1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * (C) 1997 Linus Torvalds
4 * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation)
5 */
6 #include <linux/export.h>
7 #include <linux/fs.h>
8 #include <linux/filelock.h>
9 #include <linux/mm.h>
10 #include <linux/backing-dev.h>
11 #include <linux/hash.h>
12 #include <linux/swap.h>
13 #include <linux/security.h>
14 #include <linux/cdev.h>
15 #include <linux/memblock.h>
16 #include <linux/fsnotify.h>
17 #include <linux/mount.h>
18 #include <linux/posix_acl.h>
19 #include <linux/buffer_head.h> /* for inode_has_buffers */
20 #include <linux/ratelimit.h>
21 #include <linux/list_lru.h>
22 #include <linux/iversion.h>
23 #include <linux/rw_hint.h>
24 #include <trace/events/writeback.h>
25 #include "internal.h"
26
27 /*
28 * Inode locking rules:
29 *
30 * inode->i_lock protects:
31 * inode->i_state, inode->i_hash, __iget(), inode->i_io_list
32 * Inode LRU list locks protect:
33 * inode->i_sb->s_inode_lru, inode->i_lru
34 * inode->i_sb->s_inode_list_lock protects:
35 * inode->i_sb->s_inodes, inode->i_sb_list
36 * bdi->wb.list_lock protects:
37 * bdi->wb.b_{dirty,io,more_io,dirty_time}, inode->i_io_list
38 * inode_hash_lock protects:
39 * inode_hashtable, inode->i_hash
40 *
41 * Lock ordering:
42 *
43 * inode->i_sb->s_inode_list_lock
44 * inode->i_lock
45 * Inode LRU list locks
46 *
47 * bdi->wb.list_lock
48 * inode->i_lock
49 *
50 * inode_hash_lock
51 * inode->i_sb->s_inode_list_lock
52 * inode->i_lock
53 *
54 * iunique_lock
55 * inode_hash_lock
56 */
57
58 static unsigned int i_hash_mask __ro_after_init;
59 static unsigned int i_hash_shift __ro_after_init;
60 static struct hlist_head *inode_hashtable __ro_after_init;
61 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
62
63 /*
64 * Empty aops. Can be used for the cases where the user does not
65 * define any of the address_space operations.
66 */
67 const struct address_space_operations empty_aops = {
68 };
69 EXPORT_SYMBOL(empty_aops);
70
71 static DEFINE_PER_CPU(unsigned long, nr_inodes);
72 static DEFINE_PER_CPU(unsigned long, nr_unused);
73
74 static struct kmem_cache *inode_cachep __ro_after_init;
75
get_nr_inodes(void)76 static long get_nr_inodes(void)
77 {
78 int i;
79 long sum = 0;
80 for_each_possible_cpu(i)
81 sum += per_cpu(nr_inodes, i);
82 return sum < 0 ? 0 : sum;
83 }
84
get_nr_inodes_unused(void)85 static inline long get_nr_inodes_unused(void)
86 {
87 int i;
88 long sum = 0;
89 for_each_possible_cpu(i)
90 sum += per_cpu(nr_unused, i);
91 return sum < 0 ? 0 : sum;
92 }
93
get_nr_dirty_inodes(void)94 long get_nr_dirty_inodes(void)
95 {
96 /* not actually dirty inodes, but a wild approximation */
97 long nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
98 return nr_dirty > 0 ? nr_dirty : 0;
99 }
100
101 /*
102 * Handle nr_inode sysctl
103 */
104 #ifdef CONFIG_SYSCTL
105 /*
106 * Statistics gathering..
107 */
108 static struct inodes_stat_t inodes_stat;
109
proc_nr_inodes(const struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)110 static int proc_nr_inodes(const struct ctl_table *table, int write, void *buffer,
111 size_t *lenp, loff_t *ppos)
112 {
113 inodes_stat.nr_inodes = get_nr_inodes();
114 inodes_stat.nr_unused = get_nr_inodes_unused();
115 return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
116 }
117
118 static struct ctl_table inodes_sysctls[] = {
119 {
120 .procname = "inode-nr",
121 .data = &inodes_stat,
122 .maxlen = 2*sizeof(long),
123 .mode = 0444,
124 .proc_handler = proc_nr_inodes,
125 },
126 {
127 .procname = "inode-state",
128 .data = &inodes_stat,
129 .maxlen = 7*sizeof(long),
130 .mode = 0444,
131 .proc_handler = proc_nr_inodes,
132 },
133 };
134
init_fs_inode_sysctls(void)135 static int __init init_fs_inode_sysctls(void)
136 {
137 register_sysctl_init("fs", inodes_sysctls);
138 return 0;
139 }
140 early_initcall(init_fs_inode_sysctls);
141 #endif
142
no_open(struct inode * inode,struct file * file)143 static int no_open(struct inode *inode, struct file *file)
144 {
145 return -ENXIO;
146 }
147
148 /**
149 * inode_init_always - perform inode structure initialisation
150 * @sb: superblock inode belongs to
151 * @inode: inode to initialise
152 *
153 * These are initializations that need to be done on every inode
154 * allocation as the fields are not initialised by slab allocation.
155 */
inode_init_always(struct super_block * sb,struct inode * inode)156 int inode_init_always(struct super_block *sb, struct inode *inode)
157 {
158 static const struct inode_operations empty_iops;
159 static const struct file_operations no_open_fops = {.open = no_open};
160 struct address_space *const mapping = &inode->i_data;
161
162 inode->i_sb = sb;
163 inode->i_blkbits = sb->s_blocksize_bits;
164 inode->i_flags = 0;
165 inode->i_state = 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->i_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 if (sb->s_iflags & SB_I_STABLE_WRITES)
220 mapping_set_stable_writes(mapping);
221 inode->i_private = NULL;
222 inode->i_mapping = mapping;
223 INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */
224 #ifdef CONFIG_FS_POSIX_ACL
225 inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
226 #endif
227
228 #ifdef CONFIG_FSNOTIFY
229 inode->i_fsnotify_mask = 0;
230 #endif
231 inode->i_flctx = NULL;
232
233 if (unlikely(security_inode_alloc(inode)))
234 return -ENOMEM;
235
236 this_cpu_inc(nr_inodes);
237
238 return 0;
239 }
240 EXPORT_SYMBOL(inode_init_always);
241
free_inode_nonrcu(struct inode * inode)242 void free_inode_nonrcu(struct inode *inode)
243 {
244 kmem_cache_free(inode_cachep, inode);
245 }
246 EXPORT_SYMBOL(free_inode_nonrcu);
247
i_callback(struct rcu_head * head)248 static void i_callback(struct rcu_head *head)
249 {
250 struct inode *inode = container_of(head, struct inode, i_rcu);
251 if (inode->free_inode)
252 inode->free_inode(inode);
253 else
254 free_inode_nonrcu(inode);
255 }
256
alloc_inode(struct super_block * sb)257 static struct inode *alloc_inode(struct super_block *sb)
258 {
259 const struct super_operations *ops = sb->s_op;
260 struct inode *inode;
261
262 if (ops->alloc_inode)
263 inode = ops->alloc_inode(sb);
264 else
265 inode = alloc_inode_sb(sb, inode_cachep, GFP_KERNEL);
266
267 if (!inode)
268 return NULL;
269
270 if (unlikely(inode_init_always(sb, inode))) {
271 if (ops->destroy_inode) {
272 ops->destroy_inode(inode);
273 if (!ops->free_inode)
274 return NULL;
275 }
276 inode->free_inode = ops->free_inode;
277 i_callback(&inode->i_rcu);
278 return NULL;
279 }
280
281 return inode;
282 }
283
__destroy_inode(struct inode * inode)284 void __destroy_inode(struct inode *inode)
285 {
286 BUG_ON(inode_has_buffers(inode));
287 inode_detach_wb(inode);
288 security_inode_free(inode);
289 fsnotify_inode_delete(inode);
290 locks_free_lock_context(inode);
291 if (!inode->i_nlink) {
292 WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);
293 atomic_long_dec(&inode->i_sb->s_remove_count);
294 }
295
296 #ifdef CONFIG_FS_POSIX_ACL
297 if (inode->i_acl && !is_uncached_acl(inode->i_acl))
298 posix_acl_release(inode->i_acl);
299 if (inode->i_default_acl && !is_uncached_acl(inode->i_default_acl))
300 posix_acl_release(inode->i_default_acl);
301 #endif
302 this_cpu_dec(nr_inodes);
303 }
304 EXPORT_SYMBOL(__destroy_inode);
305
destroy_inode(struct inode * inode)306 static void destroy_inode(struct inode *inode)
307 {
308 const struct super_operations *ops = inode->i_sb->s_op;
309
310 BUG_ON(!list_empty(&inode->i_lru));
311 __destroy_inode(inode);
312 if (ops->destroy_inode) {
313 ops->destroy_inode(inode);
314 if (!ops->free_inode)
315 return;
316 }
317 inode->free_inode = ops->free_inode;
318 call_rcu(&inode->i_rcu, i_callback);
319 }
320
321 /**
322 * drop_nlink - directly drop an inode's link count
323 * @inode: inode
324 *
325 * This is a low-level filesystem helper to replace any
326 * direct filesystem manipulation of i_nlink. In cases
327 * where we are attempting to track writes to the
328 * filesystem, a decrement to zero means an imminent
329 * write when the file is truncated and actually unlinked
330 * on the filesystem.
331 */
drop_nlink(struct inode * inode)332 void drop_nlink(struct inode *inode)
333 {
334 WARN_ON(inode->i_nlink == 0);
335 inode->__i_nlink--;
336 if (!inode->i_nlink)
337 atomic_long_inc(&inode->i_sb->s_remove_count);
338 }
339 EXPORT_SYMBOL(drop_nlink);
340
341 /**
342 * clear_nlink - directly zero an inode's link count
343 * @inode: inode
344 *
345 * This is a low-level filesystem helper to replace any
346 * direct filesystem manipulation of i_nlink. See
347 * drop_nlink() for why we care about i_nlink hitting zero.
348 */
clear_nlink(struct inode * inode)349 void clear_nlink(struct inode *inode)
350 {
351 if (inode->i_nlink) {
352 inode->__i_nlink = 0;
353 atomic_long_inc(&inode->i_sb->s_remove_count);
354 }
355 }
356 EXPORT_SYMBOL(clear_nlink);
357
358 /**
359 * set_nlink - directly set an inode's link count
360 * @inode: inode
361 * @nlink: new nlink (should be non-zero)
362 *
363 * This is a low-level filesystem helper to replace any
364 * direct filesystem manipulation of i_nlink.
365 */
set_nlink(struct inode * inode,unsigned int nlink)366 void set_nlink(struct inode *inode, unsigned int nlink)
367 {
368 if (!nlink) {
369 clear_nlink(inode);
370 } else {
371 /* Yes, some filesystems do change nlink from zero to one */
372 if (inode->i_nlink == 0)
373 atomic_long_dec(&inode->i_sb->s_remove_count);
374
375 inode->__i_nlink = nlink;
376 }
377 }
378 EXPORT_SYMBOL(set_nlink);
379
380 /**
381 * inc_nlink - directly increment an inode's link count
382 * @inode: inode
383 *
384 * This is a low-level filesystem helper to replace any
385 * direct filesystem manipulation of i_nlink. Currently,
386 * it is only here for parity with dec_nlink().
387 */
inc_nlink(struct inode * inode)388 void inc_nlink(struct inode *inode)
389 {
390 if (unlikely(inode->i_nlink == 0)) {
391 WARN_ON(!(inode->i_state & I_LINKABLE));
392 atomic_long_dec(&inode->i_sb->s_remove_count);
393 }
394
395 inode->__i_nlink++;
396 }
397 EXPORT_SYMBOL(inc_nlink);
398
__address_space_init_once(struct address_space * mapping)399 static void __address_space_init_once(struct address_space *mapping)
400 {
401 xa_init_flags(&mapping->i_pages, XA_FLAGS_LOCK_IRQ | XA_FLAGS_ACCOUNT);
402 init_rwsem(&mapping->i_mmap_rwsem);
403 INIT_LIST_HEAD(&mapping->i_private_list);
404 spin_lock_init(&mapping->i_private_lock);
405 mapping->i_mmap = RB_ROOT_CACHED;
406 }
407
address_space_init_once(struct address_space * mapping)408 void address_space_init_once(struct address_space *mapping)
409 {
410 memset(mapping, 0, sizeof(*mapping));
411 __address_space_init_once(mapping);
412 }
413 EXPORT_SYMBOL(address_space_init_once);
414
415 /*
416 * These are initializations that only need to be done
417 * once, because the fields are idempotent across use
418 * of the inode, so let the slab aware of that.
419 */
inode_init_once(struct inode * inode)420 void inode_init_once(struct inode *inode)
421 {
422 memset(inode, 0, sizeof(*inode));
423 INIT_HLIST_NODE(&inode->i_hash);
424 INIT_LIST_HEAD(&inode->i_devices);
425 INIT_LIST_HEAD(&inode->i_io_list);
426 INIT_LIST_HEAD(&inode->i_wb_list);
427 INIT_LIST_HEAD(&inode->i_lru);
428 INIT_LIST_HEAD(&inode->i_sb_list);
429 __address_space_init_once(&inode->i_data);
430 i_size_ordered_init(inode);
431 }
432 EXPORT_SYMBOL(inode_init_once);
433
init_once(void * foo)434 static void init_once(void *foo)
435 {
436 struct inode *inode = (struct inode *) foo;
437
438 inode_init_once(inode);
439 }
440
441 /*
442 * inode->i_lock must be held
443 */
__iget(struct inode * inode)444 void __iget(struct inode *inode)
445 {
446 atomic_inc(&inode->i_count);
447 }
448
449 /*
450 * get additional reference to inode; caller must already hold one.
451 */
ihold(struct inode * inode)452 void ihold(struct inode *inode)
453 {
454 WARN_ON(atomic_inc_return(&inode->i_count) < 2);
455 }
456 EXPORT_SYMBOL(ihold);
457
__inode_add_lru(struct inode * inode,bool rotate)458 static void __inode_add_lru(struct inode *inode, bool rotate)
459 {
460 if (inode->i_state & (I_DIRTY_ALL | I_SYNC | I_FREEING | I_WILL_FREE))
461 return;
462 if (atomic_read(&inode->i_count))
463 return;
464 if (!(inode->i_sb->s_flags & SB_ACTIVE))
465 return;
466 if (!mapping_shrinkable(&inode->i_data))
467 return;
468
469 if (list_lru_add_obj(&inode->i_sb->s_inode_lru, &inode->i_lru))
470 this_cpu_inc(nr_unused);
471 else if (rotate)
472 inode->i_state |= I_REFERENCED;
473 }
474
inode_bit_waitqueue(struct wait_bit_queue_entry * wqe,struct inode * inode,u32 bit)475 struct wait_queue_head *inode_bit_waitqueue(struct wait_bit_queue_entry *wqe,
476 struct inode *inode, u32 bit)
477 {
478 void *bit_address;
479
480 bit_address = inode_state_wait_address(inode, bit);
481 init_wait_var_entry(wqe, bit_address, 0);
482 return __var_waitqueue(bit_address);
483 }
484 EXPORT_SYMBOL(inode_bit_waitqueue);
485
486 /*
487 * Add inode to LRU if needed (inode is unused and clean).
488 *
489 * Needs inode->i_lock held.
490 */
inode_add_lru(struct inode * inode)491 void inode_add_lru(struct inode *inode)
492 {
493 __inode_add_lru(inode, false);
494 }
495
inode_lru_list_del(struct inode * inode)496 static void inode_lru_list_del(struct inode *inode)
497 {
498 if (list_lru_del_obj(&inode->i_sb->s_inode_lru, &inode->i_lru))
499 this_cpu_dec(nr_unused);
500 }
501
inode_pin_lru_isolating(struct inode * inode)502 static void inode_pin_lru_isolating(struct inode *inode)
503 {
504 lockdep_assert_held(&inode->i_lock);
505 WARN_ON(inode->i_state & (I_LRU_ISOLATING | I_FREEING | I_WILL_FREE));
506 inode->i_state |= I_LRU_ISOLATING;
507 }
508
inode_unpin_lru_isolating(struct inode * inode)509 static void inode_unpin_lru_isolating(struct inode *inode)
510 {
511 spin_lock(&inode->i_lock);
512 WARN_ON(!(inode->i_state & I_LRU_ISOLATING));
513 inode->i_state &= ~I_LRU_ISOLATING;
514 /* Called with inode->i_lock which ensures memory ordering. */
515 inode_wake_up_bit(inode, __I_LRU_ISOLATING);
516 spin_unlock(&inode->i_lock);
517 }
518
inode_wait_for_lru_isolating(struct inode * inode)519 static void inode_wait_for_lru_isolating(struct inode *inode)
520 {
521 struct wait_bit_queue_entry wqe;
522 struct wait_queue_head *wq_head;
523
524 lockdep_assert_held(&inode->i_lock);
525 if (!(inode->i_state & I_LRU_ISOLATING))
526 return;
527
528 wq_head = inode_bit_waitqueue(&wqe, inode, __I_LRU_ISOLATING);
529 for (;;) {
530 prepare_to_wait_event(wq_head, &wqe.wq_entry, TASK_UNINTERRUPTIBLE);
531 /*
532 * Checking I_LRU_ISOLATING with inode->i_lock guarantees
533 * memory ordering.
534 */
535 if (!(inode->i_state & I_LRU_ISOLATING))
536 break;
537 spin_unlock(&inode->i_lock);
538 schedule();
539 spin_lock(&inode->i_lock);
540 }
541 finish_wait(wq_head, &wqe.wq_entry);
542 WARN_ON(inode->i_state & I_LRU_ISOLATING);
543 }
544
545 /**
546 * inode_sb_list_add - add inode to the superblock list of inodes
547 * @inode: inode to add
548 */
inode_sb_list_add(struct inode * inode)549 void inode_sb_list_add(struct inode *inode)
550 {
551 spin_lock(&inode->i_sb->s_inode_list_lock);
552 list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
553 spin_unlock(&inode->i_sb->s_inode_list_lock);
554 }
555 EXPORT_SYMBOL_GPL(inode_sb_list_add);
556
inode_sb_list_del(struct inode * inode)557 static inline void inode_sb_list_del(struct inode *inode)
558 {
559 if (!list_empty(&inode->i_sb_list)) {
560 spin_lock(&inode->i_sb->s_inode_list_lock);
561 list_del_init(&inode->i_sb_list);
562 spin_unlock(&inode->i_sb->s_inode_list_lock);
563 }
564 }
565
hash(struct super_block * sb,unsigned long hashval)566 static unsigned long hash(struct super_block *sb, unsigned long hashval)
567 {
568 unsigned long tmp;
569
570 tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
571 L1_CACHE_BYTES;
572 tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
573 return tmp & i_hash_mask;
574 }
575
576 /**
577 * __insert_inode_hash - hash an inode
578 * @inode: unhashed inode
579 * @hashval: unsigned long value used to locate this object in the
580 * inode_hashtable.
581 *
582 * Add an inode to the inode hash for this superblock.
583 */
__insert_inode_hash(struct inode * inode,unsigned long hashval)584 void __insert_inode_hash(struct inode *inode, unsigned long hashval)
585 {
586 struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
587
588 spin_lock(&inode_hash_lock);
589 spin_lock(&inode->i_lock);
590 hlist_add_head_rcu(&inode->i_hash, b);
591 spin_unlock(&inode->i_lock);
592 spin_unlock(&inode_hash_lock);
593 }
594 EXPORT_SYMBOL(__insert_inode_hash);
595
596 /**
597 * __remove_inode_hash - remove an inode from the hash
598 * @inode: inode to unhash
599 *
600 * Remove an inode from the superblock.
601 */
__remove_inode_hash(struct inode * inode)602 void __remove_inode_hash(struct inode *inode)
603 {
604 spin_lock(&inode_hash_lock);
605 spin_lock(&inode->i_lock);
606 hlist_del_init_rcu(&inode->i_hash);
607 spin_unlock(&inode->i_lock);
608 spin_unlock(&inode_hash_lock);
609 }
610 EXPORT_SYMBOL(__remove_inode_hash);
611
dump_mapping(const struct address_space * mapping)612 void dump_mapping(const struct address_space *mapping)
613 {
614 struct inode *host;
615 const struct address_space_operations *a_ops;
616 struct hlist_node *dentry_first;
617 struct dentry *dentry_ptr;
618 struct dentry dentry;
619 char fname[64] = {};
620 unsigned long ino;
621
622 /*
623 * If mapping is an invalid pointer, we don't want to crash
624 * accessing it, so probe everything depending on it carefully.
625 */
626 if (get_kernel_nofault(host, &mapping->host) ||
627 get_kernel_nofault(a_ops, &mapping->a_ops)) {
628 pr_warn("invalid mapping:%px\n", mapping);
629 return;
630 }
631
632 if (!host) {
633 pr_warn("aops:%ps\n", a_ops);
634 return;
635 }
636
637 if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
638 get_kernel_nofault(ino, &host->i_ino)) {
639 pr_warn("aops:%ps invalid inode:%px\n", a_ops, host);
640 return;
641 }
642
643 if (!dentry_first) {
644 pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
645 return;
646 }
647
648 dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
649 if (get_kernel_nofault(dentry, dentry_ptr) ||
650 !dentry.d_parent || !dentry.d_name.name) {
651 pr_warn("aops:%ps ino:%lx invalid dentry:%px\n",
652 a_ops, ino, dentry_ptr);
653 return;
654 }
655
656 if (strncpy_from_kernel_nofault(fname, dentry.d_name.name, 63) < 0)
657 strscpy(fname, "<invalid>");
658 /*
659 * Even if strncpy_from_kernel_nofault() succeeded,
660 * the fname could be unreliable
661 */
662 pr_warn("aops:%ps ino:%lx dentry name(?):\"%s\"\n",
663 a_ops, ino, fname);
664 }
665
clear_inode(struct inode * inode)666 void clear_inode(struct inode *inode)
667 {
668 /*
669 * We have to cycle the i_pages lock here because reclaim can be in the
670 * process of removing the last page (in __filemap_remove_folio())
671 * and we must not free the mapping under it.
672 */
673 xa_lock_irq(&inode->i_data.i_pages);
674 BUG_ON(inode->i_data.nrpages);
675 /*
676 * Almost always, mapping_empty(&inode->i_data) here; but there are
677 * two known and long-standing ways in which nodes may get left behind
678 * (when deep radix-tree node allocation failed partway; or when THP
679 * collapse_file() failed). Until those two known cases are cleaned up,
680 * or a cleanup function is called here, do not BUG_ON(!mapping_empty),
681 * nor even WARN_ON(!mapping_empty).
682 */
683 xa_unlock_irq(&inode->i_data.i_pages);
684 BUG_ON(!list_empty(&inode->i_data.i_private_list));
685 BUG_ON(!(inode->i_state & I_FREEING));
686 BUG_ON(inode->i_state & I_CLEAR);
687 BUG_ON(!list_empty(&inode->i_wb_list));
688 /* don't need i_lock here, no concurrent mods to i_state */
689 inode->i_state = I_FREEING | I_CLEAR;
690 }
691 EXPORT_SYMBOL(clear_inode);
692
693 /*
694 * Free the inode passed in, removing it from the lists it is still connected
695 * to. We remove any pages still attached to the inode and wait for any IO that
696 * is still in progress before finally destroying the inode.
697 *
698 * An inode must already be marked I_FREEING so that we avoid the inode being
699 * moved back onto lists if we race with other code that manipulates the lists
700 * (e.g. writeback_single_inode). The caller is responsible for setting this.
701 *
702 * An inode must already be removed from the LRU list before being evicted from
703 * the cache. This should occur atomically with setting the I_FREEING state
704 * flag, so no inodes here should ever be on the LRU when being evicted.
705 */
evict(struct inode * inode)706 static void evict(struct inode *inode)
707 {
708 const struct super_operations *op = inode->i_sb->s_op;
709
710 BUG_ON(!(inode->i_state & I_FREEING));
711 BUG_ON(!list_empty(&inode->i_lru));
712
713 if (!list_empty(&inode->i_io_list))
714 inode_io_list_del(inode);
715
716 inode_sb_list_del(inode);
717
718 spin_lock(&inode->i_lock);
719 inode_wait_for_lru_isolating(inode);
720
721 /*
722 * Wait for flusher thread to be done with the inode so that filesystem
723 * does not start destroying it while writeback is still running. Since
724 * the inode has I_FREEING set, flusher thread won't start new work on
725 * the inode. We just have to wait for running writeback to finish.
726 */
727 inode_wait_for_writeback(inode);
728 spin_unlock(&inode->i_lock);
729
730 if (op->evict_inode) {
731 op->evict_inode(inode);
732 } else {
733 truncate_inode_pages_final(&inode->i_data);
734 clear_inode(inode);
735 }
736 if (S_ISCHR(inode->i_mode) && inode->i_cdev)
737 cd_forget(inode);
738
739 remove_inode_hash(inode);
740
741 /*
742 * Wake up waiters in __wait_on_freeing_inode().
743 *
744 * Lockless hash lookup may end up finding the inode before we removed
745 * it above, but only lock it *after* we are done with the wakeup below.
746 * In this case the potential waiter cannot safely block.
747 *
748 * The inode being unhashed after the call to remove_inode_hash() is
749 * used as an indicator whether blocking on it is safe.
750 */
751 spin_lock(&inode->i_lock);
752 /*
753 * Pairs with the barrier in prepare_to_wait_event() to make sure
754 * ___wait_var_event() either sees the bit cleared or
755 * waitqueue_active() check in wake_up_var() sees the waiter.
756 */
757 smp_mb();
758 inode_wake_up_bit(inode, __I_NEW);
759 BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
760 spin_unlock(&inode->i_lock);
761
762 destroy_inode(inode);
763 }
764
765 /*
766 * dispose_list - dispose of the contents of a local list
767 * @head: the head of the list to free
768 *
769 * Dispose-list gets a local list with local inodes in it, so it doesn't
770 * need to worry about list corruption and SMP locks.
771 */
dispose_list(struct list_head * head)772 static void dispose_list(struct list_head *head)
773 {
774 while (!list_empty(head)) {
775 struct inode *inode;
776
777 inode = list_first_entry(head, struct inode, i_lru);
778 list_del_init(&inode->i_lru);
779
780 evict(inode);
781 cond_resched();
782 }
783 }
784
785 /**
786 * evict_inodes - evict all evictable inodes for a superblock
787 * @sb: superblock to operate on
788 *
789 * Make sure that no inodes with zero refcount are retained. This is
790 * called by superblock shutdown after having SB_ACTIVE flag removed,
791 * so any inode reaching zero refcount during or after that call will
792 * be immediately evicted.
793 */
evict_inodes(struct super_block * sb)794 void evict_inodes(struct super_block *sb)
795 {
796 struct inode *inode, *next;
797 LIST_HEAD(dispose);
798
799 again:
800 spin_lock(&sb->s_inode_list_lock);
801 list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
802 if (atomic_read(&inode->i_count))
803 continue;
804
805 spin_lock(&inode->i_lock);
806 if (atomic_read(&inode->i_count)) {
807 spin_unlock(&inode->i_lock);
808 continue;
809 }
810 if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
811 spin_unlock(&inode->i_lock);
812 continue;
813 }
814
815 inode->i_state |= I_FREEING;
816 inode_lru_list_del(inode);
817 spin_unlock(&inode->i_lock);
818 list_add(&inode->i_lru, &dispose);
819
820 /*
821 * We can have a ton of inodes to evict at unmount time given
822 * enough memory, check to see if we need to go to sleep for a
823 * bit so we don't livelock.
824 */
825 if (need_resched()) {
826 spin_unlock(&sb->s_inode_list_lock);
827 cond_resched();
828 dispose_list(&dispose);
829 goto again;
830 }
831 }
832 spin_unlock(&sb->s_inode_list_lock);
833
834 dispose_list(&dispose);
835 }
836 EXPORT_SYMBOL_GPL(evict_inodes);
837
838 /**
839 * invalidate_inodes - attempt to free all inodes on a superblock
840 * @sb: superblock to operate on
841 *
842 * Attempts to free all inodes (including dirty inodes) for a given superblock.
843 */
invalidate_inodes(struct super_block * sb)844 void invalidate_inodes(struct super_block *sb)
845 {
846 struct inode *inode, *next;
847 LIST_HEAD(dispose);
848
849 again:
850 spin_lock(&sb->s_inode_list_lock);
851 list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
852 spin_lock(&inode->i_lock);
853 if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
854 spin_unlock(&inode->i_lock);
855 continue;
856 }
857 if (atomic_read(&inode->i_count)) {
858 spin_unlock(&inode->i_lock);
859 continue;
860 }
861
862 inode->i_state |= I_FREEING;
863 inode_lru_list_del(inode);
864 spin_unlock(&inode->i_lock);
865 list_add(&inode->i_lru, &dispose);
866 if (need_resched()) {
867 spin_unlock(&sb->s_inode_list_lock);
868 cond_resched();
869 dispose_list(&dispose);
870 goto again;
871 }
872 }
873 spin_unlock(&sb->s_inode_list_lock);
874
875 dispose_list(&dispose);
876 }
877
878 /*
879 * Isolate the inode from the LRU in preparation for freeing it.
880 *
881 * If the inode has the I_REFERENCED flag set, then it means that it has been
882 * used recently - the flag is set in iput_final(). When we encounter such an
883 * inode, clear the flag and move it to the back of the LRU so it gets another
884 * pass through the LRU before it gets reclaimed. This is necessary because of
885 * the fact we are doing lazy LRU updates to minimise lock contention so the
886 * LRU does not have strict ordering. Hence we don't want to reclaim inodes
887 * with this flag set because they are the inodes that are out of order.
888 */
inode_lru_isolate(struct list_head * item,struct list_lru_one * lru,spinlock_t * lru_lock,void * arg)889 static enum lru_status inode_lru_isolate(struct list_head *item,
890 struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
891 {
892 struct list_head *freeable = arg;
893 struct inode *inode = container_of(item, struct inode, i_lru);
894
895 /*
896 * We are inverting the lru lock/inode->i_lock here, so use a
897 * trylock. If we fail to get the lock, just skip it.
898 */
899 if (!spin_trylock(&inode->i_lock))
900 return LRU_SKIP;
901
902 /*
903 * Inodes can get referenced, redirtied, or repopulated while
904 * they're already on the LRU, and this can make them
905 * unreclaimable for a while. Remove them lazily here; iput,
906 * sync, or the last page cache deletion will requeue them.
907 */
908 if (atomic_read(&inode->i_count) ||
909 (inode->i_state & ~I_REFERENCED) ||
910 !mapping_shrinkable(&inode->i_data)) {
911 list_lru_isolate(lru, &inode->i_lru);
912 spin_unlock(&inode->i_lock);
913 this_cpu_dec(nr_unused);
914 return LRU_REMOVED;
915 }
916
917 /* Recently referenced inodes get one more pass */
918 if (inode->i_state & I_REFERENCED) {
919 inode->i_state &= ~I_REFERENCED;
920 spin_unlock(&inode->i_lock);
921 return LRU_ROTATE;
922 }
923
924 /*
925 * On highmem systems, mapping_shrinkable() permits dropping
926 * page cache in order to free up struct inodes: lowmem might
927 * be under pressure before the cache inside the highmem zone.
928 */
929 if (inode_has_buffers(inode) || !mapping_empty(&inode->i_data)) {
930 inode_pin_lru_isolating(inode);
931 spin_unlock(&inode->i_lock);
932 spin_unlock(lru_lock);
933 if (remove_inode_buffers(inode)) {
934 unsigned long reap;
935 reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
936 if (current_is_kswapd())
937 __count_vm_events(KSWAPD_INODESTEAL, reap);
938 else
939 __count_vm_events(PGINODESTEAL, reap);
940 mm_account_reclaimed_pages(reap);
941 }
942 inode_unpin_lru_isolating(inode);
943 spin_lock(lru_lock);
944 return LRU_RETRY;
945 }
946
947 WARN_ON(inode->i_state & I_NEW);
948 inode->i_state |= I_FREEING;
949 list_lru_isolate_move(lru, &inode->i_lru, freeable);
950 spin_unlock(&inode->i_lock);
951
952 this_cpu_dec(nr_unused);
953 return LRU_REMOVED;
954 }
955
956 /*
957 * Walk the superblock inode LRU for freeable inodes and attempt to free them.
958 * This is called from the superblock shrinker function with a number of inodes
959 * to trim from the LRU. Inodes to be freed are moved to a temporary list and
960 * then are freed outside inode_lock by dispose_list().
961 */
prune_icache_sb(struct super_block * sb,struct shrink_control * sc)962 long prune_icache_sb(struct super_block *sb, struct shrink_control *sc)
963 {
964 LIST_HEAD(freeable);
965 long freed;
966
967 freed = list_lru_shrink_walk(&sb->s_inode_lru, sc,
968 inode_lru_isolate, &freeable);
969 dispose_list(&freeable);
970 return freed;
971 }
972
973 static void __wait_on_freeing_inode(struct inode *inode, bool is_inode_hash_locked);
974 /*
975 * Called with the inode lock held.
976 */
find_inode(struct super_block * sb,struct hlist_head * head,int (* test)(struct inode *,void *),void * data,bool is_inode_hash_locked)977 static struct inode *find_inode(struct super_block *sb,
978 struct hlist_head *head,
979 int (*test)(struct inode *, void *),
980 void *data, bool is_inode_hash_locked)
981 {
982 struct inode *inode = NULL;
983
984 if (is_inode_hash_locked)
985 lockdep_assert_held(&inode_hash_lock);
986 else
987 lockdep_assert_not_held(&inode_hash_lock);
988
989 rcu_read_lock();
990 repeat:
991 hlist_for_each_entry_rcu(inode, head, i_hash) {
992 if (inode->i_sb != sb)
993 continue;
994 if (!test(inode, data))
995 continue;
996 spin_lock(&inode->i_lock);
997 if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
998 __wait_on_freeing_inode(inode, is_inode_hash_locked);
999 goto repeat;
1000 }
1001 if (unlikely(inode->i_state & I_CREATING)) {
1002 spin_unlock(&inode->i_lock);
1003 rcu_read_unlock();
1004 return ERR_PTR(-ESTALE);
1005 }
1006 __iget(inode);
1007 spin_unlock(&inode->i_lock);
1008 rcu_read_unlock();
1009 return inode;
1010 }
1011 rcu_read_unlock();
1012 return NULL;
1013 }
1014
1015 /*
1016 * find_inode_fast is the fast path version of find_inode, see the comment at
1017 * iget_locked for details.
1018 */
find_inode_fast(struct super_block * sb,struct hlist_head * head,unsigned long ino,bool is_inode_hash_locked)1019 static struct inode *find_inode_fast(struct super_block *sb,
1020 struct hlist_head *head, unsigned long ino,
1021 bool is_inode_hash_locked)
1022 {
1023 struct inode *inode = NULL;
1024
1025 if (is_inode_hash_locked)
1026 lockdep_assert_held(&inode_hash_lock);
1027 else
1028 lockdep_assert_not_held(&inode_hash_lock);
1029
1030 rcu_read_lock();
1031 repeat:
1032 hlist_for_each_entry_rcu(inode, head, i_hash) {
1033 if (inode->i_ino != ino)
1034 continue;
1035 if (inode->i_sb != sb)
1036 continue;
1037 spin_lock(&inode->i_lock);
1038 if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
1039 __wait_on_freeing_inode(inode, is_inode_hash_locked);
1040 goto repeat;
1041 }
1042 if (unlikely(inode->i_state & I_CREATING)) {
1043 spin_unlock(&inode->i_lock);
1044 rcu_read_unlock();
1045 return ERR_PTR(-ESTALE);
1046 }
1047 __iget(inode);
1048 spin_unlock(&inode->i_lock);
1049 rcu_read_unlock();
1050 return inode;
1051 }
1052 rcu_read_unlock();
1053 return NULL;
1054 }
1055
1056 /*
1057 * Each cpu owns a range of LAST_INO_BATCH numbers.
1058 * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
1059 * to renew the exhausted range.
1060 *
1061 * This does not significantly increase overflow rate because every CPU can
1062 * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
1063 * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
1064 * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
1065 * overflow rate by 2x, which does not seem too significant.
1066 *
1067 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1068 * error if st_ino won't fit in target struct field. Use 32bit counter
1069 * here to attempt to avoid that.
1070 */
1071 #define LAST_INO_BATCH 1024
1072 static DEFINE_PER_CPU(unsigned int, last_ino);
1073
get_next_ino(void)1074 unsigned int get_next_ino(void)
1075 {
1076 unsigned int *p = &get_cpu_var(last_ino);
1077 unsigned int res = *p;
1078
1079 #ifdef CONFIG_SMP
1080 if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
1081 static atomic_t shared_last_ino;
1082 int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
1083
1084 res = next - LAST_INO_BATCH;
1085 }
1086 #endif
1087
1088 res++;
1089 /* get_next_ino should not provide a 0 inode number */
1090 if (unlikely(!res))
1091 res++;
1092 *p = res;
1093 put_cpu_var(last_ino);
1094 return res;
1095 }
1096 EXPORT_SYMBOL(get_next_ino);
1097
1098 /**
1099 * new_inode_pseudo - obtain an inode
1100 * @sb: superblock
1101 *
1102 * Allocates a new inode for given superblock.
1103 * Inode wont be chained in superblock s_inodes list
1104 * This means :
1105 * - fs can't be unmount
1106 * - quotas, fsnotify, writeback can't work
1107 */
new_inode_pseudo(struct super_block * sb)1108 struct inode *new_inode_pseudo(struct super_block *sb)
1109 {
1110 return alloc_inode(sb);
1111 }
1112
1113 /**
1114 * new_inode - obtain an inode
1115 * @sb: superblock
1116 *
1117 * Allocates a new inode for given superblock. The default gfp_mask
1118 * for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
1119 * If HIGHMEM pages are unsuitable or it is known that pages allocated
1120 * for the page cache are not reclaimable or migratable,
1121 * mapping_set_gfp_mask() must be called with suitable flags on the
1122 * newly created inode's mapping
1123 *
1124 */
new_inode(struct super_block * sb)1125 struct inode *new_inode(struct super_block *sb)
1126 {
1127 struct inode *inode;
1128
1129 inode = new_inode_pseudo(sb);
1130 if (inode)
1131 inode_sb_list_add(inode);
1132 return inode;
1133 }
1134 EXPORT_SYMBOL(new_inode);
1135
1136 #ifdef CONFIG_DEBUG_LOCK_ALLOC
lockdep_annotate_inode_mutex_key(struct inode * inode)1137 void lockdep_annotate_inode_mutex_key(struct inode *inode)
1138 {
1139 if (S_ISDIR(inode->i_mode)) {
1140 struct file_system_type *type = inode->i_sb->s_type;
1141
1142 /* Set new key only if filesystem hasn't already changed it */
1143 if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) {
1144 /*
1145 * ensure nobody is actually holding i_mutex
1146 */
1147 // mutex_destroy(&inode->i_mutex);
1148 init_rwsem(&inode->i_rwsem);
1149 lockdep_set_class(&inode->i_rwsem,
1150 &type->i_mutex_dir_key);
1151 }
1152 }
1153 }
1154 EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
1155 #endif
1156
1157 /**
1158 * unlock_new_inode - clear the I_NEW state and wake up any waiters
1159 * @inode: new inode to unlock
1160 *
1161 * Called when the inode is fully initialised to clear the new state of the
1162 * inode and wake up anyone waiting for the inode to finish initialisation.
1163 */
unlock_new_inode(struct inode * inode)1164 void unlock_new_inode(struct inode *inode)
1165 {
1166 lockdep_annotate_inode_mutex_key(inode);
1167 spin_lock(&inode->i_lock);
1168 WARN_ON(!(inode->i_state & I_NEW));
1169 inode->i_state &= ~I_NEW & ~I_CREATING;
1170 /*
1171 * Pairs with the barrier in prepare_to_wait_event() to make sure
1172 * ___wait_var_event() either sees the bit cleared or
1173 * waitqueue_active() check in wake_up_var() sees the waiter.
1174 */
1175 smp_mb();
1176 inode_wake_up_bit(inode, __I_NEW);
1177 spin_unlock(&inode->i_lock);
1178 }
1179 EXPORT_SYMBOL(unlock_new_inode);
1180
discard_new_inode(struct inode * inode)1181 void discard_new_inode(struct inode *inode)
1182 {
1183 lockdep_annotate_inode_mutex_key(inode);
1184 spin_lock(&inode->i_lock);
1185 WARN_ON(!(inode->i_state & I_NEW));
1186 inode->i_state &= ~I_NEW;
1187 /*
1188 * Pairs with the barrier in prepare_to_wait_event() to make sure
1189 * ___wait_var_event() either sees the bit cleared or
1190 * waitqueue_active() check in wake_up_var() sees the waiter.
1191 */
1192 smp_mb();
1193 inode_wake_up_bit(inode, __I_NEW);
1194 spin_unlock(&inode->i_lock);
1195 iput(inode);
1196 }
1197 EXPORT_SYMBOL(discard_new_inode);
1198
1199 /**
1200 * lock_two_nondirectories - take two i_mutexes on non-directory objects
1201 *
1202 * Lock any non-NULL argument. Passed objects must not be directories.
1203 * Zero, one or two objects may be locked by this function.
1204 *
1205 * @inode1: first inode to lock
1206 * @inode2: second inode to lock
1207 */
lock_two_nondirectories(struct inode * inode1,struct inode * inode2)1208 void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1209 {
1210 if (inode1)
1211 WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
1212 if (inode2)
1213 WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
1214 if (inode1 > inode2)
1215 swap(inode1, inode2);
1216 if (inode1)
1217 inode_lock(inode1);
1218 if (inode2 && inode2 != inode1)
1219 inode_lock_nested(inode2, I_MUTEX_NONDIR2);
1220 }
1221 EXPORT_SYMBOL(lock_two_nondirectories);
1222
1223 /**
1224 * unlock_two_nondirectories - release locks from lock_two_nondirectories()
1225 * @inode1: first inode to unlock
1226 * @inode2: second inode to unlock
1227 */
unlock_two_nondirectories(struct inode * inode1,struct inode * inode2)1228 void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
1229 {
1230 if (inode1) {
1231 WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
1232 inode_unlock(inode1);
1233 }
1234 if (inode2 && inode2 != inode1) {
1235 WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
1236 inode_unlock(inode2);
1237 }
1238 }
1239 EXPORT_SYMBOL(unlock_two_nondirectories);
1240
1241 /**
1242 * inode_insert5 - obtain an inode from a mounted file system
1243 * @inode: pre-allocated inode to use for insert to cache
1244 * @hashval: hash value (usually inode number) to get
1245 * @test: callback used for comparisons between inodes
1246 * @set: callback used to initialize a new struct inode
1247 * @data: opaque data pointer to pass to @test and @set
1248 *
1249 * Search for the inode specified by @hashval and @data in the inode cache,
1250 * and if present it is return it with an increased reference count. This is
1251 * a variant of iget5_locked() for callers that don't want to fail on memory
1252 * allocation of inode.
1253 *
1254 * If the inode is not in cache, insert the pre-allocated inode to cache and
1255 * return it locked, hashed, and with the I_NEW flag set. The file system gets
1256 * to fill it in before unlocking it via unlock_new_inode().
1257 *
1258 * Note both @test and @set are called with the inode_hash_lock held, so can't
1259 * sleep.
1260 */
inode_insert5(struct inode * inode,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1261 struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
1262 int (*test)(struct inode *, void *),
1263 int (*set)(struct inode *, void *), void *data)
1264 {
1265 struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
1266 struct inode *old;
1267
1268 again:
1269 spin_lock(&inode_hash_lock);
1270 old = find_inode(inode->i_sb, head, test, data, true);
1271 if (unlikely(old)) {
1272 /*
1273 * Uhhuh, somebody else created the same inode under us.
1274 * Use the old inode instead of the preallocated one.
1275 */
1276 spin_unlock(&inode_hash_lock);
1277 if (IS_ERR(old))
1278 return NULL;
1279 wait_on_inode(old);
1280 if (unlikely(inode_unhashed(old))) {
1281 iput(old);
1282 goto again;
1283 }
1284 return old;
1285 }
1286
1287 if (set && unlikely(set(inode, data))) {
1288 inode = NULL;
1289 goto unlock;
1290 }
1291
1292 /*
1293 * Return the locked inode with I_NEW set, the
1294 * caller is responsible for filling in the contents
1295 */
1296 spin_lock(&inode->i_lock);
1297 inode->i_state |= I_NEW;
1298 hlist_add_head_rcu(&inode->i_hash, head);
1299 spin_unlock(&inode->i_lock);
1300
1301 /*
1302 * Add inode to the sb list if it's not already. It has I_NEW at this
1303 * point, so it should be safe to test i_sb_list locklessly.
1304 */
1305 if (list_empty(&inode->i_sb_list))
1306 inode_sb_list_add(inode);
1307 unlock:
1308 spin_unlock(&inode_hash_lock);
1309
1310 return inode;
1311 }
1312 EXPORT_SYMBOL(inode_insert5);
1313
1314 /**
1315 * iget5_locked - obtain an inode from a mounted file system
1316 * @sb: super block of file system
1317 * @hashval: hash value (usually inode number) to get
1318 * @test: callback used for comparisons between inodes
1319 * @set: callback used to initialize a new struct inode
1320 * @data: opaque data pointer to pass to @test and @set
1321 *
1322 * Search for the inode specified by @hashval and @data in the inode cache,
1323 * and if present it is return it with an increased reference count. This is
1324 * a generalized version of iget_locked() for file systems where the inode
1325 * number is not sufficient for unique identification of an inode.
1326 *
1327 * If the inode is not in cache, allocate a new inode and return it locked,
1328 * hashed, and with the I_NEW flag set. The file system gets to fill it in
1329 * before unlocking it via unlock_new_inode().
1330 *
1331 * Note both @test and @set are called with the inode_hash_lock held, so can't
1332 * sleep.
1333 */
iget5_locked(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1334 struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1335 int (*test)(struct inode *, void *),
1336 int (*set)(struct inode *, void *), void *data)
1337 {
1338 struct inode *inode = ilookup5(sb, hashval, test, data);
1339
1340 if (!inode) {
1341 struct inode *new = alloc_inode(sb);
1342
1343 if (new) {
1344 inode = inode_insert5(new, hashval, test, set, data);
1345 if (unlikely(inode != new))
1346 destroy_inode(new);
1347 }
1348 }
1349 return inode;
1350 }
1351 EXPORT_SYMBOL(iget5_locked);
1352
1353 /**
1354 * iget5_locked_rcu - obtain an inode from a mounted file system
1355 * @sb: super block of file system
1356 * @hashval: hash value (usually inode number) to get
1357 * @test: callback used for comparisons between inodes
1358 * @set: callback used to initialize a new struct inode
1359 * @data: opaque data pointer to pass to @test and @set
1360 *
1361 * This is equivalent to iget5_locked, except the @test callback must
1362 * tolerate the inode not being stable, including being mid-teardown.
1363 */
iget5_locked_rcu(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),int (* set)(struct inode *,void *),void * data)1364 struct inode *iget5_locked_rcu(struct super_block *sb, unsigned long hashval,
1365 int (*test)(struct inode *, void *),
1366 int (*set)(struct inode *, void *), void *data)
1367 {
1368 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1369 struct inode *inode, *new;
1370
1371 again:
1372 inode = find_inode(sb, head, test, data, false);
1373 if (inode) {
1374 if (IS_ERR(inode))
1375 return NULL;
1376 wait_on_inode(inode);
1377 if (unlikely(inode_unhashed(inode))) {
1378 iput(inode);
1379 goto again;
1380 }
1381 return inode;
1382 }
1383
1384 new = alloc_inode(sb);
1385 if (new) {
1386 inode = inode_insert5(new, hashval, test, set, data);
1387 if (unlikely(inode != new))
1388 destroy_inode(new);
1389 }
1390 return inode;
1391 }
1392 EXPORT_SYMBOL_GPL(iget5_locked_rcu);
1393
1394 /**
1395 * iget_locked - obtain an inode from a mounted file system
1396 * @sb: super block of file system
1397 * @ino: inode number to get
1398 *
1399 * Search for the inode specified by @ino in the inode cache and if present
1400 * return it with an increased reference count. This is for file systems
1401 * where the inode number is sufficient for unique identification of an inode.
1402 *
1403 * If the inode is not in cache, allocate a new inode and return it locked,
1404 * hashed, and with the I_NEW flag set. The file system gets to fill it in
1405 * before unlocking it via unlock_new_inode().
1406 */
iget_locked(struct super_block * sb,unsigned long ino)1407 struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1408 {
1409 struct hlist_head *head = inode_hashtable + hash(sb, ino);
1410 struct inode *inode;
1411 again:
1412 inode = find_inode_fast(sb, head, ino, false);
1413 if (inode) {
1414 if (IS_ERR(inode))
1415 return NULL;
1416 wait_on_inode(inode);
1417 if (unlikely(inode_unhashed(inode))) {
1418 iput(inode);
1419 goto again;
1420 }
1421 return inode;
1422 }
1423
1424 inode = alloc_inode(sb);
1425 if (inode) {
1426 struct inode *old;
1427
1428 spin_lock(&inode_hash_lock);
1429 /* We released the lock, so.. */
1430 old = find_inode_fast(sb, head, ino, true);
1431 if (!old) {
1432 inode->i_ino = ino;
1433 spin_lock(&inode->i_lock);
1434 inode->i_state = I_NEW;
1435 hlist_add_head_rcu(&inode->i_hash, head);
1436 spin_unlock(&inode->i_lock);
1437 inode_sb_list_add(inode);
1438 spin_unlock(&inode_hash_lock);
1439
1440 /* Return the locked inode with I_NEW set, the
1441 * caller is responsible for filling in the contents
1442 */
1443 return inode;
1444 }
1445
1446 /*
1447 * Uhhuh, somebody else created the same inode under
1448 * us. Use the old inode instead of the one we just
1449 * allocated.
1450 */
1451 spin_unlock(&inode_hash_lock);
1452 destroy_inode(inode);
1453 if (IS_ERR(old))
1454 return NULL;
1455 inode = old;
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(iget_locked);
1465
1466 /*
1467 * search the inode cache for a matching inode number.
1468 * If we find one, then the inode number we are trying to
1469 * allocate is not unique and so we should not use it.
1470 *
1471 * Returns 1 if the inode number is unique, 0 if it is not.
1472 */
test_inode_iunique(struct super_block * sb,unsigned long ino)1473 static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1474 {
1475 struct hlist_head *b = inode_hashtable + hash(sb, ino);
1476 struct inode *inode;
1477
1478 hlist_for_each_entry_rcu(inode, b, i_hash) {
1479 if (inode->i_ino == ino && inode->i_sb == sb)
1480 return 0;
1481 }
1482 return 1;
1483 }
1484
1485 /**
1486 * iunique - get a unique inode number
1487 * @sb: superblock
1488 * @max_reserved: highest reserved inode number
1489 *
1490 * Obtain an inode number that is unique on the system for a given
1491 * superblock. This is used by file systems that have no natural
1492 * permanent inode numbering system. An inode number is returned that
1493 * is higher than the reserved limit but unique.
1494 *
1495 * BUGS:
1496 * With a large number of inodes live on the file system this function
1497 * currently becomes quite slow.
1498 */
iunique(struct super_block * sb,ino_t max_reserved)1499 ino_t iunique(struct super_block *sb, ino_t max_reserved)
1500 {
1501 /*
1502 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1503 * error if st_ino won't fit in target struct field. Use 32bit counter
1504 * here to attempt to avoid that.
1505 */
1506 static DEFINE_SPINLOCK(iunique_lock);
1507 static unsigned int counter;
1508 ino_t res;
1509
1510 rcu_read_lock();
1511 spin_lock(&iunique_lock);
1512 do {
1513 if (counter <= max_reserved)
1514 counter = max_reserved + 1;
1515 res = counter++;
1516 } while (!test_inode_iunique(sb, res));
1517 spin_unlock(&iunique_lock);
1518 rcu_read_unlock();
1519
1520 return res;
1521 }
1522 EXPORT_SYMBOL(iunique);
1523
igrab(struct inode * inode)1524 struct inode *igrab(struct inode *inode)
1525 {
1526 spin_lock(&inode->i_lock);
1527 if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1528 __iget(inode);
1529 spin_unlock(&inode->i_lock);
1530 } else {
1531 spin_unlock(&inode->i_lock);
1532 /*
1533 * Handle the case where s_op->clear_inode is not been
1534 * called yet, and somebody is calling igrab
1535 * while the inode is getting freed.
1536 */
1537 inode = NULL;
1538 }
1539 return inode;
1540 }
1541 EXPORT_SYMBOL(igrab);
1542
1543 /**
1544 * ilookup5_nowait - search for an inode in the inode cache
1545 * @sb: super block of file system to search
1546 * @hashval: hash value (usually inode number) to search for
1547 * @test: callback used for comparisons between inodes
1548 * @data: opaque data pointer to pass to @test
1549 *
1550 * Search for the inode specified by @hashval and @data in the inode cache.
1551 * If the inode is in the cache, the inode is returned with an incremented
1552 * reference count.
1553 *
1554 * Note: I_NEW is not waited upon so you have to be very careful what you do
1555 * with the returned inode. You probably should be using ilookup5() instead.
1556 *
1557 * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1558 */
ilookup5_nowait(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1559 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1560 int (*test)(struct inode *, void *), void *data)
1561 {
1562 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1563 struct inode *inode;
1564
1565 spin_lock(&inode_hash_lock);
1566 inode = find_inode(sb, head, test, data, true);
1567 spin_unlock(&inode_hash_lock);
1568
1569 return IS_ERR(inode) ? NULL : inode;
1570 }
1571 EXPORT_SYMBOL(ilookup5_nowait);
1572
1573 /**
1574 * ilookup5 - search for an inode in the inode cache
1575 * @sb: super block of file system to search
1576 * @hashval: hash value (usually inode number) to search for
1577 * @test: callback used for comparisons between inodes
1578 * @data: opaque data pointer to pass to @test
1579 *
1580 * Search for the inode specified by @hashval and @data in the inode cache,
1581 * and if the inode is in the cache, return the inode with an incremented
1582 * reference count. Waits on I_NEW before returning the inode.
1583 * returned with an incremented reference count.
1584 *
1585 * This is a generalized version of ilookup() for file systems where the
1586 * inode number is not sufficient for unique identification of an inode.
1587 *
1588 * Note: @test is called with the inode_hash_lock held, so can't sleep.
1589 */
ilookup5(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1590 struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1591 int (*test)(struct inode *, void *), void *data)
1592 {
1593 struct inode *inode;
1594 again:
1595 inode = ilookup5_nowait(sb, hashval, test, data);
1596 if (inode) {
1597 wait_on_inode(inode);
1598 if (unlikely(inode_unhashed(inode))) {
1599 iput(inode);
1600 goto again;
1601 }
1602 }
1603 return inode;
1604 }
1605 EXPORT_SYMBOL(ilookup5);
1606
1607 /**
1608 * ilookup - search for an inode in the inode cache
1609 * @sb: super block of file system to search
1610 * @ino: inode number to search for
1611 *
1612 * Search for the inode @ino in the inode cache, and if the inode is in the
1613 * cache, the inode is returned with an incremented reference count.
1614 */
ilookup(struct super_block * sb,unsigned long ino)1615 struct inode *ilookup(struct super_block *sb, unsigned long ino)
1616 {
1617 struct hlist_head *head = inode_hashtable + hash(sb, ino);
1618 struct inode *inode;
1619 again:
1620 inode = find_inode_fast(sb, head, ino, false);
1621
1622 if (inode) {
1623 if (IS_ERR(inode))
1624 return NULL;
1625 wait_on_inode(inode);
1626 if (unlikely(inode_unhashed(inode))) {
1627 iput(inode);
1628 goto again;
1629 }
1630 }
1631 return inode;
1632 }
1633 EXPORT_SYMBOL(ilookup);
1634
1635 /**
1636 * find_inode_nowait - find an inode in the inode cache
1637 * @sb: super block of file system to search
1638 * @hashval: hash value (usually inode number) to search for
1639 * @match: callback used for comparisons between inodes
1640 * @data: opaque data pointer to pass to @match
1641 *
1642 * Search for the inode specified by @hashval and @data in the inode
1643 * cache, where the helper function @match will return 0 if the inode
1644 * does not match, 1 if the inode does match, and -1 if the search
1645 * should be stopped. The @match function must be responsible for
1646 * taking the i_lock spin_lock and checking i_state for an inode being
1647 * freed or being initialized, and incrementing the reference count
1648 * before returning 1. It also must not sleep, since it is called with
1649 * the inode_hash_lock spinlock held.
1650 *
1651 * This is a even more generalized version of ilookup5() when the
1652 * function must never block --- find_inode() can block in
1653 * __wait_on_freeing_inode() --- or when the caller can not increment
1654 * the reference count because the resulting iput() might cause an
1655 * inode eviction. The tradeoff is that the @match funtion must be
1656 * very carefully implemented.
1657 */
find_inode_nowait(struct super_block * sb,unsigned long hashval,int (* match)(struct inode *,unsigned long,void *),void * data)1658 struct inode *find_inode_nowait(struct super_block *sb,
1659 unsigned long hashval,
1660 int (*match)(struct inode *, unsigned long,
1661 void *),
1662 void *data)
1663 {
1664 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1665 struct inode *inode, *ret_inode = NULL;
1666 int mval;
1667
1668 spin_lock(&inode_hash_lock);
1669 hlist_for_each_entry(inode, head, i_hash) {
1670 if (inode->i_sb != sb)
1671 continue;
1672 mval = match(inode, hashval, data);
1673 if (mval == 0)
1674 continue;
1675 if (mval == 1)
1676 ret_inode = inode;
1677 goto out;
1678 }
1679 out:
1680 spin_unlock(&inode_hash_lock);
1681 return ret_inode;
1682 }
1683 EXPORT_SYMBOL(find_inode_nowait);
1684
1685 /**
1686 * find_inode_rcu - find an inode in the inode cache
1687 * @sb: Super block of file system to search
1688 * @hashval: Key to hash
1689 * @test: Function to test match on an inode
1690 * @data: Data for test function
1691 *
1692 * Search for the inode specified by @hashval and @data in the inode cache,
1693 * where the helper function @test will return 0 if the inode does not match
1694 * and 1 if it does. The @test function must be responsible for taking the
1695 * i_lock spin_lock and checking i_state for an inode being freed or being
1696 * initialized.
1697 *
1698 * If successful, this will return the inode for which the @test function
1699 * returned 1 and NULL otherwise.
1700 *
1701 * The @test function is not permitted to take a ref on any inode presented.
1702 * It is also not permitted to sleep.
1703 *
1704 * The caller must hold the RCU read lock.
1705 */
find_inode_rcu(struct super_block * sb,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1706 struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval,
1707 int (*test)(struct inode *, void *), void *data)
1708 {
1709 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1710 struct inode *inode;
1711
1712 RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1713 "suspicious find_inode_rcu() usage");
1714
1715 hlist_for_each_entry_rcu(inode, head, i_hash) {
1716 if (inode->i_sb == sb &&
1717 !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)) &&
1718 test(inode, data))
1719 return inode;
1720 }
1721 return NULL;
1722 }
1723 EXPORT_SYMBOL(find_inode_rcu);
1724
1725 /**
1726 * find_inode_by_ino_rcu - Find an inode in the inode cache
1727 * @sb: Super block of file system to search
1728 * @ino: The inode number to match
1729 *
1730 * Search for the inode specified by @hashval and @data in the inode cache,
1731 * where the helper function @test will return 0 if the inode does not match
1732 * and 1 if it does. The @test function must be responsible for taking the
1733 * i_lock spin_lock and checking i_state for an inode being freed or being
1734 * initialized.
1735 *
1736 * If successful, this will return the inode for which the @test function
1737 * returned 1 and NULL otherwise.
1738 *
1739 * The @test function is not permitted to take a ref on any inode presented.
1740 * It is also not permitted to sleep.
1741 *
1742 * The caller must hold the RCU read lock.
1743 */
find_inode_by_ino_rcu(struct super_block * sb,unsigned long ino)1744 struct inode *find_inode_by_ino_rcu(struct super_block *sb,
1745 unsigned long ino)
1746 {
1747 struct hlist_head *head = inode_hashtable + hash(sb, ino);
1748 struct inode *inode;
1749
1750 RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
1751 "suspicious find_inode_by_ino_rcu() usage");
1752
1753 hlist_for_each_entry_rcu(inode, head, i_hash) {
1754 if (inode->i_ino == ino &&
1755 inode->i_sb == sb &&
1756 !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)))
1757 return inode;
1758 }
1759 return NULL;
1760 }
1761 EXPORT_SYMBOL(find_inode_by_ino_rcu);
1762
insert_inode_locked(struct inode * inode)1763 int insert_inode_locked(struct inode *inode)
1764 {
1765 struct super_block *sb = inode->i_sb;
1766 ino_t ino = inode->i_ino;
1767 struct hlist_head *head = inode_hashtable + hash(sb, ino);
1768
1769 while (1) {
1770 struct inode *old = NULL;
1771 spin_lock(&inode_hash_lock);
1772 hlist_for_each_entry(old, head, i_hash) {
1773 if (old->i_ino != ino)
1774 continue;
1775 if (old->i_sb != sb)
1776 continue;
1777 spin_lock(&old->i_lock);
1778 if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1779 spin_unlock(&old->i_lock);
1780 continue;
1781 }
1782 break;
1783 }
1784 if (likely(!old)) {
1785 spin_lock(&inode->i_lock);
1786 inode->i_state |= I_NEW | I_CREATING;
1787 hlist_add_head_rcu(&inode->i_hash, head);
1788 spin_unlock(&inode->i_lock);
1789 spin_unlock(&inode_hash_lock);
1790 return 0;
1791 }
1792 if (unlikely(old->i_state & I_CREATING)) {
1793 spin_unlock(&old->i_lock);
1794 spin_unlock(&inode_hash_lock);
1795 return -EBUSY;
1796 }
1797 __iget(old);
1798 spin_unlock(&old->i_lock);
1799 spin_unlock(&inode_hash_lock);
1800 wait_on_inode(old);
1801 if (unlikely(!inode_unhashed(old))) {
1802 iput(old);
1803 return -EBUSY;
1804 }
1805 iput(old);
1806 }
1807 }
1808 EXPORT_SYMBOL(insert_inode_locked);
1809
insert_inode_locked4(struct inode * inode,unsigned long hashval,int (* test)(struct inode *,void *),void * data)1810 int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1811 int (*test)(struct inode *, void *), void *data)
1812 {
1813 struct inode *old;
1814
1815 inode->i_state |= I_CREATING;
1816 old = inode_insert5(inode, hashval, test, NULL, data);
1817
1818 if (old != inode) {
1819 iput(old);
1820 return -EBUSY;
1821 }
1822 return 0;
1823 }
1824 EXPORT_SYMBOL(insert_inode_locked4);
1825
1826
generic_delete_inode(struct inode * inode)1827 int generic_delete_inode(struct inode *inode)
1828 {
1829 return 1;
1830 }
1831 EXPORT_SYMBOL(generic_delete_inode);
1832
1833 /*
1834 * Called when we're dropping the last reference
1835 * to an inode.
1836 *
1837 * Call the FS "drop_inode()" function, defaulting to
1838 * the legacy UNIX filesystem behaviour. If it tells
1839 * us to evict inode, do so. Otherwise, retain inode
1840 * in cache if fs is alive, sync and evict if fs is
1841 * shutting down.
1842 */
iput_final(struct inode * inode)1843 static void iput_final(struct inode *inode)
1844 {
1845 struct super_block *sb = inode->i_sb;
1846 const struct super_operations *op = inode->i_sb->s_op;
1847 unsigned long state;
1848 int drop;
1849
1850 WARN_ON(inode->i_state & I_NEW);
1851
1852 if (op->drop_inode)
1853 drop = op->drop_inode(inode);
1854 else
1855 drop = generic_drop_inode(inode);
1856
1857 if (!drop &&
1858 !(inode->i_state & I_DONTCACHE) &&
1859 (sb->s_flags & SB_ACTIVE)) {
1860 __inode_add_lru(inode, true);
1861 spin_unlock(&inode->i_lock);
1862 return;
1863 }
1864
1865 state = inode->i_state;
1866 if (!drop) {
1867 WRITE_ONCE(inode->i_state, state | I_WILL_FREE);
1868 spin_unlock(&inode->i_lock);
1869
1870 write_inode_now(inode, 1);
1871
1872 spin_lock(&inode->i_lock);
1873 state = inode->i_state;
1874 WARN_ON(state & I_NEW);
1875 state &= ~I_WILL_FREE;
1876 }
1877
1878 WRITE_ONCE(inode->i_state, state | I_FREEING);
1879 if (!list_empty(&inode->i_lru))
1880 inode_lru_list_del(inode);
1881 spin_unlock(&inode->i_lock);
1882
1883 evict(inode);
1884 }
1885
1886 /**
1887 * iput - put an inode
1888 * @inode: inode to put
1889 *
1890 * Puts an inode, dropping its usage count. If the inode use count hits
1891 * zero, the inode is then freed and may also be destroyed.
1892 *
1893 * Consequently, iput() can sleep.
1894 */
iput(struct inode * inode)1895 void iput(struct inode *inode)
1896 {
1897 if (!inode)
1898 return;
1899 BUG_ON(inode->i_state & I_CLEAR);
1900 retry:
1901 if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
1902 if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
1903 atomic_inc(&inode->i_count);
1904 spin_unlock(&inode->i_lock);
1905 trace_writeback_lazytime_iput(inode);
1906 mark_inode_dirty_sync(inode);
1907 goto retry;
1908 }
1909 iput_final(inode);
1910 }
1911 }
1912 EXPORT_SYMBOL(iput);
1913
1914 #ifdef CONFIG_BLOCK
1915 /**
1916 * bmap - find a block number in a file
1917 * @inode: inode owning the block number being requested
1918 * @block: pointer containing the block to find
1919 *
1920 * Replaces the value in ``*block`` with the block number on the device holding
1921 * corresponding to the requested block number in the file.
1922 * That is, asked for block 4 of inode 1 the function will replace the
1923 * 4 in ``*block``, with disk block relative to the disk start that holds that
1924 * block of the file.
1925 *
1926 * Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
1927 * hole, returns 0 and ``*block`` is also set to 0.
1928 */
bmap(struct inode * inode,sector_t * block)1929 int bmap(struct inode *inode, sector_t *block)
1930 {
1931 if (!inode->i_mapping->a_ops->bmap)
1932 return -EINVAL;
1933
1934 *block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
1935 return 0;
1936 }
1937 EXPORT_SYMBOL(bmap);
1938 #endif
1939
1940 /*
1941 * With relative atime, only update atime if the previous atime is
1942 * earlier than or equal to either the ctime or mtime,
1943 * or if at least a day has passed since the last atime update.
1944 */
relatime_need_update(struct vfsmount * mnt,struct inode * inode,struct timespec64 now)1945 static bool relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1946 struct timespec64 now)
1947 {
1948 struct timespec64 atime, mtime, ctime;
1949
1950 if (!(mnt->mnt_flags & MNT_RELATIME))
1951 return true;
1952 /*
1953 * Is mtime younger than or equal to atime? If yes, update atime:
1954 */
1955 atime = inode_get_atime(inode);
1956 mtime = inode_get_mtime(inode);
1957 if (timespec64_compare(&mtime, &atime) >= 0)
1958 return true;
1959 /*
1960 * Is ctime younger than or equal to atime? If yes, update atime:
1961 */
1962 ctime = inode_get_ctime(inode);
1963 if (timespec64_compare(&ctime, &atime) >= 0)
1964 return true;
1965
1966 /*
1967 * Is the previous atime value older than a day? If yes,
1968 * update atime:
1969 */
1970 if ((long)(now.tv_sec - atime.tv_sec) >= 24*60*60)
1971 return true;
1972 /*
1973 * Good, we can skip the atime update:
1974 */
1975 return false;
1976 }
1977
1978 /**
1979 * inode_update_timestamps - update the timestamps on the inode
1980 * @inode: inode to be updated
1981 * @flags: S_* flags that needed to be updated
1982 *
1983 * The update_time function is called when an inode's timestamps need to be
1984 * updated for a read or write operation. This function handles updating the
1985 * actual timestamps. It's up to the caller to ensure that the inode is marked
1986 * dirty appropriately.
1987 *
1988 * In the case where any of S_MTIME, S_CTIME, or S_VERSION need to be updated,
1989 * attempt to update all three of them. S_ATIME updates can be handled
1990 * independently of the rest.
1991 *
1992 * Returns a set of S_* flags indicating which values changed.
1993 */
inode_update_timestamps(struct inode * inode,int flags)1994 int inode_update_timestamps(struct inode *inode, int flags)
1995 {
1996 int updated = 0;
1997 struct timespec64 now;
1998
1999 if (flags & (S_MTIME|S_CTIME|S_VERSION)) {
2000 struct timespec64 ctime = inode_get_ctime(inode);
2001 struct timespec64 mtime = inode_get_mtime(inode);
2002
2003 now = inode_set_ctime_current(inode);
2004 if (!timespec64_equal(&now, &ctime))
2005 updated |= S_CTIME;
2006 if (!timespec64_equal(&now, &mtime)) {
2007 inode_set_mtime_to_ts(inode, now);
2008 updated |= S_MTIME;
2009 }
2010 if (IS_I_VERSION(inode) && inode_maybe_inc_iversion(inode, updated))
2011 updated |= S_VERSION;
2012 } else {
2013 now = current_time(inode);
2014 }
2015
2016 if (flags & S_ATIME) {
2017 struct timespec64 atime = inode_get_atime(inode);
2018
2019 if (!timespec64_equal(&now, &atime)) {
2020 inode_set_atime_to_ts(inode, now);
2021 updated |= S_ATIME;
2022 }
2023 }
2024 return updated;
2025 }
2026 EXPORT_SYMBOL(inode_update_timestamps);
2027
2028 /**
2029 * generic_update_time - update the timestamps on the inode
2030 * @inode: inode to be updated
2031 * @flags: S_* flags that needed to be updated
2032 *
2033 * The update_time function is called when an inode's timestamps need to be
2034 * updated for a read or write operation. In the case where any of S_MTIME, S_CTIME,
2035 * or S_VERSION need to be updated we attempt to update all three of them. S_ATIME
2036 * updates can be handled done independently of the rest.
2037 *
2038 * Returns a S_* mask indicating which fields were updated.
2039 */
generic_update_time(struct inode * inode,int flags)2040 int generic_update_time(struct inode *inode, int flags)
2041 {
2042 int updated = inode_update_timestamps(inode, flags);
2043 int dirty_flags = 0;
2044
2045 if (updated & (S_ATIME|S_MTIME|S_CTIME))
2046 dirty_flags = inode->i_sb->s_flags & SB_LAZYTIME ? I_DIRTY_TIME : I_DIRTY_SYNC;
2047 if (updated & S_VERSION)
2048 dirty_flags |= I_DIRTY_SYNC;
2049 __mark_inode_dirty(inode, dirty_flags);
2050 return updated;
2051 }
2052 EXPORT_SYMBOL(generic_update_time);
2053
2054 /*
2055 * This does the actual work of updating an inodes time or version. Must have
2056 * had called mnt_want_write() before calling this.
2057 */
inode_update_time(struct inode * inode,int flags)2058 int inode_update_time(struct inode *inode, int flags)
2059 {
2060 if (inode->i_op->update_time)
2061 return inode->i_op->update_time(inode, flags);
2062 generic_update_time(inode, flags);
2063 return 0;
2064 }
2065 EXPORT_SYMBOL(inode_update_time);
2066
2067 /**
2068 * atime_needs_update - update the access time
2069 * @path: the &struct path to update
2070 * @inode: inode to update
2071 *
2072 * Update the accessed time on an inode and mark it for writeback.
2073 * This function automatically handles read only file systems and media,
2074 * as well as the "noatime" flag and inode specific "noatime" markers.
2075 */
atime_needs_update(const struct path * path,struct inode * inode)2076 bool atime_needs_update(const struct path *path, struct inode *inode)
2077 {
2078 struct vfsmount *mnt = path->mnt;
2079 struct timespec64 now, atime;
2080
2081 if (inode->i_flags & S_NOATIME)
2082 return false;
2083
2084 /* Atime updates will likely cause i_uid and i_gid to be written
2085 * back improprely if their true value is unknown to the vfs.
2086 */
2087 if (HAS_UNMAPPED_ID(mnt_idmap(mnt), inode))
2088 return false;
2089
2090 if (IS_NOATIME(inode))
2091 return false;
2092 if ((inode->i_sb->s_flags & SB_NODIRATIME) && S_ISDIR(inode->i_mode))
2093 return false;
2094
2095 if (mnt->mnt_flags & MNT_NOATIME)
2096 return false;
2097 if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
2098 return false;
2099
2100 now = current_time(inode);
2101
2102 if (!relatime_need_update(mnt, inode, now))
2103 return false;
2104
2105 atime = inode_get_atime(inode);
2106 if (timespec64_equal(&atime, &now))
2107 return false;
2108
2109 return true;
2110 }
2111
touch_atime(const struct path * path)2112 void touch_atime(const struct path *path)
2113 {
2114 struct vfsmount *mnt = path->mnt;
2115 struct inode *inode = d_inode(path->dentry);
2116
2117 if (!atime_needs_update(path, inode))
2118 return;
2119
2120 if (!sb_start_write_trylock(inode->i_sb))
2121 return;
2122
2123 if (mnt_get_write_access(mnt) != 0)
2124 goto skip_update;
2125 /*
2126 * File systems can error out when updating inodes if they need to
2127 * allocate new space to modify an inode (such is the case for
2128 * Btrfs), but since we touch atime while walking down the path we
2129 * really don't care if we failed to update the atime of the file,
2130 * so just ignore the return value.
2131 * We may also fail on filesystems that have the ability to make parts
2132 * of the fs read only, e.g. subvolumes in Btrfs.
2133 */
2134 inode_update_time(inode, S_ATIME);
2135 mnt_put_write_access(mnt);
2136 skip_update:
2137 sb_end_write(inode->i_sb);
2138 }
2139 EXPORT_SYMBOL(touch_atime);
2140
2141 /*
2142 * Return mask of changes for notify_change() that need to be done as a
2143 * response to write or truncate. Return 0 if nothing has to be changed.
2144 * Negative value on error (change should be denied).
2145 */
dentry_needs_remove_privs(struct mnt_idmap * idmap,struct dentry * dentry)2146 int dentry_needs_remove_privs(struct mnt_idmap *idmap,
2147 struct dentry *dentry)
2148 {
2149 struct inode *inode = d_inode(dentry);
2150 int mask = 0;
2151 int ret;
2152
2153 if (IS_NOSEC(inode))
2154 return 0;
2155
2156 mask = setattr_should_drop_suidgid(idmap, inode);
2157 ret = security_inode_need_killpriv(dentry);
2158 if (ret < 0)
2159 return ret;
2160 if (ret)
2161 mask |= ATTR_KILL_PRIV;
2162 return mask;
2163 }
2164
__remove_privs(struct mnt_idmap * idmap,struct dentry * dentry,int kill)2165 static int __remove_privs(struct mnt_idmap *idmap,
2166 struct dentry *dentry, int kill)
2167 {
2168 struct iattr newattrs;
2169
2170 newattrs.ia_valid = ATTR_FORCE | kill;
2171 /*
2172 * Note we call this on write, so notify_change will not
2173 * encounter any conflicting delegations:
2174 */
2175 return notify_change(idmap, dentry, &newattrs, NULL);
2176 }
2177
file_remove_privs_flags(struct file * file,unsigned int flags)2178 int file_remove_privs_flags(struct file *file, unsigned int flags)
2179 {
2180 struct dentry *dentry = file_dentry(file);
2181 struct inode *inode = file_inode(file);
2182 int error = 0;
2183 int kill;
2184
2185 if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
2186 return 0;
2187
2188 kill = dentry_needs_remove_privs(file_mnt_idmap(file), dentry);
2189 if (kill < 0)
2190 return kill;
2191
2192 if (kill) {
2193 if (flags & IOCB_NOWAIT)
2194 return -EAGAIN;
2195
2196 error = __remove_privs(file_mnt_idmap(file), dentry, kill);
2197 }
2198
2199 if (!error)
2200 inode_has_no_xattr(inode);
2201 return error;
2202 }
2203 EXPORT_SYMBOL_GPL(file_remove_privs_flags);
2204
2205 /**
2206 * file_remove_privs - remove special file privileges (suid, capabilities)
2207 * @file: file to remove privileges from
2208 *
2209 * When file is modified by a write or truncation ensure that special
2210 * file privileges are removed.
2211 *
2212 * Return: 0 on success, negative errno on failure.
2213 */
file_remove_privs(struct file * file)2214 int file_remove_privs(struct file *file)
2215 {
2216 return file_remove_privs_flags(file, 0);
2217 }
2218 EXPORT_SYMBOL(file_remove_privs);
2219
inode_needs_update_time(struct inode * inode)2220 static int inode_needs_update_time(struct inode *inode)
2221 {
2222 int sync_it = 0;
2223 struct timespec64 now = current_time(inode);
2224 struct timespec64 ts;
2225
2226 /* First try to exhaust all avenues to not sync */
2227 if (IS_NOCMTIME(inode))
2228 return 0;
2229
2230 ts = inode_get_mtime(inode);
2231 if (!timespec64_equal(&ts, &now))
2232 sync_it = S_MTIME;
2233
2234 ts = inode_get_ctime(inode);
2235 if (!timespec64_equal(&ts, &now))
2236 sync_it |= S_CTIME;
2237
2238 if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
2239 sync_it |= S_VERSION;
2240
2241 return sync_it;
2242 }
2243
__file_update_time(struct file * file,int sync_mode)2244 static int __file_update_time(struct file *file, int sync_mode)
2245 {
2246 int ret = 0;
2247 struct inode *inode = file_inode(file);
2248
2249 /* try to update time settings */
2250 if (!mnt_get_write_access_file(file)) {
2251 ret = inode_update_time(inode, sync_mode);
2252 mnt_put_write_access_file(file);
2253 }
2254
2255 return ret;
2256 }
2257
2258 /**
2259 * file_update_time - update mtime and ctime time
2260 * @file: file accessed
2261 *
2262 * Update the mtime and ctime members of an inode and mark the inode for
2263 * writeback. Note that this function is meant exclusively for usage in
2264 * the file write path of filesystems, and filesystems may choose to
2265 * explicitly ignore updates via this function with the _NOCMTIME inode
2266 * flag, e.g. for network filesystem where these imestamps are handled
2267 * by the server. This can return an error for file systems who need to
2268 * allocate space in order to update an inode.
2269 *
2270 * Return: 0 on success, negative errno on failure.
2271 */
file_update_time(struct file * file)2272 int file_update_time(struct file *file)
2273 {
2274 int ret;
2275 struct inode *inode = file_inode(file);
2276
2277 ret = inode_needs_update_time(inode);
2278 if (ret <= 0)
2279 return ret;
2280
2281 return __file_update_time(file, ret);
2282 }
2283 EXPORT_SYMBOL(file_update_time);
2284
2285 /**
2286 * file_modified_flags - handle mandated vfs changes when modifying a file
2287 * @file: file that was modified
2288 * @flags: kiocb flags
2289 *
2290 * When file has been modified ensure that special
2291 * file privileges are removed and time settings are updated.
2292 *
2293 * If IOCB_NOWAIT is set, special file privileges will not be removed and
2294 * time settings will not be updated. It will return -EAGAIN.
2295 *
2296 * Context: Caller must hold the file's inode lock.
2297 *
2298 * Return: 0 on success, negative errno on failure.
2299 */
file_modified_flags(struct file * file,int flags)2300 static int file_modified_flags(struct file *file, int flags)
2301 {
2302 int ret;
2303 struct inode *inode = file_inode(file);
2304
2305 /*
2306 * Clear the security bits if the process is not being run by root.
2307 * This keeps people from modifying setuid and setgid binaries.
2308 */
2309 ret = file_remove_privs_flags(file, flags);
2310 if (ret)
2311 return ret;
2312
2313 if (unlikely(file->f_mode & FMODE_NOCMTIME))
2314 return 0;
2315
2316 ret = inode_needs_update_time(inode);
2317 if (ret <= 0)
2318 return ret;
2319 if (flags & IOCB_NOWAIT)
2320 return -EAGAIN;
2321
2322 return __file_update_time(file, ret);
2323 }
2324
2325 /**
2326 * file_modified - handle mandated vfs changes when modifying a file
2327 * @file: file that was modified
2328 *
2329 * When file has been modified ensure that special
2330 * file privileges are removed and time settings are updated.
2331 *
2332 * Context: Caller must hold the file's inode lock.
2333 *
2334 * Return: 0 on success, negative errno on failure.
2335 */
file_modified(struct file * file)2336 int file_modified(struct file *file)
2337 {
2338 return file_modified_flags(file, 0);
2339 }
2340 EXPORT_SYMBOL(file_modified);
2341
2342 /**
2343 * kiocb_modified - handle mandated vfs changes when modifying a file
2344 * @iocb: iocb that was modified
2345 *
2346 * When file has been modified ensure that special
2347 * file privileges are removed and time settings are updated.
2348 *
2349 * Context: Caller must hold the file's inode lock.
2350 *
2351 * Return: 0 on success, negative errno on failure.
2352 */
kiocb_modified(struct kiocb * iocb)2353 int kiocb_modified(struct kiocb *iocb)
2354 {
2355 return file_modified_flags(iocb->ki_filp, iocb->ki_flags);
2356 }
2357 EXPORT_SYMBOL_GPL(kiocb_modified);
2358
inode_needs_sync(struct inode * inode)2359 int inode_needs_sync(struct inode *inode)
2360 {
2361 if (IS_SYNC(inode))
2362 return 1;
2363 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
2364 return 1;
2365 return 0;
2366 }
2367 EXPORT_SYMBOL(inode_needs_sync);
2368
2369 /*
2370 * If we try to find an inode in the inode hash while it is being
2371 * deleted, we have to wait until the filesystem completes its
2372 * deletion before reporting that it isn't found. This function waits
2373 * until the deletion _might_ have completed. Callers are responsible
2374 * to recheck inode state.
2375 *
2376 * It doesn't matter if I_NEW is not set initially, a call to
2377 * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
2378 * will DTRT.
2379 */
__wait_on_freeing_inode(struct inode * inode,bool is_inode_hash_locked)2380 static void __wait_on_freeing_inode(struct inode *inode, bool is_inode_hash_locked)
2381 {
2382 struct wait_bit_queue_entry wqe;
2383 struct wait_queue_head *wq_head;
2384
2385 /*
2386 * Handle racing against evict(), see that routine for more details.
2387 */
2388 if (unlikely(inode_unhashed(inode))) {
2389 WARN_ON(is_inode_hash_locked);
2390 spin_unlock(&inode->i_lock);
2391 return;
2392 }
2393
2394 wq_head = inode_bit_waitqueue(&wqe, inode, __I_NEW);
2395 prepare_to_wait_event(wq_head, &wqe.wq_entry, TASK_UNINTERRUPTIBLE);
2396 spin_unlock(&inode->i_lock);
2397 rcu_read_unlock();
2398 if (is_inode_hash_locked)
2399 spin_unlock(&inode_hash_lock);
2400 schedule();
2401 finish_wait(wq_head, &wqe.wq_entry);
2402 if (is_inode_hash_locked)
2403 spin_lock(&inode_hash_lock);
2404 rcu_read_lock();
2405 }
2406
2407 static __initdata unsigned long ihash_entries;
set_ihash_entries(char * str)2408 static int __init set_ihash_entries(char *str)
2409 {
2410 if (!str)
2411 return 0;
2412 ihash_entries = simple_strtoul(str, &str, 0);
2413 return 1;
2414 }
2415 __setup("ihash_entries=", set_ihash_entries);
2416
2417 /*
2418 * Initialize the waitqueues and inode hash table.
2419 */
inode_init_early(void)2420 void __init inode_init_early(void)
2421 {
2422 /* If hashes are distributed across NUMA nodes, defer
2423 * hash allocation until vmalloc space is available.
2424 */
2425 if (hashdist)
2426 return;
2427
2428 inode_hashtable =
2429 alloc_large_system_hash("Inode-cache",
2430 sizeof(struct hlist_head),
2431 ihash_entries,
2432 14,
2433 HASH_EARLY | HASH_ZERO,
2434 &i_hash_shift,
2435 &i_hash_mask,
2436 0,
2437 0);
2438 }
2439
inode_init(void)2440 void __init inode_init(void)
2441 {
2442 /* inode slab cache */
2443 inode_cachep = kmem_cache_create("inode_cache",
2444 sizeof(struct inode),
2445 0,
2446 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
2447 SLAB_ACCOUNT),
2448 init_once);
2449
2450 /* Hash may have been set up in inode_init_early */
2451 if (!hashdist)
2452 return;
2453
2454 inode_hashtable =
2455 alloc_large_system_hash("Inode-cache",
2456 sizeof(struct hlist_head),
2457 ihash_entries,
2458 14,
2459 HASH_ZERO,
2460 &i_hash_shift,
2461 &i_hash_mask,
2462 0,
2463 0);
2464 }
2465
init_special_inode(struct inode * inode,umode_t mode,dev_t rdev)2466 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
2467 {
2468 inode->i_mode = mode;
2469 if (S_ISCHR(mode)) {
2470 inode->i_fop = &def_chr_fops;
2471 inode->i_rdev = rdev;
2472 } else if (S_ISBLK(mode)) {
2473 if (IS_ENABLED(CONFIG_BLOCK))
2474 inode->i_fop = &def_blk_fops;
2475 inode->i_rdev = rdev;
2476 } else if (S_ISFIFO(mode))
2477 inode->i_fop = &pipefifo_fops;
2478 else if (S_ISSOCK(mode))
2479 ; /* leave it no_open_fops */
2480 else
2481 printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
2482 " inode %s:%lu\n", mode, inode->i_sb->s_id,
2483 inode->i_ino);
2484 }
2485 EXPORT_SYMBOL(init_special_inode);
2486
2487 /**
2488 * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
2489 * @idmap: idmap of the mount the inode was created from
2490 * @inode: New inode
2491 * @dir: Directory inode
2492 * @mode: mode of the new inode
2493 *
2494 * If the inode has been created through an idmapped mount the idmap of
2495 * the vfsmount must be passed through @idmap. This function will then take
2496 * care to map the inode according to @idmap before checking permissions
2497 * and initializing i_uid and i_gid. On non-idmapped mounts or if permission
2498 * checking is to be performed on the raw inode simply pass @nop_mnt_idmap.
2499 */
inode_init_owner(struct mnt_idmap * idmap,struct inode * inode,const struct inode * dir,umode_t mode)2500 void inode_init_owner(struct mnt_idmap *idmap, struct inode *inode,
2501 const struct inode *dir, umode_t mode)
2502 {
2503 inode_fsuid_set(inode, idmap);
2504 if (dir && dir->i_mode & S_ISGID) {
2505 inode->i_gid = dir->i_gid;
2506
2507 /* Directories are special, and always inherit S_ISGID */
2508 if (S_ISDIR(mode))
2509 mode |= S_ISGID;
2510 } else
2511 inode_fsgid_set(inode, idmap);
2512 inode->i_mode = mode;
2513 }
2514 EXPORT_SYMBOL(inode_init_owner);
2515
2516 /**
2517 * inode_owner_or_capable - check current task permissions to inode
2518 * @idmap: idmap of the mount the inode was found from
2519 * @inode: inode being checked
2520 *
2521 * Return true if current either has CAP_FOWNER in a namespace with the
2522 * inode owner uid mapped, or owns the file.
2523 *
2524 * If the inode has been found through an idmapped mount the idmap of
2525 * the vfsmount must be passed through @idmap. This function will then take
2526 * care to map the inode according to @idmap before checking permissions.
2527 * On non-idmapped mounts or if permission checking is to be performed on the
2528 * raw inode simply pass @nop_mnt_idmap.
2529 */
inode_owner_or_capable(struct mnt_idmap * idmap,const struct inode * inode)2530 bool inode_owner_or_capable(struct mnt_idmap *idmap,
2531 const struct inode *inode)
2532 {
2533 vfsuid_t vfsuid;
2534 struct user_namespace *ns;
2535
2536 vfsuid = i_uid_into_vfsuid(idmap, inode);
2537 if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
2538 return true;
2539
2540 ns = current_user_ns();
2541 if (vfsuid_has_mapping(ns, vfsuid) && ns_capable(ns, CAP_FOWNER))
2542 return true;
2543 return false;
2544 }
2545 EXPORT_SYMBOL(inode_owner_or_capable);
2546
2547 /*
2548 * Direct i/o helper functions
2549 */
inode_dio_finished(const struct inode * inode)2550 bool inode_dio_finished(const struct inode *inode)
2551 {
2552 return atomic_read(&inode->i_dio_count) == 0;
2553 }
2554 EXPORT_SYMBOL(inode_dio_finished);
2555
2556 /**
2557 * inode_dio_wait - wait for outstanding DIO requests to finish
2558 * @inode: inode to wait for
2559 *
2560 * Waits for all pending direct I/O requests to finish so that we can
2561 * proceed with a truncate or equivalent operation.
2562 *
2563 * Must be called under a lock that serializes taking new references
2564 * to i_dio_count, usually by inode->i_mutex.
2565 */
inode_dio_wait(struct inode * inode)2566 void inode_dio_wait(struct inode *inode)
2567 {
2568 wait_var_event(&inode->i_dio_count, inode_dio_finished(inode));
2569 }
2570 EXPORT_SYMBOL(inode_dio_wait);
2571
inode_dio_wait_interruptible(struct inode * inode)2572 void inode_dio_wait_interruptible(struct inode *inode)
2573 {
2574 wait_var_event_interruptible(&inode->i_dio_count,
2575 inode_dio_finished(inode));
2576 }
2577 EXPORT_SYMBOL(inode_dio_wait_interruptible);
2578
2579 /*
2580 * inode_set_flags - atomically set some inode flags
2581 *
2582 * Note: the caller should be holding i_mutex, or else be sure that
2583 * they have exclusive access to the inode structure (i.e., while the
2584 * inode is being instantiated). The reason for the cmpxchg() loop
2585 * --- which wouldn't be necessary if all code paths which modify
2586 * i_flags actually followed this rule, is that there is at least one
2587 * code path which doesn't today so we use cmpxchg() out of an abundance
2588 * of caution.
2589 *
2590 * In the long run, i_mutex is overkill, and we should probably look
2591 * at using the i_lock spinlock to protect i_flags, and then make sure
2592 * it is so documented in include/linux/fs.h and that all code follows
2593 * the locking convention!!
2594 */
inode_set_flags(struct inode * inode,unsigned int flags,unsigned int mask)2595 void inode_set_flags(struct inode *inode, unsigned int flags,
2596 unsigned int mask)
2597 {
2598 WARN_ON_ONCE(flags & ~mask);
2599 set_mask_bits(&inode->i_flags, mask, flags);
2600 }
2601 EXPORT_SYMBOL(inode_set_flags);
2602
inode_nohighmem(struct inode * inode)2603 void inode_nohighmem(struct inode *inode)
2604 {
2605 mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
2606 }
2607 EXPORT_SYMBOL(inode_nohighmem);
2608
2609 /**
2610 * timestamp_truncate - Truncate timespec to a granularity
2611 * @t: Timespec
2612 * @inode: inode being updated
2613 *
2614 * Truncate a timespec to the granularity supported by the fs
2615 * containing the inode. Always rounds down. gran must
2616 * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
2617 */
timestamp_truncate(struct timespec64 t,struct inode * inode)2618 struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
2619 {
2620 struct super_block *sb = inode->i_sb;
2621 unsigned int gran = sb->s_time_gran;
2622
2623 t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);
2624 if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))
2625 t.tv_nsec = 0;
2626
2627 /* Avoid division in the common cases 1 ns and 1 s. */
2628 if (gran == 1)
2629 ; /* nothing */
2630 else if (gran == NSEC_PER_SEC)
2631 t.tv_nsec = 0;
2632 else if (gran > 1 && gran < NSEC_PER_SEC)
2633 t.tv_nsec -= t.tv_nsec % gran;
2634 else
2635 WARN(1, "invalid file time granularity: %u", gran);
2636 return t;
2637 }
2638 EXPORT_SYMBOL(timestamp_truncate);
2639
2640 /**
2641 * current_time - Return FS time
2642 * @inode: inode.
2643 *
2644 * Return the current time truncated to the time granularity supported by
2645 * the fs.
2646 *
2647 * Note that inode and inode->sb cannot be NULL.
2648 * Otherwise, the function warns and returns time without truncation.
2649 */
current_time(struct inode * inode)2650 struct timespec64 current_time(struct inode *inode)
2651 {
2652 struct timespec64 now;
2653
2654 ktime_get_coarse_real_ts64(&now);
2655 return timestamp_truncate(now, inode);
2656 }
2657 EXPORT_SYMBOL(current_time);
2658
2659 /**
2660 * inode_set_ctime_current - set the ctime to current_time
2661 * @inode: inode
2662 *
2663 * Set the inode->i_ctime to the current value for the inode. Returns
2664 * the current value that was assigned to i_ctime.
2665 */
inode_set_ctime_current(struct inode * inode)2666 struct timespec64 inode_set_ctime_current(struct inode *inode)
2667 {
2668 struct timespec64 now = current_time(inode);
2669
2670 inode_set_ctime_to_ts(inode, now);
2671 return now;
2672 }
2673 EXPORT_SYMBOL(inode_set_ctime_current);
2674
2675 /**
2676 * in_group_or_capable - check whether caller is CAP_FSETID privileged
2677 * @idmap: idmap of the mount @inode was found from
2678 * @inode: inode to check
2679 * @vfsgid: the new/current vfsgid of @inode
2680 *
2681 * Check wether @vfsgid is in the caller's group list or if the caller is
2682 * privileged with CAP_FSETID over @inode. This can be used to determine
2683 * whether the setgid bit can be kept or must be dropped.
2684 *
2685 * Return: true if the caller is sufficiently privileged, false if not.
2686 */
in_group_or_capable(struct mnt_idmap * idmap,const struct inode * inode,vfsgid_t vfsgid)2687 bool in_group_or_capable(struct mnt_idmap *idmap,
2688 const struct inode *inode, vfsgid_t vfsgid)
2689 {
2690 if (vfsgid_in_group_p(vfsgid))
2691 return true;
2692 if (capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
2693 return true;
2694 return false;
2695 }
2696 EXPORT_SYMBOL(in_group_or_capable);
2697
2698 /**
2699 * mode_strip_sgid - handle the sgid bit for non-directories
2700 * @idmap: idmap of the mount the inode was created from
2701 * @dir: parent directory inode
2702 * @mode: mode of the file to be created in @dir
2703 *
2704 * If the @mode of the new file has both the S_ISGID and S_IXGRP bit
2705 * raised and @dir has the S_ISGID bit raised ensure that the caller is
2706 * either in the group of the parent directory or they have CAP_FSETID
2707 * in their user namespace and are privileged over the parent directory.
2708 * In all other cases, strip the S_ISGID bit from @mode.
2709 *
2710 * Return: the new mode to use for the file
2711 */
mode_strip_sgid(struct mnt_idmap * idmap,const struct inode * dir,umode_t mode)2712 umode_t mode_strip_sgid(struct mnt_idmap *idmap,
2713 const struct inode *dir, umode_t mode)
2714 {
2715 if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP))
2716 return mode;
2717 if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID))
2718 return mode;
2719 if (in_group_or_capable(idmap, dir, i_gid_into_vfsgid(idmap, dir)))
2720 return mode;
2721 return mode & ~S_ISGID;
2722 }
2723 EXPORT_SYMBOL(mode_strip_sgid);
2724