inode.c 44.6 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>
27
#include <linux/ima.h>
Linus Torvalds's avatar
Linus Torvalds committed
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_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.
 */

Nick Piggin's avatar
Nick Piggin committed
75
static LIST_HEAD(inode_lru);
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
static DEFINE_PER_CPU(unsigned int, nr_inodes);
106

107
static struct kmem_cache *inode_cachep __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
108

109
static int get_nr_inodes(void)
110
{
111 112 113 114 115
	int i;
	int sum = 0;
	for_each_possible_cpu(i)
		sum += per_cpu(nr_inodes, i);
	return sum < 0 ? 0 : sum;
116 117 118 119
}

static inline int get_nr_inodes_unused(void)
{
120
	return inodes_stat.nr_unused;
121 122 123 124
}

int get_nr_dirty_inodes(void)
{
125
	/* not actually dirty inodes, but a wild approximation */
126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141
	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();
	return proc_dointvec(table, write, buffer, lenp, ppos);
}
#endif

Joern Engel's avatar
Joern Engel committed
142 143 144 145 146 147
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
148
	wake_up_bit(&inode->i_state, __I_NEW);
Joern Engel's avatar
Joern Engel committed
149 150
}

151 152
/**
 * inode_init_always - perform inode structure intialisation
153 154
 * @sb: superblock inode belongs to
 * @inode: inode to initialise
155 156 157 158
 *
 * These are initializations that need to be done on every inode
 * allocation as the fields are not initialised by slab allocation.
 */
159
int inode_init_always(struct super_block *sb, struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
160
{
161
	static const struct address_space_operations empty_aops;
162
	static const struct inode_operations empty_iops;
163
	static const struct file_operations empty_fops;
164
	struct address_space *const mapping = &inode->i_data;
165 166 167 168 169 170 171 172

	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
173 174
	inode->i_uid = 0;
	inode->i_gid = 0;
175 176 177 178 179
	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
180
#ifdef CONFIG_QUOTA
181
	memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
Linus Torvalds's avatar
Linus Torvalds committed
182
#endif
183 184 185 186 187
	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
188 189

	if (security_inode_alloc(inode))
190
		goto out;
191 192 193 194 195 196 197 198 199 200 201 202
	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;
203
	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
204 205 206 207 208 209 210 211 212 213 214 215
	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;

216
		bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
217 218 219 220
		mapping->backing_dev_info = bdi;
	}
	inode->i_private = NULL;
	inode->i_mapping = mapping;
Al Viro's avatar
Al Viro committed
221 222 223
#ifdef CONFIG_FS_POSIX_ACL
	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
#endif
224

225 226 227 228
#ifdef CONFIG_FSNOTIFY
	inode->i_fsnotify_mask = 0;
#endif

229
	this_cpu_inc(nr_inodes);
230

231 232 233
	return 0;
out:
	return -ENOMEM;
Linus Torvalds's avatar
Linus Torvalds committed
234
}
235 236 237 238 239 240 241 242 243 244 245
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);

246 247 248 249 250 251 252 253 254 255 256 257
	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;
258
}
Linus Torvalds's avatar
Linus Torvalds committed
259

260 261 262 263 264 265
void free_inode_nonrcu(struct inode *inode)
{
	kmem_cache_free(inode_cachep, inode);
}
EXPORT_SYMBOL(free_inode_nonrcu);

Christoph Hellwig's avatar
Christoph Hellwig committed
266
void __destroy_inode(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
267
{
268
	BUG_ON(inode_has_buffers(inode));
Linus Torvalds's avatar
Linus Torvalds committed
269
	security_inode_free(inode);
270
	fsnotify_inode_delete(inode);
Al Viro's avatar
Al Viro committed
271 272 273 274 275 276
#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
277
	this_cpu_dec(nr_inodes);
Christoph Hellwig's avatar
Christoph Hellwig committed
278 279 280
}
EXPORT_SYMBOL(__destroy_inode);

Nick Piggin's avatar
Nick Piggin committed
281 282 283 284 285 286 287
static void i_callback(struct rcu_head *head)
{
	struct inode *inode = container_of(head, struct inode, i_rcu);
	INIT_LIST_HEAD(&inode->i_dentry);
	kmem_cache_free(inode_cachep, inode);
}

288
static void destroy_inode(struct inode *inode)
Christoph Hellwig's avatar
Christoph Hellwig committed
289
{
Nick Piggin's avatar
Nick Piggin committed
290
	BUG_ON(!list_empty(&inode->i_lru));
Christoph Hellwig's avatar
Christoph Hellwig committed
291
	__destroy_inode(inode);
Linus Torvalds's avatar
Linus Torvalds committed
292 293 294
	if (inode->i_sb->s_op->destroy_inode)
		inode->i_sb->s_op->destroy_inode(inode);
	else
Nick Piggin's avatar
Nick Piggin committed
295
		call_rcu(&inode->i_rcu, i_callback);
Linus Torvalds's avatar
Linus Torvalds committed
296 297
}

298 299 300 301 302 303 304 305 306 307 308 309 310 311
void address_space_init_once(struct address_space *mapping)
{
	memset(mapping, 0, sizeof(*mapping));
	INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
	spin_lock_init(&mapping->tree_lock);
	spin_lock_init(&mapping->i_mmap_lock);
	INIT_LIST_HEAD(&mapping->private_list);
	spin_lock_init(&mapping->private_lock);
	INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
	INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
	mutex_init(&mapping->unmap_mutex);
}
EXPORT_SYMBOL(address_space_init_once);

Linus Torvalds's avatar
Linus Torvalds committed
312 313 314 315 316 317 318 319 320 321 322
/*
 * 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);
Nick Piggin's avatar
Nick Piggin committed
323 324
	INIT_LIST_HEAD(&inode->i_wb_list);
	INIT_LIST_HEAD(&inode->i_lru);
325
	address_space_init_once(&inode->i_data);
Linus Torvalds's avatar
Linus Torvalds committed
326
	i_size_ordered_init(inode);
327
#ifdef CONFIG_FSNOTIFY
328
	INIT_HLIST_HEAD(&inode->i_fsnotify_marks);
329
#endif
Linus Torvalds's avatar
Linus Torvalds committed
330 331 332
}
EXPORT_SYMBOL(inode_init_once);

333
static void init_once(void *foo)
Linus Torvalds's avatar
Linus Torvalds committed
334
{
335
	struct inode *inode = (struct inode *) foo;
Linus Torvalds's avatar
Linus Torvalds committed
336

337
	inode_init_once(inode);
Linus Torvalds's avatar
Linus Torvalds committed
338 339 340 341 342
}

/*
 * inode_lock must be held
 */
343
void __iget(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
344
{
345 346
	atomic_inc(&inode->i_count);
}
347

Al Viro's avatar
Al Viro committed
348 349 350 351 352 353 354 355 356
/*
 * get additional reference to inode; caller must already hold one.
 */
void ihold(struct inode *inode)
{
	WARN_ON(atomic_inc_return(&inode->i_count) < 2);
}
EXPORT_SYMBOL(ihold);

357 358
static void inode_lru_list_add(struct inode *inode)
{
Nick Piggin's avatar
Nick Piggin committed
359 360
	if (list_empty(&inode->i_lru)) {
		list_add(&inode->i_lru, &inode_lru);
361
		inodes_stat.nr_unused++;
362 363
	}
}
364

365 366
static void inode_lru_list_del(struct inode *inode)
{
Nick Piggin's avatar
Nick Piggin committed
367 368
	if (!list_empty(&inode->i_lru)) {
		list_del_init(&inode->i_lru);
369
		inodes_stat.nr_unused--;
370
	}
Linus Torvalds's avatar
Linus Torvalds committed
371 372
}

373 374 375
static inline void __inode_sb_list_add(struct inode *inode)
{
	list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
Linus Torvalds's avatar
Linus Torvalds committed
376 377
}

378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394
/**
 * inode_sb_list_add - add inode to the superblock list of inodes
 * @inode: inode to add
 */
void inode_sb_list_add(struct inode *inode)
{
	spin_lock(&inode_lock);
	__inode_sb_list_add(inode);
	spin_unlock(&inode_lock);
}
EXPORT_SYMBOL_GPL(inode_sb_list_add);

static inline void __inode_sb_list_del(struct inode *inode)
{
	list_del_init(&inode->i_sb_list);
}

395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414
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;
}

/**
 *	__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)
{
415 416
	struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);

417
	spin_lock(&inode_lock);
418
	hlist_add_head(&inode->i_hash, b);
419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447
	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.
 */
static void __remove_inode_hash(struct inode *inode)
{
	hlist_del_init(&inode->i_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);

Al Viro's avatar
Al Viro committed
448 449 450 451 452 453 454 455
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);
Nick Piggin's avatar
Nick Piggin committed
456
	/* don't need i_lock here, no concurrent mods to i_state */
Al Viro's avatar
Al Viro committed
457 458 459 460
	inode->i_state = I_FREEING | I_CLEAR;
}
EXPORT_SYMBOL(end_writeback);

461
static void evict(struct inode *inode)
462 463 464
{
	const struct super_operations *op = inode->i_sb->s_op;

Al Viro's avatar
Al Viro committed
465 466
	if (op->evict_inode) {
		op->evict_inode(inode);
467 468 469
	} else {
		if (inode->i_data.nrpages)
			truncate_inode_pages(&inode->i_data, 0);
Al Viro's avatar
Al Viro committed
470
		end_writeback(inode);
471
	}
472 473 474 475
	if (S_ISBLK(inode->i_mode) && inode->i_bdev)
		bd_forget(inode);
	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
		cd_forget(inode);
476 477
}

Linus Torvalds's avatar
Linus Torvalds committed
478 479 480 481 482 483 484 485 486 487 488 489
/*
 * 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;

Nick Piggin's avatar
Nick Piggin committed
490 491
		inode = list_first_entry(head, struct inode, i_lru);
		list_del_init(&inode->i_lru);
Linus Torvalds's avatar
Linus Torvalds committed
492

493
		evict(inode);
494 495

		spin_lock(&inode_lock);
496
		__remove_inode_hash(inode);
497
		__inode_sb_list_del(inode);
498 499 500
		spin_unlock(&inode_lock);

		wake_up_inode(inode);
Linus Torvalds's avatar
Linus Torvalds committed
501 502 503 504
		destroy_inode(inode);
	}
}

Al Viro's avatar
Al Viro committed
505 506 507 508 509 510 511 512
/**
 * evict_inodes	- evict all evictable inodes for a superblock
 * @sb:		superblock to operate on
 *
 * Make sure that no inodes with zero refcount are retained.  This is
 * called by superblock shutdown after having MS_ACTIVE flag removed,
 * so any inode reaching zero refcount during or after that call will
 * be immediately evicted.
Linus Torvalds's avatar
Linus Torvalds committed
513
 */
Al Viro's avatar
Al Viro committed
514
void evict_inodes(struct super_block *sb)
Linus Torvalds's avatar
Linus Torvalds committed
515
{
Al Viro's avatar
Al Viro committed
516 517
	struct inode *inode, *next;
	LIST_HEAD(dispose);
Linus Torvalds's avatar
Linus Torvalds committed
518

Al Viro's avatar
Al Viro committed
519
	down_write(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
520

Al Viro's avatar
Al Viro committed
521 522 523
	spin_lock(&inode_lock);
	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
		if (atomic_read(&inode->i_count))
Nick Piggin's avatar
Nick Piggin committed
524
			continue;
Al Viro's avatar
Al Viro committed
525 526 527

		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
			WARN_ON(1);
Linus Torvalds's avatar
Linus Torvalds committed
528 529
			continue;
		}
Al Viro's avatar
Al Viro committed
530 531 532 533 534 535 536 537 538 539

		inode->i_state |= I_FREEING;

		/*
		 * Move the inode off the IO lists and LRU once I_FREEING is
		 * set so that it won't get moved back on there if it is dirty.
		 */
		list_move(&inode->i_lru, &dispose);
		list_del_init(&inode->i_wb_list);
		if (!(inode->i_state & (I_DIRTY | I_SYNC)))
540
			inodes_stat.nr_unused--;
Linus Torvalds's avatar
Linus Torvalds committed
541
	}
Al Viro's avatar
Al Viro committed
542 543 544 545
	spin_unlock(&inode_lock);

	dispose_list(&dispose);
	up_write(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
546 547 548
}

/**
549 550
 * invalidate_inodes	- attempt to free all inodes on a superblock
 * @sb:		superblock to operate on
551
 * @kill_dirty: flag to guide handling of dirty inodes
Linus Torvalds's avatar
Linus Torvalds committed
552
 *
553 554
 * Attempts to free all inodes for a given superblock.  If there were any
 * busy inodes return a non-zero value, else zero.
555 556
 * If @kill_dirty is set, discard dirty inodes too, otherwise treat
 * them as busy.
Linus Torvalds's avatar
Linus Torvalds committed
557
 */
558
int invalidate_inodes(struct super_block *sb, bool kill_dirty)
Linus Torvalds's avatar
Linus Torvalds committed
559
{
560
	int busy = 0;
561 562
	struct inode *inode, *next;
	LIST_HEAD(dispose);
Linus Torvalds's avatar
Linus Torvalds committed
563

Nick Piggin's avatar
Nick Piggin committed
564
	down_write(&iprune_sem);
565

Linus Torvalds's avatar
Linus Torvalds committed
566
	spin_lock(&inode_lock);
567
	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
Al Viro's avatar
Al Viro committed
568
		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE))
Nick Piggin's avatar
Nick Piggin committed
569
			continue;
570 571 572 573
		if (inode->i_state & I_DIRTY && !kill_dirty) {
			busy = 1;
			continue;
		}
574 575
		if (atomic_read(&inode->i_count)) {
			busy = 1;
Linus Torvalds's avatar
Linus Torvalds committed
576 577
			continue;
		}
578 579

		inode->i_state |= I_FREEING;
Nick Piggin's avatar
Nick Piggin committed
580 581 582 583 584

		/*
		 * Move the inode off the IO lists and LRU once I_FREEING is
		 * set so that it won't get moved back on there if it is dirty.
		 */
585
		list_move(&inode->i_lru, &dispose);
Nick Piggin's avatar
Nick Piggin committed
586
		list_del_init(&inode->i_wb_list);
587
		if (!(inode->i_state & (I_DIRTY | I_SYNC)))
588
			inodes_stat.nr_unused--;
Linus Torvalds's avatar
Linus Torvalds committed
589 590 591
	}
	spin_unlock(&inode_lock);

592
	dispose_list(&dispose);
Nick Piggin's avatar
Nick Piggin committed
593
	up_write(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
594 595 596 597 598 599

	return busy;
}

static int can_unuse(struct inode *inode)
{
600
	if (inode->i_state & ~I_REFERENCED)
Linus Torvalds's avatar
Linus Torvalds committed
601 602 603 604 605 606 607 608 609 610 611
		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;
}

/*
612 613
 * 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
614 615
 *
 * Any inodes which are pinned purely because of attached pagecache have their
616 617
 * 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
618
 *
619 620 621 622 623 624 625
 * 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
626 627 628 629 630 631 632
 */
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
633
	down_read(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
634 635 636 637
	spin_lock(&inode_lock);
	for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
		struct inode *inode;

Nick Piggin's avatar
Nick Piggin committed
638
		if (list_empty(&inode_lru))
Linus Torvalds's avatar
Linus Torvalds committed
639 640
			break;

Nick Piggin's avatar
Nick Piggin committed
641
		inode = list_entry(inode_lru.prev, struct inode, i_lru);
Linus Torvalds's avatar
Linus Torvalds committed
642

643 644 645 646 647 648
		/*
		 * 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)) {
Nick Piggin's avatar
Nick Piggin committed
649
			list_del_init(&inode->i_lru);
650
			inodes_stat.nr_unused--;
651 652 653 654 655
			continue;
		}

		/* recently referenced inodes get one more pass */
		if (inode->i_state & I_REFERENCED) {
Nick Piggin's avatar
Nick Piggin committed
656
			list_move(&inode->i_lru, &inode_lru);
657
			inode->i_state &= ~I_REFERENCED;
Linus Torvalds's avatar
Linus Torvalds committed
658 659 660 661 662 663
			continue;
		}
		if (inode_has_buffers(inode) || inode->i_data.nrpages) {
			__iget(inode);
			spin_unlock(&inode_lock);
			if (remove_inode_buffers(inode))
664 665
				reap += invalidate_mapping_pages(&inode->i_data,
								0, -1);
Linus Torvalds's avatar
Linus Torvalds committed
666 667 668
			iput(inode);
			spin_lock(&inode_lock);

Nick Piggin's avatar
Nick Piggin committed
669 670
			if (inode != list_entry(inode_lru.next,
						struct inode, i_lru))
Linus Torvalds's avatar
Linus Torvalds committed
671 672 673 674
				continue;	/* wrong inode or list_empty */
			if (!can_unuse(inode))
				continue;
		}
675
		WARN_ON(inode->i_state & I_NEW);
Linus Torvalds's avatar
Linus Torvalds committed
676
		inode->i_state |= I_FREEING;
Nick Piggin's avatar
Nick Piggin committed
677 678 679 680 681 682 683

		/*
		 * Move the inode off the IO lists and LRU once I_FREEING is
		 * set so that it won't get moved back on there if it is dirty.
		 */
		list_move(&inode->i_lru, &freeable);
		list_del_init(&inode->i_wb_list);
684
		inodes_stat.nr_unused--;
Linus Torvalds's avatar
Linus Torvalds committed
685
	}
686 687 688 689
	if (current_is_kswapd())
		__count_vm_events(KSWAPD_INODESTEAL, reap);
	else
		__count_vm_events(PGINODESTEAL, reap);
Linus Torvalds's avatar
Linus Torvalds committed
690 691 692
	spin_unlock(&inode_lock);

	dispose_list(&freeable);
Nick Piggin's avatar
Nick Piggin committed
693
	up_read(&iprune_sem);
Linus Torvalds's avatar
Linus Torvalds committed
694 695 696 697 698 699 700 701 702 703 704
}

/*
 * 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.
 */
705
static int shrink_icache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
Linus Torvalds's avatar
Linus Torvalds committed
706 707 708 709 710 711
{
	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..
712
		 */
Linus Torvalds's avatar
Linus Torvalds committed
713 714 715 716
		if (!(gfp_mask & __GFP_FS))
			return -1;
		prune_icache(nr);
	}
717
	return (get_nr_inodes_unused() / 100) * sysctl_vfs_cache_pressure;
Linus Torvalds's avatar
Linus Torvalds committed
718 719
}

720 721 722 723 724
static struct shrinker icache_shrinker = {
	.shrink = shrink_icache_memory,
	.seeks = DEFAULT_SEEKS,
};

Linus Torvalds's avatar
Linus Torvalds committed
725 726 727 728
static void __wait_on_freeing_inode(struct inode *inode);
/*
 * Called with the inode lock held.
 */
729 730 731 732
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
733 734
{
	struct hlist_node *node;
735
	struct inode *inode = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
736 737

repeat:
738
	hlist_for_each_entry(inode, node, head, i_hash) {
Linus Torvalds's avatar
Linus Torvalds committed
739 740 741 742
		if (inode->i_sb != sb)
			continue;
		if (!test(inode, data))
			continue;
743
		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
Linus Torvalds's avatar
Linus Torvalds committed
744 745 746
			__wait_on_freeing_inode(inode);
			goto repeat;
		}
747 748
		__iget(inode);
		return inode;
Linus Torvalds's avatar
Linus Torvalds committed
749
	}
750
	return NULL;
Linus Torvalds's avatar
Linus Torvalds committed
751 752 753 754 755 756
}

/*
 * find_inode_fast is the fast path version of find_inode, see the comment at
 * iget_locked for details.
 */
757 758
static struct inode *find_inode_fast(struct super_block *sb,
				struct hlist_head *head, unsigned long ino)
Linus Torvalds's avatar
Linus Torvalds committed
759 760
{
	struct hlist_node *node;
761
	struct inode *inode = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
762 763

repeat:
764
	hlist_for_each_entry(inode, node, head, i_hash) {
Linus Torvalds's avatar
Linus Torvalds committed
765 766 767 768
		if (inode->i_ino != ino)
			continue;
		if (inode->i_sb != sb)
			continue;
769
		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
Linus Torvalds's avatar
Linus Torvalds committed
770 771 772
			__wait_on_freeing_inode(inode);
			goto repeat;
		}
773 774
		__iget(inode);
		return inode;
Linus Torvalds's avatar
Linus Torvalds committed
775
	}
776
	return NULL;
777 778
}

779 780 781 782
/*
 * Each cpu owns a range of LAST_INO_BATCH numbers.
 * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
 * to renew the exhausted range.
783
 *
784 785 786 787 788 789 790 791 792
 * This does not significantly increase overflow rate because every CPU can
 * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
 * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
 * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
 * overflow rate by 2x, which does not seem too significant.
 *
 * 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.
793
 */
794 795 796
#define LAST_INO_BATCH 1024
static DEFINE_PER_CPU(unsigned int, last_ino);

797
unsigned int get_next_ino(void)
798
{
799 800
	unsigned int *p = &get_cpu_var(last_ino);
	unsigned int res = *p;
801

802 803 804 805 806 807 808 809 810 811 812 813
#ifdef CONFIG_SMP
	if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
		static atomic_t shared_last_ino;
		int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);

		res = next - LAST_INO_BATCH;
	}
#endif

	*p = ++res;
	put_cpu_var(last_ino);
	return res;
814
}
815
EXPORT_SYMBOL(get_next_ino);
816

Linus Torvalds's avatar
Linus Torvalds committed
817 818 819 820
/**
 *	new_inode 	- obtain an inode
 *	@sb: superblock
 *
821
 *	Allocates a new inode for given superblock. The default gfp_mask
822
 *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
823 824 825 826 827
 *	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
828 829 830
 */
struct inode *new_inode(struct super_block *sb)
{
831
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
832 833

	spin_lock_prefetch(&inode_lock);
834

Linus Torvalds's avatar
Linus Torvalds committed
835 836 837
	inode = alloc_inode(sb);
	if (inode) {
		spin_lock(&inode_lock);
838
		__inode_sb_list_add(inode);
Linus Torvalds's avatar
Linus Torvalds committed
839 840 841 842 843 844 845 846 847
		inode->i_state = 0;
		spin_unlock(&inode_lock);
	}
	return inode;
}
EXPORT_SYMBOL(new_inode);

void unlock_new_inode(struct inode *inode)
{
848
#ifdef CONFIG_DEBUG_LOCK_ALLOC
849
	if (S_ISDIR(inode->i_mode)) {
850 851
		struct file_system_type *type = inode->i_sb->s_type;

852 853 854 855 856 857 858 859 860 861 862
		/* 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);
		}
863
	}
864
#endif
Linus Torvalds's avatar
Linus Torvalds committed
865
	/*
Christoph Hellwig's avatar
Christoph Hellwig committed
866
	 * This is special!  We do not need the spinlock when clearing I_NEW,
867 868
	 * 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
869
	 * there can be no old holders that haven't tested I_NEW).
870
	 * However we must emit the memory barrier so that other CPUs reliably
Christoph Hellwig's avatar
Christoph Hellwig committed
871
	 * see the clearing of I_NEW after the other inode initialisation has
872
	 * completed.
Linus Torvalds's avatar
Linus Torvalds committed
873
	 */
874
	smp_mb();
Christoph Hellwig's avatar
Christoph Hellwig committed
875 876
	WARN_ON(!(inode->i_state & I_NEW));
	inode->i_state &= ~I_NEW;
Linus Torvalds's avatar
Linus Torvalds committed
877 878 879 880 881 882 883 884 885 886
	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
 */
887 888 889 890 891
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
892
{
893
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
894 895 896

	inode = alloc_inode(sb);
	if (inode) {
897
		struct inode *old;
Linus Torvalds's avatar
Linus Torvalds committed
898 899 900 901 902 903 904 905

		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;

906 907
			hlist_add_head(&inode->i_hash, head);
			__inode_sb_list_add(inode);
Christoph Hellwig's avatar
Christoph Hellwig committed
908
			inode->i_state = I_NEW;
Linus Torvalds's avatar
Linus Torvalds committed
909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938
			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.
		 */
		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.
 */
939 940
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
941
{
942
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
943 944 945

	inode = alloc_inode(sb);
	if (inode) {
946
		struct inode *old;
Linus Torvalds's avatar
Linus Torvalds committed
947 948 949 950 951 952

		spin_lock(&inode_lock);
		/* We released the lock, so.. */
		old = find_inode_fast(sb, head, ino);
		if (!old) {
			inode->i_ino = ino;
953 954
			hlist_add_head(&inode->i_hash, head);
			__inode_sb_list_add(inode);
Christoph Hellwig's avatar
Christoph Hellwig committed
955
			inode->i_state = I_NEW;
Linus Torvalds's avatar
Linus Torvalds committed
956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976
			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.
		 */
		spin_unlock(&inode_lock);
		destroy_inode(inode);
		inode = old;
		wait_on_inode(inode);
	}
	return inode;
}

977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997
/*
 * search the inode cache for a matching inode number.
 * If we find one, then the inode number we are trying to
 * allocate is not unique and so we should not use it.
 *
 * Returns 1 if the inode number is unique, 0 if it is not.
 */
static int test_inode_iunique(struct super_block *sb, unsigned long ino)
{
	struct hlist_head *b = inode_hashtable + hash(sb, ino);
	struct hlist_node *node;
	struct inode *inode;

	hlist_for_each_entry(inode, node, b, i_hash) {
		if (inode->i_ino == ino && inode->i_sb == sb)
			return 0;
	}

	return 1;
}

Linus Torvalds's avatar
Linus Torvalds committed
998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013
/**
 *	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)
{
1014 1015 1016 1017 1018
	/*
	 * 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.
	 */
1019
	static DEFINE_SPINLOCK(iunique_lock);
1020
	static unsigned int counter;
Linus Torvalds's avatar
Linus Torvalds committed
1021
	ino_t res;
1022

Linus Torvalds's avatar
Linus Torvalds committed
1023
	spin_lock(&inode_lock);
1024
	spin_lock(&iunique_lock);
1025 1026 1027
	do {
		if (counter <= max_reserved)
			counter = max_reserved + 1;
Linus Torvalds's avatar
Linus Torvalds committed
1028
		res = counter++;
1029 1030
	} while (!test_inode_iunique(sb, res));
	spin_unlock(&iunique_lock);
1031
	spin_unlock(&inode_lock);
Linus Torvalds's avatar
Linus Torvalds committed
1032

1033 1034
	return res;
}
Linus Torvalds's avatar
Linus Torvalds committed
1035 1036 1037 1038 1039
EXPORT_SYMBOL(iunique);

struct inode *igrab(struct inode *inode)
{
	spin_lock(&inode_lock);
1040
	if (!(inode->i_state & (I_FREEING|I_WILL_FREE)))
Linus Torvalds's avatar
Linus Torvalds committed
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059
		__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
1060
 * @wait:	if true wait for the inode to be unlocked, if false do not
Linus Torvalds's avatar
Linus Torvalds committed
1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072
 *
 * 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.
 */
1073
static struct inode *ifind(struct super_block *sb,
Linus Torvalds's avatar
Linus Torvalds committed
1074
		struct hlist_head *head, int (*test)(struct inode *, void *),
1075
		void *data, const int wait)
Linus Torvalds's avatar
Linus Torvalds committed
1076 1077 1078 1079 1080 1081 1082
{
	struct inode *inode;

	spin_lock(&inode_lock);
	inode = find_inode(sb, head, test, data);
	if (inode) {
		spin_unlock(&inode_lock);
1083 1084
		if (likely(wait))
			wait_on_inode(inode);
Linus Torvalds's avatar
Linus Torvalds committed
1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105
		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.
 */
1106
static struct inode *ifind_fast(struct super_block *sb,
Linus Torvalds's avatar
Linus Torvalds committed
1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
		struct hlist_head *head, unsigned long ino)
{
	struct inode *inode;

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

/**
1123
 * ilookup5_nowait - search for an inode in the inode cache
Linus Torvalds's avatar
Linus Torvalds committed
1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134
 * @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
1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165
 * 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
1166 1167 1168 1169 1170 1171 1172 1173 1174 1175
 *
 * 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);

1176
	return ifind(sb