inode.c 41.4 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 16 17 18 19
/*
 * 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>
Mimi Zohar's avatar
Mimi Zohar committed
20
#include <linux/ima.h>
Linus Torvalds's avatar
Linus Torvalds committed
21 22 23
#include <linux/pagemap.h>
#include <linux/cdev.h>
#include <linux/bootmem.h>
Robert Love's avatar
Robert Love committed
24
#include <linux/inotify.h>
25
#include <linux/fsnotify.h>
26
#include <linux/mount.h>
27
#include <linux/async.h>
Al Viro's avatar
Al Viro committed
28
#include <linux/posix_acl.h>
Linus Torvalds's avatar
Linus Torvalds committed
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 60 61

/*
 * 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

62 63
static unsigned int i_hash_mask __read_mostly;
static unsigned int i_hash_shift __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
64 65 66 67 68 69 70 71 72 73 74 75 76 77 78

/*
 * 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);
79
static struct hlist_head *inode_hashtable __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
80 81 82 83 84 85 86 87 88 89

/*
 * 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);

/*
Ingo Molnar's avatar
Ingo Molnar committed
90
 * iprune_mutex provides exclusion between the kswapd or try_to_free_pages
Linus Torvalds's avatar
Linus Torvalds committed
91 92 93 94 95 96
 * 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.
 */
97
static DEFINE_MUTEX(iprune_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
98 99 100 101 102 103

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

104
static struct kmem_cache *inode_cachep __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
105

Joern Engel's avatar
Joern Engel committed
106 107 108 109 110 111 112 113 114
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);
}

115 116
/**
 * inode_init_always - perform inode structure intialisation
117 118
 * @sb: superblock inode belongs to
 * @inode: inode to initialise
119 120 121 122
 *
 * These are initializations that need to be done on every inode
 * allocation as the fields are not initialised by slab allocation.
 */
123
int inode_init_always(struct super_block *sb, struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
124
{
125
	static const struct address_space_operations empty_aops;
Linus Torvalds's avatar
Linus Torvalds committed
126
	static struct inode_operations empty_iops;
127
	static const struct file_operations empty_fops;
128
	struct address_space *const mapping = &inode->i_data;
129 130 131 132 133 134 135 136

	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
137 138
	inode->i_uid = 0;
	inode->i_gid = 0;
139 140 141 142 143
	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
144
#ifdef CONFIG_QUOTA
145
	memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
Linus Torvalds's avatar
Linus Torvalds committed
146
#endif
147 148 149 150 151
	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
152 153

	if (security_inode_alloc(inode))
154
		goto out;
Mimi Zohar's avatar
Mimi Zohar committed
155 156 157 158

	/* allocate and initialize an i_integrity */
	if (ima_inode_alloc(inode))
		goto out_free_security;
159 160 161 162 163 164 165 166 167 168 169 170 171

	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;
172
	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191
	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;
Al Viro's avatar
Al Viro committed
192 193 194
#ifdef CONFIG_FS_POSIX_ACL
	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
#endif
195

196 197 198 199
#ifdef CONFIG_FSNOTIFY
	inode->i_fsnotify_mask = 0;
#endif

200
	return 0;
Mimi Zohar's avatar
Mimi Zohar committed
201 202 203

out_free_security:
	security_inode_free(inode);
204 205
out:
	return -ENOMEM;
Linus Torvalds's avatar
Linus Torvalds committed
206
}
207 208 209 210 211 212 213 214 215 216 217
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);

218 219 220 221 222 223 224 225 226 227 228 229
	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;
230
}
Linus Torvalds's avatar
Linus Torvalds committed
231

232
void destroy_inode(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
233
{
234
	BUG_ON(inode_has_buffers(inode));
Hugh Dickins's avatar
Hugh Dickins committed
235
	ima_inode_free(inode);
Linus Torvalds's avatar
Linus Torvalds committed
236
	security_inode_free(inode);
237
	fsnotify_inode_delete(inode);
Al Viro's avatar
Al Viro committed
238 239 240 241 242 243
#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
Linus Torvalds's avatar
Linus Torvalds committed
244 245 246 247 248
	if (inode->i_sb->s_op->destroy_inode)
		inode->i_sb->s_op->destroy_inode(inode);
	else
		kmem_cache_free(inode_cachep, (inode));
}
249
EXPORT_SYMBOL(destroy_inode);
Linus Torvalds's avatar
Linus Torvalds committed
250 251 252 253 254 255 256 257 258 259 260 261 262 263


/*
 * 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);
Nick Piggin's avatar
Nick Piggin committed
264
	spin_lock_init(&inode->i_data.tree_lock);
Linus Torvalds's avatar
Linus Torvalds committed
265 266 267 268 269 270
	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);
Robert Love's avatar
Robert Love committed
271 272
#ifdef CONFIG_INOTIFY
	INIT_LIST_HEAD(&inode->inotify_watches);
Ingo Molnar's avatar
Ingo Molnar committed
273
	mutex_init(&inode->inotify_mutex);
Robert Love's avatar
Robert Love committed
274
#endif
275 276 277
#ifdef CONFIG_FSNOTIFY
	INIT_HLIST_HEAD(&inode->i_fsnotify_mark_entries);
#endif
Linus Torvalds's avatar
Linus Torvalds committed
278 279 280
}
EXPORT_SYMBOL(inode_init_once);

281
static void init_once(void *foo)
Linus Torvalds's avatar
Linus Torvalds committed
282
{
283
	struct inode *inode = (struct inode *) foo;
Linus Torvalds's avatar
Linus Torvalds committed
284

285
	inode_init_once(inode);
Linus Torvalds's avatar
Linus Torvalds committed
286 287 288 289 290
}

/*
 * inode_lock must be held
 */
291
void __iget(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
292 293 294 295 296 297
{
	if (atomic_read(&inode->i_count)) {
		atomic_inc(&inode->i_count);
		return;
	}
	atomic_inc(&inode->i_count);
Joern Engel's avatar
Joern Engel committed
298
	if (!(inode->i_state & (I_DIRTY|I_SYNC)))
Linus Torvalds's avatar
Linus Torvalds committed
299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314
		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);
315

316 317 318
	BUG_ON(inode->i_data.nrpages);
	BUG_ON(!(inode->i_state & I_FREEING));
	BUG_ON(inode->i_state & I_CLEAR);
Joern Engel's avatar
Joern Engel committed
319
	inode_sync_wait(inode);
320
	vfs_dq_drop(inode);
321
	if (inode->i_sb->s_op->clear_inode)
Linus Torvalds's avatar
Linus Torvalds committed
322
		inode->i_sb->s_op->clear_inode(inode);
323
	if (S_ISBLK(inode->i_mode) && inode->i_bdev)
Linus Torvalds's avatar
Linus Torvalds committed
324
		bd_forget(inode);
325
	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
Linus Torvalds's avatar
Linus Torvalds committed
326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344
		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;

345
		inode = list_first_entry(head, struct inode, i_list);
Linus Torvalds's avatar
Linus Torvalds committed
346 347 348 349 350
		list_del(&inode->i_list);

		if (inode->i_data.nrpages)
			truncate_inode_pages(&inode->i_data, 0);
		clear_inode(inode);
351 352 353 354 355 356 357

		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
358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375
		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 (;;) {
376 377
		struct list_head *tmp = next;
		struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
378 379 380 381

		/*
		 * We can reschedule here without worrying about the list's
		 * consistency because the per-sb list of inodes must not
Ingo Molnar's avatar
Ingo Molnar committed
382
		 * change during umount anymore, and because iprune_mutex keeps
Linus Torvalds's avatar
Linus Torvalds committed
383 384 385 386 387 388 389 390
		 * 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
391 392
		if (inode->i_state & I_NEW)
			continue;
Linus Torvalds's avatar
Linus Torvalds committed
393 394 395
		invalidate_inode_buffers(inode);
		if (!atomic_read(&inode->i_count)) {
			list_move(&inode->i_list, dispose);
396
			WARN_ON(inode->i_state & I_NEW);
Linus Torvalds's avatar
Linus Torvalds committed
397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415
			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.
 */
416
int invalidate_inodes(struct super_block *sb)
Linus Torvalds's avatar
Linus Torvalds committed
417 418 419 420
{
	int busy;
	LIST_HEAD(throw_away);

Ingo Molnar's avatar
Ingo Molnar committed
421
	mutex_lock(&iprune_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
422
	spin_lock(&inode_lock);
Robert Love's avatar
Robert Love committed
423
	inotify_unmount_inodes(&sb->s_inodes);
424
	fsnotify_unmount_inodes(&sb->s_inodes);
Linus Torvalds's avatar
Linus Torvalds committed
425 426 427 428
	busy = invalidate_list(&sb->s_inodes, &throw_away);
	spin_unlock(&inode_lock);

	dispose_list(&throw_away);
Ingo Molnar's avatar
Ingo Molnar committed
429
	mutex_unlock(&iprune_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467

	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;

Ingo Molnar's avatar
Ingo Molnar committed
468
	mutex_lock(&iprune_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485
	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))
486 487
				reap += invalidate_mapping_pages(&inode->i_data,
								0, -1);
Linus Torvalds's avatar
Linus Torvalds committed
488 489 490 491 492 493 494 495 496 497
			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);
498
		WARN_ON(inode->i_state & I_NEW);
Linus Torvalds's avatar
Linus Torvalds committed
499 500 501 502
		inode->i_state |= I_FREEING;
		nr_pruned++;
	}
	inodes_stat.nr_unused -= nr_pruned;
503 504 505 506
	if (current_is_kswapd())
		__count_vm_events(KSWAPD_INODESTEAL, reap);
	else
		__count_vm_events(PGINODESTEAL, reap);
Linus Torvalds's avatar
Linus Torvalds committed
507 508 509
	spin_unlock(&inode_lock);

	dispose_list(&freeable);
Ingo Molnar's avatar
Ingo Molnar committed
510
	mutex_unlock(&iprune_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
511 512 513 514 515 516 517 518 519 520 521
}

/*
 * 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.
 */
Al Viro's avatar
Al Viro committed
522
static int shrink_icache_memory(int nr, gfp_t gfp_mask)
Linus Torvalds's avatar
Linus Torvalds committed
523 524 525 526 527 528
{
	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..
529
		 */
Linus Torvalds's avatar
Linus Torvalds committed
530 531 532 533 534 535 536
		if (!(gfp_mask & __GFP_FS))
			return -1;
		prune_icache(nr);
	}
	return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
}

537 538 539 540 541
static struct shrinker icache_shrinker = {
	.shrink = shrink_icache_memory,
	.seeks = DEFAULT_SEEKS,
};

Linus Torvalds's avatar
Linus Torvalds committed
542 543 544 545 546 547 548
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.
 */
549 550 551 552
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
553 554
{
	struct hlist_node *node;
555
	struct inode *inode = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
556 557

repeat:
558
	hlist_for_each_entry(inode, node, head, i_hash) {
Linus Torvalds's avatar
Linus Torvalds committed
559 560 561 562
		if (inode->i_sb != sb)
			continue;
		if (!test(inode, data))
			continue;
563
		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
Linus Torvalds's avatar
Linus Torvalds committed
564 565 566 567 568 569 570 571 572 573 574 575
			__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.
 */
576 577
static struct inode *find_inode_fast(struct super_block *sb,
				struct hlist_head *head, unsigned long ino)
Linus Torvalds's avatar
Linus Torvalds committed
578 579
{
	struct hlist_node *node;
580
	struct inode *inode = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
581 582

repeat:
583
	hlist_for_each_entry(inode, node, head, i_hash) {
Linus Torvalds's avatar
Linus Torvalds committed
584 585 586 587
		if (inode->i_ino != ino)
			continue;
		if (inode->i_sb != sb)
			continue;
588
		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
Linus Torvalds's avatar
Linus Torvalds committed
589 590 591 592 593 594 595 596
			__wait_on_freeing_inode(inode);
			goto repeat;
		}
		break;
	}
	return node ? inode : NULL;
}

597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619
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
620 621
 * @sb: superblock inode belongs to
 * @inode: inode to mark in use
622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639
 *
 * 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
640 641 642 643
/**
 *	new_inode 	- obtain an inode
 *	@sb: superblock
 *
644
 *	Allocates a new inode for given superblock. The default gfp_mask
645
 *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
646 647 648 649 650
 *	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
651 652 653
 */
struct inode *new_inode(struct super_block *sb)
{
654 655 656 657 658 659
	/*
	 * 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;
660
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
661 662

	spin_lock_prefetch(&inode_lock);
663

Linus Torvalds's avatar
Linus Torvalds committed
664 665 666
	inode = alloc_inode(sb);
	if (inode) {
		spin_lock(&inode_lock);
667
		__inode_add_to_lists(sb, NULL, inode);
Linus Torvalds's avatar
Linus Torvalds committed
668 669 670 671 672 673 674 675 676 677
		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)
{
678
#ifdef CONFIG_DEBUG_LOCK_ALLOC
679 680 681
	if (inode->i_mode & S_IFDIR) {
		struct file_system_type *type = inode->i_sb->s_type;

682 683 684 685 686 687 688 689 690 691 692
		/* 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);
		}
693
	}
694
#endif
Linus Torvalds's avatar
Linus Torvalds committed
695 696 697 698 699 700 701 702
	/*
	 * 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).
	 */
703
	WARN_ON((inode->i_state & (I_LOCK|I_NEW)) != (I_LOCK|I_NEW));
Linus Torvalds's avatar
Linus Torvalds committed
704 705 706 707 708 709 710 711 712 713 714
	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
 */
715 716 717 718 719
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
720
{
721
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
722 723 724

	inode = alloc_inode(sb);
	if (inode) {
725
		struct inode *old;
Linus Torvalds's avatar
Linus Torvalds committed
726 727 728 729 730 731 732 733

		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;

734
			__inode_add_to_lists(sb, head, inode);
Linus Torvalds's avatar
Linus Torvalds committed
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
			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.
 */
767 768
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
769
{
770
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
771 772 773

	inode = alloc_inode(sb);
	if (inode) {
774
		struct inode *old;
Linus Torvalds's avatar
Linus Torvalds committed
775 776 777 778 779 780

		spin_lock(&inode_lock);
		/* We released the lock, so.. */
		old = find_inode_fast(sb, head, ino);
		if (!old) {
			inode->i_ino = ino;
781
			__inode_add_to_lists(sb, head, inode);
Linus Torvalds's avatar
Linus Torvalds committed
782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820
			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)
{
821 822 823 824 825 826
	/*
	 * 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
827
	struct inode *inode;
828
	struct hlist_head *head;
Linus Torvalds's avatar
Linus Torvalds committed
829
	ino_t res;
830

Linus Torvalds's avatar
Linus Torvalds committed
831
	spin_lock(&inode_lock);
832 833 834
	do {
		if (counter <= max_reserved)
			counter = max_reserved + 1;
Linus Torvalds's avatar
Linus Torvalds committed
835
		res = counter++;
836
		head = inode_hashtable + hash(sb, res);
Linus Torvalds's avatar
Linus Torvalds committed
837
		inode = find_inode_fast(sb, head, res);
838 839
	} while (inode != NULL);
	spin_unlock(&inode_lock);
Linus Torvalds's avatar
Linus Torvalds committed
840

841 842
	return res;
}
Linus Torvalds's avatar
Linus Torvalds committed
843 844 845 846 847
EXPORT_SYMBOL(iunique);

struct inode *igrab(struct inode *inode)
{
	spin_lock(&inode_lock);
848
	if (!(inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)))
Linus Torvalds's avatar
Linus Torvalds committed
849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867
		__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
868
 * @wait:	if true wait for the inode to be unlocked, if false do not
Linus Torvalds's avatar
Linus Torvalds committed
869 870 871 872 873 874 875 876 877 878 879 880
 *
 * 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.
 */
881
static struct inode *ifind(struct super_block *sb,
Linus Torvalds's avatar
Linus Torvalds committed
882
		struct hlist_head *head, int (*test)(struct inode *, void *),
883
		void *data, const int wait)
Linus Torvalds's avatar
Linus Torvalds committed
884 885 886 887 888 889 890 891
{
	struct inode *inode;

	spin_lock(&inode_lock);
	inode = find_inode(sb, head, test, data);
	if (inode) {
		__iget(inode);
		spin_unlock(&inode_lock);
892 893
		if (likely(wait))
			wait_on_inode(inode);
Linus Torvalds's avatar
Linus Torvalds committed
894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914
		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.
 */
915
static struct inode *ifind_fast(struct super_block *sb,
Linus Torvalds's avatar
Linus Torvalds committed
916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932
		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;
}

/**
933
 * ilookup5_nowait - search for an inode in the inode cache
Linus Torvalds's avatar
Linus Torvalds committed
934 935 936 937 938 939 940 941 942 943 944
 * @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
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
 * 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
976 977 978 979 980 981 982 983 984 985
 *
 * 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);

986
	return ifind(sb, head, test, data, 1);
Linus Torvalds's avatar
Linus Torvalds committed
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 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038
}
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;

1039
	inode = ifind(sb, head, test, data, 1);
Linus Torvalds's avatar
Linus Torvalds committed
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
	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);

1081 1082 1083 1084 1085 1086 1087 1088
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);

	inode->i_state |= I_LOCK|I_NEW;
	while (1) {
1089 1090
		struct hlist_node *node;
		struct inode *old = NULL;
1091
		spin_lock(&inode_lock);
1092 1093 1094 1095 1096 1097 1098 1099 1100 1101
		hlist_for_each_entry(old, node, head, i_hash) {
			if (old->i_ino != ino)
				continue;
			if (old->i_sb != sb)
				continue;
			if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
				continue;
			break;
		}
		if (likely(!node)) {
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
			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);

	inode->i_state |= I_LOCK|I_NEW;

	while (1) {
1127 1128 1129
		struct hlist_node *node;
		struct inode *old = NULL;

1130
		spin_lock(&inode_lock);
1131 1132 1133 1134 1135 1136 1137 1138 1139 1140
		hlist_for_each_entry(old, node, head, i_hash) {
			if (old->i_sb != sb)
				continue;
			if (!test(old, data))
				continue;
			if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
				continue;
			break;
		}
		if (likely(!node)) {
1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156
			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);

Linus Torvalds's avatar
Linus Torvalds committed
1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199
/**
 *	__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.
 */
1200
void generic_delete_inode(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
1201
{
1202
	const struct super_operations *op = inode->i_sb->s_op;
Linus Torvalds's avatar
Linus Torvalds committed
1203

1204 1205
	list_del_init(&inode->i_list);
	list_del_init(&inode->i_sb_list);
1206
	WARN_ON(inode->i_state & I_NEW);
1207 1208 1209 1210
	inode->i_state |= I_FREEING;
	inodes_stat.nr_inodes--;
	spin_unlock(&inode_lock);

Linus Torvalds's avatar
Linus Torvalds committed
1211 1212 1213 1214 1215
	security_inode_delete(inode);

	if (op->delete_inode) {
		void (*delete)(struct inode *) = op->delete_inode;
		if (!is_bad_inode(inode))
1216
			vfs_dq_init(inode);
1217 1218 1219 1220
		/* Filesystems implementing their own
		 * s_op->delete_inode are required to call
		 * truncate_inode_pages and clear_inode()
		 * internally */
Linus Torvalds's avatar
Linus Torvalds committed
1221
		delete(inode);
1222 1223
	} else {
		truncate_inode_pages(&inode->i_data, 0);
Linus Torvalds's avatar
Linus Torvalds committed
1224
		clear_inode(inode);
1225
	}
Linus Torvalds's avatar
Linus Torvalds committed
1226 1227 1228 1229
	spin_lock(&inode_lock);
	hlist_del_init(&inode->i_hash);
	spin_unlock(&inode_lock);
	wake_up_inode(inode);
1230
	BUG_ON(inode->i_state != I_CLEAR);
Linus Torvalds's avatar
Linus Torvalds committed
1231 1232 1233 1234 1235 1236 1237 1238 1239
	destroy_inode(inode);
}
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)) {
Joern Engel's avatar
Joern Engel committed
1240
		if (!(inode->i_state & (I_DIRTY|I_SYNC)))
Linus Torvalds's avatar
Linus Torvalds committed
1241 1242
			list_move(&inode->i_list, &inode_unused);
		inodes_stat.nr_unused++;
1243
		if (sb->s_flags & MS_ACTIVE) {
1244
			spin_unlock(&inode_lock);
Linus Torvalds's avatar
Linus Torvalds committed
1245
			return;
1246
		}
1247
		WARN_ON(inode->i_state & I_NEW);
1248 1249
		inode->i_state |= I_WILL_FREE;
		spin_unlock(&inode_lock);
Linus Torvalds's avatar
Linus Torvalds committed
1250 1251
		write_inode_now(inode, 1);
		spin_lock(&inode_lock);
1252
		WARN_ON(inode->i_state & I_NEW);
1253
		inode->i_state &= ~I_WILL_FREE;
Linus Torvalds's avatar
Linus Torvalds committed
1254 1255 1256 1257 1258
		inodes_stat.nr_unused--;
		hlist_del_init(&inode->i_hash);
	}
	list_del_init(&inode->i_list);
	list_del_init(&inode->i_sb_list);
1259
	WARN_ON(inode->i_state & I_NEW);
1260
	inode->i_state |= I_FREEING;
Linus Torvalds's avatar
Linus Torvalds committed
1261 1262 1263 1264 1265
	inodes_stat.nr_inodes--;
	spin_unlock(&inode_lock);
	if (inode->i_data.nrpages)
		truncate_inode_pages(&inode->i_data, 0);
	clear_inode(inode);
1266
	wake_up_inode(inode);
Linus Torvalds's avatar
Linus Torvalds committed
1267 1268 1269 1270 1271 1272 1273 1274
	destroy_inode(inode);
}

/*
 * Normal UNIX filesystem behaviour: delete the
 * inode when the usage count drops to zero, and
 * i_nlink is zero.
 */
1275
void generic_drop_inode(struct inode *inode)
Linus Torvalds's avatar
Linus Torvalds committed
1276 1277 1278 1279 1280 1281
{
	if (!inode->i_nlink)
		generic_delete_inode(inode);
	else
		generic_forget_inode(inode);
}
1282 1283
EXPORT_SYMBOL_GPL(generic_drop_inode);

Linus Torvalds's avatar
Linus Torvalds committed
1284 1285
/*
 * Called when we're dropping the last reference
1286
 * to an inode.
Linus Torvalds's avatar
Linus Torvalds committed
1287 1288 1289 1290 1291 1292 1293 1294 1295 1296
 *
 * 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)
{
1297
	const struct super_operations *op = inode->i_sb->s_op;
Linus Torvalds's avatar
Linus Torvalds committed
1298 1299 1300 1301 1302 1303 1304 1305
	void (*drop)(struct inode *) = generic_drop_inode;

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

/**
1306
 *	iput	- put an inode
Linus Torvalds's avatar
Linus Torvalds committed
1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332
 *	@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
1333
 *	disk block relative to the disk start that holds that block of the
Linus Torvalds's avatar
Linus Torvalds committed
1334 1335
 *	file.
 */
1336
sector_t bmap(struct inode *inode, sector_t block)
Linus Torvalds's avatar
Linus Torvalds committed
1337 1338 1339 1340 1341 1342 1343 1344
{
	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);

1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378
/*
 * With relative atime, only update atime if the previous atime is
 * earlier than either the ctime or mtime or if at least a day has
 * passed since the last atime update.
 */
static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
			     struct timespec now)
{

	if (!(mnt->mnt_flags & MNT_RELATIME))
		return 1;
	/*
	 * Is mtime younger than atime? If yes, update atime:
	 */
	if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
		return 1;
	/*
	 * Is ctime younger than atime? If yes, update atime:
	 */
	if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
		return 1;

	/*
	 * Is the previous atime value older than a day? If yes,
	 * update atime:
	 */
	if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
		return 1;
	/*
	 * Good, we can skip the atime update:
	 */
	return 0;
}

Linus Torvalds's avatar
Linus Torvalds committed
1379
/**
1380 1381
 *	touch_atime	-	update the access time
 *	@mnt: mount the inode is accessed on
1382
 *	@dentry: dentry accessed
Linus Torvalds's avatar
Linus Torvalds committed
1383 1384 1385 1386 1387
 *
 *	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.
 */
1388
void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
Linus Torvalds's avatar
Linus Torvalds committed
1389
{
1390
	struct inode *inode = dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1391 1392
	struct timespec now;