xref: /openbmc/linux/fs/inode.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * linux/fs/inode.c
3  *
4  * (C) 1997 Linus Torvalds
5  */
6 
7 #include <linux/fs.h>
8 #include <linux/mm.h>
9 #include <linux/dcache.h>
10 #include <linux/init.h>
11 #include <linux/quotaops.h>
12 #include <linux/slab.h>
13 #include <linux/writeback.h>
14 #include <linux/module.h>
15 #include <linux/backing-dev.h>
16 #include <linux/wait.h>
17 #include <linux/hash.h>
18 #include <linux/swap.h>
19 #include <linux/security.h>
20 #include <linux/pagemap.h>
21 #include <linux/cdev.h>
22 #include <linux/bootmem.h>
23 #include <linux/inotify.h>
24 #include <linux/mount.h>
25 
26 /*
27  * This is needed for the following functions:
28  *  - inode_has_buffers
29  *  - invalidate_inode_buffers
30  *  - invalidate_bdev
31  *
32  * FIXME: remove all knowledge of the buffer layer from this file
33  */
34 #include <linux/buffer_head.h>
35 
36 /*
37  * New inode.c implementation.
38  *
39  * This implementation has the basic premise of trying
40  * to be extremely low-overhead and SMP-safe, yet be
41  * simple enough to be "obviously correct".
42  *
43  * Famous last words.
44  */
45 
46 /* inode dynamic allocation 1999, Andrea Arcangeli <andrea@suse.de> */
47 
48 /* #define INODE_PARANOIA 1 */
49 /* #define INODE_DEBUG 1 */
50 
51 /*
52  * Inode lookup is no longer as critical as it used to be:
53  * most of the lookups are going to be through the dcache.
54  */
55 #define I_HASHBITS	i_hash_shift
56 #define I_HASHMASK	i_hash_mask
57 
58 static unsigned int i_hash_mask __read_mostly;
59 static unsigned int i_hash_shift __read_mostly;
60 
61 /*
62  * Each inode can be on two separate lists. One is
63  * the hash list of the inode, used for lookups. The
64  * other linked list is the "type" list:
65  *  "in_use" - valid inode, i_count > 0, i_nlink > 0
66  *  "dirty"  - as "in_use" but also dirty
67  *  "unused" - valid inode, i_count = 0
68  *
69  * A "dirty" list is maintained for each super block,
70  * allowing for low-overhead inode sync() operations.
71  */
72 
73 LIST_HEAD(inode_in_use);
74 LIST_HEAD(inode_unused);
75 static struct hlist_head *inode_hashtable __read_mostly;
76 
77 /*
78  * A simple spinlock to protect the list manipulations.
79  *
80  * NOTE! You also have to own the lock if you change
81  * the i_state of an inode while it is in use..
82  */
83 DEFINE_SPINLOCK(inode_lock);
84 
85 /*
86  * iprune_mutex provides exclusion between the kswapd or try_to_free_pages
87  * icache shrinking path, and the umount path.  Without this exclusion,
88  * by the time prune_icache calls iput for the inode whose pages it has
89  * been invalidating, or by the time it calls clear_inode & destroy_inode
90  * from its final dispose_list, the struct super_block they refer to
91  * (for inode->i_sb->s_op) may already have been freed and reused.
92  */
93 static DEFINE_MUTEX(iprune_mutex);
94 
95 /*
96  * Statistics gathering..
97  */
98 struct inodes_stat_t inodes_stat;
99 
100 static struct kmem_cache * inode_cachep __read_mostly;
101 
102 static struct inode *alloc_inode(struct super_block *sb)
103 {
104 	static const struct address_space_operations empty_aops;
105 	static struct inode_operations empty_iops;
106 	static const struct file_operations empty_fops;
107 	struct inode *inode;
108 
109 	if (sb->s_op->alloc_inode)
110 		inode = sb->s_op->alloc_inode(sb);
111 	else
112 		inode = (struct inode *) kmem_cache_alloc(inode_cachep, GFP_KERNEL);
113 
114 	if (inode) {
115 		struct address_space * const mapping = &inode->i_data;
116 
117 		inode->i_sb = sb;
118 		inode->i_blkbits = sb->s_blocksize_bits;
119 		inode->i_flags = 0;
120 		atomic_set(&inode->i_count, 1);
121 		inode->i_op = &empty_iops;
122 		inode->i_fop = &empty_fops;
123 		inode->i_nlink = 1;
124 		atomic_set(&inode->i_writecount, 0);
125 		inode->i_size = 0;
126 		inode->i_blocks = 0;
127 		inode->i_bytes = 0;
128 		inode->i_generation = 0;
129 #ifdef CONFIG_QUOTA
130 		memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
131 #endif
132 		inode->i_pipe = NULL;
133 		inode->i_bdev = NULL;
134 		inode->i_cdev = NULL;
135 		inode->i_rdev = 0;
136 		inode->dirtied_when = 0;
137 		if (security_inode_alloc(inode)) {
138 			if (inode->i_sb->s_op->destroy_inode)
139 				inode->i_sb->s_op->destroy_inode(inode);
140 			else
141 				kmem_cache_free(inode_cachep, (inode));
142 			return NULL;
143 		}
144 
145 		mapping->a_ops = &empty_aops;
146  		mapping->host = inode;
147 		mapping->flags = 0;
148 		mapping_set_gfp_mask(mapping, GFP_HIGHUSER);
149 		mapping->assoc_mapping = NULL;
150 		mapping->backing_dev_info = &default_backing_dev_info;
151 
152 		/*
153 		 * If the block_device provides a backing_dev_info for client
154 		 * inodes then use that.  Otherwise the inode share the bdev's
155 		 * backing_dev_info.
156 		 */
157 		if (sb->s_bdev) {
158 			struct backing_dev_info *bdi;
159 
160 			bdi = sb->s_bdev->bd_inode_backing_dev_info;
161 			if (!bdi)
162 				bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
163 			mapping->backing_dev_info = bdi;
164 		}
165 		inode->i_private = NULL;
166 		inode->i_mapping = mapping;
167 	}
168 	return inode;
169 }
170 
171 void destroy_inode(struct inode *inode)
172 {
173 	BUG_ON(inode_has_buffers(inode));
174 	security_inode_free(inode);
175 	if (inode->i_sb->s_op->destroy_inode)
176 		inode->i_sb->s_op->destroy_inode(inode);
177 	else
178 		kmem_cache_free(inode_cachep, (inode));
179 }
180 
181 
182 /*
183  * These are initializations that only need to be done
184  * once, because the fields are idempotent across use
185  * of the inode, so let the slab aware of that.
186  */
187 void inode_init_once(struct inode *inode)
188 {
189 	memset(inode, 0, sizeof(*inode));
190 	INIT_HLIST_NODE(&inode->i_hash);
191 	INIT_LIST_HEAD(&inode->i_dentry);
192 	INIT_LIST_HEAD(&inode->i_devices);
193 	mutex_init(&inode->i_mutex);
194 	init_rwsem(&inode->i_alloc_sem);
195 	INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
196 	rwlock_init(&inode->i_data.tree_lock);
197 	spin_lock_init(&inode->i_data.i_mmap_lock);
198 	INIT_LIST_HEAD(&inode->i_data.private_list);
199 	spin_lock_init(&inode->i_data.private_lock);
200 	INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
201 	INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
202 	spin_lock_init(&inode->i_lock);
203 	i_size_ordered_init(inode);
204 #ifdef CONFIG_INOTIFY
205 	INIT_LIST_HEAD(&inode->inotify_watches);
206 	mutex_init(&inode->inotify_mutex);
207 #endif
208 }
209 
210 EXPORT_SYMBOL(inode_init_once);
211 
212 static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
213 {
214 	struct inode * inode = (struct inode *) foo;
215 
216 	if (flags & SLAB_CTOR_CONSTRUCTOR)
217 		inode_init_once(inode);
218 }
219 
220 /*
221  * inode_lock must be held
222  */
223 void __iget(struct inode * inode)
224 {
225 	if (atomic_read(&inode->i_count)) {
226 		atomic_inc(&inode->i_count);
227 		return;
228 	}
229 	atomic_inc(&inode->i_count);
230 	if (!(inode->i_state & (I_DIRTY|I_LOCK)))
231 		list_move(&inode->i_list, &inode_in_use);
232 	inodes_stat.nr_unused--;
233 }
234 
235 /**
236  * clear_inode - clear an inode
237  * @inode: inode to clear
238  *
239  * This is called by the filesystem to tell us
240  * that the inode is no longer useful. We just
241  * terminate it with extreme prejudice.
242  */
243 void clear_inode(struct inode *inode)
244 {
245 	might_sleep();
246 	invalidate_inode_buffers(inode);
247 
248 	BUG_ON(inode->i_data.nrpages);
249 	BUG_ON(!(inode->i_state & I_FREEING));
250 	BUG_ON(inode->i_state & I_CLEAR);
251 	wait_on_inode(inode);
252 	DQUOT_DROP(inode);
253 	if (inode->i_sb->s_op->clear_inode)
254 		inode->i_sb->s_op->clear_inode(inode);
255 	if (S_ISBLK(inode->i_mode) && inode->i_bdev)
256 		bd_forget(inode);
257 	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
258 		cd_forget(inode);
259 	inode->i_state = I_CLEAR;
260 }
261 
262 EXPORT_SYMBOL(clear_inode);
263 
264 /*
265  * dispose_list - dispose of the contents of a local list
266  * @head: the head of the list to free
267  *
268  * Dispose-list gets a local list with local inodes in it, so it doesn't
269  * need to worry about list corruption and SMP locks.
270  */
271 static void dispose_list(struct list_head *head)
272 {
273 	int nr_disposed = 0;
274 
275 	while (!list_empty(head)) {
276 		struct inode *inode;
277 
278 		inode = list_first_entry(head, struct inode, i_list);
279 		list_del(&inode->i_list);
280 
281 		if (inode->i_data.nrpages)
282 			truncate_inode_pages(&inode->i_data, 0);
283 		clear_inode(inode);
284 
285 		spin_lock(&inode_lock);
286 		hlist_del_init(&inode->i_hash);
287 		list_del_init(&inode->i_sb_list);
288 		spin_unlock(&inode_lock);
289 
290 		wake_up_inode(inode);
291 		destroy_inode(inode);
292 		nr_disposed++;
293 	}
294 	spin_lock(&inode_lock);
295 	inodes_stat.nr_inodes -= nr_disposed;
296 	spin_unlock(&inode_lock);
297 }
298 
299 /*
300  * Invalidate all inodes for a device.
301  */
302 static int invalidate_list(struct list_head *head, struct list_head *dispose)
303 {
304 	struct list_head *next;
305 	int busy = 0, count = 0;
306 
307 	next = head->next;
308 	for (;;) {
309 		struct list_head * tmp = next;
310 		struct inode * inode;
311 
312 		/*
313 		 * We can reschedule here without worrying about the list's
314 		 * consistency because the per-sb list of inodes must not
315 		 * change during umount anymore, and because iprune_mutex keeps
316 		 * shrink_icache_memory() away.
317 		 */
318 		cond_resched_lock(&inode_lock);
319 
320 		next = next->next;
321 		if (tmp == head)
322 			break;
323 		inode = list_entry(tmp, struct inode, i_sb_list);
324 		invalidate_inode_buffers(inode);
325 		if (!atomic_read(&inode->i_count)) {
326 			list_move(&inode->i_list, dispose);
327 			inode->i_state |= I_FREEING;
328 			count++;
329 			continue;
330 		}
331 		busy = 1;
332 	}
333 	/* only unused inodes may be cached with i_count zero */
334 	inodes_stat.nr_unused -= count;
335 	return busy;
336 }
337 
338 /**
339  *	invalidate_inodes	- discard the inodes on a device
340  *	@sb: superblock
341  *
342  *	Discard all of the inodes for a given superblock. If the discard
343  *	fails because there are busy inodes then a non zero value is returned.
344  *	If the discard is successful all the inodes have been discarded.
345  */
346 int invalidate_inodes(struct super_block * sb)
347 {
348 	int busy;
349 	LIST_HEAD(throw_away);
350 
351 	mutex_lock(&iprune_mutex);
352 	spin_lock(&inode_lock);
353 	inotify_unmount_inodes(&sb->s_inodes);
354 	busy = invalidate_list(&sb->s_inodes, &throw_away);
355 	spin_unlock(&inode_lock);
356 
357 	dispose_list(&throw_away);
358 	mutex_unlock(&iprune_mutex);
359 
360 	return busy;
361 }
362 
363 EXPORT_SYMBOL(invalidate_inodes);
364 
365 static int can_unuse(struct inode *inode)
366 {
367 	if (inode->i_state)
368 		return 0;
369 	if (inode_has_buffers(inode))
370 		return 0;
371 	if (atomic_read(&inode->i_count))
372 		return 0;
373 	if (inode->i_data.nrpages)
374 		return 0;
375 	return 1;
376 }
377 
378 /*
379  * Scan `goal' inodes on the unused list for freeable ones. They are moved to
380  * a temporary list and then are freed outside inode_lock by dispose_list().
381  *
382  * Any inodes which are pinned purely because of attached pagecache have their
383  * pagecache removed.  We expect the final iput() on that inode to add it to
384  * the front of the inode_unused list.  So look for it there and if the
385  * inode is still freeable, proceed.  The right inode is found 99.9% of the
386  * time in testing on a 4-way.
387  *
388  * If the inode has metadata buffers attached to mapping->private_list then
389  * try to remove them.
390  */
391 static void prune_icache(int nr_to_scan)
392 {
393 	LIST_HEAD(freeable);
394 	int nr_pruned = 0;
395 	int nr_scanned;
396 	unsigned long reap = 0;
397 
398 	mutex_lock(&iprune_mutex);
399 	spin_lock(&inode_lock);
400 	for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
401 		struct inode *inode;
402 
403 		if (list_empty(&inode_unused))
404 			break;
405 
406 		inode = list_entry(inode_unused.prev, struct inode, i_list);
407 
408 		if (inode->i_state || atomic_read(&inode->i_count)) {
409 			list_move(&inode->i_list, &inode_unused);
410 			continue;
411 		}
412 		if (inode_has_buffers(inode) || inode->i_data.nrpages) {
413 			__iget(inode);
414 			spin_unlock(&inode_lock);
415 			if (remove_inode_buffers(inode))
416 				reap += invalidate_mapping_pages(&inode->i_data,
417 								0, -1);
418 			iput(inode);
419 			spin_lock(&inode_lock);
420 
421 			if (inode != list_entry(inode_unused.next,
422 						struct inode, i_list))
423 				continue;	/* wrong inode or list_empty */
424 			if (!can_unuse(inode))
425 				continue;
426 		}
427 		list_move(&inode->i_list, &freeable);
428 		inode->i_state |= I_FREEING;
429 		nr_pruned++;
430 	}
431 	inodes_stat.nr_unused -= nr_pruned;
432 	if (current_is_kswapd())
433 		__count_vm_events(KSWAPD_INODESTEAL, reap);
434 	else
435 		__count_vm_events(PGINODESTEAL, reap);
436 	spin_unlock(&inode_lock);
437 
438 	dispose_list(&freeable);
439 	mutex_unlock(&iprune_mutex);
440 }
441 
442 /*
443  * shrink_icache_memory() will attempt to reclaim some unused inodes.  Here,
444  * "unused" means that no dentries are referring to the inodes: the files are
445  * not open and the dcache references to those inodes have already been
446  * reclaimed.
447  *
448  * This function is passed the number of inodes to scan, and it returns the
449  * total number of remaining possibly-reclaimable inodes.
450  */
451 static int shrink_icache_memory(int nr, gfp_t gfp_mask)
452 {
453 	if (nr) {
454 		/*
455 		 * Nasty deadlock avoidance.  We may hold various FS locks,
456 		 * and we don't want to recurse into the FS that called us
457 		 * in clear_inode() and friends..
458 	 	 */
459 		if (!(gfp_mask & __GFP_FS))
460 			return -1;
461 		prune_icache(nr);
462 	}
463 	return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
464 }
465 
466 static void __wait_on_freeing_inode(struct inode *inode);
467 /*
468  * Called with the inode lock held.
469  * NOTE: we are not increasing the inode-refcount, you must call __iget()
470  * by hand after calling find_inode now! This simplifies iunique and won't
471  * add any additional branch in the common code.
472  */
473 static struct inode * find_inode(struct super_block * sb, struct hlist_head *head, int (*test)(struct inode *, void *), void *data)
474 {
475 	struct hlist_node *node;
476 	struct inode * inode = NULL;
477 
478 repeat:
479 	hlist_for_each (node, head) {
480 		inode = hlist_entry(node, struct inode, i_hash);
481 		if (inode->i_sb != sb)
482 			continue;
483 		if (!test(inode, data))
484 			continue;
485 		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
486 			__wait_on_freeing_inode(inode);
487 			goto repeat;
488 		}
489 		break;
490 	}
491 	return node ? inode : NULL;
492 }
493 
494 /*
495  * find_inode_fast is the fast path version of find_inode, see the comment at
496  * iget_locked for details.
497  */
498 static struct inode * find_inode_fast(struct super_block * sb, struct hlist_head *head, unsigned long ino)
499 {
500 	struct hlist_node *node;
501 	struct inode * inode = NULL;
502 
503 repeat:
504 	hlist_for_each (node, head) {
505 		inode = hlist_entry(node, struct inode, i_hash);
506 		if (inode->i_ino != ino)
507 			continue;
508 		if (inode->i_sb != sb)
509 			continue;
510 		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
511 			__wait_on_freeing_inode(inode);
512 			goto repeat;
513 		}
514 		break;
515 	}
516 	return node ? inode : NULL;
517 }
518 
519 /**
520  *	new_inode 	- obtain an inode
521  *	@sb: superblock
522  *
523  *	Allocates a new inode for given superblock.
524  */
525 struct inode *new_inode(struct super_block *sb)
526 {
527 	/*
528 	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
529 	 * error if st_ino won't fit in target struct field. Use 32bit counter
530 	 * here to attempt to avoid that.
531 	 */
532 	static unsigned int last_ino;
533 	struct inode * inode;
534 
535 	spin_lock_prefetch(&inode_lock);
536 
537 	inode = alloc_inode(sb);
538 	if (inode) {
539 		spin_lock(&inode_lock);
540 		inodes_stat.nr_inodes++;
541 		list_add(&inode->i_list, &inode_in_use);
542 		list_add(&inode->i_sb_list, &sb->s_inodes);
543 		inode->i_ino = ++last_ino;
544 		inode->i_state = 0;
545 		spin_unlock(&inode_lock);
546 	}
547 	return inode;
548 }
549 
550 EXPORT_SYMBOL(new_inode);
551 
552 void unlock_new_inode(struct inode *inode)
553 {
554 	/*
555 	 * This is special!  We do not need the spinlock
556 	 * when clearing I_LOCK, because we're guaranteed
557 	 * that nobody else tries to do anything about the
558 	 * state of the inode when it is locked, as we
559 	 * just created it (so there can be no old holders
560 	 * that haven't tested I_LOCK).
561 	 */
562 	inode->i_state &= ~(I_LOCK|I_NEW);
563 	wake_up_inode(inode);
564 }
565 
566 EXPORT_SYMBOL(unlock_new_inode);
567 
568 /*
569  * This is called without the inode lock held.. Be careful.
570  *
571  * We no longer cache the sb_flags in i_flags - see fs.h
572  *	-- rmk@arm.uk.linux.org
573  */
574 static struct inode * get_new_inode(struct super_block *sb, struct hlist_head *head, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *data)
575 {
576 	struct inode * inode;
577 
578 	inode = alloc_inode(sb);
579 	if (inode) {
580 		struct inode * old;
581 
582 		spin_lock(&inode_lock);
583 		/* We released the lock, so.. */
584 		old = find_inode(sb, head, test, data);
585 		if (!old) {
586 			if (set(inode, data))
587 				goto set_failed;
588 
589 			inodes_stat.nr_inodes++;
590 			list_add(&inode->i_list, &inode_in_use);
591 			list_add(&inode->i_sb_list, &sb->s_inodes);
592 			hlist_add_head(&inode->i_hash, head);
593 			inode->i_state = I_LOCK|I_NEW;
594 			spin_unlock(&inode_lock);
595 
596 			/* Return the locked inode with I_NEW set, the
597 			 * caller is responsible for filling in the contents
598 			 */
599 			return inode;
600 		}
601 
602 		/*
603 		 * Uhhuh, somebody else created the same inode under
604 		 * us. Use the old inode instead of the one we just
605 		 * allocated.
606 		 */
607 		__iget(old);
608 		spin_unlock(&inode_lock);
609 		destroy_inode(inode);
610 		inode = old;
611 		wait_on_inode(inode);
612 	}
613 	return inode;
614 
615 set_failed:
616 	spin_unlock(&inode_lock);
617 	destroy_inode(inode);
618 	return NULL;
619 }
620 
621 /*
622  * get_new_inode_fast is the fast path version of get_new_inode, see the
623  * comment at iget_locked for details.
624  */
625 static struct inode * get_new_inode_fast(struct super_block *sb, struct hlist_head *head, unsigned long ino)
626 {
627 	struct inode * inode;
628 
629 	inode = alloc_inode(sb);
630 	if (inode) {
631 		struct inode * old;
632 
633 		spin_lock(&inode_lock);
634 		/* We released the lock, so.. */
635 		old = find_inode_fast(sb, head, ino);
636 		if (!old) {
637 			inode->i_ino = ino;
638 			inodes_stat.nr_inodes++;
639 			list_add(&inode->i_list, &inode_in_use);
640 			list_add(&inode->i_sb_list, &sb->s_inodes);
641 			hlist_add_head(&inode->i_hash, head);
642 			inode->i_state = I_LOCK|I_NEW;
643 			spin_unlock(&inode_lock);
644 
645 			/* Return the locked inode with I_NEW set, the
646 			 * caller is responsible for filling in the contents
647 			 */
648 			return inode;
649 		}
650 
651 		/*
652 		 * Uhhuh, somebody else created the same inode under
653 		 * us. Use the old inode instead of the one we just
654 		 * allocated.
655 		 */
656 		__iget(old);
657 		spin_unlock(&inode_lock);
658 		destroy_inode(inode);
659 		inode = old;
660 		wait_on_inode(inode);
661 	}
662 	return inode;
663 }
664 
665 static unsigned long hash(struct super_block *sb, unsigned long hashval)
666 {
667 	unsigned long tmp;
668 
669 	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
670 			L1_CACHE_BYTES;
671 	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
672 	return tmp & I_HASHMASK;
673 }
674 
675 /**
676  *	iunique - get a unique inode number
677  *	@sb: superblock
678  *	@max_reserved: highest reserved inode number
679  *
680  *	Obtain an inode number that is unique on the system for a given
681  *	superblock. This is used by file systems that have no natural
682  *	permanent inode numbering system. An inode number is returned that
683  *	is higher than the reserved limit but unique.
684  *
685  *	BUGS:
686  *	With a large number of inodes live on the file system this function
687  *	currently becomes quite slow.
688  */
689 ino_t iunique(struct super_block *sb, ino_t max_reserved)
690 {
691 	/*
692 	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
693 	 * error if st_ino won't fit in target struct field. Use 32bit counter
694 	 * here to attempt to avoid that.
695 	 */
696 	static unsigned int counter;
697 	struct inode *inode;
698 	struct hlist_head *head;
699 	ino_t res;
700 
701 	spin_lock(&inode_lock);
702 	do {
703 		if (counter <= max_reserved)
704 			counter = max_reserved + 1;
705 		res = counter++;
706 		head = inode_hashtable + hash(sb, res);
707 		inode = find_inode_fast(sb, head, res);
708 	} while (inode != NULL);
709 	spin_unlock(&inode_lock);
710 
711 	return res;
712 }
713 EXPORT_SYMBOL(iunique);
714 
715 struct inode *igrab(struct inode *inode)
716 {
717 	spin_lock(&inode_lock);
718 	if (!(inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)))
719 		__iget(inode);
720 	else
721 		/*
722 		 * Handle the case where s_op->clear_inode is not been
723 		 * called yet, and somebody is calling igrab
724 		 * while the inode is getting freed.
725 		 */
726 		inode = NULL;
727 	spin_unlock(&inode_lock);
728 	return inode;
729 }
730 
731 EXPORT_SYMBOL(igrab);
732 
733 /**
734  * ifind - internal function, you want ilookup5() or iget5().
735  * @sb:		super block of file system to search
736  * @head:       the head of the list to search
737  * @test:	callback used for comparisons between inodes
738  * @data:	opaque data pointer to pass to @test
739  * @wait:	if true wait for the inode to be unlocked, if false do not
740  *
741  * ifind() searches for the inode specified by @data in the inode
742  * cache. This is a generalized version of ifind_fast() for file systems where
743  * the inode number is not sufficient for unique identification of an inode.
744  *
745  * If the inode is in the cache, the inode is returned with an incremented
746  * reference count.
747  *
748  * Otherwise NULL is returned.
749  *
750  * Note, @test is called with the inode_lock held, so can't sleep.
751  */
752 static struct inode *ifind(struct super_block *sb,
753 		struct hlist_head *head, int (*test)(struct inode *, void *),
754 		void *data, const int wait)
755 {
756 	struct inode *inode;
757 
758 	spin_lock(&inode_lock);
759 	inode = find_inode(sb, head, test, data);
760 	if (inode) {
761 		__iget(inode);
762 		spin_unlock(&inode_lock);
763 		if (likely(wait))
764 			wait_on_inode(inode);
765 		return inode;
766 	}
767 	spin_unlock(&inode_lock);
768 	return NULL;
769 }
770 
771 /**
772  * ifind_fast - internal function, you want ilookup() or iget().
773  * @sb:		super block of file system to search
774  * @head:       head of the list to search
775  * @ino:	inode number to search for
776  *
777  * ifind_fast() searches for the inode @ino in the inode cache. This is for
778  * file systems where the inode number is sufficient for unique identification
779  * of an inode.
780  *
781  * If the inode is in the cache, the inode is returned with an incremented
782  * reference count.
783  *
784  * Otherwise NULL is returned.
785  */
786 static struct inode *ifind_fast(struct super_block *sb,
787 		struct hlist_head *head, unsigned long ino)
788 {
789 	struct inode *inode;
790 
791 	spin_lock(&inode_lock);
792 	inode = find_inode_fast(sb, head, ino);
793 	if (inode) {
794 		__iget(inode);
795 		spin_unlock(&inode_lock);
796 		wait_on_inode(inode);
797 		return inode;
798 	}
799 	spin_unlock(&inode_lock);
800 	return NULL;
801 }
802 
803 /**
804  * ilookup5_nowait - search for an inode in the inode cache
805  * @sb:		super block of file system to search
806  * @hashval:	hash value (usually inode number) to search for
807  * @test:	callback used for comparisons between inodes
808  * @data:	opaque data pointer to pass to @test
809  *
810  * ilookup5() uses ifind() to search for the inode specified by @hashval and
811  * @data in the inode cache. This is a generalized version of ilookup() for
812  * file systems where the inode number is not sufficient for unique
813  * identification of an inode.
814  *
815  * If the inode is in the cache, the inode is returned with an incremented
816  * reference count.  Note, the inode lock is not waited upon so you have to be
817  * very careful what you do with the returned inode.  You probably should be
818  * using ilookup5() instead.
819  *
820  * Otherwise NULL is returned.
821  *
822  * Note, @test is called with the inode_lock held, so can't sleep.
823  */
824 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
825 		int (*test)(struct inode *, void *), void *data)
826 {
827 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
828 
829 	return ifind(sb, head, test, data, 0);
830 }
831 
832 EXPORT_SYMBOL(ilookup5_nowait);
833 
834 /**
835  * ilookup5 - search for an inode in the inode cache
836  * @sb:		super block of file system to search
837  * @hashval:	hash value (usually inode number) to search for
838  * @test:	callback used for comparisons between inodes
839  * @data:	opaque data pointer to pass to @test
840  *
841  * ilookup5() uses ifind() to search for the inode specified by @hashval and
842  * @data in the inode cache. This is a generalized version of ilookup() for
843  * file systems where the inode number is not sufficient for unique
844  * identification of an inode.
845  *
846  * If the inode is in the cache, the inode lock is waited upon and the inode is
847  * returned with an incremented reference count.
848  *
849  * Otherwise NULL is returned.
850  *
851  * Note, @test is called with the inode_lock held, so can't sleep.
852  */
853 struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
854 		int (*test)(struct inode *, void *), void *data)
855 {
856 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
857 
858 	return ifind(sb, head, test, data, 1);
859 }
860 
861 EXPORT_SYMBOL(ilookup5);
862 
863 /**
864  * ilookup - search for an inode in the inode cache
865  * @sb:		super block of file system to search
866  * @ino:	inode number to search for
867  *
868  * ilookup() uses ifind_fast() to search for the inode @ino in the inode cache.
869  * This is for file systems where the inode number is sufficient for unique
870  * identification of an inode.
871  *
872  * If the inode is in the cache, the inode is returned with an incremented
873  * reference count.
874  *
875  * Otherwise NULL is returned.
876  */
877 struct inode *ilookup(struct super_block *sb, unsigned long ino)
878 {
879 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
880 
881 	return ifind_fast(sb, head, ino);
882 }
883 
884 EXPORT_SYMBOL(ilookup);
885 
886 /**
887  * iget5_locked - obtain an inode from a mounted file system
888  * @sb:		super block of file system
889  * @hashval:	hash value (usually inode number) to get
890  * @test:	callback used for comparisons between inodes
891  * @set:	callback used to initialize a new struct inode
892  * @data:	opaque data pointer to pass to @test and @set
893  *
894  * This is iget() without the read_inode() portion of get_new_inode().
895  *
896  * iget5_locked() uses ifind() to search for the inode specified by @hashval
897  * and @data in the inode cache and if present it is returned with an increased
898  * reference count. This is a generalized version of iget_locked() for file
899  * systems where the inode number is not sufficient for unique identification
900  * of an inode.
901  *
902  * If the inode is not in cache, get_new_inode() is called to allocate a new
903  * inode and this is returned locked, hashed, and with the I_NEW flag set. The
904  * file system gets to fill it in before unlocking it via unlock_new_inode().
905  *
906  * Note both @test and @set are called with the inode_lock held, so can't sleep.
907  */
908 struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
909 		int (*test)(struct inode *, void *),
910 		int (*set)(struct inode *, void *), void *data)
911 {
912 	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
913 	struct inode *inode;
914 
915 	inode = ifind(sb, head, test, data, 1);
916 	if (inode)
917 		return inode;
918 	/*
919 	 * get_new_inode() will do the right thing, re-trying the search
920 	 * in case it had to block at any point.
921 	 */
922 	return get_new_inode(sb, head, test, set, data);
923 }
924 
925 EXPORT_SYMBOL(iget5_locked);
926 
927 /**
928  * iget_locked - obtain an inode from a mounted file system
929  * @sb:		super block of file system
930  * @ino:	inode number to get
931  *
932  * This is iget() without the read_inode() portion of get_new_inode_fast().
933  *
934  * iget_locked() uses ifind_fast() to search for the inode specified by @ino in
935  * the inode cache and if present it is returned with an increased reference
936  * count. This is for file systems where the inode number is sufficient for
937  * unique identification of an inode.
938  *
939  * If the inode is not in cache, get_new_inode_fast() is called to allocate a
940  * new inode and this is returned locked, hashed, and with the I_NEW flag set.
941  * The file system gets to fill it in before unlocking it via
942  * unlock_new_inode().
943  */
944 struct inode *iget_locked(struct super_block *sb, unsigned long ino)
945 {
946 	struct hlist_head *head = inode_hashtable + hash(sb, ino);
947 	struct inode *inode;
948 
949 	inode = ifind_fast(sb, head, ino);
950 	if (inode)
951 		return inode;
952 	/*
953 	 * get_new_inode_fast() will do the right thing, re-trying the search
954 	 * in case it had to block at any point.
955 	 */
956 	return get_new_inode_fast(sb, head, ino);
957 }
958 
959 EXPORT_SYMBOL(iget_locked);
960 
961 /**
962  *	__insert_inode_hash - hash an inode
963  *	@inode: unhashed inode
964  *	@hashval: unsigned long value used to locate this object in the
965  *		inode_hashtable.
966  *
967  *	Add an inode to the inode hash for this superblock.
968  */
969 void __insert_inode_hash(struct inode *inode, unsigned long hashval)
970 {
971 	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
972 	spin_lock(&inode_lock);
973 	hlist_add_head(&inode->i_hash, head);
974 	spin_unlock(&inode_lock);
975 }
976 
977 EXPORT_SYMBOL(__insert_inode_hash);
978 
979 /**
980  *	remove_inode_hash - remove an inode from the hash
981  *	@inode: inode to unhash
982  *
983  *	Remove an inode from the superblock.
984  */
985 void remove_inode_hash(struct inode *inode)
986 {
987 	spin_lock(&inode_lock);
988 	hlist_del_init(&inode->i_hash);
989 	spin_unlock(&inode_lock);
990 }
991 
992 EXPORT_SYMBOL(remove_inode_hash);
993 
994 /*
995  * Tell the filesystem that this inode is no longer of any interest and should
996  * be completely destroyed.
997  *
998  * We leave the inode in the inode hash table until *after* the filesystem's
999  * ->delete_inode completes.  This ensures that an iget (such as nfsd might
1000  * instigate) will always find up-to-date information either in the hash or on
1001  * disk.
1002  *
1003  * I_FREEING is set so that no-one will take a new reference to the inode while
1004  * it is being deleted.
1005  */
1006 void generic_delete_inode(struct inode *inode)
1007 {
1008 	const struct super_operations *op = inode->i_sb->s_op;
1009 
1010 	list_del_init(&inode->i_list);
1011 	list_del_init(&inode->i_sb_list);
1012 	inode->i_state |= I_FREEING;
1013 	inodes_stat.nr_inodes--;
1014 	spin_unlock(&inode_lock);
1015 
1016 	security_inode_delete(inode);
1017 
1018 	if (op->delete_inode) {
1019 		void (*delete)(struct inode *) = op->delete_inode;
1020 		if (!is_bad_inode(inode))
1021 			DQUOT_INIT(inode);
1022 		/* Filesystems implementing their own
1023 		 * s_op->delete_inode are required to call
1024 		 * truncate_inode_pages and clear_inode()
1025 		 * internally */
1026 		delete(inode);
1027 	} else {
1028 		truncate_inode_pages(&inode->i_data, 0);
1029 		clear_inode(inode);
1030 	}
1031 	spin_lock(&inode_lock);
1032 	hlist_del_init(&inode->i_hash);
1033 	spin_unlock(&inode_lock);
1034 	wake_up_inode(inode);
1035 	BUG_ON(inode->i_state != I_CLEAR);
1036 	destroy_inode(inode);
1037 }
1038 
1039 EXPORT_SYMBOL(generic_delete_inode);
1040 
1041 static void generic_forget_inode(struct inode *inode)
1042 {
1043 	struct super_block *sb = inode->i_sb;
1044 
1045 	if (!hlist_unhashed(&inode->i_hash)) {
1046 		if (!(inode->i_state & (I_DIRTY|I_LOCK)))
1047 			list_move(&inode->i_list, &inode_unused);
1048 		inodes_stat.nr_unused++;
1049 		if (sb->s_flags & MS_ACTIVE) {
1050 			spin_unlock(&inode_lock);
1051 			return;
1052 		}
1053 		inode->i_state |= I_WILL_FREE;
1054 		spin_unlock(&inode_lock);
1055 		write_inode_now(inode, 1);
1056 		spin_lock(&inode_lock);
1057 		inode->i_state &= ~I_WILL_FREE;
1058 		inodes_stat.nr_unused--;
1059 		hlist_del_init(&inode->i_hash);
1060 	}
1061 	list_del_init(&inode->i_list);
1062 	list_del_init(&inode->i_sb_list);
1063 	inode->i_state |= I_FREEING;
1064 	inodes_stat.nr_inodes--;
1065 	spin_unlock(&inode_lock);
1066 	if (inode->i_data.nrpages)
1067 		truncate_inode_pages(&inode->i_data, 0);
1068 	clear_inode(inode);
1069 	wake_up_inode(inode);
1070 	destroy_inode(inode);
1071 }
1072 
1073 /*
1074  * Normal UNIX filesystem behaviour: delete the
1075  * inode when the usage count drops to zero, and
1076  * i_nlink is zero.
1077  */
1078 void generic_drop_inode(struct inode *inode)
1079 {
1080 	if (!inode->i_nlink)
1081 		generic_delete_inode(inode);
1082 	else
1083 		generic_forget_inode(inode);
1084 }
1085 
1086 EXPORT_SYMBOL_GPL(generic_drop_inode);
1087 
1088 /*
1089  * Called when we're dropping the last reference
1090  * to an inode.
1091  *
1092  * Call the FS "drop()" function, defaulting to
1093  * the legacy UNIX filesystem behaviour..
1094  *
1095  * NOTE! NOTE! NOTE! We're called with the inode lock
1096  * held, and the drop function is supposed to release
1097  * the lock!
1098  */
1099 static inline void iput_final(struct inode *inode)
1100 {
1101 	const struct super_operations *op = inode->i_sb->s_op;
1102 	void (*drop)(struct inode *) = generic_drop_inode;
1103 
1104 	if (op && op->drop_inode)
1105 		drop = op->drop_inode;
1106 	drop(inode);
1107 }
1108 
1109 /**
1110  *	iput	- put an inode
1111  *	@inode: inode to put
1112  *
1113  *	Puts an inode, dropping its usage count. If the inode use count hits
1114  *	zero, the inode is then freed and may also be destroyed.
1115  *
1116  *	Consequently, iput() can sleep.
1117  */
1118 void iput(struct inode *inode)
1119 {
1120 	if (inode) {
1121 		const struct super_operations *op = inode->i_sb->s_op;
1122 
1123 		BUG_ON(inode->i_state == I_CLEAR);
1124 
1125 		if (op && op->put_inode)
1126 			op->put_inode(inode);
1127 
1128 		if (atomic_dec_and_lock(&inode->i_count, &inode_lock))
1129 			iput_final(inode);
1130 	}
1131 }
1132 
1133 EXPORT_SYMBOL(iput);
1134 
1135 /**
1136  *	bmap	- find a block number in a file
1137  *	@inode: inode of file
1138  *	@block: block to find
1139  *
1140  *	Returns the block number on the device holding the inode that
1141  *	is the disk block number for the block of the file requested.
1142  *	That is, asked for block 4 of inode 1 the function will return the
1143  *	disk block relative to the disk start that holds that block of the
1144  *	file.
1145  */
1146 sector_t bmap(struct inode * inode, sector_t block)
1147 {
1148 	sector_t res = 0;
1149 	if (inode->i_mapping->a_ops->bmap)
1150 		res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1151 	return res;
1152 }
1153 EXPORT_SYMBOL(bmap);
1154 
1155 /**
1156  *	touch_atime	-	update the access time
1157  *	@mnt: mount the inode is accessed on
1158  *	@dentry: dentry accessed
1159  *
1160  *	Update the accessed time on an inode and mark it for writeback.
1161  *	This function automatically handles read only file systems and media,
1162  *	as well as the "noatime" flag and inode specific "noatime" markers.
1163  */
1164 void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
1165 {
1166 	struct inode *inode = dentry->d_inode;
1167 	struct timespec now;
1168 
1169 	if (inode->i_flags & S_NOATIME)
1170 		return;
1171 	if (IS_NOATIME(inode))
1172 		return;
1173 	if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1174 		return;
1175 
1176 	/*
1177 	 * We may have a NULL vfsmount when coming from NFSD
1178 	 */
1179 	if (mnt) {
1180 		if (mnt->mnt_flags & MNT_NOATIME)
1181 			return;
1182 		if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1183 			return;
1184 
1185 		if (mnt->mnt_flags & MNT_RELATIME) {
1186 			/*
1187 			 * With relative atime, only update atime if the
1188 			 * previous atime is earlier than either the ctime or
1189 			 * mtime.
1190 			 */
1191 			if (timespec_compare(&inode->i_mtime,
1192 						&inode->i_atime) < 0 &&
1193 			    timespec_compare(&inode->i_ctime,
1194 						&inode->i_atime) < 0)
1195 				return;
1196 		}
1197 	}
1198 
1199 	now = current_fs_time(inode->i_sb);
1200 	if (timespec_equal(&inode->i_atime, &now))
1201 		return;
1202 
1203 	inode->i_atime = now;
1204 	mark_inode_dirty_sync(inode);
1205 }
1206 EXPORT_SYMBOL(touch_atime);
1207 
1208 /**
1209  *	file_update_time	-	update mtime and ctime time
1210  *	@file: file accessed
1211  *
1212  *	Update the mtime and ctime members of an inode and mark the inode
1213  *	for writeback.  Note that this function is meant exclusively for
1214  *	usage in the file write path of filesystems, and filesystems may
1215  *	choose to explicitly ignore update via this function with the
1216  *	S_NOCTIME inode flag, e.g. for network filesystem where these
1217  *	timestamps are handled by the server.
1218  */
1219 
1220 void file_update_time(struct file *file)
1221 {
1222 	struct inode *inode = file->f_path.dentry->d_inode;
1223 	struct timespec now;
1224 	int sync_it = 0;
1225 
1226 	if (IS_NOCMTIME(inode))
1227 		return;
1228 	if (IS_RDONLY(inode))
1229 		return;
1230 
1231 	now = current_fs_time(inode->i_sb);
1232 	if (!timespec_equal(&inode->i_mtime, &now)) {
1233 		inode->i_mtime = now;
1234 		sync_it = 1;
1235 	}
1236 
1237 	if (!timespec_equal(&inode->i_ctime, &now)) {
1238 		inode->i_ctime = now;
1239 		sync_it = 1;
1240 	}
1241 
1242 	if (sync_it)
1243 		mark_inode_dirty_sync(inode);
1244 }
1245 
1246 EXPORT_SYMBOL(file_update_time);
1247 
1248 int inode_needs_sync(struct inode *inode)
1249 {
1250 	if (IS_SYNC(inode))
1251 		return 1;
1252 	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1253 		return 1;
1254 	return 0;
1255 }
1256 
1257 EXPORT_SYMBOL(inode_needs_sync);
1258 
1259 int inode_wait(void *word)
1260 {
1261 	schedule();
1262 	return 0;
1263 }
1264 
1265 /*
1266  * If we try to find an inode in the inode hash while it is being
1267  * deleted, we have to wait until the filesystem completes its
1268  * deletion before reporting that it isn't found.  This function waits
1269  * until the deletion _might_ have completed.  Callers are responsible
1270  * to recheck inode state.
1271  *
1272  * It doesn't matter if I_LOCK is not set initially, a call to
1273  * wake_up_inode() after removing from the hash list will DTRT.
1274  *
1275  * This is called with inode_lock held.
1276  */
1277 static void __wait_on_freeing_inode(struct inode *inode)
1278 {
1279 	wait_queue_head_t *wq;
1280 	DEFINE_WAIT_BIT(wait, &inode->i_state, __I_LOCK);
1281 	wq = bit_waitqueue(&inode->i_state, __I_LOCK);
1282 	prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1283 	spin_unlock(&inode_lock);
1284 	schedule();
1285 	finish_wait(wq, &wait.wait);
1286 	spin_lock(&inode_lock);
1287 }
1288 
1289 void wake_up_inode(struct inode *inode)
1290 {
1291 	/*
1292 	 * Prevent speculative execution through spin_unlock(&inode_lock);
1293 	 */
1294 	smp_mb();
1295 	wake_up_bit(&inode->i_state, __I_LOCK);
1296 }
1297 
1298 /*
1299  * We rarely want to lock two inodes that do not have a parent/child
1300  * relationship (such as directory, child inode) simultaneously. The
1301  * vast majority of file systems should be able to get along fine
1302  * without this. Do not use these functions except as a last resort.
1303  */
1304 void inode_double_lock(struct inode *inode1, struct inode *inode2)
1305 {
1306 	if (inode1 == NULL || inode2 == NULL || inode1 == inode2) {
1307 		if (inode1)
1308 			mutex_lock(&inode1->i_mutex);
1309 		else if (inode2)
1310 			mutex_lock(&inode2->i_mutex);
1311 		return;
1312 	}
1313 
1314 	if (inode1 < inode2) {
1315 		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
1316 		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
1317 	} else {
1318 		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
1319 		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
1320 	}
1321 }
1322 EXPORT_SYMBOL(inode_double_lock);
1323 
1324 void inode_double_unlock(struct inode *inode1, struct inode *inode2)
1325 {
1326 	if (inode1)
1327 		mutex_unlock(&inode1->i_mutex);
1328 
1329 	if (inode2 && inode2 != inode1)
1330 		mutex_unlock(&inode2->i_mutex);
1331 }
1332 EXPORT_SYMBOL(inode_double_unlock);
1333 
1334 static __initdata unsigned long ihash_entries;
1335 static int __init set_ihash_entries(char *str)
1336 {
1337 	if (!str)
1338 		return 0;
1339 	ihash_entries = simple_strtoul(str, &str, 0);
1340 	return 1;
1341 }
1342 __setup("ihash_entries=", set_ihash_entries);
1343 
1344 /*
1345  * Initialize the waitqueues and inode hash table.
1346  */
1347 void __init inode_init_early(void)
1348 {
1349 	int loop;
1350 
1351 	/* If hashes are distributed across NUMA nodes, defer
1352 	 * hash allocation until vmalloc space is available.
1353 	 */
1354 	if (hashdist)
1355 		return;
1356 
1357 	inode_hashtable =
1358 		alloc_large_system_hash("Inode-cache",
1359 					sizeof(struct hlist_head),
1360 					ihash_entries,
1361 					14,
1362 					HASH_EARLY,
1363 					&i_hash_shift,
1364 					&i_hash_mask,
1365 					0);
1366 
1367 	for (loop = 0; loop < (1 << i_hash_shift); loop++)
1368 		INIT_HLIST_HEAD(&inode_hashtable[loop]);
1369 }
1370 
1371 void __init inode_init(unsigned long mempages)
1372 {
1373 	int loop;
1374 
1375 	/* inode slab cache */
1376 	inode_cachep = kmem_cache_create("inode_cache",
1377 					 sizeof(struct inode),
1378 					 0,
1379 					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1380 					 SLAB_MEM_SPREAD),
1381 					 init_once,
1382 					 NULL);
1383 	set_shrinker(DEFAULT_SEEKS, shrink_icache_memory);
1384 
1385 	/* Hash may have been set up in inode_init_early */
1386 	if (!hashdist)
1387 		return;
1388 
1389 	inode_hashtable =
1390 		alloc_large_system_hash("Inode-cache",
1391 					sizeof(struct hlist_head),
1392 					ihash_entries,
1393 					14,
1394 					0,
1395 					&i_hash_shift,
1396 					&i_hash_mask,
1397 					0);
1398 
1399 	for (loop = 0; loop < (1 << i_hash_shift); loop++)
1400 		INIT_HLIST_HEAD(&inode_hashtable[loop]);
1401 }
1402 
1403 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
1404 {
1405 	inode->i_mode = mode;
1406 	if (S_ISCHR(mode)) {
1407 		inode->i_fop = &def_chr_fops;
1408 		inode->i_rdev = rdev;
1409 	} else if (S_ISBLK(mode)) {
1410 		inode->i_fop = &def_blk_fops;
1411 		inode->i_rdev = rdev;
1412 	} else if (S_ISFIFO(mode))
1413 		inode->i_fop = &def_fifo_fops;
1414 	else if (S_ISSOCK(mode))
1415 		inode->i_fop = &bad_sock_fops;
1416 	else
1417 		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o)\n",
1418 		       mode);
1419 }
1420 EXPORT_SYMBOL(init_special_inode);
1421