4 * (C) 1997 Linus Torvalds
9 #include <linux/dcache.h>
10 #include <linux/init.h>
11 #include <linux/quotaops.h>
12 #include <linux/slab.h>
13 #include <linux/writeback.h>
14 #include <linux/module.h>
15 #include <linux/backing-dev.h>
16 #include <linux/wait.h>
17 #include <linux/hash.h>
18 #include <linux/swap.h>
19 #include <linux/security.h>
20 #include <linux/pagemap.h>
21 #include <linux/cdev.h>
22 #include <linux/bootmem.h>
23 #include <linux/inotify.h>
24 #include <linux/mount.h>
27 * This is needed for the following functions:
29 * - invalidate_inode_buffers
32 * FIXME: remove all knowledge of the buffer layer from this file
34 #include <linux/buffer_head.h>
37 * New inode.c implementation.
39 * This implementation has the basic premise of trying
40 * to be extremely low-overhead and SMP-safe, yet be
41 * simple enough to be "obviously correct".
46 /* inode dynamic allocation 1999, Andrea Arcangeli <andrea@suse.de> */
48 /* #define INODE_PARANOIA 1 */
49 /* #define INODE_DEBUG 1 */
52 * Inode lookup is no longer as critical as it used to be:
53 * most of the lookups are going to be through the dcache.
55 #define I_HASHBITS i_hash_shift
56 #define I_HASHMASK i_hash_mask
58 static unsigned int i_hash_mask __read_mostly;
59 static unsigned int i_hash_shift __read_mostly;
62 * Each inode can be on two separate lists. One is
63 * the hash list of the inode, used for lookups. The
64 * other linked list is the "type" list:
65 * "in_use" - valid inode, i_count > 0, i_nlink > 0
66 * "dirty" - as "in_use" but also dirty
67 * "unused" - valid inode, i_count = 0
69 * A "dirty" list is maintained for each super block,
70 * allowing for low-overhead inode sync() operations.
73 LIST_HEAD(inode_in_use);
74 LIST_HEAD(inode_unused);
75 static struct hlist_head *inode_hashtable __read_mostly;
78 * A simple spinlock to protect the list manipulations.
80 * NOTE! You also have to own the lock if you change
81 * the i_state of an inode while it is in use..
83 DEFINE_SPINLOCK(inode_lock);
86 * iprune_mutex provides exclusion between the kswapd or try_to_free_pages
87 * icache shrinking path, and the umount path. Without this exclusion,
88 * by the time prune_icache calls iput for the inode whose pages it has
89 * been invalidating, or by the time it calls clear_inode & destroy_inode
90 * from its final dispose_list, the struct super_block they refer to
91 * (for inode->i_sb->s_op) may already have been freed and reused.
93 static DEFINE_MUTEX(iprune_mutex);
96 * Statistics gathering..
98 struct inodes_stat_t inodes_stat;
100 static struct kmem_cache * inode_cachep __read_mostly;
102 static void wake_up_inode(struct inode *inode)
105 * Prevent speculative execution through spin_unlock(&inode_lock);
108 wake_up_bit(&inode->i_state, __I_LOCK);
112 * inode_init_always - perform inode structure intialisation
113 * @sb - superblock inode belongs to.
114 * @inode - inode to initialise
116 * These are initializations that need to be done on every inode
117 * allocation as the fields are not initialised by slab allocation.
119 struct inode *inode_init_always(struct super_block *sb, struct inode *inode)
121 static const struct address_space_operations empty_aops;
122 static struct inode_operations empty_iops;
123 static const struct file_operations empty_fops;
125 struct address_space * const mapping = &inode->i_data;
128 inode->i_blkbits = sb->s_blocksize_bits;
130 atomic_set(&inode->i_count, 1);
131 inode->i_op = &empty_iops;
132 inode->i_fop = &empty_fops;
134 atomic_set(&inode->i_writecount, 0);
138 inode->i_generation = 0;
140 memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
142 inode->i_pipe = NULL;
143 inode->i_bdev = NULL;
144 inode->i_cdev = NULL;
146 inode->dirtied_when = 0;
147 if (security_inode_alloc(inode)) {
148 if (inode->i_sb->s_op->destroy_inode)
149 inode->i_sb->s_op->destroy_inode(inode);
151 kmem_cache_free(inode_cachep, (inode));
155 spin_lock_init(&inode->i_lock);
156 lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
158 mutex_init(&inode->i_mutex);
159 lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
161 init_rwsem(&inode->i_alloc_sem);
162 lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
164 mapping->a_ops = &empty_aops;
165 mapping->host = inode;
167 mapping_set_gfp_mask(mapping, GFP_HIGHUSER_PAGECACHE);
168 mapping->assoc_mapping = NULL;
169 mapping->backing_dev_info = &default_backing_dev_info;
170 mapping->writeback_index = 0;
173 * If the block_device provides a backing_dev_info for client
174 * inodes then use that. Otherwise the inode share the bdev's
178 struct backing_dev_info *bdi;
180 bdi = sb->s_bdev->bd_inode_backing_dev_info;
182 bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
183 mapping->backing_dev_info = bdi;
185 inode->i_private = NULL;
186 inode->i_mapping = mapping;
190 EXPORT_SYMBOL(inode_init_always);
192 static struct inode *alloc_inode(struct super_block *sb)
196 if (sb->s_op->alloc_inode)
197 inode = sb->s_op->alloc_inode(sb);
199 inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
202 return inode_init_always(sb, inode);
206 void destroy_inode(struct inode *inode)
208 BUG_ON(inode_has_buffers(inode));
209 security_inode_free(inode);
210 if (inode->i_sb->s_op->destroy_inode)
211 inode->i_sb->s_op->destroy_inode(inode);
213 kmem_cache_free(inode_cachep, (inode));
218 * These are initializations that only need to be done
219 * once, because the fields are idempotent across use
220 * of the inode, so let the slab aware of that.
222 void inode_init_once(struct inode *inode)
224 memset(inode, 0, sizeof(*inode));
225 INIT_HLIST_NODE(&inode->i_hash);
226 INIT_LIST_HEAD(&inode->i_dentry);
227 INIT_LIST_HEAD(&inode->i_devices);
228 INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
229 spin_lock_init(&inode->i_data.tree_lock);
230 spin_lock_init(&inode->i_data.i_mmap_lock);
231 INIT_LIST_HEAD(&inode->i_data.private_list);
232 spin_lock_init(&inode->i_data.private_lock);
233 INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
234 INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
235 i_size_ordered_init(inode);
236 #ifdef CONFIG_INOTIFY
237 INIT_LIST_HEAD(&inode->inotify_watches);
238 mutex_init(&inode->inotify_mutex);
242 EXPORT_SYMBOL(inode_init_once);
244 static void init_once(void *foo)
246 struct inode * inode = (struct inode *) foo;
248 inode_init_once(inode);
252 * inode_lock must be held
254 void __iget(struct inode * inode)
256 if (atomic_read(&inode->i_count)) {
257 atomic_inc(&inode->i_count);
260 atomic_inc(&inode->i_count);
261 if (!(inode->i_state & (I_DIRTY|I_SYNC)))
262 list_move(&inode->i_list, &inode_in_use);
263 inodes_stat.nr_unused--;
267 * clear_inode - clear an inode
268 * @inode: inode to clear
270 * This is called by the filesystem to tell us
271 * that the inode is no longer useful. We just
272 * terminate it with extreme prejudice.
274 void clear_inode(struct inode *inode)
277 invalidate_inode_buffers(inode);
279 BUG_ON(inode->i_data.nrpages);
280 BUG_ON(!(inode->i_state & I_FREEING));
281 BUG_ON(inode->i_state & I_CLEAR);
282 inode_sync_wait(inode);
284 if (inode->i_sb->s_op->clear_inode)
285 inode->i_sb->s_op->clear_inode(inode);
286 if (S_ISBLK(inode->i_mode) && inode->i_bdev)
288 if (S_ISCHR(inode->i_mode) && inode->i_cdev)
290 inode->i_state = I_CLEAR;
293 EXPORT_SYMBOL(clear_inode);
296 * dispose_list - dispose of the contents of a local list
297 * @head: the head of the list to free
299 * Dispose-list gets a local list with local inodes in it, so it doesn't
300 * need to worry about list corruption and SMP locks.
302 static void dispose_list(struct list_head *head)
306 while (!list_empty(head)) {
309 inode = list_first_entry(head, struct inode, i_list);
310 list_del(&inode->i_list);
312 if (inode->i_data.nrpages)
313 truncate_inode_pages(&inode->i_data, 0);
316 spin_lock(&inode_lock);
317 hlist_del_init(&inode->i_hash);
318 list_del_init(&inode->i_sb_list);
319 spin_unlock(&inode_lock);
321 wake_up_inode(inode);
322 destroy_inode(inode);
325 spin_lock(&inode_lock);
326 inodes_stat.nr_inodes -= nr_disposed;
327 spin_unlock(&inode_lock);
331 * Invalidate all inodes for a device.
333 static int invalidate_list(struct list_head *head, struct list_head *dispose)
335 struct list_head *next;
336 int busy = 0, count = 0;
340 struct list_head * tmp = next;
341 struct inode * inode;
344 * We can reschedule here without worrying about the list's
345 * consistency because the per-sb list of inodes must not
346 * change during umount anymore, and because iprune_mutex keeps
347 * shrink_icache_memory() away.
349 cond_resched_lock(&inode_lock);
354 inode = list_entry(tmp, struct inode, i_sb_list);
355 invalidate_inode_buffers(inode);
356 if (!atomic_read(&inode->i_count)) {
357 list_move(&inode->i_list, dispose);
358 inode->i_state |= I_FREEING;
364 /* only unused inodes may be cached with i_count zero */
365 inodes_stat.nr_unused -= count;
370 * invalidate_inodes - discard the inodes on a device
373 * Discard all of the inodes for a given superblock. If the discard
374 * fails because there are busy inodes then a non zero value is returned.
375 * If the discard is successful all the inodes have been discarded.
377 int invalidate_inodes(struct super_block * sb)
380 LIST_HEAD(throw_away);
382 mutex_lock(&iprune_mutex);
383 spin_lock(&inode_lock);
384 inotify_unmount_inodes(&sb->s_inodes);
385 busy = invalidate_list(&sb->s_inodes, &throw_away);
386 spin_unlock(&inode_lock);
388 dispose_list(&throw_away);
389 mutex_unlock(&iprune_mutex);
394 EXPORT_SYMBOL(invalidate_inodes);
396 static int can_unuse(struct inode *inode)
400 if (inode_has_buffers(inode))
402 if (atomic_read(&inode->i_count))
404 if (inode->i_data.nrpages)
410 * Scan `goal' inodes on the unused list for freeable ones. They are moved to
411 * a temporary list and then are freed outside inode_lock by dispose_list().
413 * Any inodes which are pinned purely because of attached pagecache have their
414 * pagecache removed. We expect the final iput() on that inode to add it to
415 * the front of the inode_unused list. So look for it there and if the
416 * inode is still freeable, proceed. The right inode is found 99.9% of the
417 * time in testing on a 4-way.
419 * If the inode has metadata buffers attached to mapping->private_list then
420 * try to remove them.
422 static void prune_icache(int nr_to_scan)
427 unsigned long reap = 0;
429 mutex_lock(&iprune_mutex);
430 spin_lock(&inode_lock);
431 for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
434 if (list_empty(&inode_unused))
437 inode = list_entry(inode_unused.prev, struct inode, i_list);
439 if (inode->i_state || atomic_read(&inode->i_count)) {
440 list_move(&inode->i_list, &inode_unused);
443 if (inode_has_buffers(inode) || inode->i_data.nrpages) {
445 spin_unlock(&inode_lock);
446 if (remove_inode_buffers(inode))
447 reap += invalidate_mapping_pages(&inode->i_data,
450 spin_lock(&inode_lock);
452 if (inode != list_entry(inode_unused.next,
453 struct inode, i_list))
454 continue; /* wrong inode or list_empty */
455 if (!can_unuse(inode))
458 list_move(&inode->i_list, &freeable);
459 inode->i_state |= I_FREEING;
462 inodes_stat.nr_unused -= nr_pruned;
463 if (current_is_kswapd())
464 __count_vm_events(KSWAPD_INODESTEAL, reap);
466 __count_vm_events(PGINODESTEAL, reap);
467 spin_unlock(&inode_lock);
469 dispose_list(&freeable);
470 mutex_unlock(&iprune_mutex);
474 * shrink_icache_memory() will attempt to reclaim some unused inodes. Here,
475 * "unused" means that no dentries are referring to the inodes: the files are
476 * not open and the dcache references to those inodes have already been
479 * This function is passed the number of inodes to scan, and it returns the
480 * total number of remaining possibly-reclaimable inodes.
482 static int shrink_icache_memory(int nr, gfp_t gfp_mask)
486 * Nasty deadlock avoidance. We may hold various FS locks,
487 * and we don't want to recurse into the FS that called us
488 * in clear_inode() and friends..
490 if (!(gfp_mask & __GFP_FS))
494 return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
497 static struct shrinker icache_shrinker = {
498 .shrink = shrink_icache_memory,
499 .seeks = DEFAULT_SEEKS,
502 static void __wait_on_freeing_inode(struct inode *inode);
504 * Called with the inode lock held.
505 * NOTE: we are not increasing the inode-refcount, you must call __iget()
506 * by hand after calling find_inode now! This simplifies iunique and won't
507 * add any additional branch in the common code.
509 static struct inode * find_inode(struct super_block * sb, struct hlist_head *head, int (*test)(struct inode *, void *), void *data)
511 struct hlist_node *node;
512 struct inode * inode = NULL;
515 hlist_for_each_entry(inode, node, head, i_hash) {
516 if (inode->i_sb != sb)
518 if (!test(inode, data))
520 if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
521 __wait_on_freeing_inode(inode);
526 return node ? inode : NULL;
530 * find_inode_fast is the fast path version of find_inode, see the comment at
531 * iget_locked for details.
533 static struct inode * find_inode_fast(struct super_block * sb, struct hlist_head *head, unsigned long ino)
535 struct hlist_node *node;
536 struct inode * inode = NULL;
539 hlist_for_each_entry(inode, node, head, i_hash) {
540 if (inode->i_ino != ino)
542 if (inode->i_sb != sb)
544 if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
545 __wait_on_freeing_inode(inode);
550 return node ? inode : NULL;
553 static unsigned long hash(struct super_block *sb, unsigned long hashval)
557 tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
559 tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
560 return tmp & I_HASHMASK;
564 __inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
567 inodes_stat.nr_inodes++;
568 list_add(&inode->i_list, &inode_in_use);
569 list_add(&inode->i_sb_list, &sb->s_inodes);
571 hlist_add_head(&inode->i_hash, head);
575 * inode_add_to_lists - add a new inode to relevant lists
576 * @sb - superblock inode belongs to.
577 * @inode - inode to mark in use
579 * When an inode is allocated it needs to be accounted for, added to the in use
580 * list, the owning superblock and the inode hash. This needs to be done under
581 * the inode_lock, so export a function to do this rather than the inode lock
582 * itself. We calculate the hash list to add to here so it is all internal
583 * which requires the caller to have already set up the inode number in the
586 void inode_add_to_lists(struct super_block *sb, struct inode *inode)
588 struct hlist_head *head = inode_hashtable + hash(sb, inode->i_ino);
590 spin_lock(&inode_lock);
591 __inode_add_to_lists(sb, head, inode);
592 spin_unlock(&inode_lock);
594 EXPORT_SYMBOL_GPL(inode_add_to_lists);
597 * new_inode - obtain an inode
600 * Allocates a new inode for given superblock. The default gfp_mask
601 * for allocations related to inode->i_mapping is GFP_HIGHUSER_PAGECACHE.
602 * If HIGHMEM pages are unsuitable or it is known that pages allocated
603 * for the page cache are not reclaimable or migratable,
604 * mapping_set_gfp_mask() must be called with suitable flags on the
605 * newly created inode's mapping
608 struct inode *new_inode(struct super_block *sb)
611 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
612 * error if st_ino won't fit in target struct field. Use 32bit counter
613 * here to attempt to avoid that.
615 static unsigned int last_ino;
616 struct inode * inode;
618 spin_lock_prefetch(&inode_lock);
620 inode = alloc_inode(sb);
622 spin_lock(&inode_lock);
623 __inode_add_to_lists(sb, NULL, inode);
624 inode->i_ino = ++last_ino;
626 spin_unlock(&inode_lock);
631 EXPORT_SYMBOL(new_inode);
633 void unlock_new_inode(struct inode *inode)
635 #ifdef CONFIG_DEBUG_LOCK_ALLOC
636 if (inode->i_mode & S_IFDIR) {
637 struct file_system_type *type = inode->i_sb->s_type;
640 * ensure nobody is actually holding i_mutex
642 mutex_destroy(&inode->i_mutex);
643 mutex_init(&inode->i_mutex);
644 lockdep_set_class(&inode->i_mutex, &type->i_mutex_dir_key);
648 * This is special! We do not need the spinlock
649 * when clearing I_LOCK, because we're guaranteed
650 * that nobody else tries to do anything about the
651 * state of the inode when it is locked, as we
652 * just created it (so there can be no old holders
653 * that haven't tested I_LOCK).
655 inode->i_state &= ~(I_LOCK|I_NEW);
656 wake_up_inode(inode);
659 EXPORT_SYMBOL(unlock_new_inode);
662 * This is called without the inode lock held.. Be careful.
664 * We no longer cache the sb_flags in i_flags - see fs.h
665 * -- rmk@arm.uk.linux.org
667 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)
669 struct inode * inode;
671 inode = alloc_inode(sb);
675 spin_lock(&inode_lock);
676 /* We released the lock, so.. */
677 old = find_inode(sb, head, test, data);
679 if (set(inode, data))
682 __inode_add_to_lists(sb, head, inode);
683 inode->i_state = I_LOCK|I_NEW;
684 spin_unlock(&inode_lock);
686 /* Return the locked inode with I_NEW set, the
687 * caller is responsible for filling in the contents
693 * Uhhuh, somebody else created the same inode under
694 * us. Use the old inode instead of the one we just
698 spin_unlock(&inode_lock);
699 destroy_inode(inode);
701 wait_on_inode(inode);
706 spin_unlock(&inode_lock);
707 destroy_inode(inode);
712 * get_new_inode_fast is the fast path version of get_new_inode, see the
713 * comment at iget_locked for details.
715 static struct inode * get_new_inode_fast(struct super_block *sb, struct hlist_head *head, unsigned long ino)
717 struct inode * inode;
719 inode = alloc_inode(sb);
723 spin_lock(&inode_lock);
724 /* We released the lock, so.. */
725 old = find_inode_fast(sb, head, ino);
728 __inode_add_to_lists(sb, head, inode);
729 inode->i_state = I_LOCK|I_NEW;
730 spin_unlock(&inode_lock);
732 /* Return the locked inode with I_NEW set, the
733 * caller is responsible for filling in the contents
739 * Uhhuh, somebody else created the same inode under
740 * us. Use the old inode instead of the one we just
744 spin_unlock(&inode_lock);
745 destroy_inode(inode);
747 wait_on_inode(inode);
753 * iunique - get a unique inode number
755 * @max_reserved: highest reserved inode number
757 * Obtain an inode number that is unique on the system for a given
758 * superblock. This is used by file systems that have no natural
759 * permanent inode numbering system. An inode number is returned that
760 * is higher than the reserved limit but unique.
763 * With a large number of inodes live on the file system this function
764 * currently becomes quite slow.
766 ino_t iunique(struct super_block *sb, ino_t max_reserved)
769 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
770 * error if st_ino won't fit in target struct field. Use 32bit counter
771 * here to attempt to avoid that.
773 static unsigned int counter;
775 struct hlist_head *head;
778 spin_lock(&inode_lock);
780 if (counter <= max_reserved)
781 counter = max_reserved + 1;
783 head = inode_hashtable + hash(sb, res);
784 inode = find_inode_fast(sb, head, res);
785 } while (inode != NULL);
786 spin_unlock(&inode_lock);
790 EXPORT_SYMBOL(iunique);
792 struct inode *igrab(struct inode *inode)
794 spin_lock(&inode_lock);
795 if (!(inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)))
799 * Handle the case where s_op->clear_inode is not been
800 * called yet, and somebody is calling igrab
801 * while the inode is getting freed.
804 spin_unlock(&inode_lock);
808 EXPORT_SYMBOL(igrab);
811 * ifind - internal function, you want ilookup5() or iget5().
812 * @sb: super block of file system to search
813 * @head: the head of the list to search
814 * @test: callback used for comparisons between inodes
815 * @data: opaque data pointer to pass to @test
816 * @wait: if true wait for the inode to be unlocked, if false do not
818 * ifind() searches for the inode specified by @data in the inode
819 * cache. This is a generalized version of ifind_fast() for file systems where
820 * the inode number is not sufficient for unique identification of an inode.
822 * If the inode is in the cache, the inode is returned with an incremented
825 * Otherwise NULL is returned.
827 * Note, @test is called with the inode_lock held, so can't sleep.
829 static struct inode *ifind(struct super_block *sb,
830 struct hlist_head *head, int (*test)(struct inode *, void *),
831 void *data, const int wait)
835 spin_lock(&inode_lock);
836 inode = find_inode(sb, head, test, data);
839 spin_unlock(&inode_lock);
841 wait_on_inode(inode);
844 spin_unlock(&inode_lock);
849 * ifind_fast - internal function, you want ilookup() or iget().
850 * @sb: super block of file system to search
851 * @head: head of the list to search
852 * @ino: inode number to search for
854 * ifind_fast() searches for the inode @ino in the inode cache. This is for
855 * file systems where the inode number is sufficient for unique identification
858 * If the inode is in the cache, the inode is returned with an incremented
861 * Otherwise NULL is returned.
863 static struct inode *ifind_fast(struct super_block *sb,
864 struct hlist_head *head, unsigned long ino)
868 spin_lock(&inode_lock);
869 inode = find_inode_fast(sb, head, ino);
872 spin_unlock(&inode_lock);
873 wait_on_inode(inode);
876 spin_unlock(&inode_lock);
881 * ilookup5_nowait - search for an inode in the inode cache
882 * @sb: super block of file system to search
883 * @hashval: hash value (usually inode number) to search for
884 * @test: callback used for comparisons between inodes
885 * @data: opaque data pointer to pass to @test
887 * ilookup5() uses ifind() to search for the inode specified by @hashval and
888 * @data in the inode cache. This is a generalized version of ilookup() for
889 * file systems where the inode number is not sufficient for unique
890 * identification of an inode.
892 * If the inode is in the cache, the inode is returned with an incremented
893 * reference count. Note, the inode lock is not waited upon so you have to be
894 * very careful what you do with the returned inode. You probably should be
895 * using ilookup5() instead.
897 * Otherwise NULL is returned.
899 * Note, @test is called with the inode_lock held, so can't sleep.
901 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
902 int (*test)(struct inode *, void *), void *data)
904 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
906 return ifind(sb, head, test, data, 0);
909 EXPORT_SYMBOL(ilookup5_nowait);
912 * ilookup5 - search for an inode in the inode cache
913 * @sb: super block of file system to search
914 * @hashval: hash value (usually inode number) to search for
915 * @test: callback used for comparisons between inodes
916 * @data: opaque data pointer to pass to @test
918 * ilookup5() uses ifind() to search for the inode specified by @hashval and
919 * @data in the inode cache. This is a generalized version of ilookup() for
920 * file systems where the inode number is not sufficient for unique
921 * identification of an inode.
923 * If the inode is in the cache, the inode lock is waited upon and the inode is
924 * returned with an incremented reference count.
926 * Otherwise NULL is returned.
928 * Note, @test is called with the inode_lock held, so can't sleep.
930 struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
931 int (*test)(struct inode *, void *), void *data)
933 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
935 return ifind(sb, head, test, data, 1);
938 EXPORT_SYMBOL(ilookup5);
941 * ilookup - search for an inode in the inode cache
942 * @sb: super block of file system to search
943 * @ino: inode number to search for
945 * ilookup() uses ifind_fast() to search for the inode @ino in the inode cache.
946 * This is for file systems where the inode number is sufficient for unique
947 * identification of an inode.
949 * If the inode is in the cache, the inode is returned with an incremented
952 * Otherwise NULL is returned.
954 struct inode *ilookup(struct super_block *sb, unsigned long ino)
956 struct hlist_head *head = inode_hashtable + hash(sb, ino);
958 return ifind_fast(sb, head, ino);
961 EXPORT_SYMBOL(ilookup);
964 * iget5_locked - obtain an inode from a mounted file system
965 * @sb: super block of file system
966 * @hashval: hash value (usually inode number) to get
967 * @test: callback used for comparisons between inodes
968 * @set: callback used to initialize a new struct inode
969 * @data: opaque data pointer to pass to @test and @set
971 * iget5_locked() uses ifind() to search for the inode specified by @hashval
972 * and @data in the inode cache and if present it is returned with an increased
973 * reference count. This is a generalized version of iget_locked() for file
974 * systems where the inode number is not sufficient for unique identification
977 * If the inode is not in cache, get_new_inode() is called to allocate a new
978 * inode and this is returned locked, hashed, and with the I_NEW flag set. The
979 * file system gets to fill it in before unlocking it via unlock_new_inode().
981 * Note both @test and @set are called with the inode_lock held, so can't sleep.
983 struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
984 int (*test)(struct inode *, void *),
985 int (*set)(struct inode *, void *), void *data)
987 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
990 inode = ifind(sb, head, test, data, 1);
994 * get_new_inode() will do the right thing, re-trying the search
995 * in case it had to block at any point.
997 return get_new_inode(sb, head, test, set, data);
1000 EXPORT_SYMBOL(iget5_locked);
1003 * iget_locked - obtain an inode from a mounted file system
1004 * @sb: super block of file system
1005 * @ino: inode number to get
1007 * iget_locked() uses ifind_fast() to search for the inode specified by @ino in
1008 * the inode cache and if present it is returned with an increased reference
1009 * count. This is for file systems where the inode number is sufficient for
1010 * unique identification of an inode.
1012 * If the inode is not in cache, get_new_inode_fast() is called to allocate a
1013 * new inode and this is returned locked, hashed, and with the I_NEW flag set.
1014 * The file system gets to fill it in before unlocking it via
1015 * unlock_new_inode().
1017 struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1019 struct hlist_head *head = inode_hashtable + hash(sb, ino);
1020 struct inode *inode;
1022 inode = ifind_fast(sb, head, ino);
1026 * get_new_inode_fast() will do the right thing, re-trying the search
1027 * in case it had to block at any point.
1029 return get_new_inode_fast(sb, head, ino);
1032 EXPORT_SYMBOL(iget_locked);
1035 * __insert_inode_hash - hash an inode
1036 * @inode: unhashed inode
1037 * @hashval: unsigned long value used to locate this object in the
1040 * Add an inode to the inode hash for this superblock.
1042 void __insert_inode_hash(struct inode *inode, unsigned long hashval)
1044 struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
1045 spin_lock(&inode_lock);
1046 hlist_add_head(&inode->i_hash, head);
1047 spin_unlock(&inode_lock);
1050 EXPORT_SYMBOL(__insert_inode_hash);
1053 * remove_inode_hash - remove an inode from the hash
1054 * @inode: inode to unhash
1056 * Remove an inode from the superblock.
1058 void remove_inode_hash(struct inode *inode)
1060 spin_lock(&inode_lock);
1061 hlist_del_init(&inode->i_hash);
1062 spin_unlock(&inode_lock);
1065 EXPORT_SYMBOL(remove_inode_hash);
1068 * Tell the filesystem that this inode is no longer of any interest and should
1069 * be completely destroyed.
1071 * We leave the inode in the inode hash table until *after* the filesystem's
1072 * ->delete_inode completes. This ensures that an iget (such as nfsd might
1073 * instigate) will always find up-to-date information either in the hash or on
1076 * I_FREEING is set so that no-one will take a new reference to the inode while
1077 * it is being deleted.
1079 void generic_delete_inode(struct inode *inode)
1081 const struct super_operations *op = inode->i_sb->s_op;
1083 list_del_init(&inode->i_list);
1084 list_del_init(&inode->i_sb_list);
1085 inode->i_state |= I_FREEING;
1086 inodes_stat.nr_inodes--;
1087 spin_unlock(&inode_lock);
1089 security_inode_delete(inode);
1091 if (op->delete_inode) {
1092 void (*delete)(struct inode *) = op->delete_inode;
1093 if (!is_bad_inode(inode))
1095 /* Filesystems implementing their own
1096 * s_op->delete_inode are required to call
1097 * truncate_inode_pages and clear_inode()
1101 truncate_inode_pages(&inode->i_data, 0);
1104 spin_lock(&inode_lock);
1105 hlist_del_init(&inode->i_hash);
1106 spin_unlock(&inode_lock);
1107 wake_up_inode(inode);
1108 BUG_ON(inode->i_state != I_CLEAR);
1109 destroy_inode(inode);
1112 EXPORT_SYMBOL(generic_delete_inode);
1114 static void generic_forget_inode(struct inode *inode)
1116 struct super_block *sb = inode->i_sb;
1118 if (!hlist_unhashed(&inode->i_hash)) {
1119 if (!(inode->i_state & (I_DIRTY|I_SYNC)))
1120 list_move(&inode->i_list, &inode_unused);
1121 inodes_stat.nr_unused++;
1122 if (sb->s_flags & MS_ACTIVE) {
1123 spin_unlock(&inode_lock);
1126 inode->i_state |= I_WILL_FREE;
1127 spin_unlock(&inode_lock);
1128 write_inode_now(inode, 1);
1129 spin_lock(&inode_lock);
1130 inode->i_state &= ~I_WILL_FREE;
1131 inodes_stat.nr_unused--;
1132 hlist_del_init(&inode->i_hash);
1134 list_del_init(&inode->i_list);
1135 list_del_init(&inode->i_sb_list);
1136 inode->i_state |= I_FREEING;
1137 inodes_stat.nr_inodes--;
1138 spin_unlock(&inode_lock);
1139 if (inode->i_data.nrpages)
1140 truncate_inode_pages(&inode->i_data, 0);
1142 wake_up_inode(inode);
1143 destroy_inode(inode);
1147 * Normal UNIX filesystem behaviour: delete the
1148 * inode when the usage count drops to zero, and
1151 void generic_drop_inode(struct inode *inode)
1153 if (!inode->i_nlink)
1154 generic_delete_inode(inode);
1156 generic_forget_inode(inode);
1159 EXPORT_SYMBOL_GPL(generic_drop_inode);
1162 * Called when we're dropping the last reference
1165 * Call the FS "drop()" function, defaulting to
1166 * the legacy UNIX filesystem behaviour..
1168 * NOTE! NOTE! NOTE! We're called with the inode lock
1169 * held, and the drop function is supposed to release
1172 static inline void iput_final(struct inode *inode)
1174 const struct super_operations *op = inode->i_sb->s_op;
1175 void (*drop)(struct inode *) = generic_drop_inode;
1177 if (op && op->drop_inode)
1178 drop = op->drop_inode;
1183 * iput - put an inode
1184 * @inode: inode to put
1186 * Puts an inode, dropping its usage count. If the inode use count hits
1187 * zero, the inode is then freed and may also be destroyed.
1189 * Consequently, iput() can sleep.
1191 void iput(struct inode *inode)
1194 BUG_ON(inode->i_state == I_CLEAR);
1196 if (atomic_dec_and_lock(&inode->i_count, &inode_lock))
1201 EXPORT_SYMBOL(iput);
1204 * bmap - find a block number in a file
1205 * @inode: inode of file
1206 * @block: block to find
1208 * Returns the block number on the device holding the inode that
1209 * is the disk block number for the block of the file requested.
1210 * That is, asked for block 4 of inode 1 the function will return the
1211 * disk block relative to the disk start that holds that block of the
1214 sector_t bmap(struct inode * inode, sector_t block)
1217 if (inode->i_mapping->a_ops->bmap)
1218 res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1221 EXPORT_SYMBOL(bmap);
1224 * touch_atime - update the access time
1225 * @mnt: mount the inode is accessed on
1226 * @dentry: dentry accessed
1228 * Update the accessed time on an inode and mark it for writeback.
1229 * This function automatically handles read only file systems and media,
1230 * as well as the "noatime" flag and inode specific "noatime" markers.
1232 void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
1234 struct inode *inode = dentry->d_inode;
1235 struct timespec now;
1237 if (mnt_want_write(mnt))
1239 if (inode->i_flags & S_NOATIME)
1241 if (IS_NOATIME(inode))
1243 if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1246 if (mnt->mnt_flags & MNT_NOATIME)
1248 if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1250 if (mnt->mnt_flags & MNT_RELATIME) {
1252 * With relative atime, only update atime if the previous
1253 * atime is earlier than either the ctime or mtime.
1255 if (timespec_compare(&inode->i_mtime, &inode->i_atime) < 0 &&
1256 timespec_compare(&inode->i_ctime, &inode->i_atime) < 0)
1260 now = current_fs_time(inode->i_sb);
1261 if (timespec_equal(&inode->i_atime, &now))
1264 inode->i_atime = now;
1265 mark_inode_dirty_sync(inode);
1267 mnt_drop_write(mnt);
1269 EXPORT_SYMBOL(touch_atime);
1272 * file_update_time - update mtime and ctime time
1273 * @file: file accessed
1275 * Update the mtime and ctime members of an inode and mark the inode
1276 * for writeback. Note that this function is meant exclusively for
1277 * usage in the file write path of filesystems, and filesystems may
1278 * choose to explicitly ignore update via this function with the
1279 * S_NOCTIME inode flag, e.g. for network filesystem where these
1280 * timestamps are handled by the server.
1283 void file_update_time(struct file *file)
1285 struct inode *inode = file->f_path.dentry->d_inode;
1286 struct timespec now;
1290 if (IS_NOCMTIME(inode))
1293 err = mnt_want_write(file->f_path.mnt);
1297 now = current_fs_time(inode->i_sb);
1298 if (!timespec_equal(&inode->i_mtime, &now)) {
1299 inode->i_mtime = now;
1303 if (!timespec_equal(&inode->i_ctime, &now)) {
1304 inode->i_ctime = now;
1308 if (IS_I_VERSION(inode)) {
1309 inode_inc_iversion(inode);
1314 mark_inode_dirty_sync(inode);
1315 mnt_drop_write(file->f_path.mnt);
1318 EXPORT_SYMBOL(file_update_time);
1320 int inode_needs_sync(struct inode *inode)
1324 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1329 EXPORT_SYMBOL(inode_needs_sync);
1331 int inode_wait(void *word)
1338 * If we try to find an inode in the inode hash while it is being
1339 * deleted, we have to wait until the filesystem completes its
1340 * deletion before reporting that it isn't found. This function waits
1341 * until the deletion _might_ have completed. Callers are responsible
1342 * to recheck inode state.
1344 * It doesn't matter if I_LOCK is not set initially, a call to
1345 * wake_up_inode() after removing from the hash list will DTRT.
1347 * This is called with inode_lock held.
1349 static void __wait_on_freeing_inode(struct inode *inode)
1351 wait_queue_head_t *wq;
1352 DEFINE_WAIT_BIT(wait, &inode->i_state, __I_LOCK);
1353 wq = bit_waitqueue(&inode->i_state, __I_LOCK);
1354 prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1355 spin_unlock(&inode_lock);
1357 finish_wait(wq, &wait.wait);
1358 spin_lock(&inode_lock);
1362 * We rarely want to lock two inodes that do not have a parent/child
1363 * relationship (such as directory, child inode) simultaneously. The
1364 * vast majority of file systems should be able to get along fine
1365 * without this. Do not use these functions except as a last resort.
1367 void inode_double_lock(struct inode *inode1, struct inode *inode2)
1369 if (inode1 == NULL || inode2 == NULL || inode1 == inode2) {
1371 mutex_lock(&inode1->i_mutex);
1373 mutex_lock(&inode2->i_mutex);
1377 if (inode1 < inode2) {
1378 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
1379 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
1381 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
1382 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
1385 EXPORT_SYMBOL(inode_double_lock);
1387 void inode_double_unlock(struct inode *inode1, struct inode *inode2)
1390 mutex_unlock(&inode1->i_mutex);
1392 if (inode2 && inode2 != inode1)
1393 mutex_unlock(&inode2->i_mutex);
1395 EXPORT_SYMBOL(inode_double_unlock);
1397 static __initdata unsigned long ihash_entries;
1398 static int __init set_ihash_entries(char *str)
1402 ihash_entries = simple_strtoul(str, &str, 0);
1405 __setup("ihash_entries=", set_ihash_entries);
1408 * Initialize the waitqueues and inode hash table.
1410 void __init inode_init_early(void)
1414 /* If hashes are distributed across NUMA nodes, defer
1415 * hash allocation until vmalloc space is available.
1421 alloc_large_system_hash("Inode-cache",
1422 sizeof(struct hlist_head),
1430 for (loop = 0; loop < (1 << i_hash_shift); loop++)
1431 INIT_HLIST_HEAD(&inode_hashtable[loop]);
1434 void __init inode_init(void)
1438 /* inode slab cache */
1439 inode_cachep = kmem_cache_create("inode_cache",
1440 sizeof(struct inode),
1442 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1445 register_shrinker(&icache_shrinker);
1447 /* Hash may have been set up in inode_init_early */
1452 alloc_large_system_hash("Inode-cache",
1453 sizeof(struct hlist_head),
1461 for (loop = 0; loop < (1 << i_hash_shift); loop++)
1462 INIT_HLIST_HEAD(&inode_hashtable[loop]);
1465 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
1467 inode->i_mode = mode;
1468 if (S_ISCHR(mode)) {
1469 inode->i_fop = &def_chr_fops;
1470 inode->i_rdev = rdev;
1471 } else if (S_ISBLK(mode)) {
1472 inode->i_fop = &def_blk_fops;
1473 inode->i_rdev = rdev;
1474 } else if (S_ISFIFO(mode))
1475 inode->i_fop = &def_fifo_fops;
1476 else if (S_ISSOCK(mode))
1477 inode->i_fop = &bad_sock_fops;
1479 printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o)\n",
1482 EXPORT_SYMBOL(init_special_inode);