~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/inode.c

Version: ~ [ linux-5.13-rc7 ] ~ [ linux-5.12.12 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.45 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.127 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.195 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.237 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.273 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.273 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp