inode.c 42.3 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
/*
 * 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/slab.h>
#include <linux/writeback.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/wait.h>
Nick Piggin's avatar
Nick Piggin committed
16
#include <linux/rwsem.h>
Linus Torvalds's avatar
Linus Torvalds committed
17 18 19 20 21 22
#include <linux/hash.h>
#include <linux/swap.h>
#include <linux/security.h>
#include <linux/pagemap.h>
#include <linux/cdev.h>
#include <linux/bootmem.h>
23
#include <linux/fsnotify.h>
24
#include <linux/mount.h>
25
#include <linux/async.h>
Al Viro's avatar
Al Viro committed
26
#include <linux/posix_acl.h>
Linus Torvalds's avatar
Linus Torvalds committed
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 59

/*
 * 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

60 61
static unsigned int i_hash_mask __read_mostly;
static unsigned int i_hash_shift __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
62 63 64 65 66 67 68 69 70 71 72 73 74

/*
 * 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.
 */

75
static LIST_HEAD(inode_unused);
76
static struct hlist_head *inode_hashtable __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
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);

/*
Nick Piggin's avatar
Nick Piggin committed
87
 * iprune_sem provides exclusion between the kswapd or try_to_free_pages
Linus Torvalds's avatar
Linus Torvalds committed
88 89 90 91 92
 * 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.
Nick Piggin's avatar
Nick Piggin committed
93 94 95 96
 *
 * We make this an rwsem because the fastpath is icache shrinking. In
 * some cases a filesystem may be doing a significant amount of work in
 * its inode reclaim code, so this should improve parallelism.
Linus Torvalds's avatar
Linus Torvalds committed
97
 */
Nick Piggin's avatar
Nick Piggin committed
98
static DECLARE_RWSEM(iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
99 100 101 102 103 104

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

105 106 107
static struct percpu_counter nr_inodes __cacheline_aligned_in_smp;
static struct percpu_counter nr_inodes_unused __cacheline_aligned_in_smp;

108
static struct kmem_cache *inode_cachep __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
109

110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139
static inline int get_nr_inodes(void)
{
	return percpu_counter_sum_positive(&nr_inodes);
}

static inline int get_nr_inodes_unused(void)
{
	return percpu_counter_sum_positive(&nr_inodes_unused);
}

int get_nr_dirty_inodes(void)
{
	int nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
	return nr_dirty > 0 ? nr_dirty : 0;

}

/*
 * Handle nr_inode sysctl
 */
#ifdef CONFIG_SYSCTL
int proc_nr_inodes(ctl_table *table, int write,
		   void __user *buffer, size_t *lenp, loff_t *ppos)
{
	inodes_stat.nr_inodes = get_nr_inodes();
	inodes_stat.nr_unused = get_nr_inodes_unused();
	return proc_dointvec(table, write, buffer, lenp, ppos);
}
#endif

Joern Engel's avatar
Joern Engel committed
140 141 142 143 144 145
static void wake_up_inode(struct inode *inode)
{
	/*
	 * Prevent speculative execution through spin_unlock(&inode_lock);
	 */
	smp_mb();
Christoph Hellwig's avatar
Christoph Hellwig committed
146
	wake_up_bit(&inode->i_state, __I_NEW);
Joern Engel's avatar
Joern Engel committed
147 148
}

149 150
/**
 * inode_init_always - perform inode structure intialisation
151 152
 * @sb: superblock inode belongs to
 * @inode: inode to initialise
153 154 155 156
 *
 * These are initializations that need to be done on every inode
 * allocation as the fields are not initialised by slab allocation.
 */
157
int inode_init_always(struct super_block *sb, struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
158
{
159
	static const struct address_space_operations empty_aops;
160
	static const struct inode_operations empty_iops;
161
	static const struct file_operations empty_fops;
162
	struct address_space *const mapping = &inode->i_data;
163 164 165 166 167 168 169 170

	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;
Al Viro's avatar
Al Viro committed
171 172
	inode->i_uid = 0;
	inode->i_gid = 0;
173 174 175 176 177
	atomic_set(&inode->i_writecount, 0);
	inode->i_size = 0;
	inode->i_blocks = 0;
	inode->i_bytes = 0;
	inode->i_generation = 0;
Linus Torvalds's avatar
Linus Torvalds committed
178
#ifdef CONFIG_QUOTA
179
	memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
Linus Torvalds's avatar
Linus Torvalds committed
180
#endif
181 182 183 184 185
	inode->i_pipe = NULL;
	inode->i_bdev = NULL;
	inode->i_cdev = NULL;
	inode->i_rdev = 0;
	inode->dirtied_when = 0;
Mimi Zohar's avatar
Mimi Zohar committed
186 187

	if (security_inode_alloc(inode))
188
		goto out;
189 190 191 192 193 194 195 196 197 198 199 200
	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;
201
	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
202 203 204 205 206 207 208 209 210 211 212 213
	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;

214
		bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
215 216 217 218
		mapping->backing_dev_info = bdi;
	}
	inode->i_private = NULL;
	inode->i_mapping = mapping;
Al Viro's avatar
Al Viro committed
219 220 221
#ifdef CONFIG_FS_POSIX_ACL
	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
#endif
222

223 224 225 226
#ifdef CONFIG_FSNOTIFY
	inode->i_fsnotify_mask = 0;
#endif

227 228
	percpu_counter_inc(&nr_inodes);

229 230 231
	return 0;
out:
	return -ENOMEM;
Linus Torvalds's avatar
Linus Torvalds committed
232
}
233 234 235 236 237 238 239 240 241 242 243
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);

244 245 246 247 248 249 250 251 252 253 254 255
	if (!inode)
		return NULL;

	if (unlikely(inode_init_always(sb, 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;
	}

	return inode;
256
}
Linus Torvalds's avatar
Linus Torvalds committed
257

Christoph Hellwig's avatar
Christoph Hellwig committed
258
void __destroy_inode(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
259
{
260
	BUG_ON(inode_has_buffers(inode));
Linus Torvalds's avatar
Linus Torvalds committed
261
	security_inode_free(inode);
262
	fsnotify_inode_delete(inode);
Al Viro's avatar
Al Viro committed
263 264 265 266 267 268
#ifdef CONFIG_FS_POSIX_ACL
	if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
		posix_acl_release(inode->i_acl);
	if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
		posix_acl_release(inode->i_default_acl);
#endif
269
	percpu_counter_dec(&nr_inodes);
Christoph Hellwig's avatar
Christoph Hellwig committed
270 271 272
}
EXPORT_SYMBOL(__destroy_inode);

273
static void destroy_inode(struct inode *inode)
Christoph Hellwig's avatar
Christoph Hellwig committed
274 275
{
	__destroy_inode(inode);
Linus Torvalds's avatar
Linus Torvalds committed
276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292
	if (inode->i_sb->s_op->destroy_inode)
		inode->i_sb->s_op->destroy_inode(inode);
	else
		kmem_cache_free(inode_cachep, (inode));
}

/*
 * 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);
293
	INIT_LIST_HEAD(&inode->i_list);
Linus Torvalds's avatar
Linus Torvalds committed
294
	INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
Nick Piggin's avatar
Nick Piggin committed
295
	spin_lock_init(&inode->i_data.tree_lock);
Linus Torvalds's avatar
Linus Torvalds committed
296 297 298 299 300 301
	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);
302
#ifdef CONFIG_FSNOTIFY
303
	INIT_HLIST_HEAD(&inode->i_fsnotify_marks);
304
#endif
Linus Torvalds's avatar
Linus Torvalds committed
305 306 307
}
EXPORT_SYMBOL(inode_init_once);

308
static void init_once(void *foo)
Linus Torvalds's avatar
Linus Torvalds committed
309
{
310
	struct inode *inode = (struct inode *) foo;
Linus Torvalds's avatar
Linus Torvalds committed
311

312
	inode_init_once(inode);
Linus Torvalds's avatar
Linus Torvalds committed
313 314 315 316 317
}

/*
 * inode_lock must be held
 */
318
void __iget(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
319
{
320 321
	atomic_inc(&inode->i_count);
}
322

323 324 325 326 327 328 329 330 331 332 333 334 335 336
static void inode_lru_list_add(struct inode *inode)
{
	if (list_empty(&inode->i_list)) {
		list_add(&inode->i_list, &inode_unused);
		percpu_counter_inc(&nr_inodes_unused);
	}
}

static void inode_lru_list_del(struct inode *inode)
{
	if (!list_empty(&inode->i_list)) {
		list_del_init(&inode->i_list);
		percpu_counter_dec(&nr_inodes_unused);
	}
Linus Torvalds's avatar
Linus Torvalds committed
337 338
}

Al Viro's avatar
Al Viro committed
339 340 341 342 343 344 345 346 347 348 349 350
void end_writeback(struct inode *inode)
{
	might_sleep();
	BUG_ON(inode->i_data.nrpages);
	BUG_ON(!list_empty(&inode->i_data.private_list));
	BUG_ON(!(inode->i_state & I_FREEING));
	BUG_ON(inode->i_state & I_CLEAR);
	inode_sync_wait(inode);
	inode->i_state = I_FREEING | I_CLEAR;
}
EXPORT_SYMBOL(end_writeback);

351
static void evict(struct inode *inode)
352 353 354
{
	const struct super_operations *op = inode->i_sb->s_op;

Al Viro's avatar
Al Viro committed
355 356
	if (op->evict_inode) {
		op->evict_inode(inode);
357 358 359
	} else {
		if (inode->i_data.nrpages)
			truncate_inode_pages(&inode->i_data, 0);
Al Viro's avatar
Al Viro committed
360
		end_writeback(inode);
361
	}
362 363 364 365
	if (S_ISBLK(inode->i_mode) && inode->i_bdev)
		bd_forget(inode);
	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
		cd_forget(inode);
366 367
}

Linus Torvalds's avatar
Linus Torvalds committed
368 369 370 371 372 373 374 375 376 377 378 379
/*
 * 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)
{
	while (!list_empty(head)) {
		struct inode *inode;

380
		inode = list_first_entry(head, struct inode, i_list);
381
		list_del_init(&inode->i_list);
Linus Torvalds's avatar
Linus Torvalds committed
382

383
		evict(inode);
384 385 386 387 388 389 390

		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);
Linus Torvalds's avatar
Linus Torvalds committed
391 392 393 394 395 396 397 398 399 400
		destroy_inode(inode);
	}
}

/*
 * Invalidate all inodes for a device.
 */
static int invalidate_list(struct list_head *head, struct list_head *dispose)
{
	struct list_head *next;
401
	int busy = 0;
Linus Torvalds's avatar
Linus Torvalds committed
402 403 404

	next = head->next;
	for (;;) {
405 406
		struct list_head *tmp = next;
		struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
407 408 409 410

		/*
		 * We can reschedule here without worrying about the list's
		 * consistency because the per-sb list of inodes must not
Nick Piggin's avatar
Nick Piggin committed
411
		 * change during umount anymore, and because iprune_sem keeps
Linus Torvalds's avatar
Linus Torvalds committed
412 413 414 415 416 417 418 419
		 * 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);
Nick Piggin's avatar
Nick Piggin committed
420 421
		if (inode->i_state & I_NEW)
			continue;
Linus Torvalds's avatar
Linus Torvalds committed
422 423 424
		invalidate_inode_buffers(inode);
		if (!atomic_read(&inode->i_count)) {
			list_move(&inode->i_list, dispose);
425
			WARN_ON(inode->i_state & I_NEW);
Linus Torvalds's avatar
Linus Torvalds committed
426
			inode->i_state |= I_FREEING;
427 428
			if (!(inode->i_state & (I_DIRTY | I_SYNC)))
				percpu_counter_dec(&nr_inodes_unused);
Linus Torvalds's avatar
Linus Torvalds committed
429 430 431 432 433 434 435 436 437 438 439 440 441 442 443
			continue;
		}
		busy = 1;
	}
	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.
 */
444
int invalidate_inodes(struct super_block *sb)
Linus Torvalds's avatar
Linus Torvalds committed
445 446 447 448
{
	int busy;
	LIST_HEAD(throw_away);

Nick Piggin's avatar
Nick Piggin committed
449
	down_write(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
450
	spin_lock(&inode_lock);
451
	fsnotify_unmount_inodes(&sb->s_inodes);
Linus Torvalds's avatar
Linus Torvalds committed
452 453 454 455
	busy = invalidate_list(&sb->s_inodes, &throw_away);
	spin_unlock(&inode_lock);

	dispose_list(&throw_away);
Nick Piggin's avatar
Nick Piggin committed
456
	up_write(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
457 458 459 460 461 462

	return busy;
}

static int can_unuse(struct inode *inode)
{
463
	if (inode->i_state & ~I_REFERENCED)
Linus Torvalds's avatar
Linus Torvalds committed
464 465 466 467 468 469 470 471 472 473 474
		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;
}

/*
475 476
 * 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().
Linus Torvalds's avatar
Linus Torvalds committed
477 478
 *
 * Any inodes which are pinned purely because of attached pagecache have their
479 480
 * pagecache removed.  If the inode has metadata buffers attached to
 * mapping->private_list then try to remove them.
Linus Torvalds's avatar
Linus Torvalds committed
481
 *
482 483 484 485 486 487 488
 * If the inode has the I_REFERENCED flag set, then it means that it has been
 * used recently - the flag is set in iput_final(). When we encounter such an
 * inode, clear the flag and move it to the back of the LRU so it gets another
 * pass through the LRU before it gets reclaimed. This is necessary because of
 * the fact we are doing lazy LRU updates to minimise lock contention so the
 * LRU does not have strict ordering. Hence we don't want to reclaim inodes
 * with this flag set because they are the inodes that are out of order.
Linus Torvalds's avatar
Linus Torvalds committed
489 490 491 492 493 494 495
 */
static void prune_icache(int nr_to_scan)
{
	LIST_HEAD(freeable);
	int nr_scanned;
	unsigned long reap = 0;

Nick Piggin's avatar
Nick Piggin committed
496
	down_read(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
497 498 499 500 501 502 503 504 505
	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);

506 507 508 509 510 511 512 513 514 515 516 517 518
		/*
		 * Referenced or dirty inodes are still in use. Give them
		 * another pass through the LRU as we canot reclaim them now.
		 */
		if (atomic_read(&inode->i_count) ||
		    (inode->i_state & ~I_REFERENCED)) {
			list_del_init(&inode->i_list);
			percpu_counter_dec(&nr_inodes_unused);
			continue;
		}

		/* recently referenced inodes get one more pass */
		if (inode->i_state & I_REFERENCED) {
Linus Torvalds's avatar
Linus Torvalds committed
519
			list_move(&inode->i_list, &inode_unused);
520
			inode->i_state &= ~I_REFERENCED;
Linus Torvalds's avatar
Linus Torvalds committed
521 522 523 524 525 526
			continue;
		}
		if (inode_has_buffers(inode) || inode->i_data.nrpages) {
			__iget(inode);
			spin_unlock(&inode_lock);
			if (remove_inode_buffers(inode))
527 528
				reap += invalidate_mapping_pages(&inode->i_data,
								0, -1);
Linus Torvalds's avatar
Linus Torvalds committed
529 530 531 532 533 534 535 536 537 538
			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);
539
		WARN_ON(inode->i_state & I_NEW);
Linus Torvalds's avatar
Linus Torvalds committed
540
		inode->i_state |= I_FREEING;
541
		percpu_counter_dec(&nr_inodes_unused);
Linus Torvalds's avatar
Linus Torvalds committed
542
	}
543 544 545 546
	if (current_is_kswapd())
		__count_vm_events(KSWAPD_INODESTEAL, reap);
	else
		__count_vm_events(PGINODESTEAL, reap);
Linus Torvalds's avatar
Linus Torvalds committed
547 548 549
	spin_unlock(&inode_lock);

	dispose_list(&freeable);
Nick Piggin's avatar
Nick Piggin committed
550
	up_read(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
551 552 553 554 555 556 557 558 559 560 561
}

/*
 * 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.
 */
562
static int shrink_icache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
Linus Torvalds's avatar
Linus Torvalds committed
563 564 565 566 567 568
{
	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..
569
		 */
Linus Torvalds's avatar
Linus Torvalds committed
570 571 572 573
		if (!(gfp_mask & __GFP_FS))
			return -1;
		prune_icache(nr);
	}
574
	return (get_nr_inodes_unused() / 100) * sysctl_vfs_cache_pressure;
Linus Torvalds's avatar
Linus Torvalds committed
575 576
}

577 578 579 580 581
static struct shrinker icache_shrinker = {
	.shrink = shrink_icache_memory,
	.seeks = DEFAULT_SEEKS,
};

Linus Torvalds's avatar
Linus Torvalds committed
582 583 584 585 586 587 588
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.
 */
589 590 591 592
static struct inode *find_inode(struct super_block *sb,
				struct hlist_head *head,
				int (*test)(struct inode *, void *),
				void *data)
Linus Torvalds's avatar
Linus Torvalds committed
593 594
{
	struct hlist_node *node;
595
	struct inode *inode = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
596 597

repeat:
598
	hlist_for_each_entry(inode, node, head, i_hash) {
Linus Torvalds's avatar
Linus Torvalds committed
599 600 601 602
		if (inode->i_sb != sb)
			continue;
		if (!test(inode, data))
			continue;
603
		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
Linus Torvalds's avatar
Linus Torvalds committed
604 605 606 607 608 609 610 611 612 613 614 615
			__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.
 */
616 617
static struct inode *find_inode_fast(struct super_block *sb,
				struct hlist_head *head, unsigned long ino)
Linus Torvalds's avatar
Linus Torvalds committed
618 619
{
	struct hlist_node *node;
620
	struct inode *inode = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
621 622

repeat:
623
	hlist_for_each_entry(inode, node, head, i_hash) {
Linus Torvalds's avatar
Linus Torvalds committed
624 625 626 627
		if (inode->i_ino != ino)
			continue;
		if (inode->i_sb != sb)
			continue;
628
		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
Linus Torvalds's avatar
Linus Torvalds committed
629 630 631 632 633 634 635 636
			__wait_on_freeing_inode(inode);
			goto repeat;
		}
		break;
	}
	return node ? inode : NULL;
}

637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657
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)
{
	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
658 659
 * @sb: superblock inode belongs to
 * @inode: inode to mark in use
660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677
 *
 * 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);

Linus Torvalds's avatar
Linus Torvalds committed
678 679 680 681
/**
 *	new_inode 	- obtain an inode
 *	@sb: superblock
 *
682
 *	Allocates a new inode for given superblock. The default gfp_mask
683
 *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
684 685 686 687 688
 *	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
 *
Linus Torvalds's avatar
Linus Torvalds committed
689 690 691
 */
struct inode *new_inode(struct super_block *sb)
{
692 693 694 695 696 697
	/*
	 * 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;
698
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
699 700

	spin_lock_prefetch(&inode_lock);
701

Linus Torvalds's avatar
Linus Torvalds committed
702 703 704
	inode = alloc_inode(sb);
	if (inode) {
		spin_lock(&inode_lock);
705
		__inode_add_to_lists(sb, NULL, inode);
Linus Torvalds's avatar
Linus Torvalds committed
706 707 708 709 710 711 712 713 714 715
		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)
{
716
#ifdef CONFIG_DEBUG_LOCK_ALLOC
717
	if (S_ISDIR(inode->i_mode)) {
718 719
		struct file_system_type *type = inode->i_sb->s_type;

720 721 722 723 724 725 726 727 728 729 730
		/* Set new key only if filesystem hasn't already changed it */
		if (!lockdep_match_class(&inode->i_mutex,
		    &type->i_mutex_key)) {
			/*
			 * ensure nobody is actually holding i_mutex
			 */
			mutex_destroy(&inode->i_mutex);
			mutex_init(&inode->i_mutex);
			lockdep_set_class(&inode->i_mutex,
					  &type->i_mutex_dir_key);
		}
731
	}
732
#endif
Linus Torvalds's avatar
Linus Torvalds committed
733
	/*
Christoph Hellwig's avatar
Christoph Hellwig committed
734
	 * This is special!  We do not need the spinlock when clearing I_NEW,
735 736
	 * 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
Christoph Hellwig's avatar
Christoph Hellwig committed
737
	 * there can be no old holders that haven't tested I_NEW).
738
	 * However we must emit the memory barrier so that other CPUs reliably
Christoph Hellwig's avatar
Christoph Hellwig committed
739
	 * see the clearing of I_NEW after the other inode initialisation has
740
	 * completed.
Linus Torvalds's avatar
Linus Torvalds committed
741
	 */
742
	smp_mb();
Christoph Hellwig's avatar
Christoph Hellwig committed
743 744
	WARN_ON(!(inode->i_state & I_NEW));
	inode->i_state &= ~I_NEW;
Linus Torvalds's avatar
Linus Torvalds committed
745 746 747 748 749 750 751 752 753 754
	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
 */
755 756 757 758 759
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)
Linus Torvalds's avatar
Linus Torvalds committed
760
{
761
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
762 763 764

	inode = alloc_inode(sb);
	if (inode) {
765
		struct inode *old;
Linus Torvalds's avatar
Linus Torvalds committed
766 767 768 769 770 771 772 773

		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;

774
			__inode_add_to_lists(sb, head, inode);
Christoph Hellwig's avatar
Christoph Hellwig committed
775
			inode->i_state = I_NEW;
Linus Torvalds's avatar
Linus Torvalds committed
776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806
			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.
 */
807 808
static struct inode *get_new_inode_fast(struct super_block *sb,
				struct hlist_head *head, unsigned long ino)
Linus Torvalds's avatar
Linus Torvalds committed
809
{
810
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
811 812 813

	inode = alloc_inode(sb);
	if (inode) {
814
		struct inode *old;
Linus Torvalds's avatar
Linus Torvalds committed
815 816 817 818 819 820

		spin_lock(&inode_lock);
		/* We released the lock, so.. */
		old = find_inode_fast(sb, head, ino);
		if (!old) {
			inode->i_ino = ino;
821
			__inode_add_to_lists(sb, head, inode);
Christoph Hellwig's avatar
Christoph Hellwig committed
822
			inode->i_state = I_NEW;
Linus Torvalds's avatar
Linus Torvalds committed
823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860
			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)
{
861 862 863 864 865 866
	/*
	 * 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;
Linus Torvalds's avatar
Linus Torvalds committed
867
	struct inode *inode;
868
	struct hlist_head *head;
Linus Torvalds's avatar
Linus Torvalds committed
869
	ino_t res;
870

Linus Torvalds's avatar
Linus Torvalds committed
871
	spin_lock(&inode_lock);
872 873 874
	do {
		if (counter <= max_reserved)
			counter = max_reserved + 1;
Linus Torvalds's avatar
Linus Torvalds committed
875
		res = counter++;
876
		head = inode_hashtable + hash(sb, res);
Linus Torvalds's avatar
Linus Torvalds committed
877
		inode = find_inode_fast(sb, head, res);
878 879
	} while (inode != NULL);
	spin_unlock(&inode_lock);
Linus Torvalds's avatar
Linus Torvalds committed
880

881 882
	return res;
}
Linus Torvalds's avatar
Linus Torvalds committed
883 884 885 886 887
EXPORT_SYMBOL(iunique);

struct inode *igrab(struct inode *inode)
{
	spin_lock(&inode_lock);
888
	if (!(inode->i_state & (I_FREEING|I_WILL_FREE)))
Linus Torvalds's avatar
Linus Torvalds committed
889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907
		__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
908
 * @wait:	if true wait for the inode to be unlocked, if false do not
Linus Torvalds's avatar
Linus Torvalds committed
909 910 911 912 913 914 915 916 917 918 919 920
 *
 * 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.
 */
921
static struct inode *ifind(struct super_block *sb,
Linus Torvalds's avatar
Linus Torvalds committed
922
		struct hlist_head *head, int (*test)(struct inode *, void *),
923
		void *data, const int wait)
Linus Torvalds's avatar
Linus Torvalds committed
924 925 926 927 928 929 930 931
{
	struct inode *inode;

	spin_lock(&inode_lock);
	inode = find_inode(sb, head, test, data);
	if (inode) {
		__iget(inode);
		spin_unlock(&inode_lock);
932 933
		if (likely(wait))
			wait_on_inode(inode);
Linus Torvalds's avatar
Linus Torvalds committed
934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954
		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.
 */
955
static struct inode *ifind_fast(struct super_block *sb,
Linus Torvalds's avatar
Linus Torvalds committed
956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972
		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;
}

/**
973
 * ilookup5_nowait - search for an inode in the inode cache
Linus Torvalds's avatar
Linus Torvalds committed
974 975 976 977 978 979 980 981 982 983 984
 * @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
985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015
 * 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.
Linus Torvalds's avatar
Linus Torvalds committed
1016 1017 1018 1019 1020 1021 1022 1023 1024 1025
 *
 * 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);

1026
	return ifind(sb, head, test, data, 1);
Linus Torvalds's avatar
Linus Torvalds committed
1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 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
}
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;

1079
	inode = ifind(sb, head, test, data, 1);
Linus Torvalds's avatar
Linus Torvalds committed
1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120
	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);

1121 1122 1123 1124 1125 1126
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);

Christoph Hellwig's avatar
Christoph Hellwig committed
1127
	inode->i_state |= I_NEW;
1128
	while (1) {
1129 1130
		struct hlist_node *node;
		struct inode *old = NULL;
1131
		spin_lock(&inode_lock);
1132 1133 1134 1135 1136
		hlist_for_each_entry(old, node, head, i_hash) {
			if (old->i_ino != ino)
				continue;
			if (old->i_sb != sb)
				continue;
1137
			if (old->i_state & (I_FREEING|I_WILL_FREE))
1138 1139 1140 1141
				continue;
			break;
		}
		if (likely(!node)) {
1142 1143 1144 1145 1146 1147 1148
			hlist_add_head(&inode->i_hash, head);
			spin_unlock(&inode_lock);
			return 0;
		}
		__iget(old);
		spin_unlock(&inode_lock);
		wait_on_inode(old);
Al Viro's avatar
Al Viro committed
1149
		if (unlikely(!inode_unhashed(old))) {
1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163
			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);

Christoph Hellwig's avatar
Christoph Hellwig committed
1164
	inode->i_state |= I_NEW;
1165 1166

	while (1) {
1167 1168 1169
		struct hlist_node *node;
		struct inode *old = NULL;

1170
		spin_lock(&inode_lock);
1171 1172 1173 1174 1175
		hlist_for_each_entry(old, node, head, i_hash) {
			if (old->i_sb != sb)
				continue;
			if (!test(old, data))
				continue;
1176
			if (old->i_state & (I_FREEING|I_WILL_FREE))
1177 1178 1179 1180
				continue;
			break;
		}
		if (likely(!node)) {
1181 1182 1183 1184 1185 1186 1187
			hlist_add_head(&inode->i_hash, head);
			spin_unlock(&inode_lock);
			return 0;
		}
		__iget(old);
		spin_unlock(&inode_lock);
		wait_on_inode(old);
Al Viro's avatar
Al Viro committed
1188
		if (unlikely(!inode_unhashed(old))) {
1189 1190 1191 1192 1193 1194 1195 1196
			iput(old);
			return -EBUSY;
		}
		iput(old);
	}
}
EXPORT_SYMBOL(insert_inode_locked4);

Linus Torvalds's avatar
Linus Torvalds committed
1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227
/**
 *	__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);

1228 1229 1230 1231 1232 1233
int generic_delete_inode(struct inode *inode)
{
	return 1;
}
EXPORT_SYMBOL(generic_delete_inode);

Linus Torvalds's avatar
Linus Torvalds committed
1234
/*
1235 1236 1237
 * Normal UNIX filesystem behaviour: delete the
 * inode when the usage count drops to zero, and
 * i_nlink is zero.
Linus Torvalds's avatar
Linus Torvalds committed
1238
 */
1239
int generic_drop_inode(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
1240
{
Al Viro's avatar
Al Viro committed
1241
	return !inode->i_nlink || inode_unhashed(inode);
Linus Torvalds's avatar
Linus Torvalds committed
1242
}
1243
EXPORT_SYMBOL_GPL(generic_drop_inode);
Linus Torvalds's avatar
Linus Torvalds committed
1244

1245 1246 1247
/*
 * Called when we're dropping the last reference
 * to an inode.
1248
 *
1249 1250 1251 1252 1253
 * Call the FS "drop_inode()" function, defaulting to
 * the legacy UNIX filesystem behaviour.  If it tells
 * us to evict inode, do so.  Otherwise, retain inode
 * in cache if fs is alive, sync and evict if fs is
 * shutting down.
1254
 */
1255
static void iput_final(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
1256 1257
{
	struct super_block *sb = inode->i_sb;
1258 1259 1260 1261 1262 1263 1264
	const struct super_operations *op = inode->i_sb->s_op;
	int drop;

	if (op && op->drop_inode)
		drop = op->drop_inode(inode);
	else
		drop = generic_drop_inode(inode);
Linus Torvalds's avatar
Linus Torvalds committed
1265

1266
	if (!drop) {
1267
		if (sb->s_flags & MS_ACTIVE) {
1268 1269 1270 1271
			inode->i_state |= I_REFERENCED;
			if (!(inode->i_state & (I_DIRTY|I_SYNC))) {
				inode_lru_list_add(inode);
			}
1272
			spin_unlock(&inode_lock);
1273
			return;
1274
		}
1275
		WARN_ON(inode->i_state & I_NEW);
1276 1277
		inode->i_state |= I_WILL_FREE;
		spin_unlock(&inode_lock);
Linus Torvalds's avatar
Linus Torvalds committed
1278 1279
		write_inode_now(inode, 1);
		spin_lock(&inode_lock);
1280
		WARN_ON(inode->i_state & I_NEW);
1281
		inode->i_state &= ~I_WILL_FREE;
Linus Torvalds's avatar
Linus Torvalds committed
1282 1283
		hlist_del_init(&inode->i_hash);
	}
1284
	WARN_ON(inode->i_state & I_NEW);
1285
	inode->i_state |= I_FREEING;
1286 1287 1288 1289