inode.c 40.4 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
/*
 * linux/fs/inode.c
 *
 * (C) 1997 Linus Torvalds
 */

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/dcache.h>
#include <linux/init.h>
#include <linux/quotaops.h>
#include <linux/slab.h>
#include <linux/writeback.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/wait.h>
#include <linux/hash.h>
#include <linux/swap.h>
#include <linux/security.h>
#include <linux/pagemap.h>
#include <linux/cdev.h>
#include <linux/bootmem.h>
R
Robert Love 已提交
23
#include <linux/inotify.h>
24
#include <linux/mount.h>
25
#include <linux/async.h>
L
Linus Torvalds 已提交
26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58

/*
 * This is needed for the following functions:
 *  - inode_has_buffers
 *  - invalidate_inode_buffers
 *  - invalidate_bdev
 *
 * FIXME: remove all knowledge of the buffer layer from this file
 */
#include <linux/buffer_head.h>

/*
 * New inode.c implementation.
 *
 * This implementation has the basic premise of trying
 * to be extremely low-overhead and SMP-safe, yet be
 * simple enough to be "obviously correct".
 *
 * Famous last words.
 */

/* inode dynamic allocation 1999, Andrea Arcangeli <andrea@suse.de> */

/* #define INODE_PARANOIA 1 */
/* #define INODE_DEBUG 1 */

/*
 * Inode lookup is no longer as critical as it used to be:
 * most of the lookups are going to be through the dcache.
 */
#define I_HASHBITS	i_hash_shift
#define I_HASHMASK	i_hash_mask

59 60
static unsigned int i_hash_mask __read_mostly;
static unsigned int i_hash_shift __read_mostly;
L
Linus Torvalds 已提交
61 62 63 64 65 66 67 68 69 70 71 72 73 74 75

/*
 * Each inode can be on two separate lists. One is
 * the hash list of the inode, used for lookups. The
 * other linked list is the "type" list:
 *  "in_use" - valid inode, i_count > 0, i_nlink > 0
 *  "dirty"  - as "in_use" but also dirty
 *  "unused" - valid inode, i_count = 0
 *
 * A "dirty" list is maintained for each super block,
 * allowing for low-overhead inode sync() operations.
 */

LIST_HEAD(inode_in_use);
LIST_HEAD(inode_unused);
76
static struct hlist_head *inode_hashtable __read_mostly;
L
Linus Torvalds 已提交
77 78 79 80 81 82 83 84 85 86

/*
 * A simple spinlock to protect the list manipulations.
 *
 * NOTE! You also have to own the lock if you change
 * the i_state of an inode while it is in use..
 */
DEFINE_SPINLOCK(inode_lock);

/*
I
Ingo Molnar 已提交
87
 * iprune_mutex provides exclusion between the kswapd or try_to_free_pages
L
Linus Torvalds 已提交
88 89 90 91 92 93
 * icache shrinking path, and the umount path.  Without this exclusion,
 * by the time prune_icache calls iput for the inode whose pages it has
 * been invalidating, or by the time it calls clear_inode & destroy_inode
 * from its final dispose_list, the struct super_block they refer to
 * (for inode->i_sb->s_op) may already have been freed and reused.
 */
94
static DEFINE_MUTEX(iprune_mutex);
L
Linus Torvalds 已提交
95 96 97 98 99 100

/*
 * Statistics gathering..
 */
struct inodes_stat_t inodes_stat;

101
static struct kmem_cache * inode_cachep __read_mostly;
L
Linus Torvalds 已提交
102

J
Joern Engel 已提交
103 104 105 106 107 108 109 110 111
static void wake_up_inode(struct inode *inode)
{
	/*
	 * Prevent speculative execution through spin_unlock(&inode_lock);
	 */
	smp_mb();
	wake_up_bit(&inode->i_state, __I_LOCK);
}

D
David Chinner 已提交
112 113
/**
 * inode_init_always - perform inode structure intialisation
R
Randy Dunlap 已提交
114 115
 * @sb: superblock inode belongs to
 * @inode: inode to initialise
D
David Chinner 已提交
116 117 118 119 120
 *
 * These are initializations that need to be done on every inode
 * allocation as the fields are not initialised by slab allocation.
 */
struct inode *inode_init_always(struct super_block *sb, struct inode *inode)
L
Linus Torvalds 已提交
121
{
122
	static const struct address_space_operations empty_aops;
L
Linus Torvalds 已提交
123
	static struct inode_operations empty_iops;
124
	static const struct file_operations empty_fops;
L
Linus Torvalds 已提交
125

D
David Chinner 已提交
126 127 128 129 130 131 132 133 134
	struct address_space * const mapping = &inode->i_data;

	inode->i_sb = sb;
	inode->i_blkbits = sb->s_blocksize_bits;
	inode->i_flags = 0;
	atomic_set(&inode->i_count, 1);
	inode->i_op = &empty_iops;
	inode->i_fop = &empty_fops;
	inode->i_nlink = 1;
A
Al Viro 已提交
135 136
	inode->i_uid = 0;
	inode->i_gid = 0;
D
David Chinner 已提交
137 138 139 140 141
	atomic_set(&inode->i_writecount, 0);
	inode->i_size = 0;
	inode->i_blocks = 0;
	inode->i_bytes = 0;
	inode->i_generation = 0;
L
Linus Torvalds 已提交
142
#ifdef CONFIG_QUOTA
D
David Chinner 已提交
143
	memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
L
Linus Torvalds 已提交
144
#endif
D
David Chinner 已提交
145 146 147 148 149 150 151 152 153 154 155
	inode->i_pipe = NULL;
	inode->i_bdev = NULL;
	inode->i_cdev = NULL;
	inode->i_rdev = 0;
	inode->dirtied_when = 0;
	if (security_inode_alloc(inode)) {
		if (inode->i_sb->s_op->destroy_inode)
			inode->i_sb->s_op->destroy_inode(inode);
		else
			kmem_cache_free(inode_cachep, (inode));
		return NULL;
L
Linus Torvalds 已提交
156
	}
D
David Chinner 已提交
157 158 159 160 161 162 163 164 165 166 167 168 169

	spin_lock_init(&inode->i_lock);
	lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);

	mutex_init(&inode->i_mutex);
	lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);

	init_rwsem(&inode->i_alloc_sem);
	lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);

	mapping->a_ops = &empty_aops;
	mapping->host = inode;
	mapping->flags = 0;
H
Hugh Dickins 已提交
170
	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
D
David Chinner 已提交
171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190
	mapping->assoc_mapping = NULL;
	mapping->backing_dev_info = &default_backing_dev_info;
	mapping->writeback_index = 0;

	/*
	 * If the block_device provides a backing_dev_info for client
	 * inodes then use that.  Otherwise the inode share the bdev's
	 * backing_dev_info.
	 */
	if (sb->s_bdev) {
		struct backing_dev_info *bdi;

		bdi = sb->s_bdev->bd_inode_backing_dev_info;
		if (!bdi)
			bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
		mapping->backing_dev_info = bdi;
	}
	inode->i_private = NULL;
	inode->i_mapping = mapping;

L
Linus Torvalds 已提交
191 192
	return inode;
}
D
David Chinner 已提交
193 194 195 196 197 198 199 200 201 202 203 204 205 206 207
EXPORT_SYMBOL(inode_init_always);

static struct inode *alloc_inode(struct super_block *sb)
{
	struct inode *inode;

	if (sb->s_op->alloc_inode)
		inode = sb->s_op->alloc_inode(sb);
	else
		inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);

	if (inode)
		return inode_init_always(sb, inode);
	return NULL;
}
L
Linus Torvalds 已提交
208 209 210

void destroy_inode(struct inode *inode) 
{
211
	BUG_ON(inode_has_buffers(inode));
L
Linus Torvalds 已提交
212 213 214 215 216 217
	security_inode_free(inode);
	if (inode->i_sb->s_op->destroy_inode)
		inode->i_sb->s_op->destroy_inode(inode);
	else
		kmem_cache_free(inode_cachep, (inode));
}
218
EXPORT_SYMBOL(destroy_inode);
L
Linus Torvalds 已提交
219 220 221 222 223 224 225 226 227 228 229 230 231 232


/*
 * These are initializations that only need to be done
 * once, because the fields are idempotent across use
 * of the inode, so let the slab aware of that.
 */
void inode_init_once(struct inode *inode)
{
	memset(inode, 0, sizeof(*inode));
	INIT_HLIST_NODE(&inode->i_hash);
	INIT_LIST_HEAD(&inode->i_dentry);
	INIT_LIST_HEAD(&inode->i_devices);
	INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
N
Nick Piggin 已提交
233
	spin_lock_init(&inode->i_data.tree_lock);
L
Linus Torvalds 已提交
234 235 236 237 238 239
	spin_lock_init(&inode->i_data.i_mmap_lock);
	INIT_LIST_HEAD(&inode->i_data.private_list);
	spin_lock_init(&inode->i_data.private_lock);
	INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
	INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
	i_size_ordered_init(inode);
R
Robert Love 已提交
240 241
#ifdef CONFIG_INOTIFY
	INIT_LIST_HEAD(&inode->inotify_watches);
I
Ingo Molnar 已提交
242
	mutex_init(&inode->inotify_mutex);
R
Robert Love 已提交
243
#endif
L
Linus Torvalds 已提交
244 245 246 247
}

EXPORT_SYMBOL(inode_init_once);

248
static void init_once(void *foo)
L
Linus Torvalds 已提交
249 250 251
{
	struct inode * inode = (struct inode *) foo;

C
Christoph Lameter 已提交
252
	inode_init_once(inode);
L
Linus Torvalds 已提交
253 254 255 256 257 258 259 260 261 262 263 264
}

/*
 * inode_lock must be held
 */
void __iget(struct inode * inode)
{
	if (atomic_read(&inode->i_count)) {
		atomic_inc(&inode->i_count);
		return;
	}
	atomic_inc(&inode->i_count);
J
Joern Engel 已提交
265
	if (!(inode->i_state & (I_DIRTY|I_SYNC)))
L
Linus Torvalds 已提交
266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282
		list_move(&inode->i_list, &inode_in_use);
	inodes_stat.nr_unused--;
}

/**
 * clear_inode - clear an inode
 * @inode: inode to clear
 *
 * This is called by the filesystem to tell us
 * that the inode is no longer useful. We just
 * terminate it with extreme prejudice.
 */
void clear_inode(struct inode *inode)
{
	might_sleep();
	invalidate_inode_buffers(inode);
       
283 284 285
	BUG_ON(inode->i_data.nrpages);
	BUG_ON(!(inode->i_state & I_FREEING));
	BUG_ON(inode->i_state & I_CLEAR);
J
Joern Engel 已提交
286
	inode_sync_wait(inode);
L
Linus Torvalds 已提交
287
	DQUOT_DROP(inode);
288
	if (inode->i_sb->s_op->clear_inode)
L
Linus Torvalds 已提交
289
		inode->i_sb->s_op->clear_inode(inode);
290
	if (S_ISBLK(inode->i_mode) && inode->i_bdev)
L
Linus Torvalds 已提交
291
		bd_forget(inode);
292
	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
L
Linus Torvalds 已提交
293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312
		cd_forget(inode);
	inode->i_state = I_CLEAR;
}

EXPORT_SYMBOL(clear_inode);

/*
 * dispose_list - dispose of the contents of a local list
 * @head: the head of the list to free
 *
 * Dispose-list gets a local list with local inodes in it, so it doesn't
 * need to worry about list corruption and SMP locks.
 */
static void dispose_list(struct list_head *head)
{
	int nr_disposed = 0;

	while (!list_empty(head)) {
		struct inode *inode;

313
		inode = list_first_entry(head, struct inode, i_list);
L
Linus Torvalds 已提交
314 315 316 317 318
		list_del(&inode->i_list);

		if (inode->i_data.nrpages)
			truncate_inode_pages(&inode->i_data, 0);
		clear_inode(inode);
319 320 321 322 323 324 325

		spin_lock(&inode_lock);
		hlist_del_init(&inode->i_hash);
		list_del_init(&inode->i_sb_list);
		spin_unlock(&inode_lock);

		wake_up_inode(inode);
L
Linus Torvalds 已提交
326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349
		destroy_inode(inode);
		nr_disposed++;
	}
	spin_lock(&inode_lock);
	inodes_stat.nr_inodes -= nr_disposed;
	spin_unlock(&inode_lock);
}

/*
 * Invalidate all inodes for a device.
 */
static int invalidate_list(struct list_head *head, struct list_head *dispose)
{
	struct list_head *next;
	int busy = 0, count = 0;

	next = head->next;
	for (;;) {
		struct list_head * tmp = next;
		struct inode * inode;

		/*
		 * We can reschedule here without worrying about the list's
		 * consistency because the per-sb list of inodes must not
I
Ingo Molnar 已提交
350
		 * change during umount anymore, and because iprune_mutex keeps
L
Linus Torvalds 已提交
351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385
		 * shrink_icache_memory() away.
		 */
		cond_resched_lock(&inode_lock);

		next = next->next;
		if (tmp == head)
			break;
		inode = list_entry(tmp, struct inode, i_sb_list);
		invalidate_inode_buffers(inode);
		if (!atomic_read(&inode->i_count)) {
			list_move(&inode->i_list, dispose);
			inode->i_state |= I_FREEING;
			count++;
			continue;
		}
		busy = 1;
	}
	/* only unused inodes may be cached with i_count zero */
	inodes_stat.nr_unused -= count;
	return busy;
}

/**
 *	invalidate_inodes	- discard the inodes on a device
 *	@sb: superblock
 *
 *	Discard all of the inodes for a given superblock. If the discard
 *	fails because there are busy inodes then a non zero value is returned.
 *	If the discard is successful all the inodes have been discarded.
 */
int invalidate_inodes(struct super_block * sb)
{
	int busy;
	LIST_HEAD(throw_away);

I
Ingo Molnar 已提交
386
	mutex_lock(&iprune_mutex);
L
Linus Torvalds 已提交
387
	spin_lock(&inode_lock);
R
Robert Love 已提交
388
	inotify_unmount_inodes(&sb->s_inodes);
L
Linus Torvalds 已提交
389 390 391 392
	busy = invalidate_list(&sb->s_inodes, &throw_away);
	spin_unlock(&inode_lock);

	dispose_list(&throw_away);
I
Ingo Molnar 已提交
393
	mutex_unlock(&iprune_mutex);
L
Linus Torvalds 已提交
394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432

	return busy;
}

EXPORT_SYMBOL(invalidate_inodes);

static int can_unuse(struct inode *inode)
{
	if (inode->i_state)
		return 0;
	if (inode_has_buffers(inode))
		return 0;
	if (atomic_read(&inode->i_count))
		return 0;
	if (inode->i_data.nrpages)
		return 0;
	return 1;
}

/*
 * Scan `goal' inodes on the unused list for freeable ones. They are moved to
 * a temporary list and then are freed outside inode_lock by dispose_list().
 *
 * Any inodes which are pinned purely because of attached pagecache have their
 * pagecache removed.  We expect the final iput() on that inode to add it to
 * the front of the inode_unused list.  So look for it there and if the
 * inode is still freeable, proceed.  The right inode is found 99.9% of the
 * time in testing on a 4-way.
 *
 * If the inode has metadata buffers attached to mapping->private_list then
 * try to remove them.
 */
static void prune_icache(int nr_to_scan)
{
	LIST_HEAD(freeable);
	int nr_pruned = 0;
	int nr_scanned;
	unsigned long reap = 0;

I
Ingo Molnar 已提交
433
	mutex_lock(&iprune_mutex);
L
Linus Torvalds 已提交
434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450
	spin_lock(&inode_lock);
	for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
		struct inode *inode;

		if (list_empty(&inode_unused))
			break;

		inode = list_entry(inode_unused.prev, struct inode, i_list);

		if (inode->i_state || atomic_read(&inode->i_count)) {
			list_move(&inode->i_list, &inode_unused);
			continue;
		}
		if (inode_has_buffers(inode) || inode->i_data.nrpages) {
			__iget(inode);
			spin_unlock(&inode_lock);
			if (remove_inode_buffers(inode))
451 452
				reap += invalidate_mapping_pages(&inode->i_data,
								0, -1);
L
Linus Torvalds 已提交
453 454 455 456 457 458 459 460 461 462 463 464 465 466
			iput(inode);
			spin_lock(&inode_lock);

			if (inode != list_entry(inode_unused.next,
						struct inode, i_list))
				continue;	/* wrong inode or list_empty */
			if (!can_unuse(inode))
				continue;
		}
		list_move(&inode->i_list, &freeable);
		inode->i_state |= I_FREEING;
		nr_pruned++;
	}
	inodes_stat.nr_unused -= nr_pruned;
467 468 469 470
	if (current_is_kswapd())
		__count_vm_events(KSWAPD_INODESTEAL, reap);
	else
		__count_vm_events(PGINODESTEAL, reap);
L
Linus Torvalds 已提交
471 472 473
	spin_unlock(&inode_lock);

	dispose_list(&freeable);
I
Ingo Molnar 已提交
474
	mutex_unlock(&iprune_mutex);
L
Linus Torvalds 已提交
475 476 477 478 479 480 481 482 483 484 485
}

/*
 * shrink_icache_memory() will attempt to reclaim some unused inodes.  Here,
 * "unused" means that no dentries are referring to the inodes: the files are
 * not open and the dcache references to those inodes have already been
 * reclaimed.
 *
 * This function is passed the number of inodes to scan, and it returns the
 * total number of remaining possibly-reclaimable inodes.
 */
A
Al Viro 已提交
486
static int shrink_icache_memory(int nr, gfp_t gfp_mask)
L
Linus Torvalds 已提交
487 488 489 490 491 492 493 494 495 496 497 498 499 500
{
	if (nr) {
		/*
		 * Nasty deadlock avoidance.  We may hold various FS locks,
		 * and we don't want to recurse into the FS that called us
		 * in clear_inode() and friends..
	 	 */
		if (!(gfp_mask & __GFP_FS))
			return -1;
		prune_icache(nr);
	}
	return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
}

501 502 503 504 505
static struct shrinker icache_shrinker = {
	.shrink = shrink_icache_memory,
	.seeks = DEFAULT_SEEKS,
};

L
Linus Torvalds 已提交
506 507 508 509 510 511 512 513 514 515 516 517 518
static void __wait_on_freeing_inode(struct inode *inode);
/*
 * Called with the inode lock held.
 * NOTE: we are not increasing the inode-refcount, you must call __iget()
 * by hand after calling find_inode now! This simplifies iunique and won't
 * add any additional branch in the common code.
 */
static struct inode * find_inode(struct super_block * sb, struct hlist_head *head, int (*test)(struct inode *, void *), void *data)
{
	struct hlist_node *node;
	struct inode * inode = NULL;

repeat:
519
	hlist_for_each_entry(inode, node, head, i_hash) {
L
Linus Torvalds 已提交
520 521 522 523
		if (inode->i_sb != sb)
			continue;
		if (!test(inode, data))
			continue;
524
		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
L
Linus Torvalds 已提交
525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542
			__wait_on_freeing_inode(inode);
			goto repeat;
		}
		break;
	}
	return node ? inode : NULL;
}

/*
 * find_inode_fast is the fast path version of find_inode, see the comment at
 * iget_locked for details.
 */
static struct inode * find_inode_fast(struct super_block * sb, struct hlist_head *head, unsigned long ino)
{
	struct hlist_node *node;
	struct inode * inode = NULL;

repeat:
543
	hlist_for_each_entry(inode, node, head, i_hash) {
L
Linus Torvalds 已提交
544 545 546 547
		if (inode->i_ino != ino)
			continue;
		if (inode->i_sb != sb)
			continue;
548
		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
L
Linus Torvalds 已提交
549 550 551 552 553 554 555 556
			__wait_on_freeing_inode(inode);
			goto repeat;
		}
		break;
	}
	return node ? inode : NULL;
}

557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579
static unsigned long hash(struct super_block *sb, unsigned long hashval)
{
	unsigned long tmp;

	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
			L1_CACHE_BYTES;
	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
	return tmp & I_HASHMASK;
}

static inline void
__inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
			struct inode *inode)
{
	inodes_stat.nr_inodes++;
	list_add(&inode->i_list, &inode_in_use);
	list_add(&inode->i_sb_list, &sb->s_inodes);
	if (head)
		hlist_add_head(&inode->i_hash, head);
}

/**
 * inode_add_to_lists - add a new inode to relevant lists
R
Randy Dunlap 已提交
580 581
 * @sb: superblock inode belongs to
 * @inode: inode to mark in use
582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599
 *
 * When an inode is allocated it needs to be accounted for, added to the in use
 * list, the owning superblock and the inode hash. This needs to be done under
 * the inode_lock, so export a function to do this rather than the inode lock
 * itself. We calculate the hash list to add to here so it is all internal
 * which requires the caller to have already set up the inode number in the
 * inode to add.
 */
void inode_add_to_lists(struct super_block *sb, struct inode *inode)
{
	struct hlist_head *head = inode_hashtable + hash(sb, inode->i_ino);

	spin_lock(&inode_lock);
	__inode_add_to_lists(sb, head, inode);
	spin_unlock(&inode_lock);
}
EXPORT_SYMBOL_GPL(inode_add_to_lists);

L
Linus Torvalds 已提交
600 601 602 603
/**
 *	new_inode 	- obtain an inode
 *	@sb: superblock
 *
604
 *	Allocates a new inode for given superblock. The default gfp_mask
H
Hugh Dickins 已提交
605
 *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
606 607 608 609 610
 *	If HIGHMEM pages are unsuitable or it is known that pages allocated
 *	for the page cache are not reclaimable or migratable,
 *	mapping_set_gfp_mask() must be called with suitable flags on the
 *	newly created inode's mapping
 *
L
Linus Torvalds 已提交
611 612 613
 */
struct inode *new_inode(struct super_block *sb)
{
614 615 616 617 618 619
	/*
	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
	 * error if st_ino won't fit in target struct field. Use 32bit counter
	 * here to attempt to avoid that.
	 */
	static unsigned int last_ino;
L
Linus Torvalds 已提交
620 621 622 623 624 625 626
	struct inode * inode;

	spin_lock_prefetch(&inode_lock);
	
	inode = alloc_inode(sb);
	if (inode) {
		spin_lock(&inode_lock);
627
		__inode_add_to_lists(sb, NULL, inode);
L
Linus Torvalds 已提交
628 629 630 631 632 633 634 635 636 637 638
		inode->i_ino = ++last_ino;
		inode->i_state = 0;
		spin_unlock(&inode_lock);
	}
	return inode;
}

EXPORT_SYMBOL(new_inode);

void unlock_new_inode(struct inode *inode)
{
639
#ifdef CONFIG_DEBUG_LOCK_ALLOC
640 641 642 643 644 645 646 647
	if (inode->i_mode & S_IFDIR) {
		struct file_system_type *type = inode->i_sb->s_type;

		/*
		 * ensure nobody is actually holding i_mutex
		 */
		mutex_destroy(&inode->i_mutex);
		mutex_init(&inode->i_mutex);
648
		lockdep_set_class(&inode->i_mutex, &type->i_mutex_dir_key);
649
	}
650
#endif
L
Linus Torvalds 已提交
651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685
	/*
	 * This is special!  We do not need the spinlock
	 * when clearing I_LOCK, because we're guaranteed
	 * that nobody else tries to do anything about the
	 * state of the inode when it is locked, as we
	 * just created it (so there can be no old holders
	 * that haven't tested I_LOCK).
	 */
	inode->i_state &= ~(I_LOCK|I_NEW);
	wake_up_inode(inode);
}

EXPORT_SYMBOL(unlock_new_inode);

/*
 * This is called without the inode lock held.. Be careful.
 *
 * We no longer cache the sb_flags in i_flags - see fs.h
 *	-- rmk@arm.uk.linux.org
 */
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)
{
	struct inode * inode;

	inode = alloc_inode(sb);
	if (inode) {
		struct inode * old;

		spin_lock(&inode_lock);
		/* We released the lock, so.. */
		old = find_inode(sb, head, test, data);
		if (!old) {
			if (set(inode, data))
				goto set_failed;

686
			__inode_add_to_lists(sb, head, inode);
L
Linus Torvalds 已提交
687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731
			inode->i_state = I_LOCK|I_NEW;
			spin_unlock(&inode_lock);

			/* Return the locked inode with I_NEW set, the
			 * caller is responsible for filling in the contents
			 */
			return inode;
		}

		/*
		 * Uhhuh, somebody else created the same inode under
		 * us. Use the old inode instead of the one we just
		 * allocated.
		 */
		__iget(old);
		spin_unlock(&inode_lock);
		destroy_inode(inode);
		inode = old;
		wait_on_inode(inode);
	}
	return inode;

set_failed:
	spin_unlock(&inode_lock);
	destroy_inode(inode);
	return NULL;
}

/*
 * get_new_inode_fast is the fast path version of get_new_inode, see the
 * comment at iget_locked for details.
 */
static struct inode * get_new_inode_fast(struct super_block *sb, struct hlist_head *head, unsigned long ino)
{
	struct inode * inode;

	inode = alloc_inode(sb);
	if (inode) {
		struct inode * old;

		spin_lock(&inode_lock);
		/* We released the lock, so.. */
		old = find_inode_fast(sb, head, ino);
		if (!old) {
			inode->i_ino = ino;
732
			__inode_add_to_lists(sb, head, inode);
L
Linus Torvalds 已提交
733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771
			inode->i_state = I_LOCK|I_NEW;
			spin_unlock(&inode_lock);

			/* Return the locked inode with I_NEW set, the
			 * caller is responsible for filling in the contents
			 */
			return inode;
		}

		/*
		 * Uhhuh, somebody else created the same inode under
		 * us. Use the old inode instead of the one we just
		 * allocated.
		 */
		__iget(old);
		spin_unlock(&inode_lock);
		destroy_inode(inode);
		inode = old;
		wait_on_inode(inode);
	}
	return inode;
}

/**
 *	iunique - get a unique inode number
 *	@sb: superblock
 *	@max_reserved: highest reserved inode number
 *
 *	Obtain an inode number that is unique on the system for a given
 *	superblock. This is used by file systems that have no natural
 *	permanent inode numbering system. An inode number is returned that
 *	is higher than the reserved limit but unique.
 *
 *	BUGS:
 *	With a large number of inodes live on the file system this function
 *	currently becomes quite slow.
 */
ino_t iunique(struct super_block *sb, ino_t max_reserved)
{
772 773 774 775 776 777
	/*
	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
	 * error if st_ino won't fit in target struct field. Use 32bit counter
	 * here to attempt to avoid that.
	 */
	static unsigned int counter;
L
Linus Torvalds 已提交
778
	struct inode *inode;
779
	struct hlist_head *head;
L
Linus Torvalds 已提交
780
	ino_t res;
781

L
Linus Torvalds 已提交
782
	spin_lock(&inode_lock);
783 784 785
	do {
		if (counter <= max_reserved)
			counter = max_reserved + 1;
L
Linus Torvalds 已提交
786
		res = counter++;
787
		head = inode_hashtable + hash(sb, res);
L
Linus Torvalds 已提交
788
		inode = find_inode_fast(sb, head, res);
789 790
	} while (inode != NULL);
	spin_unlock(&inode_lock);
L
Linus Torvalds 已提交
791

792 793
	return res;
}
L
Linus Torvalds 已提交
794 795 796 797 798
EXPORT_SYMBOL(iunique);

struct inode *igrab(struct inode *inode)
{
	spin_lock(&inode_lock);
799
	if (!(inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)))
L
Linus Torvalds 已提交
800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819
		__iget(inode);
	else
		/*
		 * Handle the case where s_op->clear_inode is not been
		 * called yet, and somebody is calling igrab
		 * while the inode is getting freed.
		 */
		inode = NULL;
	spin_unlock(&inode_lock);
	return inode;
}

EXPORT_SYMBOL(igrab);

/**
 * ifind - internal function, you want ilookup5() or iget5().
 * @sb:		super block of file system to search
 * @head:       the head of the list to search
 * @test:	callback used for comparisons between inodes
 * @data:	opaque data pointer to pass to @test
820
 * @wait:	if true wait for the inode to be unlocked, if false do not
L
Linus Torvalds 已提交
821 822 823 824 825 826 827 828 829 830 831 832
 *
 * ifind() searches for the inode specified by @data in the inode
 * cache. This is a generalized version of ifind_fast() for file systems where
 * the inode number is not sufficient for unique identification of an inode.
 *
 * If the inode is in the cache, the inode is returned with an incremented
 * reference count.
 *
 * Otherwise NULL is returned.
 *
 * Note, @test is called with the inode_lock held, so can't sleep.
 */
833
static struct inode *ifind(struct super_block *sb,
L
Linus Torvalds 已提交
834
		struct hlist_head *head, int (*test)(struct inode *, void *),
835
		void *data, const int wait)
L
Linus Torvalds 已提交
836 837 838 839 840 841 842 843
{
	struct inode *inode;

	spin_lock(&inode_lock);
	inode = find_inode(sb, head, test, data);
	if (inode) {
		__iget(inode);
		spin_unlock(&inode_lock);
844 845
		if (likely(wait))
			wait_on_inode(inode);
L
Linus Torvalds 已提交
846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866
		return inode;
	}
	spin_unlock(&inode_lock);
	return NULL;
}

/**
 * ifind_fast - internal function, you want ilookup() or iget().
 * @sb:		super block of file system to search
 * @head:       head of the list to search
 * @ino:	inode number to search for
 *
 * ifind_fast() searches for the inode @ino in the inode cache. This is for
 * file systems where the inode number is sufficient for unique identification
 * of an inode.
 *
 * If the inode is in the cache, the inode is returned with an incremented
 * reference count.
 *
 * Otherwise NULL is returned.
 */
867
static struct inode *ifind_fast(struct super_block *sb,
L
Linus Torvalds 已提交
868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884
		struct hlist_head *head, unsigned long ino)
{
	struct inode *inode;

	spin_lock(&inode_lock);
	inode = find_inode_fast(sb, head, ino);
	if (inode) {
		__iget(inode);
		spin_unlock(&inode_lock);
		wait_on_inode(inode);
		return inode;
	}
	spin_unlock(&inode_lock);
	return NULL;
}

/**
885
 * ilookup5_nowait - search for an inode in the inode cache
L
Linus Torvalds 已提交
886 887 888 889 890 891 892 893 894 895 896
 * @sb:		super block of file system to search
 * @hashval:	hash value (usually inode number) to search for
 * @test:	callback used for comparisons between inodes
 * @data:	opaque data pointer to pass to @test
 *
 * ilookup5() uses ifind() to search for the inode specified by @hashval and
 * @data in the inode cache. This is a generalized version of ilookup() for
 * file systems where the inode number is not sufficient for unique
 * identification of an inode.
 *
 * If the inode is in the cache, the inode is returned with an incremented
897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928
 * reference count.  Note, the inode lock is not waited upon so you have to be
 * very careful what you do with the returned inode.  You probably should be
 * using ilookup5() instead.
 *
 * Otherwise NULL is returned.
 *
 * Note, @test is called with the inode_lock held, so can't sleep.
 */
struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
		int (*test)(struct inode *, void *), void *data)
{
	struct hlist_head *head = inode_hashtable + hash(sb, hashval);

	return ifind(sb, head, test, data, 0);
}

EXPORT_SYMBOL(ilookup5_nowait);

/**
 * ilookup5 - search for an inode in the inode cache
 * @sb:		super block of file system to search
 * @hashval:	hash value (usually inode number) to search for
 * @test:	callback used for comparisons between inodes
 * @data:	opaque data pointer to pass to @test
 *
 * ilookup5() uses ifind() to search for the inode specified by @hashval and
 * @data in the inode cache. This is a generalized version of ilookup() for
 * file systems where the inode number is not sufficient for unique
 * identification of an inode.
 *
 * If the inode is in the cache, the inode lock is waited upon and the inode is
 * returned with an incremented reference count.
L
Linus Torvalds 已提交
929 930 931 932 933 934 935 936 937 938
 *
 * Otherwise NULL is returned.
 *
 * Note, @test is called with the inode_lock held, so can't sleep.
 */
struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
		int (*test)(struct inode *, void *), void *data)
{
	struct hlist_head *head = inode_hashtable + hash(sb, hashval);

939
	return ifind(sb, head, test, data, 1);
L
Linus Torvalds 已提交
940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993
}

EXPORT_SYMBOL(ilookup5);

/**
 * ilookup - search for an inode in the inode cache
 * @sb:		super block of file system to search
 * @ino:	inode number to search for
 *
 * ilookup() uses ifind_fast() to search for the inode @ino in the inode cache.
 * This is for file systems where the inode number is sufficient for unique
 * identification of an inode.
 *
 * If the inode is in the cache, the inode is returned with an incremented
 * reference count.
 *
 * Otherwise NULL is returned.
 */
struct inode *ilookup(struct super_block *sb, unsigned long ino)
{
	struct hlist_head *head = inode_hashtable + hash(sb, ino);

	return ifind_fast(sb, head, ino);
}

EXPORT_SYMBOL(ilookup);

/**
 * iget5_locked - obtain an inode from a mounted file system
 * @sb:		super block of file system
 * @hashval:	hash value (usually inode number) to get
 * @test:	callback used for comparisons between inodes
 * @set:	callback used to initialize a new struct inode
 * @data:	opaque data pointer to pass to @test and @set
 *
 * iget5_locked() uses ifind() to search for the inode specified by @hashval
 * and @data in the inode cache and if present it is returned with an increased
 * reference count. This is a generalized version of iget_locked() for file
 * systems where the inode number is not sufficient for unique identification
 * of an inode.
 *
 * If the inode is not in cache, get_new_inode() is called to allocate a new
 * inode and this is returned locked, hashed, and with the I_NEW flag set. The
 * file system gets to fill it in before unlocking it via unlock_new_inode().
 *
 * Note both @test and @set are called with the inode_lock held, so can't sleep.
 */
struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
		int (*test)(struct inode *, void *),
		int (*set)(struct inode *, void *), void *data)
{
	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
	struct inode *inode;

994
	inode = ifind(sb, head, test, data, 1);
L
Linus Torvalds 已提交
995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
	if (inode)
		return inode;
	/*
	 * get_new_inode() will do the right thing, re-trying the search
	 * in case it had to block at any point.
	 */
	return get_new_inode(sb, head, test, set, data);
}

EXPORT_SYMBOL(iget5_locked);

/**
 * iget_locked - obtain an inode from a mounted file system
 * @sb:		super block of file system
 * @ino:	inode number to get
 *
 * iget_locked() uses ifind_fast() to search for the inode specified by @ino in
 * the inode cache and if present it is returned with an increased reference
 * count. This is for file systems where the inode number is sufficient for
 * unique identification of an inode.
 *
 * If the inode is not in cache, get_new_inode_fast() is called to allocate a
 * new inode and this is returned locked, hashed, and with the I_NEW flag set.
 * The file system gets to fill it in before unlocking it via
 * unlock_new_inode().
 */
struct inode *iget_locked(struct super_block *sb, unsigned long ino)
{
	struct hlist_head *head = inode_hashtable + hash(sb, ino);
	struct inode *inode;

	inode = ifind_fast(sb, head, ino);
	if (inode)
		return inode;
	/*
	 * get_new_inode_fast() will do the right thing, re-trying the search
	 * in case it had to block at any point.
	 */
	return get_new_inode_fast(sb, head, ino);
}

EXPORT_SYMBOL(iget_locked);

A
Al Viro 已提交
1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096
int insert_inode_locked(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	ino_t ino = inode->i_ino;
	struct hlist_head *head = inode_hashtable + hash(sb, ino);
	struct inode *old;

	inode->i_state |= I_LOCK|I_NEW;
	while (1) {
		spin_lock(&inode_lock);
		old = find_inode_fast(sb, head, ino);
		if (likely(!old)) {
			hlist_add_head(&inode->i_hash, head);
			spin_unlock(&inode_lock);
			return 0;
		}
		__iget(old);
		spin_unlock(&inode_lock);
		wait_on_inode(old);
		if (unlikely(!hlist_unhashed(&old->i_hash))) {
			iput(old);
			return -EBUSY;
		}
		iput(old);
	}
}

EXPORT_SYMBOL(insert_inode_locked);

int insert_inode_locked4(struct inode *inode, unsigned long hashval,
		int (*test)(struct inode *, void *), void *data)
{
	struct super_block *sb = inode->i_sb;
	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
	struct inode *old;

	inode->i_state |= I_LOCK|I_NEW;

	while (1) {
		spin_lock(&inode_lock);
		old = find_inode(sb, head, test, data);
		if (likely(!old)) {
			hlist_add_head(&inode->i_hash, head);
			spin_unlock(&inode_lock);
			return 0;
		}
		__iget(old);
		spin_unlock(&inode_lock);
		wait_on_inode(old);
		if (unlikely(!hlist_unhashed(&old->i_hash))) {
			iput(old);
			return -EBUSY;
		}
		iput(old);
	}
}

EXPORT_SYMBOL(insert_inode_locked4);

L
Linus Torvalds 已提交
1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141
/**
 *	__insert_inode_hash - hash an inode
 *	@inode: unhashed inode
 *	@hashval: unsigned long value used to locate this object in the
 *		inode_hashtable.
 *
 *	Add an inode to the inode hash for this superblock.
 */
void __insert_inode_hash(struct inode *inode, unsigned long hashval)
{
	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
	spin_lock(&inode_lock);
	hlist_add_head(&inode->i_hash, head);
	spin_unlock(&inode_lock);
}

EXPORT_SYMBOL(__insert_inode_hash);

/**
 *	remove_inode_hash - remove an inode from the hash
 *	@inode: inode to unhash
 *
 *	Remove an inode from the superblock.
 */
void remove_inode_hash(struct inode *inode)
{
	spin_lock(&inode_lock);
	hlist_del_init(&inode->i_hash);
	spin_unlock(&inode_lock);
}

EXPORT_SYMBOL(remove_inode_hash);

/*
 * Tell the filesystem that this inode is no longer of any interest and should
 * be completely destroyed.
 *
 * We leave the inode in the inode hash table until *after* the filesystem's
 * ->delete_inode completes.  This ensures that an iget (such as nfsd might
 * instigate) will always find up-to-date information either in the hash or on
 * disk.
 *
 * I_FREEING is set so that no-one will take a new reference to the inode while
 * it is being deleted.
 */
1142
static void generic_delete_inode_async(void *data, async_cookie_t cookie)
L
Linus Torvalds 已提交
1143
{
1144
	struct inode *inode = data;
1145
	const struct super_operations *op = inode->i_sb->s_op;
L
Linus Torvalds 已提交
1146 1147 1148 1149 1150 1151 1152

	security_inode_delete(inode);

	if (op->delete_inode) {
		void (*delete)(struct inode *) = op->delete_inode;
		if (!is_bad_inode(inode))
			DQUOT_INIT(inode);
1153 1154 1155 1156
		/* Filesystems implementing their own
		 * s_op->delete_inode are required to call
		 * truncate_inode_pages and clear_inode()
		 * internally */
L
Linus Torvalds 已提交
1157
		delete(inode);
1158 1159
	} else {
		truncate_inode_pages(&inode->i_data, 0);
L
Linus Torvalds 已提交
1160
		clear_inode(inode);
1161
	}
L
Linus Torvalds 已提交
1162 1163 1164 1165
	spin_lock(&inode_lock);
	hlist_del_init(&inode->i_hash);
	spin_unlock(&inode_lock);
	wake_up_inode(inode);
1166
	BUG_ON(inode->i_state != I_CLEAR);
L
Linus Torvalds 已提交
1167 1168 1169
	destroy_inode(inode);
}

1170 1171 1172 1173 1174 1175 1176 1177 1178 1179
void generic_delete_inode(struct inode *inode)
{
	list_del_init(&inode->i_list);
	list_del_init(&inode->i_sb_list);
	inode->i_state |= I_FREEING;
	inodes_stat.nr_inodes--;
	spin_unlock(&inode_lock);
	async_schedule_special(generic_delete_inode_async, inode, &inode->i_sb->s_async_list);
}

L
Linus Torvalds 已提交
1180 1181 1182 1183 1184 1185 1186
EXPORT_SYMBOL(generic_delete_inode);

static void generic_forget_inode(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;

	if (!hlist_unhashed(&inode->i_hash)) {
J
Joern Engel 已提交
1187
		if (!(inode->i_state & (I_DIRTY|I_SYNC)))
L
Linus Torvalds 已提交
1188 1189
			list_move(&inode->i_list, &inode_unused);
		inodes_stat.nr_unused++;
1190
		if (sb->s_flags & MS_ACTIVE) {
1191
			spin_unlock(&inode_lock);
L
Linus Torvalds 已提交
1192
			return;
1193 1194 1195
		}
		inode->i_state |= I_WILL_FREE;
		spin_unlock(&inode_lock);
L
Linus Torvalds 已提交
1196 1197
		write_inode_now(inode, 1);
		spin_lock(&inode_lock);
1198
		inode->i_state &= ~I_WILL_FREE;
L
Linus Torvalds 已提交
1199 1200 1201 1202 1203
		inodes_stat.nr_unused--;
		hlist_del_init(&inode->i_hash);
	}
	list_del_init(&inode->i_list);
	list_del_init(&inode->i_sb_list);
1204
	inode->i_state |= I_FREEING;
L
Linus Torvalds 已提交
1205 1206 1207 1208 1209
	inodes_stat.nr_inodes--;
	spin_unlock(&inode_lock);
	if (inode->i_data.nrpages)
		truncate_inode_pages(&inode->i_data, 0);
	clear_inode(inode);
1210
	wake_up_inode(inode);
L
Linus Torvalds 已提交
1211 1212 1213 1214 1215 1216 1217 1218
	destroy_inode(inode);
}

/*
 * Normal UNIX filesystem behaviour: delete the
 * inode when the usage count drops to zero, and
 * i_nlink is zero.
 */
1219
void generic_drop_inode(struct inode *inode)
L
Linus Torvalds 已提交
1220 1221 1222 1223 1224 1225 1226
{
	if (!inode->i_nlink)
		generic_delete_inode(inode);
	else
		generic_forget_inode(inode);
}

1227 1228
EXPORT_SYMBOL_GPL(generic_drop_inode);

L
Linus Torvalds 已提交
1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241
/*
 * Called when we're dropping the last reference
 * to an inode. 
 *
 * Call the FS "drop()" function, defaulting to
 * the legacy UNIX filesystem behaviour..
 *
 * NOTE! NOTE! NOTE! We're called with the inode lock
 * held, and the drop function is supposed to release
 * the lock!
 */
static inline void iput_final(struct inode *inode)
{
1242
	const struct super_operations *op = inode->i_sb->s_op;
L
Linus Torvalds 已提交
1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291
	void (*drop)(struct inode *) = generic_drop_inode;

	if (op && op->drop_inode)
		drop = op->drop_inode;
	drop(inode);
}

/**
 *	iput	- put an inode 
 *	@inode: inode to put
 *
 *	Puts an inode, dropping its usage count. If the inode use count hits
 *	zero, the inode is then freed and may also be destroyed.
 *
 *	Consequently, iput() can sleep.
 */
void iput(struct inode *inode)
{
	if (inode) {
		BUG_ON(inode->i_state == I_CLEAR);

		if (atomic_dec_and_lock(&inode->i_count, &inode_lock))
			iput_final(inode);
	}
}

EXPORT_SYMBOL(iput);

/**
 *	bmap	- find a block number in a file
 *	@inode: inode of file
 *	@block: block to find
 *
 *	Returns the block number on the device holding the inode that
 *	is the disk block number for the block of the file requested.
 *	That is, asked for block 4 of inode 1 the function will return the
 *	disk block relative to the disk start that holds that block of the 
 *	file.
 */
sector_t bmap(struct inode * inode, sector_t block)
{
	sector_t res = 0;
	if (inode->i_mapping->a_ops->bmap)
		res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
	return res;
}
EXPORT_SYMBOL(bmap);

/**
C
Christoph Hellwig 已提交
1292 1293
 *	touch_atime	-	update the access time
 *	@mnt: mount the inode is accessed on
1294
 *	@dentry: dentry accessed
L
Linus Torvalds 已提交
1295 1296 1297 1298 1299
 *
 *	Update the accessed time on an inode and mark it for writeback.
 *	This function automatically handles read only file systems and media,
 *	as well as the "noatime" flag and inode specific "noatime" markers.
 */
C
Christoph Hellwig 已提交
1300
void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
L
Linus Torvalds 已提交
1301
{
C
Christoph Hellwig 已提交
1302
	struct inode *inode = dentry->d_inode;
L
Linus Torvalds 已提交
1303 1304
	struct timespec now;

1305
	if (mnt_want_write(mnt))
A
Andrew Morton 已提交
1306
		return;
1307 1308
	if (inode->i_flags & S_NOATIME)
		goto out;
1309
	if (IS_NOATIME(inode))
1310
		goto out;
A
Andrew Morton 已提交
1311
	if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1312
		goto out;
V
Valerie Henson 已提交
1313

1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325
	if (mnt->mnt_flags & MNT_NOATIME)
		goto out;
	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
		goto out;
	if (mnt->mnt_flags & MNT_RELATIME) {
		/*
		 * With relative atime, only update atime if the previous
		 * atime is earlier than either the ctime or mtime.
		 */
		if (timespec_compare(&inode->i_mtime, &inode->i_atime) < 0 &&
		    timespec_compare(&inode->i_ctime, &inode->i_atime) < 0)
			goto out;
A
Andrew Morton 已提交
1326
	}
L
Linus Torvalds 已提交
1327 1328

	now = current_fs_time(inode->i_sb);
V
Valerie Henson 已提交
1329
	if (timespec_equal(&inode->i_atime, &now))
1330
		goto out;
V
Valerie Henson 已提交
1331 1332 1333

	inode->i_atime = now;
	mark_inode_dirty_sync(inode);
1334 1335
out:
	mnt_drop_write(mnt);
L
Linus Torvalds 已提交
1336
}
C
Christoph Hellwig 已提交
1337
EXPORT_SYMBOL(touch_atime);
L
Linus Torvalds 已提交
1338 1339

/**
1340 1341
 *	file_update_time	-	update mtime and ctime time
 *	@file: file accessed
L
Linus Torvalds 已提交
1342
 *
1343 1344 1345 1346 1347 1348
 *	Update the mtime and ctime members of an inode and mark the inode
 *	for writeback.  Note that this function is meant exclusively for
 *	usage in the file write path of filesystems, and filesystems may
 *	choose to explicitly ignore update via this function with the
 *	S_NOCTIME inode flag, e.g. for network filesystem where these
 *	timestamps are handled by the server.
L
Linus Torvalds 已提交
1349 1350
 */

1351
void file_update_time(struct file *file)
L
Linus Torvalds 已提交
1352
{
1353
	struct inode *inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1354 1355
	struct timespec now;
	int sync_it = 0;
1356
	int err;
L
Linus Torvalds 已提交
1357 1358 1359

	if (IS_NOCMTIME(inode))
		return;
1360 1361 1362

	err = mnt_want_write(file->f_path.mnt);
	if (err)
L
Linus Torvalds 已提交
1363 1364 1365
		return;

	now = current_fs_time(inode->i_sb);
A
Andreas Mohr 已提交
1366 1367
	if (!timespec_equal(&inode->i_mtime, &now)) {
		inode->i_mtime = now;
L
Linus Torvalds 已提交
1368
		sync_it = 1;
A
Andreas Mohr 已提交
1369
	}
L
Linus Torvalds 已提交
1370

A
Andreas Mohr 已提交
1371 1372
	if (!timespec_equal(&inode->i_ctime, &now)) {
		inode->i_ctime = now;
1373
		sync_it = 1;
A
Andreas Mohr 已提交
1374
	}
1375

1376 1377 1378 1379 1380
	if (IS_I_VERSION(inode)) {
		inode_inc_iversion(inode);
		sync_it = 1;
	}

L
Linus Torvalds 已提交
1381 1382
	if (sync_it)
		mark_inode_dirty_sync(inode);
1383
	mnt_drop_write(file->f_path.mnt);
L
Linus Torvalds 已提交
1384 1385
}

1386
EXPORT_SYMBOL(file_update_time);
L
Linus Torvalds 已提交
1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403

int inode_needs_sync(struct inode *inode)
{
	if (IS_SYNC(inode))
		return 1;
	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
		return 1;
	return 0;
}

EXPORT_SYMBOL(inode_needs_sync);

int inode_wait(void *word)
{
	schedule();
	return 0;
}
1404
EXPORT_SYMBOL(inode_wait);
L
Linus Torvalds 已提交
1405 1406

/*
1407 1408 1409 1410 1411 1412 1413 1414 1415
 * If we try to find an inode in the inode hash while it is being
 * deleted, we have to wait until the filesystem completes its
 * deletion before reporting that it isn't found.  This function waits
 * until the deletion _might_ have completed.  Callers are responsible
 * to recheck inode state.
 *
 * It doesn't matter if I_LOCK is not set initially, a call to
 * wake_up_inode() after removing from the hash list will DTRT.
 *
L
Linus Torvalds 已提交
1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429
 * This is called with inode_lock held.
 */
static void __wait_on_freeing_inode(struct inode *inode)
{
	wait_queue_head_t *wq;
	DEFINE_WAIT_BIT(wait, &inode->i_state, __I_LOCK);
	wq = bit_waitqueue(&inode->i_state, __I_LOCK);
	prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
	spin_unlock(&inode_lock);
	schedule();
	finish_wait(wq, &wait.wait);
	spin_lock(&inode_lock);
}

1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465
/*
 * We rarely want to lock two inodes that do not have a parent/child
 * relationship (such as directory, child inode) simultaneously. The
 * vast majority of file systems should be able to get along fine
 * without this. Do not use these functions except as a last resort.
 */
void inode_double_lock(struct inode *inode1, struct inode *inode2)
{
	if (inode1 == NULL || inode2 == NULL || inode1 == inode2) {
		if (inode1)
			mutex_lock(&inode1->i_mutex);
		else if (inode2)
			mutex_lock(&inode2->i_mutex);
		return;
	}

	if (inode1 < inode2) {
		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
	} else {
		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
	}
}
EXPORT_SYMBOL(inode_double_lock);

void inode_double_unlock(struct inode *inode1, struct inode *inode2)
{
	if (inode1)
		mutex_unlock(&inode1->i_mutex);

	if (inode2 && inode2 != inode1)
		mutex_unlock(&inode2->i_mutex);
}
EXPORT_SYMBOL(inode_double_unlock);

L
Linus Torvalds 已提交
1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502
static __initdata unsigned long ihash_entries;
static int __init set_ihash_entries(char *str)
{
	if (!str)
		return 0;
	ihash_entries = simple_strtoul(str, &str, 0);
	return 1;
}
__setup("ihash_entries=", set_ihash_entries);

/*
 * Initialize the waitqueues and inode hash table.
 */
void __init inode_init_early(void)
{
	int loop;

	/* If hashes are distributed across NUMA nodes, defer
	 * hash allocation until vmalloc space is available.
	 */
	if (hashdist)
		return;

	inode_hashtable =
		alloc_large_system_hash("Inode-cache",
					sizeof(struct hlist_head),
					ihash_entries,
					14,
					HASH_EARLY,
					&i_hash_shift,
					&i_hash_mask,
					0);

	for (loop = 0; loop < (1 << i_hash_shift); loop++)
		INIT_HLIST_HEAD(&inode_hashtable[loop]);
}

1503
void __init inode_init(void)
L
Linus Torvalds 已提交
1504 1505 1506 1507
{
	int loop;

	/* inode slab cache */
1508 1509 1510 1511 1512
	inode_cachep = kmem_cache_create("inode_cache",
					 sizeof(struct inode),
					 0,
					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
					 SLAB_MEM_SPREAD),
1513
					 init_once);
1514
	register_shrinker(&icache_shrinker);
L
Linus Torvalds 已提交
1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551

	/* Hash may have been set up in inode_init_early */
	if (!hashdist)
		return;

	inode_hashtable =
		alloc_large_system_hash("Inode-cache",
					sizeof(struct hlist_head),
					ihash_entries,
					14,
					0,
					&i_hash_shift,
					&i_hash_mask,
					0);

	for (loop = 0; loop < (1 << i_hash_shift); loop++)
		INIT_HLIST_HEAD(&inode_hashtable[loop]);
}

void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
{
	inode->i_mode = mode;
	if (S_ISCHR(mode)) {
		inode->i_fop = &def_chr_fops;
		inode->i_rdev = rdev;
	} else if (S_ISBLK(mode)) {
		inode->i_fop = &def_blk_fops;
		inode->i_rdev = rdev;
	} else if (S_ISFIFO(mode))
		inode->i_fop = &def_fifo_fops;
	else if (S_ISSOCK(mode))
		inode->i_fop = &bad_sock_fops;
	else
		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o)\n",
		       mode);
}
EXPORT_SYMBOL(init_special_inode);