4 * (C) 1997 Linus Torvalds
9 #include <linux/dcache.h>
10 #include <linux/init.h>
11 #include <linux/slab.h>
12 #include <linux/writeback.h>
13 #include <linux/module.h>
14 #include <linux/backing-dev.h>
15 #include <linux/wait.h>
16 #include <linux/rwsem.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/fsnotify.h>
24 #include <linux/mount.h>
25 #include <linux/async.h>
26 #include <linux/posix_acl.h>
29 * This is needed for the following functions:
31 * - invalidate_inode_buffers
34 * FIXME: remove all knowledge of the buffer layer from this file
36 #include <linux/buffer_head.h>
39 * New inode.c implementation.
41 * This implementation has the basic premise of trying
42 * to be extremely low-overhead and SMP-safe, yet be
43 * simple enough to be "obviously correct".
48 /* inode dynamic allocation 1999, Andrea Arcangeli <andrea@suse.de> */
50 /* #define INODE_PARANOIA 1 */
51 /* #define INODE_DEBUG 1 */
54 * Inode lookup is no longer as critical as it used to be:
55 * most of the lookups are going to be through the dcache.
57 #define I_HASHBITS i_hash_shift
58 #define I_HASHMASK i_hash_mask
60 static unsigned int i_hash_mask __read_mostly;
61 static unsigned int i_hash_shift __read_mostly;
64 * Each inode can be on two separate lists. One is
65 * the hash list of the inode, used for lookups. The
66 * other linked list is the "type" list:
67 * "in_use" - valid inode, i_count > 0, i_nlink > 0
68 * "dirty" - as "in_use" but also dirty
69 * "unused" - valid inode, i_count = 0
71 * A "dirty" list is maintained for each super block,
72 * allowing for low-overhead inode sync() operations.
75 static LIST_HEAD(inode_unused);
76 static struct hlist_head *inode_hashtable __read_mostly;
79 * A simple spinlock to protect the list manipulations.
81 * NOTE! You also have to own the lock if you change
82 * the i_state of an inode while it is in use..
84 DEFINE_SPINLOCK(inode_lock);
87 * iprune_sem provides exclusion between the kswapd or try_to_free_pages
88 * icache shrinking path, and the umount path. Without this exclusion,
89 * by the time prune_icache calls iput for the inode whose pages it has
90 * been invalidating, or by the time it calls clear_inode & destroy_inode
91 * from its final dispose_list, the struct super_block they refer to
92 * (for inode->i_sb->s_op) may already have been freed and reused.
94 * We make this an rwsem because the fastpath is icache shrinking. In
95 * some cases a filesystem may be doing a significant amount of work in
96 * its inode reclaim code, so this should improve parallelism.
98 static DECLARE_RWSEM(iprune_sem);
101 * Statistics gathering..
103 struct inodes_stat_t inodes_stat;
105 static struct percpu_counter nr_inodes __cacheline_aligned_in_smp;
106 static struct percpu_counter nr_inodes_unused __cacheline_aligned_in_smp;
108 static struct kmem_cache *inode_cachep __read_mostly;
110 static inline int get_nr_inodes(void)
112 return percpu_counter_sum_positive(&nr_inodes);
115 static inline int get_nr_inodes_unused(void)
117 return percpu_counter_sum_positive(&nr_inodes_unused);
120 int get_nr_dirty_inodes(void)
122 int nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
123 return nr_dirty > 0 ? nr_dirty : 0;
128 * Handle nr_inode sysctl
131 int proc_nr_inodes(ctl_table *table, int write,
132 void __user *buffer, size_t *lenp, loff_t *ppos)
134 inodes_stat.nr_inodes = get_nr_inodes();
135 inodes_stat.nr_unused = get_nr_inodes_unused();
136 return proc_dointvec(table, write, buffer, lenp, ppos);
140 static void wake_up_inode(struct inode *inode)
143 * Prevent speculative execution through spin_unlock(&inode_lock);
146 wake_up_bit(&inode->i_state, __I_NEW);
150 * inode_init_always - perform inode structure intialisation
151 * @sb: superblock inode belongs to
152 * @inode: inode to initialise
154 * These are initializations that need to be done on every inode
155 * allocation as the fields are not initialised by slab allocation.
157 int inode_init_always(struct super_block *sb, struct inode *inode)
159 static const struct address_space_operations empty_aops;
160 static const struct inode_operations empty_iops;
161 static const struct file_operations empty_fops;
162 struct address_space *const mapping = &inode->i_data;
165 inode->i_blkbits = sb->s_blocksize_bits;
167 atomic_set(&inode->i_count, 1);
168 inode->i_op = &empty_iops;
169 inode->i_fop = &empty_fops;
173 atomic_set(&inode->i_writecount, 0);
177 inode->i_generation = 0;
179 memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
181 inode->i_pipe = NULL;
182 inode->i_bdev = NULL;
183 inode->i_cdev = NULL;
185 inode->dirtied_when = 0;
187 if (security_inode_alloc(inode))
189 spin_lock_init(&inode->i_lock);
190 lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
192 mutex_init(&inode->i_mutex);
193 lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
195 init_rwsem(&inode->i_alloc_sem);
196 lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
198 mapping->a_ops = &empty_aops;
199 mapping->host = inode;
201 mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
202 mapping->assoc_mapping = NULL;
203 mapping->backing_dev_info = &default_backing_dev_info;
204 mapping->writeback_index = 0;
207 * If the block_device provides a backing_dev_info for client
208 * inodes then use that. Otherwise the inode share the bdev's
212 struct backing_dev_info *bdi;
214 bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
215 mapping->backing_dev_info = bdi;
217 inode->i_private = NULL;
218 inode->i_mapping = mapping;
219 #ifdef CONFIG_FS_POSIX_ACL
220 inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
223 #ifdef CONFIG_FSNOTIFY
224 inode->i_fsnotify_mask = 0;
227 percpu_counter_inc(&nr_inodes);
233 EXPORT_SYMBOL(inode_init_always);
235 static struct inode *alloc_inode(struct super_block *sb)
239 if (sb->s_op->alloc_inode)
240 inode = sb->s_op->alloc_inode(sb);
242 inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
247 if (unlikely(inode_init_always(sb, inode))) {
248 if (inode->i_sb->s_op->destroy_inode)
249 inode->i_sb->s_op->destroy_inode(inode);
251 kmem_cache_free(inode_cachep, inode);
258 void __destroy_inode(struct inode *inode)
260 BUG_ON(inode_has_buffers(inode));
261 security_inode_free(inode);
262 fsnotify_inode_delete(inode);
263 #ifdef CONFIG_FS_POSIX_ACL
264 if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
265 posix_acl_release(inode->i_acl);
266 if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
267 posix_acl_release(inode->i_default_acl);
269 percpu_counter_dec(&nr_inodes);
271 EXPORT_SYMBOL(__destroy_inode);
273 static void destroy_inode(struct inode *inode)
275 __destroy_inode(inode);
276 if (inode->i_sb->s_op->destroy_inode)
277 inode->i_sb->s_op->destroy_inode(inode);
279 kmem_cache_free(inode_cachep, (inode));
283 * These are initializations that only need to be done
284 * once, because the fields are idempotent across use
285 * of the inode, so let the slab aware of that.
287 void inode_init_once(struct inode *inode)
289 memset(inode, 0, sizeof(*inode));
290 INIT_HLIST_NODE(&inode->i_hash);
291 INIT_LIST_HEAD(&inode->i_dentry);
292 INIT_LIST_HEAD(&inode->i_devices);
293 INIT_LIST_HEAD(&inode->i_list);
294 INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
295 spin_lock_init(&inode->i_data.tree_lock);
296 spin_lock_init(&inode->i_data.i_mmap_lock);
297 INIT_LIST_HEAD(&inode->i_data.private_list);
298 spin_lock_init(&inode->i_data.private_lock);
299 INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
300 INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
301 i_size_ordered_init(inode);
302 #ifdef CONFIG_FSNOTIFY
303 INIT_HLIST_HEAD(&inode->i_fsnotify_marks);
306 EXPORT_SYMBOL(inode_init_once);
308 static void init_once(void *foo)
310 struct inode *inode = (struct inode *) foo;
312 inode_init_once(inode);
316 * inode_lock must be held
318 void __iget(struct inode *inode)
320 atomic_inc(&inode->i_count);
323 static void inode_lru_list_add(struct inode *inode)
325 if (list_empty(&inode->i_list)) {
326 list_add(&inode->i_list, &inode_unused);
327 percpu_counter_inc(&nr_inodes_unused);
331 static void inode_lru_list_del(struct inode *inode)
333 if (!list_empty(&inode->i_list)) {
334 list_del_init(&inode->i_list);
335 percpu_counter_dec(&nr_inodes_unused);
339 static unsigned long hash(struct super_block *sb, unsigned long hashval)
343 tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
345 tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
346 return tmp & I_HASHMASK;
350 * __insert_inode_hash - hash an inode
351 * @inode: unhashed inode
352 * @hashval: unsigned long value used to locate this object in the
355 * Add an inode to the inode hash for this superblock.
357 void __insert_inode_hash(struct inode *inode, unsigned long hashval)
359 struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
360 spin_lock(&inode_lock);
361 hlist_add_head(&inode->i_hash, head);
362 spin_unlock(&inode_lock);
364 EXPORT_SYMBOL(__insert_inode_hash);
367 * __remove_inode_hash - remove an inode from the hash
368 * @inode: inode to unhash
370 * Remove an inode from the superblock.
372 static void __remove_inode_hash(struct inode *inode)
374 hlist_del_init(&inode->i_hash);
378 * remove_inode_hash - remove an inode from the hash
379 * @inode: inode to unhash
381 * Remove an inode from the superblock.
383 void remove_inode_hash(struct inode *inode)
385 spin_lock(&inode_lock);
386 hlist_del_init(&inode->i_hash);
387 spin_unlock(&inode_lock);
389 EXPORT_SYMBOL(remove_inode_hash);
391 void end_writeback(struct inode *inode)
394 BUG_ON(inode->i_data.nrpages);
395 BUG_ON(!list_empty(&inode->i_data.private_list));
396 BUG_ON(!(inode->i_state & I_FREEING));
397 BUG_ON(inode->i_state & I_CLEAR);
398 inode_sync_wait(inode);
399 inode->i_state = I_FREEING | I_CLEAR;
401 EXPORT_SYMBOL(end_writeback);
403 static void evict(struct inode *inode)
405 const struct super_operations *op = inode->i_sb->s_op;
407 if (op->evict_inode) {
408 op->evict_inode(inode);
410 if (inode->i_data.nrpages)
411 truncate_inode_pages(&inode->i_data, 0);
412 end_writeback(inode);
414 if (S_ISBLK(inode->i_mode) && inode->i_bdev)
416 if (S_ISCHR(inode->i_mode) && inode->i_cdev)
421 * dispose_list - dispose of the contents of a local list
422 * @head: the head of the list to free
424 * Dispose-list gets a local list with local inodes in it, so it doesn't
425 * need to worry about list corruption and SMP locks.
427 static void dispose_list(struct list_head *head)
429 while (!list_empty(head)) {
432 inode = list_first_entry(head, struct inode, i_list);
433 list_del_init(&inode->i_list);
437 spin_lock(&inode_lock);
438 __remove_inode_hash(inode);
439 list_del_init(&inode->i_sb_list);
440 spin_unlock(&inode_lock);
442 wake_up_inode(inode);
443 destroy_inode(inode);
448 * Invalidate all inodes for a device.
450 static int invalidate_list(struct list_head *head, struct list_head *dispose)
452 struct list_head *next;
457 struct list_head *tmp = next;
461 * We can reschedule here without worrying about the list's
462 * consistency because the per-sb list of inodes must not
463 * change during umount anymore, and because iprune_sem keeps
464 * shrink_icache_memory() away.
466 cond_resched_lock(&inode_lock);
471 inode = list_entry(tmp, struct inode, i_sb_list);
472 if (inode->i_state & I_NEW)
474 invalidate_inode_buffers(inode);
475 if (!atomic_read(&inode->i_count)) {
476 list_move(&inode->i_list, dispose);
477 WARN_ON(inode->i_state & I_NEW);
478 inode->i_state |= I_FREEING;
479 if (!(inode->i_state & (I_DIRTY | I_SYNC)))
480 percpu_counter_dec(&nr_inodes_unused);
489 * invalidate_inodes - discard the inodes on a device
492 * Discard all of the inodes for a given superblock. If the discard
493 * fails because there are busy inodes then a non zero value is returned.
494 * If the discard is successful all the inodes have been discarded.
496 int invalidate_inodes(struct super_block *sb)
499 LIST_HEAD(throw_away);
501 down_write(&iprune_sem);
502 spin_lock(&inode_lock);
503 fsnotify_unmount_inodes(&sb->s_inodes);
504 busy = invalidate_list(&sb->s_inodes, &throw_away);
505 spin_unlock(&inode_lock);
507 dispose_list(&throw_away);
508 up_write(&iprune_sem);
513 static int can_unuse(struct inode *inode)
515 if (inode->i_state & ~I_REFERENCED)
517 if (inode_has_buffers(inode))
519 if (atomic_read(&inode->i_count))
521 if (inode->i_data.nrpages)
527 * Scan `goal' inodes on the unused list for freeable ones. They are moved to a
528 * temporary list and then are freed outside inode_lock by dispose_list().
530 * Any inodes which are pinned purely because of attached pagecache have their
531 * pagecache removed. If the inode has metadata buffers attached to
532 * mapping->private_list then try to remove them.
534 * If the inode has the I_REFERENCED flag set, then it means that it has been
535 * used recently - the flag is set in iput_final(). When we encounter such an
536 * inode, clear the flag and move it to the back of the LRU so it gets another
537 * pass through the LRU before it gets reclaimed. This is necessary because of
538 * the fact we are doing lazy LRU updates to minimise lock contention so the
539 * LRU does not have strict ordering. Hence we don't want to reclaim inodes
540 * with this flag set because they are the inodes that are out of order.
542 static void prune_icache(int nr_to_scan)
546 unsigned long reap = 0;
548 down_read(&iprune_sem);
549 spin_lock(&inode_lock);
550 for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
553 if (list_empty(&inode_unused))
556 inode = list_entry(inode_unused.prev, struct inode, i_list);
559 * Referenced or dirty inodes are still in use. Give them
560 * another pass through the LRU as we canot reclaim them now.
562 if (atomic_read(&inode->i_count) ||
563 (inode->i_state & ~I_REFERENCED)) {
564 list_del_init(&inode->i_list);
565 percpu_counter_dec(&nr_inodes_unused);
569 /* recently referenced inodes get one more pass */
570 if (inode->i_state & I_REFERENCED) {
571 list_move(&inode->i_list, &inode_unused);
572 inode->i_state &= ~I_REFERENCED;
575 if (inode_has_buffers(inode) || inode->i_data.nrpages) {
577 spin_unlock(&inode_lock);
578 if (remove_inode_buffers(inode))
579 reap += invalidate_mapping_pages(&inode->i_data,
582 spin_lock(&inode_lock);
584 if (inode != list_entry(inode_unused.next,
585 struct inode, i_list))
586 continue; /* wrong inode or list_empty */
587 if (!can_unuse(inode))
590 list_move(&inode->i_list, &freeable);
591 WARN_ON(inode->i_state & I_NEW);
592 inode->i_state |= I_FREEING;
593 percpu_counter_dec(&nr_inodes_unused);
595 if (current_is_kswapd())
596 __count_vm_events(KSWAPD_INODESTEAL, reap);
598 __count_vm_events(PGINODESTEAL, reap);
599 spin_unlock(&inode_lock);
601 dispose_list(&freeable);
602 up_read(&iprune_sem);
606 * shrink_icache_memory() will attempt to reclaim some unused inodes. Here,
607 * "unused" means that no dentries are referring to the inodes: the files are
608 * not open and the dcache references to those inodes have already been
611 * This function is passed the number of inodes to scan, and it returns the
612 * total number of remaining possibly-reclaimable inodes.
614 static int shrink_icache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
618 * Nasty deadlock avoidance. We may hold various FS locks,
619 * and we don't want to recurse into the FS that called us
620 * in clear_inode() and friends..
622 if (!(gfp_mask & __GFP_FS))
626 return (get_nr_inodes_unused() / 100) * sysctl_vfs_cache_pressure;
629 static struct shrinker icache_shrinker = {
630 .shrink = shrink_icache_memory,
631 .seeks = DEFAULT_SEEKS,
634 static void __wait_on_freeing_inode(struct inode *inode);
636 * Called with the inode lock held.
638 static struct inode *find_inode(struct super_block *sb,
639 struct hlist_head *head,
640 int (*test)(struct inode *, void *),
643 struct hlist_node *node;
644 struct inode *inode = NULL;
647 hlist_for_each_entry(inode, node, head, i_hash) {
648 if (inode->i_sb != sb)
650 if (!test(inode, data))
652 if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
653 __wait_on_freeing_inode(inode);
663 * find_inode_fast is the fast path version of find_inode, see the comment at
664 * iget_locked for details.
666 static struct inode *find_inode_fast(struct super_block *sb,
667 struct hlist_head *head, unsigned long ino)
669 struct hlist_node *node;
670 struct inode *inode = NULL;
673 hlist_for_each_entry(inode, node, head, i_hash) {
674 if (inode->i_ino != ino)
676 if (inode->i_sb != sb)
678 if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
679 __wait_on_freeing_inode(inode);
689 __inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
692 list_add(&inode->i_sb_list, &sb->s_inodes);
694 hlist_add_head(&inode->i_hash, head);
698 * inode_add_to_lists - add a new inode to relevant lists
699 * @sb: superblock inode belongs to
700 * @inode: inode to mark in use
702 * When an inode is allocated it needs to be accounted for, added to the in use
703 * list, the owning superblock and the inode hash. This needs to be done under
704 * the inode_lock, so export a function to do this rather than the inode lock
705 * itself. We calculate the hash list to add to here so it is all internal
706 * which requires the caller to have already set up the inode number in the
709 void inode_add_to_lists(struct super_block *sb, struct inode *inode)
711 struct hlist_head *head = inode_hashtable + hash(sb, inode->i_ino);
713 spin_lock(&inode_lock);
714 __inode_add_to_lists(sb, head, inode);
715 spin_unlock(&inode_lock);
717 EXPORT_SYMBOL_GPL(inode_add_to_lists);
720 * new_inode - obtain an inode
723 * Allocates a new inode for given superblock. The default gfp_mask
724 * for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
725 * If HIGHMEM pages are unsuitable or it is known that pages allocated
726 * for the page cache are not reclaimable or migratable,
727 * mapping_set_gfp_mask() must be called with suitable flags on the
728 * newly created inode's mapping
731 struct inode *new_inode(struct super_block *sb)
734 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
735 * error if st_ino won't fit in target struct field. Use 32bit counter
736 * here to attempt to avoid that.
738 static unsigned int last_ino;
741 spin_lock_prefetch(&inode_lock);
743 inode = alloc_inode(sb);
745 spin_lock(&inode_lock);
746 __inode_add_to_lists(sb, NULL, inode);
747 inode->i_ino = ++last_ino;
749 spin_unlock(&inode_lock);
753 EXPORT_SYMBOL(new_inode);
755 void unlock_new_inode(struct inode *inode)
757 #ifdef CONFIG_DEBUG_LOCK_ALLOC
758 if (S_ISDIR(inode->i_mode)) {
759 struct file_system_type *type = inode->i_sb->s_type;
761 /* Set new key only if filesystem hasn't already changed it */
762 if (!lockdep_match_class(&inode->i_mutex,
763 &type->i_mutex_key)) {
765 * ensure nobody is actually holding i_mutex
767 mutex_destroy(&inode->i_mutex);
768 mutex_init(&inode->i_mutex);
769 lockdep_set_class(&inode->i_mutex,
770 &type->i_mutex_dir_key);
775 * This is special! We do not need the spinlock when clearing I_NEW,
776 * because we're guaranteed that nobody else tries to do anything about
777 * the state of the inode when it is locked, as we just created it (so
778 * there can be no old holders that haven't tested I_NEW).
779 * However we must emit the memory barrier so that other CPUs reliably
780 * see the clearing of I_NEW after the other inode initialisation has
784 WARN_ON(!(inode->i_state & I_NEW));
785 inode->i_state &= ~I_NEW;
786 wake_up_inode(inode);
788 EXPORT_SYMBOL(unlock_new_inode);
791 * This is called without the inode lock held.. Be careful.
793 * We no longer cache the sb_flags in i_flags - see fs.h
794 * -- rmk@arm.uk.linux.org
796 static struct inode *get_new_inode(struct super_block *sb,
797 struct hlist_head *head,
798 int (*test)(struct inode *, void *),
799 int (*set)(struct inode *, void *),
804 inode = alloc_inode(sb);
808 spin_lock(&inode_lock);
809 /* We released the lock, so.. */
810 old = find_inode(sb, head, test, data);
812 if (set(inode, data))
815 __inode_add_to_lists(sb, head, inode);
816 inode->i_state = I_NEW;
817 spin_unlock(&inode_lock);
819 /* Return the locked inode with I_NEW set, the
820 * caller is responsible for filling in the contents
826 * Uhhuh, somebody else created the same inode under
827 * us. Use the old inode instead of the one we just
830 spin_unlock(&inode_lock);
831 destroy_inode(inode);
833 wait_on_inode(inode);
838 spin_unlock(&inode_lock);
839 destroy_inode(inode);
844 * get_new_inode_fast is the fast path version of get_new_inode, see the
845 * comment at iget_locked for details.
847 static struct inode *get_new_inode_fast(struct super_block *sb,
848 struct hlist_head *head, unsigned long ino)
852 inode = alloc_inode(sb);
856 spin_lock(&inode_lock);
857 /* We released the lock, so.. */
858 old = find_inode_fast(sb, head, ino);
861 __inode_add_to_lists(sb, head, inode);
862 inode->i_state = I_NEW;
863 spin_unlock(&inode_lock);
865 /* Return the locked inode with I_NEW set, the
866 * caller is responsible for filling in the contents
872 * Uhhuh, somebody else created the same inode under
873 * us. Use the old inode instead of the one we just
876 spin_unlock(&inode_lock);
877 destroy_inode(inode);
879 wait_on_inode(inode);
885 * search the inode cache for a matching inode number.
886 * If we find one, then the inode number we are trying to
887 * allocate is not unique and so we should not use it.
889 * Returns 1 if the inode number is unique, 0 if it is not.
891 static int test_inode_iunique(struct super_block *sb, unsigned long ino)
893 struct hlist_head *b = inode_hashtable + hash(sb, ino);
894 struct hlist_node *node;
897 hlist_for_each_entry(inode, node, b, i_hash) {
898 if (inode->i_ino == ino && inode->i_sb == sb)
906 * iunique - get a unique inode number
908 * @max_reserved: highest reserved inode number
910 * Obtain an inode number that is unique on the system for a given
911 * superblock. This is used by file systems that have no natural
912 * permanent inode numbering system. An inode number is returned that
913 * is higher than the reserved limit but unique.
916 * With a large number of inodes live on the file system this function
917 * currently becomes quite slow.
919 ino_t iunique(struct super_block *sb, ino_t max_reserved)
922 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
923 * error if st_ino won't fit in target struct field. Use 32bit counter
924 * here to attempt to avoid that.
926 static DEFINE_SPINLOCK(iunique_lock);
927 static unsigned int counter;
930 spin_lock(&inode_lock);
931 spin_lock(&iunique_lock);
933 if (counter <= max_reserved)
934 counter = max_reserved + 1;
936 } while (!test_inode_iunique(sb, res));
937 spin_unlock(&iunique_lock);
938 spin_unlock(&inode_lock);
942 EXPORT_SYMBOL(iunique);
944 struct inode *igrab(struct inode *inode)
946 spin_lock(&inode_lock);
947 if (!(inode->i_state & (I_FREEING|I_WILL_FREE)))
951 * Handle the case where s_op->clear_inode is not been
952 * called yet, and somebody is calling igrab
953 * while the inode is getting freed.
956 spin_unlock(&inode_lock);
959 EXPORT_SYMBOL(igrab);
962 * ifind - internal function, you want ilookup5() or iget5().
963 * @sb: super block of file system to search
964 * @head: the head of the list to search
965 * @test: callback used for comparisons between inodes
966 * @data: opaque data pointer to pass to @test
967 * @wait: if true wait for the inode to be unlocked, if false do not
969 * ifind() searches for the inode specified by @data in the inode
970 * cache. This is a generalized version of ifind_fast() for file systems where
971 * the inode number is not sufficient for unique identification of an inode.
973 * If the inode is in the cache, the inode is returned with an incremented
976 * Otherwise NULL is returned.
978 * Note, @test is called with the inode_lock held, so can't sleep.
980 static struct inode *ifind(struct super_block *sb,
981 struct hlist_head *head, int (*test)(struct inode *, void *),
982 void *data, const int wait)
986 spin_lock(&inode_lock);
987 inode = find_inode(sb, head, test, data);
989 spin_unlock(&inode_lock);
991 wait_on_inode(inode);
994 spin_unlock(&inode_lock);
999 * ifind_fast - internal function, you want ilookup() or iget().
1000 * @sb: super block of file system to search
1001 * @head: head of the list to search
1002 * @ino: inode number to search for
1004 * ifind_fast() searches for the inode @ino in the inode cache. This is for
1005 * file systems where the inode number is sufficient for unique identification
1008 * If the inode is in the cache, the inode is returned with an incremented
1011 * Otherwise NULL is returned.
1013 static struct inode *ifind_fast(struct super_block *sb,
1014 struct hlist_head *head, unsigned long ino)
1016 struct inode *inode;
1018 spin_lock(&inode_lock);
1019 inode = find_inode_fast(sb, head, ino);
1021 spin_unlock(&inode_lock);
1022 wait_on_inode(inode);
1025 spin_unlock(&inode_lock);
1030 * ilookup5_nowait - search for an inode in the inode cache
1031 * @sb: super block of file system to search
1032 * @hashval: hash value (usually inode number) to search for
1033 * @test: callback used for comparisons between inodes
1034 * @data: opaque data pointer to pass to @test
1036 * ilookup5() uses ifind() to search for the inode specified by @hashval and
1037 * @data in the inode cache. This is a generalized version of ilookup() for
1038 * file systems where the inode number is not sufficient for unique
1039 * identification of an inode.
1041 * If the inode is in the cache, the inode is returned with an incremented
1042 * reference count. Note, the inode lock is not waited upon so you have to be
1043 * very careful what you do with the returned inode. You probably should be
1044 * using ilookup5() instead.
1046 * Otherwise NULL is returned.
1048 * Note, @test is called with the inode_lock held, so can't sleep.
1050 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1051 int (*test)(struct inode *, void *), void *data)
1053 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1055 return ifind(sb, head, test, data, 0);
1057 EXPORT_SYMBOL(ilookup5_nowait);
1060 * ilookup5 - search for an inode in the inode cache
1061 * @sb: super block of file system to search
1062 * @hashval: hash value (usually inode number) to search for
1063 * @test: callback used for comparisons between inodes
1064 * @data: opaque data pointer to pass to @test
1066 * ilookup5() uses ifind() to search for the inode specified by @hashval and
1067 * @data in the inode cache. This is a generalized version of ilookup() for
1068 * file systems where the inode number is not sufficient for unique
1069 * identification of an inode.
1071 * If the inode is in the cache, the inode lock is waited upon and the inode is
1072 * returned with an incremented reference count.
1074 * Otherwise NULL is returned.
1076 * Note, @test is called with the inode_lock held, so can't sleep.
1078 struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1079 int (*test)(struct inode *, void *), void *data)
1081 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1083 return ifind(sb, head, test, data, 1);
1085 EXPORT_SYMBOL(ilookup5);
1088 * ilookup - search for an inode in the inode cache
1089 * @sb: super block of file system to search
1090 * @ino: inode number to search for
1092 * ilookup() uses ifind_fast() to search for the inode @ino in the inode cache.
1093 * This is for file systems where the inode number is sufficient for unique
1094 * identification of an inode.
1096 * If the inode is in the cache, the inode is returned with an incremented
1099 * Otherwise NULL is returned.
1101 struct inode *ilookup(struct super_block *sb, unsigned long ino)
1103 struct hlist_head *head = inode_hashtable + hash(sb, ino);
1105 return ifind_fast(sb, head, ino);
1107 EXPORT_SYMBOL(ilookup);
1110 * iget5_locked - obtain an inode from a mounted file system
1111 * @sb: super block of file system
1112 * @hashval: hash value (usually inode number) to get
1113 * @test: callback used for comparisons between inodes
1114 * @set: callback used to initialize a new struct inode
1115 * @data: opaque data pointer to pass to @test and @set
1117 * iget5_locked() uses ifind() to search for the inode specified by @hashval
1118 * and @data in the inode cache and if present it is returned with an increased
1119 * reference count. This is a generalized version of iget_locked() for file
1120 * systems where the inode number is not sufficient for unique identification
1123 * If the inode is not in cache, get_new_inode() is called to allocate a new
1124 * inode and this is returned locked, hashed, and with the I_NEW flag set. The
1125 * file system gets to fill it in before unlocking it via unlock_new_inode().
1127 * Note both @test and @set are called with the inode_lock held, so can't sleep.
1129 struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1130 int (*test)(struct inode *, void *),
1131 int (*set)(struct inode *, void *), void *data)
1133 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1134 struct inode *inode;
1136 inode = ifind(sb, head, test, data, 1);
1140 * get_new_inode() will do the right thing, re-trying the search
1141 * in case it had to block at any point.
1143 return get_new_inode(sb, head, test, set, data);
1145 EXPORT_SYMBOL(iget5_locked);
1148 * iget_locked - obtain an inode from a mounted file system
1149 * @sb: super block of file system
1150 * @ino: inode number to get
1152 * iget_locked() uses ifind_fast() to search for the inode specified by @ino in
1153 * the inode cache and if present it is returned with an increased reference
1154 * count. This is for file systems where the inode number is sufficient for
1155 * unique identification of an inode.
1157 * If the inode is not in cache, get_new_inode_fast() is called to allocate a
1158 * new inode and this is returned locked, hashed, and with the I_NEW flag set.
1159 * The file system gets to fill it in before unlocking it via
1160 * unlock_new_inode().
1162 struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1164 struct hlist_head *head = inode_hashtable + hash(sb, ino);
1165 struct inode *inode;
1167 inode = ifind_fast(sb, head, ino);
1171 * get_new_inode_fast() will do the right thing, re-trying the search
1172 * in case it had to block at any point.
1174 return get_new_inode_fast(sb, head, ino);
1176 EXPORT_SYMBOL(iget_locked);
1178 int insert_inode_locked(struct inode *inode)
1180 struct super_block *sb = inode->i_sb;
1181 ino_t ino = inode->i_ino;
1182 struct hlist_head *head = inode_hashtable + hash(sb, ino);
1184 inode->i_state |= I_NEW;
1186 struct hlist_node *node;
1187 struct inode *old = NULL;
1188 spin_lock(&inode_lock);
1189 hlist_for_each_entry(old, node, head, i_hash) {
1190 if (old->i_ino != ino)
1192 if (old->i_sb != sb)
1194 if (old->i_state & (I_FREEING|I_WILL_FREE))
1198 if (likely(!node)) {
1199 hlist_add_head(&inode->i_hash, head);
1200 spin_unlock(&inode_lock);
1204 spin_unlock(&inode_lock);
1206 if (unlikely(!inode_unhashed(old))) {
1213 EXPORT_SYMBOL(insert_inode_locked);
1215 int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1216 int (*test)(struct inode *, void *), void *data)
1218 struct super_block *sb = inode->i_sb;
1219 struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1221 inode->i_state |= I_NEW;
1224 struct hlist_node *node;
1225 struct inode *old = NULL;
1227 spin_lock(&inode_lock);
1228 hlist_for_each_entry(old, node, head, i_hash) {
1229 if (old->i_sb != sb)
1231 if (!test(old, data))
1233 if (old->i_state & (I_FREEING|I_WILL_FREE))
1237 if (likely(!node)) {
1238 hlist_add_head(&inode->i_hash, head);
1239 spin_unlock(&inode_lock);
1243 spin_unlock(&inode_lock);
1245 if (unlikely(!inode_unhashed(old))) {
1252 EXPORT_SYMBOL(insert_inode_locked4);
1255 int generic_delete_inode(struct inode *inode)
1259 EXPORT_SYMBOL(generic_delete_inode);
1262 * Normal UNIX filesystem behaviour: delete the
1263 * inode when the usage count drops to zero, and
1266 int generic_drop_inode(struct inode *inode)
1268 return !inode->i_nlink || inode_unhashed(inode);
1270 EXPORT_SYMBOL_GPL(generic_drop_inode);
1273 * Called when we're dropping the last reference
1276 * Call the FS "drop_inode()" function, defaulting to
1277 * the legacy UNIX filesystem behaviour. If it tells
1278 * us to evict inode, do so. Otherwise, retain inode
1279 * in cache if fs is alive, sync and evict if fs is
1282 static void iput_final(struct inode *inode)
1284 struct super_block *sb = inode->i_sb;
1285 const struct super_operations *op = inode->i_sb->s_op;
1288 if (op && op->drop_inode)
1289 drop = op->drop_inode(inode);
1291 drop = generic_drop_inode(inode);
1294 if (sb->s_flags & MS_ACTIVE) {
1295 inode->i_state |= I_REFERENCED;
1296 if (!(inode->i_state & (I_DIRTY|I_SYNC))) {
1297 inode_lru_list_add(inode);
1299 spin_unlock(&inode_lock);
1302 WARN_ON(inode->i_state & I_NEW);
1303 inode->i_state |= I_WILL_FREE;
1304 spin_unlock(&inode_lock);
1305 write_inode_now(inode, 1);
1306 spin_lock(&inode_lock);
1307 WARN_ON(inode->i_state & I_NEW);
1308 inode->i_state &= ~I_WILL_FREE;
1309 __remove_inode_hash(inode);
1311 WARN_ON(inode->i_state & I_NEW);
1312 inode->i_state |= I_FREEING;
1315 * After we delete the inode from the LRU here, we avoid moving dirty
1316 * inodes back onto the LRU now because I_FREEING is set and hence
1317 * writeback_single_inode() won't move the inode around.
1319 inode_lru_list_del(inode);
1321 list_del_init(&inode->i_sb_list);
1322 spin_unlock(&inode_lock);
1324 remove_inode_hash(inode);
1325 wake_up_inode(inode);
1326 BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
1327 destroy_inode(inode);
1331 * iput - put an inode
1332 * @inode: inode to put
1334 * Puts an inode, dropping its usage count. If the inode use count hits
1335 * zero, the inode is then freed and may also be destroyed.
1337 * Consequently, iput() can sleep.
1339 void iput(struct inode *inode)
1342 BUG_ON(inode->i_state & I_CLEAR);
1344 if (atomic_dec_and_lock(&inode->i_count, &inode_lock))
1348 EXPORT_SYMBOL(iput);
1351 * bmap - find a block number in a file
1352 * @inode: inode of file
1353 * @block: block to find
1355 * Returns the block number on the device holding the inode that
1356 * is the disk block number for the block of the file requested.
1357 * That is, asked for block 4 of inode 1 the function will return the
1358 * disk block relative to the disk start that holds that block of the
1361 sector_t bmap(struct inode *inode, sector_t block)
1364 if (inode->i_mapping->a_ops->bmap)
1365 res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1368 EXPORT_SYMBOL(bmap);
1371 * With relative atime, only update atime if the previous atime is
1372 * earlier than either the ctime or mtime or if at least a day has
1373 * passed since the last atime update.
1375 static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1376 struct timespec now)
1379 if (!(mnt->mnt_flags & MNT_RELATIME))
1382 * Is mtime younger than atime? If yes, update atime:
1384 if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1387 * Is ctime younger than atime? If yes, update atime:
1389 if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1393 * Is the previous atime value older than a day? If yes,
1396 if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1399 * Good, we can skip the atime update:
1405 * touch_atime - update the access time
1406 * @mnt: mount the inode is accessed on
1407 * @dentry: dentry accessed
1409 * Update the accessed time on an inode and mark it for writeback.
1410 * This function automatically handles read only file systems and media,
1411 * as well as the "noatime" flag and inode specific "noatime" markers.
1413 void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
1415 struct inode *inode = dentry->d_inode;
1416 struct timespec now;
1418 if (inode->i_flags & S_NOATIME)
1420 if (IS_NOATIME(inode))
1422 if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1425 if (mnt->mnt_flags & MNT_NOATIME)
1427 if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1430 now = current_fs_time(inode->i_sb);
1432 if (!relatime_need_update(mnt, inode, now))
1435 if (timespec_equal(&inode->i_atime, &now))
1438 if (mnt_want_write(mnt))
1441 inode->i_atime = now;
1442 mark_inode_dirty_sync(inode);
1443 mnt_drop_write(mnt);
1445 EXPORT_SYMBOL(touch_atime);
1448 * file_update_time - update mtime and ctime time
1449 * @file: file accessed
1451 * Update the mtime and ctime members of an inode and mark the inode
1452 * for writeback. Note that this function is meant exclusively for
1453 * usage in the file write path of filesystems, and filesystems may
1454 * choose to explicitly ignore update via this function with the
1455 * S_NOCMTIME inode flag, e.g. for network filesystem where these
1456 * timestamps are handled by the server.
1459 void file_update_time(struct file *file)
1461 struct inode *inode = file->f_path.dentry->d_inode;
1462 struct timespec now;
1463 enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
1465 /* First try to exhaust all avenues to not sync */
1466 if (IS_NOCMTIME(inode))
1469 now = current_fs_time(inode->i_sb);
1470 if (!timespec_equal(&inode->i_mtime, &now))
1473 if (!timespec_equal(&inode->i_ctime, &now))
1476 if (IS_I_VERSION(inode))
1477 sync_it |= S_VERSION;
1482 /* Finally allowed to write? Takes lock. */
1483 if (mnt_want_write_file(file))
1486 /* Only change inode inside the lock region */
1487 if (sync_it & S_VERSION)
1488 inode_inc_iversion(inode);
1489 if (sync_it & S_CTIME)
1490 inode->i_ctime = now;
1491 if (sync_it & S_MTIME)
1492 inode->i_mtime = now;
1493 mark_inode_dirty_sync(inode);
1494 mnt_drop_write(file->f_path.mnt);
1496 EXPORT_SYMBOL(file_update_time);
1498 int inode_needs_sync(struct inode *inode)
1502 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1506 EXPORT_SYMBOL(inode_needs_sync);
1508 int inode_wait(void *word)
1513 EXPORT_SYMBOL(inode_wait);
1516 * If we try to find an inode in the inode hash while it is being
1517 * deleted, we have to wait until the filesystem completes its
1518 * deletion before reporting that it isn't found. This function waits
1519 * until the deletion _might_ have completed. Callers are responsible
1520 * to recheck inode state.
1522 * It doesn't matter if I_NEW is not set initially, a call to
1523 * wake_up_inode() after removing from the hash list will DTRT.
1525 * This is called with inode_lock held.
1527 static void __wait_on_freeing_inode(struct inode *inode)
1529 wait_queue_head_t *wq;
1530 DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
1531 wq = bit_waitqueue(&inode->i_state, __I_NEW);
1532 prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1533 spin_unlock(&inode_lock);
1535 finish_wait(wq, &wait.wait);
1536 spin_lock(&inode_lock);
1539 static __initdata unsigned long ihash_entries;
1540 static int __init set_ihash_entries(char *str)
1544 ihash_entries = simple_strtoul(str, &str, 0);
1547 __setup("ihash_entries=", set_ihash_entries);
1550 * Initialize the waitqueues and inode hash table.
1552 void __init inode_init_early(void)
1556 /* If hashes are distributed across NUMA nodes, defer
1557 * hash allocation until vmalloc space is available.
1563 alloc_large_system_hash("Inode-cache",
1564 sizeof(struct hlist_head),
1572 for (loop = 0; loop < (1 << i_hash_shift); loop++)
1573 INIT_HLIST_HEAD(&inode_hashtable[loop]);
1576 void __init inode_init(void)
1580 /* inode slab cache */
1581 inode_cachep = kmem_cache_create("inode_cache",
1582 sizeof(struct inode),
1584 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1587 register_shrinker(&icache_shrinker);
1588 percpu_counter_init(&nr_inodes, 0);
1589 percpu_counter_init(&nr_inodes_unused, 0);
1591 /* Hash may have been set up in inode_init_early */
1596 alloc_large_system_hash("Inode-cache",
1597 sizeof(struct hlist_head),
1605 for (loop = 0; loop < (1 << i_hash_shift); loop++)
1606 INIT_HLIST_HEAD(&inode_hashtable[loop]);
1609 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
1611 inode->i_mode = mode;
1612 if (S_ISCHR(mode)) {
1613 inode->i_fop = &def_chr_fops;
1614 inode->i_rdev = rdev;
1615 } else if (S_ISBLK(mode)) {
1616 inode->i_fop = &def_blk_fops;
1617 inode->i_rdev = rdev;
1618 } else if (S_ISFIFO(mode))
1619 inode->i_fop = &def_fifo_fops;
1620 else if (S_ISSOCK(mode))
1621 inode->i_fop = &bad_sock_fops;
1623 printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
1624 " inode %s:%lu\n", mode, inode->i_sb->s_id,
1627 EXPORT_SYMBOL(init_special_inode);
1630 * Init uid,gid,mode for new inode according to posix standards
1632 * @dir: Directory inode
1633 * @mode: mode of the new inode
1635 void inode_init_owner(struct inode *inode, const struct inode *dir,
1638 inode->i_uid = current_fsuid();
1639 if (dir && dir->i_mode & S_ISGID) {
1640 inode->i_gid = dir->i_gid;
1644 inode->i_gid = current_fsgid();
1645 inode->i_mode = mode;
1647 EXPORT_SYMBOL(inode_init_owner);