encounter any conflicting delegations:
1984  	 */
1985  	return notify_change(idmap, dentry, &newattrs, NULL);
1986  }
1987  
1988  static int __file_remove_privs(struct file *file, unsigned int flags)
1989  {
1990  	struct dentry *dentry = file_dentry(file);
1991  	struct inode *inode = file_inode(file);
1992  	int error = 0;
1993  	int kill;
1994  
1995  	if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
1996  		return 0;
1997  
1998  	kill = dentry_needs_remove_privs(file_mnt_idmap(file), dentry);
1999  	if (kill < 0)
2000  		return kill;
2001  
2002  	if (kill) {
2003  		if (flags & IOCB_NOWAIT)
2004  			return -EAGAIN;
2005  
2006  		error = __remove_privs(file_mnt_idmap(file), dentry, kill);
2007  	}
2008  
2009  	if (!error)
2010  		inode_has_no_xattr(inode);
2011  	return error;
2012  }
2013  
2014  /**
2015   * file_remove_privs - remove special file privileges (suid, capabilities)
2016   * @file: file to remove privileges from
2017   *
2018   * When file is modified by a write or truncation ensure that special
2019   * file privileges are removed.
2020   *
2021   * Return: 0 on success, negative errno on failure.
2022   */
2023  int file_remove_privs(struct file *file)
2024  {
2025  	return __file_remove_privs(file, 0);
2026  }
2027  EXPORT_SYMBOL(file_remove_privs);
2028  
2029  static int inode_needs_update_time(struct inode *inode, struct timespec64 *now)
2030  {
2031  	int sync_it = 0;
2032  
2033  	/* First try to exhaust all avenues to not sync */
2034  	if (IS_NOCMTIME(inode))
2035  		return 0;
2036  
2037  	if (!timespec64_equal(&inode->i_mtime, now))
2038  		sync_it = S_MTIME;
2039  
2040  	if (!timespec64_equal(&inode->i_ctime, now))
2041  		sync_it |= S_CTIME;
2042  
2043  	if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
2044  		sync_it |= S_VERSION;
2045  
2046  	return sync_it;
2047  }
2048  
2049  static int __file_update_time(struct file *file, struct timespec64 *now,
2050  			int sync_mode)
2051  {
2052  	int ret = 0;
2053  	struct inode *inode = file_inode(file);
2054  
2055  	/* try to update time settings */
2056  	if (!__mnt_want_write_file(file)) {
2057  		ret = inode_update_time(inode, now, sync_mode);
2058  		__mnt_drop_write_file(file);
2059  	}
2060  
2061  	return ret;
2062  }
2063  
2064  /**
2065   * file_update_time - update mtime and ctime time
2066   * @file: file accessed
2067   *
2068   * Update the mtime and ctime members of an inode and mark the inode for
2069   * writeback. Note that this function is meant exclusively for usage in
2070   * the file write path of filesystems, and filesystems may choose to
2071   * explicitly ignore updates via this function with the _NOCMTIME inode
2072   * flag, e.g. for network filesystem where these imestamps are handled
2073   * by the server. This can return an error for file systems who need to
2074   * allocate space in order to update an inode.
2075   *
2076   * Return: 0 on success, negative errno on failure.
2077   */
2078  int file_update_time(struct file *file)
2079  {
2080  	int ret;
2081  	struct inode *inode = file_inode(file);
2082  	struct timespec64 now = current_time(inode);
2083  
2084  	ret = inode_needs_update_time(inode, &now);
2085  	if (ret <= 0)
2086  		return ret;
2087  
2088  	return __file_update_time(file, &now, ret);
2089  }
2090  EXPORT_SYMBOL(file_update_time);
2091  
2092  /**
2093   * file_modified_flags - handle mandated vfs changes when modifying a file
2094   * @file: file that was modified
2095   * @flags: kiocb flags
2096   *
2097   * When file has been modified ensure that special
2098   * file privileges are removed and time settings are updated.
2099   *
2100   * If IOCB_NOWAIT is set, special file privileges will not be removed and
2101   * time settings will not be updated. It will return -EAGAIN.
2102   *
2103   * Context: Caller must hold the file's inode lock.
2104   *
2105   * Return: 0 on success, negative errno on failure.
2106   */
2107  static int file_modified_flags(struct file *file, int flags)
2108  {
2109  	int ret;
2110  	struct inode *inode = file_inode(file);
2111  	struct timespec64 now = current_time(inode);
2112  
2113  	/*
2114  	 * Clear the security bits if the process is not being run by root.
2115  	 * This keeps people from modifying setuid and setgid binaries.
2116  	 */
2117  	ret = __file_remove_privs(file, flags);
2118  	if (ret)
2119  		return ret;
2120  
2121  	if (unlikely(file->f_mode & FMODE_NOCMTIME))
2122  		return 0;
2123  
2124  	ret = inode_needs_update_time(inode, &now);
2125  	if (ret <= 0)
2126  		return ret;
2127  	if (flags & IOCB_NOWAIT)
2128  		return -EAGAIN;
2129  
2130  	return __file_update_time(file, &now, ret);
2131  }
2132  
2133  /**
2134   * file_modified - handle mandated vfs changes when modifying a file
2135   * @file: file that was modified
2136   *
2137   * When file has been modified ensure that special
2138   * file privileges are removed and time settings are updated.
2139   *
2140   * Context: Caller must hold the file's inode lock.
2141   *
2142   * Return: 0 on success, negative errno on failure.
2143   */
2144  int file_modified(struct file *file)
2145  {
2146  	return file_modified_flags(file, 0);
2147  }
2148  EXPORT_SYMBOL(file_modified);
2149  
2150  /**
2151   * kiocb_modified - handle mandated vfs changes when modifying a file
2152   * @iocb: iocb that was modified
2153   *
2154   * When file has been modified ensure that special
2155   * file privileges are removed and time settings are updated.
2156   *
2157   * Context: Caller must hold the file's inode lock.
2158   *
2159   * Return: 0 on success, negative errno on failure.
2160   */
2161  int kiocb_modified(struct kiocb *iocb)
2162  {
2163  	return file_modified_flags(iocb->ki_filp, iocb->ki_flags);
2164  }
2165  EXPORT_SYMBOL_GPL(kiocb_modified);
2166  
2167  int inode_needs_sync(struct inode *inode)
2168  {
2169  	if (IS_SYNC(inode))
2170  		return 1;
2171  	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
2172  		return 1;
2173  	return 0;
2174  }
2175  EXPORT_SYMBOL(inode_needs_sync);
2176  
2177  /*
2178   * If we try to find an inode in the inode hash while it is being
2179   * deleted, we have to wait until the filesystem completes its
2180   * deletion before reporting that it isn't found.  This function waits
2181   * until the deletion _might_ have completed.  Callers are responsible
2182   * to recheck inode state.
2183   *
2184   * It doesn't matter if I_NEW is not set initially, a call to
2185   * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
2186   * will DTRT.
2187   */
2188  static void __wait_on_freeing_inode(struct inode *inode)
2189  {
2190  	wait_queue_head_t *wq;
2191  	DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
2192  	wq = bit_waitqueue(&inode->i_state, __I_NEW);
2193  	prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
2194  	spin_unlock(&inode->i_lock);
2195  	spin_unlock(&inode_hash_lock);
2196  	schedule();
2197  	finish_wait(wq, &wait.wq_entry);
2198  	spin_lock(&inode_hash_lock);
2199  }
2200  
2201  static __initdata unsigned long ihash_entries;
2202  static int __init set_ihash_entries(char *str)
2203  {
2204  	if (!str)
2205  		return 0;
2206  	ihash_entries = simple_strtoul(str, &str, 0);
2207  	return 1;
2208  }
2209  __setup("ihash_entries=", set_ihash_entries);
2210  
2211  /*
2212   * Initialize the waitqueues and inode hash table.
2213   */
2214  void __init inode_init_early(void)
2215  {
2216  	/* If hashes are distributed across NUMA nodes, defer
2217  	 * hash allocation until vmalloc space is available.
2218  	 */
2219  	if (hashdist)
2220  		return;
2221  
2222  	inode_hashtable =
2223  		alloc_large_system_hash("Inode-cache",
2224  					sizeof(struct hlist_head),
2225  					ihash_entries,
2226  					14,
2227  					HASH_EARLY | HASH_ZERO,
2228  					&i_hash_shift,
2229  					&i_hash_mask,
2230  					0,
2231  					0);
2232  }
2233  
2234  void __init inode_init(void)
2235  {
2236  	/* inode slab cache */
2237  	inode_cachep = kmem_cache_create("inode_cache",
2238  					 sizeof(struct inode),
2239  					 0,
2240  					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
2241  					 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
2242  					 init_once);
2243  
2244  	/* Hash may have been set up in inode_init_early */
2245  	if (!hashdist)
2246  		return;
2247  
2248  	inode_hashtable =
2249  		alloc_large_system_hash("Inode-cache",
2250  					sizeof(struct hlist_head),
2251  					ihash_entries,
2252  					14,
2253  					HASH_ZERO,
2254  					&i_hash_shift,
2255  					&i_hash_mask,
2256  					0,
2257  					0);
2258  }
2259  
2260  void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
2261  {
2262  	inode->i_mode = mode;
2263  	if (S_ISCHR(mode)) {
2264  		inode->i_fop = &def_chr_fops;
2265  		inode->i_rdev = rdev;
2266  	} else if (S_ISBLK(mode)) {
2267  		inode->i_fop = &def_blk_fops;
2268  		inode->i_rdev = rdev;
2269  	} else if (S_ISFIFO(mode))
2270  		inode->i_fop = &pipefifo_fops;
2271  	else if (S_ISSOCK(mode))
2272  		;	/* leave it no_open_fops */
2273  	else
2274  		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
2275  				  " inode %s:%lu\n", mode, inode->i_sb->s_id,
2276  				  inode->i_ino);
2277  }
2278  EXPORT_SYMBOL(init_special_inode);
2279  
2280  /**
2281   * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
2282   * @idmap: idmap of the mount the inode was created from
2283   * @inode: New inode
2284   * @dir: Directory inode
2285   * @mode: mode of the new inode
2286   *
2287   * If the inode has been created through an idmapped mount the idmap of
2288   * the vfsmount must be passed through @idmap. This function will then take
2289   * care to map the inode according to @idmap before checking permissions
2290   * and initializing i_uid and i_gid. On non-idmapped mounts or if permission
2291   * checking is to be performed on the raw inode simply pass @nop_mnt_idmap.
2292   */
2293  void inode_init_owner(struct mnt_idmap *idmap, struct inode *inode,
2294  		      const struct inode *dir, umode_t mode)
2295  {
2296  	inode_fsuid_set(inode, idmap);
2297  	if (dir && dir->i_mode & S_ISGID) {
2298  		inode->i_gid = dir->i_gid;
2299  
2300  		/* Directories are special, and always inherit S_ISGID */
2301  		if (S_ISDIR(mode))
2302  			mode |= S_ISGID;
2303  	} else
2304  		inode_fsgid_set(inode, idmap);
2305  	inode->i_mode = mode;
2306  }
2307  EXPORT_SYMBOL(inode_init_owner);
2308  
2309  /**
2310   * inode_owner_or_capable - check current task permissions to inode
2311   * @idmap: idmap of the mount the inode was found from
2312   * @inode: inode being checked
2313   *
2314   * Return true if current either has CAP_FOWNER in a namespace with the
2315   * inode owner uid mapped, or owns the file.
2316   *
2317   * If the inode has been found through an idmapped mount the idmap of
2318   * the vfsmount must be passed through @idmap. This function will then take
2319   * care to map the inode according to @idmap before checking permissions.
2320   * On non-idmapped mounts or if permission checking is to be performed on the
2321   * raw inode simply passs @nop_mnt_idmap.
2322   */
2323  bool inode_owner_or_capable(struct mnt_idmap *idmap,
2324  			    const struct inode *inode)
2325  {
2326  	vfsuid_t vfsuid;
2327  	struct user_namespace *ns;
2328  
2329  	vfsuid = i_uid_into_vfsuid(idmap, inode);
2330  	if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
2331  		return true;
2332  
2333  	ns = current_user_ns();
2334  	if (vfsuid_has_mapping(ns, vfsuid) && ns_capable(ns, CAP_FOWNER))
2335  		return true;
2336  	return false;
2337  }
2338  EXPORT_SYMBOL(inode_owner_or_capable);
2339  
2340  /*
2341   * Direct i/o helper functions
2342   */
2343  static void __inode_dio_wait(struct inode *inode)
2344  {
2345  	wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP);
2346  	DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP);
2347  
2348  	do {
2349  		prepare_to_wait(wq, &q.wq_entry, TASK_UNINTERRUPTIBLE);
2350  		if (atomic_read(&inode->i_dio_count))
2351  			schedule();
2352  	} while (atomic_read(&inode->i_dio_count));
2353  	finish_wait(wq, &q.wq_entry);
2354  }
2355  
2356  /**
2357   * inode_dio_wait - wait for outstanding DIO requests to finish
2358   * @inode: inode to wait for
2359   *
2360   * Waits for all pending direct I/O requests to finish so that we can
2361   * proceed with a truncate or equivalent operation.
2362   *
2363   * Must be called under a lock that serializes taking new references
2364   * to i_dio_count, usually by inode->i_mutex.
2365   */
2366  void inode_dio_wait(struct inode *inode)
2367  {
2368  	if (atomic_read(&inode->i_dio_count))
2369  		__inode_dio_wait(inode);
2370  }
2371  EXPORT_SYMBOL(inode_dio_wait);
2372  
2373  /*
2374   * inode_set_flags - atomically set some inode flags
2375   *
2376   * Note: the caller should be holding i_mutex, or else be sure that
2377   * they have exclusive access to the inode structure (i.e., while the
2378   * inode is being instantiated).  The reason for the cmpxchg() loop
2379   * --- which wouldn't be necessary if all code paths which modify
2380   * i_flags actually followed this rule, is that there is at least one
2381   * code path which doesn't today so we use cmpxchg() out of an abundance
2382   * of caution.
2383   *
2384   * In the long run, i_mutex is overkill, and we should probably look
2385   * at using the i_lock spinlock to protect i_flags, and then make sure
2386   * it is so documented in include/linux/fs.h and that all code follows
2387   * the locking convention!!
2388   */
2389  void inode_set_flags(struct inode *inode, unsigned int flags,
2390  		     unsigned int mask)
2391  {
2392  	WARN_ON_ONCE(flags & ~mask);
2393  	set_mask_bits(&inode->i_flags, mask, flags);
2394  }
2395  EXPORT_SYMBOL(inode_set_flags);
2396  
2397  void inode_nohighmem(struct inode *inode)
2398  {
2399  	mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
2400  }
2401  EXPORT_SYMBOL(inode_nohighmem);
2402  
2403  /**
2404   * timestamp_truncate - Truncate timespec to a granularity
2405   * @t: Timespec
2406   * @inode: inode being updated
2407   *
2408   * Truncate a timespec to the granularity supported by the fs
2409   * containing the inode. Always rounds down. gran must
2410   * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
2411   */
2412  struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
2413  {
2414  	struct super_block *sb = inode->i_sb;
2415  	unsigned int gran = sb->s_time_gran;
2416  
2417  	t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);
2418  	if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))
2419  		t.tv_nsec = 0;
2420  
2421  	/* Avoid division in the common cases 1 ns and 1 s. */
2422  	if (gran == 1)
2423  		; /* nothing */
2424  	else if (gran == NSEC_PER_SEC)
2425  		t.tv_nsec = 0;
2426  	else if (gran > 1 && gran < NSEC_PER_SEC)
2427  		t.tv_nsec -= t.tv_nsec % gran;
2428  	else
2429  		WARN(1, "invalid file time granularity: %u", gran);
2430  	return t;
2431  }
2432  EXPORT_SYMBOL(timestamp_truncate);
2433  
2434  /**
2435   * current_time - Return FS time
2436   * @inode: inode.
2437   *
2438   * Return the current time truncated to the time granularity supported by
2439   * the fs.
2440   *
2441   * Note that inode and inode->sb cannot be NULL.
2442   * Otherwise, the function warns and returns time without truncation.
2443   */
2444  struct timespec64 current_time(struct inode *inode)
2445  {
2446  	struct timespec64 now;
2447  
2448  	ktime_get_coarse_real_ts64(&now);
2449  
2450  	if (unlikely(!inode->i_sb)) {
2451  		WARN(1, "current_time() called with uninitialized super_block in the inode");
2452  		return now;
2453  	}
2454  
2455  	return timestamp_truncate(now, inode);
2456  }
2457  EXPORT_SYMBOL(current_time);
2458  
2459  /**
2460   * in_group_or_capable - check whether caller is CAP_FSETID privileged
2461   * @idmap:	idmap of the mount @inode was found from
2462   * @inode:	inode to check
2463   * @vfsgid:	the new/current vfsgid of @inode
2464   *
2465   * Check wether @vfsgid is in the caller's group list or if the caller is
2466   * privileged with CAP_FSETID over @inode. This can be used to determine
2467   * whether the setgid bit can be kept or must be dropped.
2468   *
2469   * Return: true if the caller is sufficiently privileged, false if not.
2470   */
2471  bool in_group_or_capable(struct mnt_idmap *idmap,
2472  			 const struct inode *inode, vfsgid_t vfsgid)
2473  {
2474  	if (vfsgid_in_group_p(vfsgid))
2475  		return true;
2476  	if (capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
2477  		return true;
2478  	return false;
2479  }
2480  
2481  /**
2482   * mode_strip_sgid - handle the sgid bit for non-directories
2483   * @idmap: idmap of the mount the inode was created from
2484   * @dir: parent directory inode
2485   * @mode: mode of the file to be created in @dir
2486   *
2487   * If the @mode of the new file has both the S_ISGID and S_IXGRP bit
2488   * raised and @dir has the S_ISGID bit raised ensure that the caller is
2489   * either in the group of the parent directory or they have CAP_FSETID
2490   * in their user namespace and are privileged over the parent directory.
2491   * In all other cases, strip the S_ISGID bit from @mode.
2492   *
2493   * Return: the new mode to use for the file
2494   */
2495  umode_t mode_strip_sgid(struct mnt_idmap *idmap,
2496  			const struct inode *dir, umode_t mode)
2497  {
2498  	if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP))
2499  		return mode;
2500  	if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID))
2501  		return mode;
2502  	if (in_group_or_capable(idmap, dir, i_gid_into_vfsgid(idmap, dir)))
2503  		return mode;
2504  	return mode & ~S_ISGID;
2505  }
2506  EXPORT_SYMBOL(mode_strip_sgid);
2507