Root/fs/inode.c

1/*
2 * linux/fs/inode.c
3 *
4 * (C) 1997 Linus Torvalds
5 */
6
7#include <linux/fs.h>
8#include <linux/mm.h>
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/inotify.h>
24#include <linux/fsnotify.h>
25#include <linux/mount.h>
26#include <linux/async.h>
27#include <linux/posix_acl.h>
28
29/*
30 * This is needed for the following functions:
31 * - inode_has_buffers
32 * - invalidate_inode_buffers
33 * - invalidate_bdev
34 *
35 * FIXME: remove all knowledge of the buffer layer from this file
36 */
37#include <linux/buffer_head.h>
38
39/*
40 * New inode.c implementation.
41 *
42 * This implementation has the basic premise of trying
43 * to be extremely low-overhead and SMP-safe, yet be
44 * simple enough to be "obviously correct".
45 *
46 * Famous last words.
47 */
48
49/* inode dynamic allocation 1999, Andrea Arcangeli <andrea@suse.de> */
50
51/* #define INODE_PARANOIA 1 */
52/* #define INODE_DEBUG 1 */
53
54/*
55 * Inode lookup is no longer as critical as it used to be:
56 * most of the lookups are going to be through the dcache.
57 */
58#define I_HASHBITS i_hash_shift
59#define I_HASHMASK i_hash_mask
60
61static unsigned int i_hash_mask __read_mostly;
62static unsigned int i_hash_shift __read_mostly;
63
64/*
65 * Each inode can be on two separate lists. One is
66 * the hash list of the inode, used for lookups. The
67 * other linked list is the "type" list:
68 * "in_use" - valid inode, i_count > 0, i_nlink > 0
69 * "dirty" - as "in_use" but also dirty
70 * "unused" - valid inode, i_count = 0
71 *
72 * A "dirty" list is maintained for each super block,
73 * allowing for low-overhead inode sync() operations.
74 */
75
76LIST_HEAD(inode_in_use);
77LIST_HEAD(inode_unused);
78static struct hlist_head *inode_hashtable __read_mostly;
79
80/*
81 * A simple spinlock to protect the list manipulations.
82 *
83 * NOTE! You also have to own the lock if you change
84 * the i_state of an inode while it is in use..
85 */
86DEFINE_SPINLOCK(inode_lock);
87
88/*
89 * iprune_sem provides exclusion between the kswapd or try_to_free_pages
90 * icache shrinking path, and the umount path. Without this exclusion,
91 * by the time prune_icache calls iput for the inode whose pages it has
92 * been invalidating, or by the time it calls clear_inode & destroy_inode
93 * from its final dispose_list, the struct super_block they refer to
94 * (for inode->i_sb->s_op) may already have been freed and reused.
95 *
96 * We make this an rwsem because the fastpath is icache shrinking. In
97 * some cases a filesystem may be doing a significant amount of work in
98 * its inode reclaim code, so this should improve parallelism.
99 */
100static DECLARE_RWSEM(iprune_sem);
101
102/*
103 * Statistics gathering..
104 */
105struct inodes_stat_t inodes_stat;
106
107static struct kmem_cache *inode_cachep __read_mostly;
108
109static void wake_up_inode(struct inode *inode)
110{
111    /*
112     * Prevent speculative execution through spin_unlock(&inode_lock);
113     */
114    smp_mb();
115    wake_up_bit(&inode->i_state, __I_NEW);
116}
117
118/**
119 * inode_init_always - perform inode structure intialisation
120 * @sb: superblock inode belongs to
121 * @inode: inode to initialise
122 *
123 * These are initializations that need to be done on every inode
124 * allocation as the fields are not initialised by slab allocation.
125 */
126int inode_init_always(struct super_block *sb, struct inode *inode)
127{
128    static const struct address_space_operations empty_aops;
129    static const struct inode_operations empty_iops;
130    static const struct file_operations empty_fops;
131    struct address_space *const mapping = &inode->i_data;
132
133    inode->i_sb = sb;
134    inode->i_blkbits = sb->s_blocksize_bits;
135    inode->i_flags = 0;
136    atomic_set(&inode->i_count, 1);
137    inode->i_op = &empty_iops;
138    inode->i_fop = &empty_fops;
139    inode->i_nlink = 1;
140    inode->i_uid = 0;
141    inode->i_gid = 0;
142    atomic_set(&inode->i_writecount, 0);
143    inode->i_size = 0;
144    inode->i_blocks = 0;
145    inode->i_bytes = 0;
146    inode->i_generation = 0;
147#ifdef CONFIG_QUOTA
148    memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
149#endif
150    inode->i_pipe = NULL;
151    inode->i_bdev = NULL;
152    inode->i_cdev = NULL;
153    inode->i_rdev = 0;
154    inode->dirtied_when = 0;
155
156    if (security_inode_alloc(inode))
157        goto out;
158    spin_lock_init(&inode->i_lock);
159    lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
160
161    mutex_init(&inode->i_mutex);
162    lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
163
164    init_rwsem(&inode->i_alloc_sem);
165    lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
166
167    mapping->a_ops = &empty_aops;
168    mapping->host = inode;
169    mapping->flags = 0;
170    mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
171    mapping->assoc_mapping = NULL;
172    mapping->backing_dev_info = &default_backing_dev_info;
173    mapping->writeback_index = 0;
174
175    /*
176     * If the block_device provides a backing_dev_info for client
177     * inodes then use that. Otherwise the inode share the bdev's
178     * backing_dev_info.
179     */
180    if (sb->s_bdev) {
181        struct backing_dev_info *bdi;
182
183        bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
184        mapping->backing_dev_info = bdi;
185    }
186    inode->i_private = NULL;
187    inode->i_mapping = mapping;
188#ifdef CONFIG_FS_POSIX_ACL
189    inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
190#endif
191
192#ifdef CONFIG_FSNOTIFY
193    inode->i_fsnotify_mask = 0;
194#endif
195
196    return 0;
197out:
198    return -ENOMEM;
199}
200EXPORT_SYMBOL(inode_init_always);
201
202static struct inode *alloc_inode(struct super_block *sb)
203{
204    struct inode *inode;
205
206    if (sb->s_op->alloc_inode)
207        inode = sb->s_op->alloc_inode(sb);
208    else
209        inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
210
211    if (!inode)
212        return NULL;
213
214    if (unlikely(inode_init_always(sb, inode))) {
215        if (inode->i_sb->s_op->destroy_inode)
216            inode->i_sb->s_op->destroy_inode(inode);
217        else
218            kmem_cache_free(inode_cachep, inode);
219        return NULL;
220    }
221
222    return inode;
223}
224
225void __destroy_inode(struct inode *inode)
226{
227    BUG_ON(inode_has_buffers(inode));
228    security_inode_free(inode);
229    fsnotify_inode_delete(inode);
230#ifdef CONFIG_FS_POSIX_ACL
231    if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
232        posix_acl_release(inode->i_acl);
233    if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
234        posix_acl_release(inode->i_default_acl);
235#endif
236}
237EXPORT_SYMBOL(__destroy_inode);
238
239void destroy_inode(struct inode *inode)
240{
241    __destroy_inode(inode);
242    if (inode->i_sb->s_op->destroy_inode)
243        inode->i_sb->s_op->destroy_inode(inode);
244    else
245        kmem_cache_free(inode_cachep, (inode));
246}
247
248/*
249 * These are initializations that only need to be done
250 * once, because the fields are idempotent across use
251 * of the inode, so let the slab aware of that.
252 */
253void inode_init_once(struct inode *inode)
254{
255    memset(inode, 0, sizeof(*inode));
256    INIT_HLIST_NODE(&inode->i_hash);
257    INIT_LIST_HEAD(&inode->i_dentry);
258    INIT_LIST_HEAD(&inode->i_devices);
259    INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
260    spin_lock_init(&inode->i_data.tree_lock);
261    spin_lock_init(&inode->i_data.i_mmap_lock);
262    INIT_LIST_HEAD(&inode->i_data.private_list);
263    spin_lock_init(&inode->i_data.private_lock);
264    INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
265    INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
266    i_size_ordered_init(inode);
267#ifdef CONFIG_INOTIFY
268    INIT_LIST_HEAD(&inode->inotify_watches);
269    mutex_init(&inode->inotify_mutex);
270#endif
271#ifdef CONFIG_FSNOTIFY
272    INIT_HLIST_HEAD(&inode->i_fsnotify_mark_entries);
273#endif
274}
275EXPORT_SYMBOL(inode_init_once);
276
277static void init_once(void *foo)
278{
279    struct inode *inode = (struct inode *) foo;
280
281    inode_init_once(inode);
282}
283
284/*
285 * inode_lock must be held
286 */
287void __iget(struct inode *inode)
288{
289    if (atomic_read(&inode->i_count)) {
290        atomic_inc(&inode->i_count);
291        return;
292    }
293    atomic_inc(&inode->i_count);
294    if (!(inode->i_state & (I_DIRTY|I_SYNC)))
295        list_move(&inode->i_list, &inode_in_use);
296    inodes_stat.nr_unused--;
297}
298
299/**
300 * clear_inode - clear an inode
301 * @inode: inode to clear
302 *
303 * This is called by the filesystem to tell us
304 * that the inode is no longer useful. We just
305 * terminate it with extreme prejudice.
306 */
307void clear_inode(struct inode *inode)
308{
309    might_sleep();
310    invalidate_inode_buffers(inode);
311
312    BUG_ON(inode->i_data.nrpages);
313    BUG_ON(!(inode->i_state & I_FREEING));
314    BUG_ON(inode->i_state & I_CLEAR);
315    inode_sync_wait(inode);
316    if (inode->i_sb->s_op->clear_inode)
317        inode->i_sb->s_op->clear_inode(inode);
318    if (S_ISBLK(inode->i_mode) && inode->i_bdev)
319        bd_forget(inode);
320    if (S_ISCHR(inode->i_mode) && inode->i_cdev)
321        cd_forget(inode);
322    inode->i_state = I_CLEAR;
323}
324EXPORT_SYMBOL(clear_inode);
325
326/*
327 * dispose_list - dispose of the contents of a local list
328 * @head: the head of the list to free
329 *
330 * Dispose-list gets a local list with local inodes in it, so it doesn't
331 * need to worry about list corruption and SMP locks.
332 */
333static void dispose_list(struct list_head *head)
334{
335    int nr_disposed = 0;
336
337    while (!list_empty(head)) {
338        struct inode *inode;
339
340        inode = list_first_entry(head, struct inode, i_list);
341        list_del(&inode->i_list);
342
343        if (inode->i_data.nrpages)
344            truncate_inode_pages(&inode->i_data, 0);
345        clear_inode(inode);
346
347        spin_lock(&inode_lock);
348        hlist_del_init(&inode->i_hash);
349        list_del_init(&inode->i_sb_list);
350        spin_unlock(&inode_lock);
351
352        wake_up_inode(inode);
353        destroy_inode(inode);
354        nr_disposed++;
355    }
356    spin_lock(&inode_lock);
357    inodes_stat.nr_inodes -= nr_disposed;
358    spin_unlock(&inode_lock);
359}
360
361/*
362 * Invalidate all inodes for a device.
363 */
364static int invalidate_list(struct list_head *head, struct list_head *dispose)
365{
366    struct list_head *next;
367    int busy = 0, count = 0;
368
369    next = head->next;
370    for (;;) {
371        struct list_head *tmp = next;
372        struct inode *inode;
373
374        /*
375         * We can reschedule here without worrying about the list's
376         * consistency because the per-sb list of inodes must not
377         * change during umount anymore, and because iprune_sem keeps
378         * shrink_icache_memory() away.
379         */
380        cond_resched_lock(&inode_lock);
381
382        next = next->next;
383        if (tmp == head)
384            break;
385        inode = list_entry(tmp, struct inode, i_sb_list);
386        if (inode->i_state & I_NEW)
387            continue;
388        invalidate_inode_buffers(inode);
389        if (!atomic_read(&inode->i_count)) {
390            list_move(&inode->i_list, dispose);
391            WARN_ON(inode->i_state & I_NEW);
392            inode->i_state |= I_FREEING;
393            count++;
394            continue;
395        }
396        busy = 1;
397    }
398    /* only unused inodes may be cached with i_count zero */
399    inodes_stat.nr_unused -= count;
400    return busy;
401}
402
403/**
404 * invalidate_inodes - discard the inodes on a device
405 * @sb: superblock
406 *
407 * Discard all of the inodes for a given superblock. If the discard
408 * fails because there are busy inodes then a non zero value is returned.
409 * If the discard is successful all the inodes have been discarded.
410 */
411int invalidate_inodes(struct super_block *sb)
412{
413    int busy;
414    LIST_HEAD(throw_away);
415
416    down_write(&iprune_sem);
417    spin_lock(&inode_lock);
418    inotify_unmount_inodes(&sb->s_inodes);
419    fsnotify_unmount_inodes(&sb->s_inodes);
420    busy = invalidate_list(&sb->s_inodes, &throw_away);
421    spin_unlock(&inode_lock);
422
423    dispose_list(&throw_away);
424    up_write(&iprune_sem);
425
426    return busy;
427}
428EXPORT_SYMBOL(invalidate_inodes);
429
430static int can_unuse(struct inode *inode)
431{
432    if (inode->i_state)
433        return 0;
434    if (inode_has_buffers(inode))
435        return 0;
436    if (atomic_read(&inode->i_count))
437        return 0;
438    if (inode->i_data.nrpages)
439        return 0;
440    return 1;
441}
442
443/*
444 * Scan `goal' inodes on the unused list for freeable ones. They are moved to
445 * a temporary list and then are freed outside inode_lock by dispose_list().
446 *
447 * Any inodes which are pinned purely because of attached pagecache have their
448 * pagecache removed. We expect the final iput() on that inode to add it to
449 * the front of the inode_unused list. So look for it there and if the
450 * inode is still freeable, proceed. The right inode is found 99.9% of the
451 * time in testing on a 4-way.
452 *
453 * If the inode has metadata buffers attached to mapping->private_list then
454 * try to remove them.
455 */
456static void prune_icache(int nr_to_scan)
457{
458    LIST_HEAD(freeable);
459    int nr_pruned = 0;
460    int nr_scanned;
461    unsigned long reap = 0;
462
463    down_read(&iprune_sem);
464    spin_lock(&inode_lock);
465    for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
466        struct inode *inode;
467
468        if (list_empty(&inode_unused))
469            break;
470
471        inode = list_entry(inode_unused.prev, struct inode, i_list);
472
473        if (inode->i_state || atomic_read(&inode->i_count)) {
474            list_move(&inode->i_list, &inode_unused);
475            continue;
476        }
477        if (inode_has_buffers(inode) || inode->i_data.nrpages) {
478            __iget(inode);
479            spin_unlock(&inode_lock);
480            if (remove_inode_buffers(inode))
481                reap += invalidate_mapping_pages(&inode->i_data,
482                                0, -1);
483            iput(inode);
484            spin_lock(&inode_lock);
485
486            if (inode != list_entry(inode_unused.next,
487                        struct inode, i_list))
488                continue; /* wrong inode or list_empty */
489            if (!can_unuse(inode))
490                continue;
491        }
492        list_move(&inode->i_list, &freeable);
493        WARN_ON(inode->i_state & I_NEW);
494        inode->i_state |= I_FREEING;
495        nr_pruned++;
496    }
497    inodes_stat.nr_unused -= nr_pruned;
498    if (current_is_kswapd())
499        __count_vm_events(KSWAPD_INODESTEAL, reap);
500    else
501        __count_vm_events(PGINODESTEAL, reap);
502    spin_unlock(&inode_lock);
503
504    dispose_list(&freeable);
505    up_read(&iprune_sem);
506}
507
508/*
509 * shrink_icache_memory() will attempt to reclaim some unused inodes. Here,
510 * "unused" means that no dentries are referring to the inodes: the files are
511 * not open and the dcache references to those inodes have already been
512 * reclaimed.
513 *
514 * This function is passed the number of inodes to scan, and it returns the
515 * total number of remaining possibly-reclaimable inodes.
516 */
517static int shrink_icache_memory(int nr, gfp_t gfp_mask)
518{
519    if (nr) {
520        /*
521         * Nasty deadlock avoidance. We may hold various FS locks,
522         * and we don't want to recurse into the FS that called us
523         * in clear_inode() and friends..
524         */
525        if (!(gfp_mask & __GFP_FS))
526            return -1;
527        prune_icache(nr);
528    }
529    return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
530}
531
532static struct shrinker icache_shrinker = {
533    .shrink = shrink_icache_memory,
534    .seeks = DEFAULT_SEEKS,
535};
536
537static void __wait_on_freeing_inode(struct inode *inode);
538/*
539 * Called with the inode lock held.
540 * NOTE: we are not increasing the inode-refcount, you must call __iget()
541 * by hand after calling find_inode now! This simplifies iunique and won't
542 * add any additional branch in the common code.
543 */
544static struct inode *find_inode(struct super_block *sb,
545                struct hlist_head *head,
546                int (*test)(struct inode *, void *),
547                void *data)
548{
549    struct hlist_node *node;
550    struct inode *inode = NULL;
551
552repeat:
553    hlist_for_each_entry(inode, node, head, i_hash) {
554        if (inode->i_sb != sb)
555            continue;
556        if (!test(inode, data))
557            continue;
558        if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
559            __wait_on_freeing_inode(inode);
560            goto repeat;
561        }
562        break;
563    }
564    return node ? inode : NULL;
565}
566
567/*
568 * find_inode_fast is the fast path version of find_inode, see the comment at
569 * iget_locked for details.
570 */
571static struct inode *find_inode_fast(struct super_block *sb,
572                struct hlist_head *head, unsigned long ino)
573{
574    struct hlist_node *node;
575    struct inode *inode = NULL;
576
577repeat:
578    hlist_for_each_entry(inode, node, head, i_hash) {
579        if (inode->i_ino != ino)
580            continue;
581        if (inode->i_sb != sb)
582            continue;
583        if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
584            __wait_on_freeing_inode(inode);
585            goto repeat;
586        }
587        break;
588    }
589    return node ? inode : NULL;
590}
591
592static unsigned long hash(struct super_block *sb, unsigned long hashval)
593{
594    unsigned long tmp;
595
596    tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
597            L1_CACHE_BYTES;
598    tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
599    return tmp & I_HASHMASK;
600}
601
602static inline void
603__inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
604            struct inode *inode)
605{
606    inodes_stat.nr_inodes++;
607    list_add(&inode->i_list, &inode_in_use);
608    list_add(&inode->i_sb_list, &sb->s_inodes);
609    if (head)
610        hlist_add_head(&inode->i_hash, head);
611}
612
613/**
614 * inode_add_to_lists - add a new inode to relevant lists
615 * @sb: superblock inode belongs to
616 * @inode: inode to mark in use
617 *
618 * When an inode is allocated it needs to be accounted for, added to the in use
619 * list, the owning superblock and the inode hash. This needs to be done under
620 * the inode_lock, so export a function to do this rather than the inode lock
621 * itself. We calculate the hash list to add to here so it is all internal
622 * which requires the caller to have already set up the inode number in the
623 * inode to add.
624 */
625void inode_add_to_lists(struct super_block *sb, struct inode *inode)
626{
627    struct hlist_head *head = inode_hashtable + hash(sb, inode->i_ino);
628
629    spin_lock(&inode_lock);
630    __inode_add_to_lists(sb, head, inode);
631    spin_unlock(&inode_lock);
632}
633EXPORT_SYMBOL_GPL(inode_add_to_lists);
634
635/**
636 * new_inode - obtain an inode
637 * @sb: superblock
638 *
639 * Allocates a new inode for given superblock. The default gfp_mask
640 * for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
641 * If HIGHMEM pages are unsuitable or it is known that pages allocated
642 * for the page cache are not reclaimable or migratable,
643 * mapping_set_gfp_mask() must be called with suitable flags on the
644 * newly created inode's mapping
645 *
646 */
647struct inode *new_inode(struct super_block *sb)
648{
649    /*
650     * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
651     * error if st_ino won't fit in target struct field. Use 32bit counter
652     * here to attempt to avoid that.
653     */
654    static unsigned int last_ino;
655    struct inode *inode;
656
657    spin_lock_prefetch(&inode_lock);
658
659    inode = alloc_inode(sb);
660    if (inode) {
661        spin_lock(&inode_lock);
662        __inode_add_to_lists(sb, NULL, inode);
663        inode->i_ino = ++last_ino;
664        inode->i_state = 0;
665        spin_unlock(&inode_lock);
666    }
667    return inode;
668}
669EXPORT_SYMBOL(new_inode);
670
671void unlock_new_inode(struct inode *inode)
672{
673#ifdef CONFIG_DEBUG_LOCK_ALLOC
674    if (inode->i_mode & S_IFDIR) {
675        struct file_system_type *type = inode->i_sb->s_type;
676
677        /* Set new key only if filesystem hasn't already changed it */
678        if (!lockdep_match_class(&inode->i_mutex,
679            &type->i_mutex_key)) {
680            /*
681             * ensure nobody is actually holding i_mutex
682             */
683            mutex_destroy(&inode->i_mutex);
684            mutex_init(&inode->i_mutex);
685            lockdep_set_class(&inode->i_mutex,
686                      &type->i_mutex_dir_key);
687        }
688    }
689#endif
690    /*
691     * This is special! We do not need the spinlock when clearing I_NEW,
692     * because we're guaranteed that nobody else tries to do anything about
693     * the state of the inode when it is locked, as we just created it (so
694     * there can be no old holders that haven't tested I_NEW).
695     * However we must emit the memory barrier so that other CPUs reliably
696     * see the clearing of I_NEW after the other inode initialisation has
697     * completed.
698     */
699    smp_mb();
700    WARN_ON(!(inode->i_state & I_NEW));
701    inode->i_state &= ~I_NEW;
702    wake_up_inode(inode);
703}
704EXPORT_SYMBOL(unlock_new_inode);
705
706/*
707 * This is called without the inode lock held.. Be careful.
708 *
709 * We no longer cache the sb_flags in i_flags - see fs.h
710 * -- rmk@arm.uk.linux.org
711 */
712static struct inode *get_new_inode(struct super_block *sb,
713                struct hlist_head *head,
714                int (*test)(struct inode *, void *),
715                int (*set)(struct inode *, void *),
716                void *data)
717{
718    struct inode *inode;
719
720    inode = alloc_inode(sb);
721    if (inode) {
722        struct inode *old;
723
724        spin_lock(&inode_lock);
725        /* We released the lock, so.. */
726        old = find_inode(sb, head, test, data);
727        if (!old) {
728            if (set(inode, data))
729                goto set_failed;
730
731            __inode_add_to_lists(sb, head, inode);
732            inode->i_state = I_NEW;
733            spin_unlock(&inode_lock);
734
735            /* Return the locked inode with I_NEW set, the
736             * caller is responsible for filling in the contents
737             */
738            return inode;
739        }
740
741        /*
742         * Uhhuh, somebody else created the same inode under
743         * us. Use the old inode instead of the one we just
744         * allocated.
745         */
746        __iget(old);
747        spin_unlock(&inode_lock);
748        destroy_inode(inode);
749        inode = old;
750        wait_on_inode(inode);
751    }
752    return inode;
753
754set_failed:
755    spin_unlock(&inode_lock);
756    destroy_inode(inode);
757    return NULL;
758}
759
760/*
761 * get_new_inode_fast is the fast path version of get_new_inode, see the
762 * comment at iget_locked for details.
763 */
764static struct inode *get_new_inode_fast(struct super_block *sb,
765                struct hlist_head *head, unsigned long ino)
766{
767    struct inode *inode;
768
769    inode = alloc_inode(sb);
770    if (inode) {
771        struct inode *old;
772
773        spin_lock(&inode_lock);
774        /* We released the lock, so.. */
775        old = find_inode_fast(sb, head, ino);
776        if (!old) {
777            inode->i_ino = ino;
778            __inode_add_to_lists(sb, head, inode);
779            inode->i_state = I_NEW;
780            spin_unlock(&inode_lock);
781
782            /* Return the locked inode with I_NEW set, the
783             * caller is responsible for filling in the contents
784             */
785            return inode;
786        }
787
788        /*
789         * Uhhuh, somebody else created the same inode under
790         * us. Use the old inode instead of the one we just
791         * allocated.
792         */
793        __iget(old);
794        spin_unlock(&inode_lock);
795        destroy_inode(inode);
796        inode = old;
797        wait_on_inode(inode);
798    }
799    return inode;
800}
801
802/**
803 * iunique - get a unique inode number
804 * @sb: superblock
805 * @max_reserved: highest reserved inode number
806 *
807 * Obtain an inode number that is unique on the system for a given
808 * superblock. This is used by file systems that have no natural
809 * permanent inode numbering system. An inode number is returned that
810 * is higher than the reserved limit but unique.
811 *
812 * BUGS:
813 * With a large number of inodes live on the file system this function
814 * currently becomes quite slow.
815 */
816ino_t iunique(struct super_block *sb, ino_t max_reserved)
817{
818    /*
819     * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
820     * error if st_ino won't fit in target struct field. Use 32bit counter
821     * here to attempt to avoid that.
822     */
823    static unsigned int counter;
824    struct inode *inode;
825    struct hlist_head *head;
826    ino_t res;
827
828    spin_lock(&inode_lock);
829    do {
830        if (counter <= max_reserved)
831            counter = max_reserved + 1;
832        res = counter++;
833        head = inode_hashtable + hash(sb, res);
834        inode = find_inode_fast(sb, head, res);
835    } while (inode != NULL);
836    spin_unlock(&inode_lock);
837
838    return res;
839}
840EXPORT_SYMBOL(iunique);
841
842struct inode *igrab(struct inode *inode)
843{
844    spin_lock(&inode_lock);
845    if (!(inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)))
846        __iget(inode);
847    else
848        /*
849         * Handle the case where s_op->clear_inode is not been
850         * called yet, and somebody is calling igrab
851         * while the inode is getting freed.
852         */
853        inode = NULL;
854    spin_unlock(&inode_lock);
855    return inode;
856}
857EXPORT_SYMBOL(igrab);
858
859/**
860 * ifind - internal function, you want ilookup5() or iget5().
861 * @sb: super block of file system to search
862 * @head: the head of the list to search
863 * @test: callback used for comparisons between inodes
864 * @data: opaque data pointer to pass to @test
865 * @wait: if true wait for the inode to be unlocked, if false do not
866 *
867 * ifind() searches for the inode specified by @data in the inode
868 * cache. This is a generalized version of ifind_fast() for file systems where
869 * the inode number is not sufficient for unique identification of an inode.
870 *
871 * If the inode is in the cache, the inode is returned with an incremented
872 * reference count.
873 *
874 * Otherwise NULL is returned.
875 *
876 * Note, @test is called with the inode_lock held, so can't sleep.
877 */
878static struct inode *ifind(struct super_block *sb,
879        struct hlist_head *head, int (*test)(struct inode *, void *),
880        void *data, const int wait)
881{
882    struct inode *inode;
883
884    spin_lock(&inode_lock);
885    inode = find_inode(sb, head, test, data);
886    if (inode) {
887        __iget(inode);
888        spin_unlock(&inode_lock);
889        if (likely(wait))
890            wait_on_inode(inode);
891        return inode;
892    }
893    spin_unlock(&inode_lock);
894    return NULL;
895}
896
897/**
898 * ifind_fast - internal function, you want ilookup() or iget().
899 * @sb: super block of file system to search
900 * @head: head of the list to search
901 * @ino: inode number to search for
902 *
903 * ifind_fast() searches for the inode @ino in the inode cache. This is for
904 * file systems where the inode number is sufficient for unique identification
905 * of an inode.
906 *
907 * If the inode is in the cache, the inode is returned with an incremented
908 * reference count.
909 *
910 * Otherwise NULL is returned.
911 */
912static struct inode *ifind_fast(struct super_block *sb,
913        struct hlist_head *head, unsigned long ino)
914{
915    struct inode *inode;
916
917    spin_lock(&inode_lock);
918    inode = find_inode_fast(sb, head, ino);
919    if (inode) {
920        __iget(inode);
921        spin_unlock(&inode_lock);
922        wait_on_inode(inode);
923        return inode;
924    }
925    spin_unlock(&inode_lock);
926    return NULL;
927}
928
929/**
930 * ilookup5_nowait - search for an inode in the inode cache
931 * @sb: super block of file system to search
932 * @hashval: hash value (usually inode number) to search for
933 * @test: callback used for comparisons between inodes
934 * @data: opaque data pointer to pass to @test
935 *
936 * ilookup5() uses ifind() to search for the inode specified by @hashval and
937 * @data in the inode cache. This is a generalized version of ilookup() for
938 * file systems where the inode number is not sufficient for unique
939 * identification of an inode.
940 *
941 * If the inode is in the cache, the inode is returned with an incremented
942 * reference count. Note, the inode lock is not waited upon so you have to be
943 * very careful what you do with the returned inode. You probably should be
944 * using ilookup5() instead.
945 *
946 * Otherwise NULL is returned.
947 *
948 * Note, @test is called with the inode_lock held, so can't sleep.
949 */
950struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
951        int (*test)(struct inode *, void *), void *data)
952{
953    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
954
955    return ifind(sb, head, test, data, 0);
956}
957EXPORT_SYMBOL(ilookup5_nowait);
958
959/**
960 * ilookup5 - search for an inode in the inode cache
961 * @sb: super block of file system to search
962 * @hashval: hash value (usually inode number) to search for
963 * @test: callback used for comparisons between inodes
964 * @data: opaque data pointer to pass to @test
965 *
966 * ilookup5() uses ifind() to search for the inode specified by @hashval and
967 * @data in the inode cache. This is a generalized version of ilookup() for
968 * file systems where the inode number is not sufficient for unique
969 * identification of an inode.
970 *
971 * If the inode is in the cache, the inode lock is waited upon and the inode is
972 * returned with an incremented reference count.
973 *
974 * Otherwise NULL is returned.
975 *
976 * Note, @test is called with the inode_lock held, so can't sleep.
977 */
978struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
979        int (*test)(struct inode *, void *), void *data)
980{
981    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
982
983    return ifind(sb, head, test, data, 1);
984}
985EXPORT_SYMBOL(ilookup5);
986
987/**
988 * ilookup - search for an inode in the inode cache
989 * @sb: super block of file system to search
990 * @ino: inode number to search for
991 *
992 * ilookup() uses ifind_fast() to search for the inode @ino in the inode cache.
993 * This is for file systems where the inode number is sufficient for unique
994 * identification of an inode.
995 *
996 * If the inode is in the cache, the inode is returned with an incremented
997 * reference count.
998 *
999 * Otherwise NULL is returned.
1000 */
1001struct inode *ilookup(struct super_block *sb, unsigned long ino)
1002{
1003    struct hlist_head *head = inode_hashtable + hash(sb, ino);
1004
1005    return ifind_fast(sb, head, ino);
1006}
1007EXPORT_SYMBOL(ilookup);
1008
1009/**
1010 * iget5_locked - obtain an inode from a mounted file system
1011 * @sb: super block of file system
1012 * @hashval: hash value (usually inode number) to get
1013 * @test: callback used for comparisons between inodes
1014 * @set: callback used to initialize a new struct inode
1015 * @data: opaque data pointer to pass to @test and @set
1016 *
1017 * iget5_locked() uses ifind() to search for the inode specified by @hashval
1018 * and @data in the inode cache and if present it is returned with an increased
1019 * reference count. This is a generalized version of iget_locked() for file
1020 * systems where the inode number is not sufficient for unique identification
1021 * of an inode.
1022 *
1023 * If the inode is not in cache, get_new_inode() is called to allocate a new
1024 * inode and this is returned locked, hashed, and with the I_NEW flag set. The
1025 * file system gets to fill it in before unlocking it via unlock_new_inode().
1026 *
1027 * Note both @test and @set are called with the inode_lock held, so can't sleep.
1028 */
1029struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1030        int (*test)(struct inode *, void *),
1031        int (*set)(struct inode *, void *), void *data)
1032{
1033    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1034    struct inode *inode;
1035
1036    inode = ifind(sb, head, test, data, 1);
1037    if (inode)
1038        return inode;
1039    /*
1040     * get_new_inode() will do the right thing, re-trying the search
1041     * in case it had to block at any point.
1042     */
1043    return get_new_inode(sb, head, test, set, data);
1044}
1045EXPORT_SYMBOL(iget5_locked);
1046
1047/**
1048 * iget_locked - obtain an inode from a mounted file system
1049 * @sb: super block of file system
1050 * @ino: inode number to get
1051 *
1052 * iget_locked() uses ifind_fast() to search for the inode specified by @ino in
1053 * the inode cache and if present it is returned with an increased reference
1054 * count. This is for file systems where the inode number is sufficient for
1055 * unique identification of an inode.
1056 *
1057 * If the inode is not in cache, get_new_inode_fast() is called to allocate a
1058 * new inode and this is returned locked, hashed, and with the I_NEW flag set.
1059 * The file system gets to fill it in before unlocking it via
1060 * unlock_new_inode().
1061 */
1062struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1063{
1064    struct hlist_head *head = inode_hashtable + hash(sb, ino);
1065    struct inode *inode;
1066
1067    inode = ifind_fast(sb, head, ino);
1068    if (inode)
1069        return inode;
1070    /*
1071     * get_new_inode_fast() will do the right thing, re-trying the search
1072     * in case it had to block at any point.
1073     */
1074    return get_new_inode_fast(sb, head, ino);
1075}
1076EXPORT_SYMBOL(iget_locked);
1077
1078int insert_inode_locked(struct inode *inode)
1079{
1080    struct super_block *sb = inode->i_sb;
1081    ino_t ino = inode->i_ino;
1082    struct hlist_head *head = inode_hashtable + hash(sb, ino);
1083
1084    inode->i_state |= I_NEW;
1085    while (1) {
1086        struct hlist_node *node;
1087        struct inode *old = NULL;
1088        spin_lock(&inode_lock);
1089        hlist_for_each_entry(old, node, head, i_hash) {
1090            if (old->i_ino != ino)
1091                continue;
1092            if (old->i_sb != sb)
1093                continue;
1094            if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
1095                continue;
1096            break;
1097        }
1098        if (likely(!node)) {
1099            hlist_add_head(&inode->i_hash, head);
1100            spin_unlock(&inode_lock);
1101            return 0;
1102        }
1103        __iget(old);
1104        spin_unlock(&inode_lock);
1105        wait_on_inode(old);
1106        if (unlikely(!hlist_unhashed(&old->i_hash))) {
1107            iput(old);
1108            return -EBUSY;
1109        }
1110        iput(old);
1111    }
1112}
1113EXPORT_SYMBOL(insert_inode_locked);
1114
1115int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1116        int (*test)(struct inode *, void *), void *data)
1117{
1118    struct super_block *sb = inode->i_sb;
1119    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1120
1121    inode->i_state |= I_NEW;
1122
1123    while (1) {
1124        struct hlist_node *node;
1125        struct inode *old = NULL;
1126
1127        spin_lock(&inode_lock);
1128        hlist_for_each_entry(old, node, head, i_hash) {
1129            if (old->i_sb != sb)
1130                continue;
1131            if (!test(old, data))
1132                continue;
1133            if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
1134                continue;
1135            break;
1136        }
1137        if (likely(!node)) {
1138            hlist_add_head(&inode->i_hash, head);
1139            spin_unlock(&inode_lock);
1140            return 0;
1141        }
1142        __iget(old);
1143        spin_unlock(&inode_lock);
1144        wait_on_inode(old);
1145        if (unlikely(!hlist_unhashed(&old->i_hash))) {
1146            iput(old);
1147            return -EBUSY;
1148        }
1149        iput(old);
1150    }
1151}
1152EXPORT_SYMBOL(insert_inode_locked4);
1153
1154/**
1155 * __insert_inode_hash - hash an inode
1156 * @inode: unhashed inode
1157 * @hashval: unsigned long value used to locate this object in the
1158 * inode_hashtable.
1159 *
1160 * Add an inode to the inode hash for this superblock.
1161 */
1162void __insert_inode_hash(struct inode *inode, unsigned long hashval)
1163{
1164    struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
1165    spin_lock(&inode_lock);
1166    hlist_add_head(&inode->i_hash, head);
1167    spin_unlock(&inode_lock);
1168}
1169EXPORT_SYMBOL(__insert_inode_hash);
1170
1171/**
1172 * remove_inode_hash - remove an inode from the hash
1173 * @inode: inode to unhash
1174 *
1175 * Remove an inode from the superblock.
1176 */
1177void remove_inode_hash(struct inode *inode)
1178{
1179    spin_lock(&inode_lock);
1180    hlist_del_init(&inode->i_hash);
1181    spin_unlock(&inode_lock);
1182}
1183EXPORT_SYMBOL(remove_inode_hash);
1184
1185/*
1186 * Tell the filesystem that this inode is no longer of any interest and should
1187 * be completely destroyed.
1188 *
1189 * We leave the inode in the inode hash table until *after* the filesystem's
1190 * ->delete_inode completes. This ensures that an iget (such as nfsd might
1191 * instigate) will always find up-to-date information either in the hash or on
1192 * disk.
1193 *
1194 * I_FREEING is set so that no-one will take a new reference to the inode while
1195 * it is being deleted.
1196 */
1197void generic_delete_inode(struct inode *inode)
1198{
1199    const struct super_operations *op = inode->i_sb->s_op;
1200
1201    list_del_init(&inode->i_list);
1202    list_del_init(&inode->i_sb_list);
1203    WARN_ON(inode->i_state & I_NEW);
1204    inode->i_state |= I_FREEING;
1205    inodes_stat.nr_inodes--;
1206    spin_unlock(&inode_lock);
1207
1208    security_inode_delete(inode);
1209
1210    if (op->delete_inode) {
1211        void (*delete)(struct inode *) = op->delete_inode;
1212        /* Filesystems implementing their own
1213         * s_op->delete_inode are required to call
1214         * truncate_inode_pages and clear_inode()
1215         * internally */
1216        delete(inode);
1217    } else {
1218        truncate_inode_pages(&inode->i_data, 0);
1219        clear_inode(inode);
1220    }
1221    spin_lock(&inode_lock);
1222    hlist_del_init(&inode->i_hash);
1223    spin_unlock(&inode_lock);
1224    wake_up_inode(inode);
1225    BUG_ON(inode->i_state != I_CLEAR);
1226    destroy_inode(inode);
1227}
1228EXPORT_SYMBOL(generic_delete_inode);
1229
1230/**
1231 * generic_detach_inode - remove inode from inode lists
1232 * @inode: inode to remove
1233 *
1234 * Remove inode from inode lists, write it if it's dirty. This is just an
1235 * internal VFS helper exported for hugetlbfs. Do not use!
1236 *
1237 * Returns 1 if inode should be completely destroyed.
1238 */
1239int generic_detach_inode(struct inode *inode)
1240{
1241    struct super_block *sb = inode->i_sb;
1242
1243    if (!hlist_unhashed(&inode->i_hash)) {
1244        if (!(inode->i_state & (I_DIRTY|I_SYNC)))
1245            list_move(&inode->i_list, &inode_unused);
1246        inodes_stat.nr_unused++;
1247        if (sb->s_flags & MS_ACTIVE) {
1248            spin_unlock(&inode_lock);
1249            return 0;
1250        }
1251        WARN_ON(inode->i_state & I_NEW);
1252        inode->i_state |= I_WILL_FREE;
1253        spin_unlock(&inode_lock);
1254        write_inode_now(inode, 1);
1255        spin_lock(&inode_lock);
1256        WARN_ON(inode->i_state & I_NEW);
1257        inode->i_state &= ~I_WILL_FREE;
1258        inodes_stat.nr_unused--;
1259        hlist_del_init(&inode->i_hash);
1260    }
1261    list_del_init(&inode->i_list);
1262    list_del_init(&inode->i_sb_list);
1263    WARN_ON(inode->i_state & I_NEW);
1264    inode->i_state |= I_FREEING;
1265    inodes_stat.nr_inodes--;
1266    spin_unlock(&inode_lock);
1267    return 1;
1268}
1269EXPORT_SYMBOL_GPL(generic_detach_inode);
1270
1271static void generic_forget_inode(struct inode *inode)
1272{
1273    if (!generic_detach_inode(inode))
1274        return;
1275    if (inode->i_data.nrpages)
1276        truncate_inode_pages(&inode->i_data, 0);
1277    clear_inode(inode);
1278    wake_up_inode(inode);
1279    destroy_inode(inode);
1280}
1281
1282/*
1283 * Normal UNIX filesystem behaviour: delete the
1284 * inode when the usage count drops to zero, and
1285 * i_nlink is zero.
1286 */
1287void generic_drop_inode(struct inode *inode)
1288{
1289    if (!inode->i_nlink)
1290        generic_delete_inode(inode);
1291    else
1292        generic_forget_inode(inode);
1293}
1294EXPORT_SYMBOL_GPL(generic_drop_inode);
1295
1296/*
1297 * Called when we're dropping the last reference
1298 * to an inode.
1299 *
1300 * Call the FS "drop()" function, defaulting to
1301 * the legacy UNIX filesystem behaviour..
1302 *
1303 * NOTE! NOTE! NOTE! We're called with the inode lock
1304 * held, and the drop function is supposed to release
1305 * the lock!
1306 */
1307static inline void iput_final(struct inode *inode)
1308{
1309    const struct super_operations *op = inode->i_sb->s_op;
1310    void (*drop)(struct inode *) = generic_drop_inode;
1311
1312    if (op && op->drop_inode)
1313        drop = op->drop_inode;
1314    drop(inode);
1315}
1316
1317/**
1318 * iput - put an inode
1319 * @inode: inode to put
1320 *
1321 * Puts an inode, dropping its usage count. If the inode use count hits
1322 * zero, the inode is then freed and may also be destroyed.
1323 *
1324 * Consequently, iput() can sleep.
1325 */
1326void iput(struct inode *inode)
1327{
1328    if (inode) {
1329        BUG_ON(inode->i_state == I_CLEAR);
1330
1331        if (atomic_dec_and_lock(&inode->i_count, &inode_lock))
1332            iput_final(inode);
1333    }
1334}
1335EXPORT_SYMBOL(iput);
1336
1337/**
1338 * bmap - find a block number in a file
1339 * @inode: inode of file
1340 * @block: block to find
1341 *
1342 * Returns the block number on the device holding the inode that
1343 * is the disk block number for the block of the file requested.
1344 * That is, asked for block 4 of inode 1 the function will return the
1345 * disk block relative to the disk start that holds that block of the
1346 * file.
1347 */
1348sector_t bmap(struct inode *inode, sector_t block)
1349{
1350    sector_t res = 0;
1351    if (inode->i_mapping->a_ops->bmap)
1352        res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1353    return res;
1354}
1355EXPORT_SYMBOL(bmap);
1356
1357/*
1358 * With relative atime, only update atime if the previous atime is
1359 * earlier than either the ctime or mtime or if at least a day has
1360 * passed since the last atime update.
1361 */
1362static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1363                 struct timespec now)
1364{
1365
1366    if (!(mnt->mnt_flags & MNT_RELATIME))
1367        return 1;
1368    /*
1369     * Is mtime younger than atime? If yes, update atime:
1370     */
1371    if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1372        return 1;
1373    /*
1374     * Is ctime younger than atime? If yes, update atime:
1375     */
1376    if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1377        return 1;
1378
1379    /*
1380     * Is the previous atime value older than a day? If yes,
1381     * update atime:
1382     */
1383    if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1384        return 1;
1385    /*
1386     * Good, we can skip the atime update:
1387     */
1388    return 0;
1389}
1390
1391/**
1392 * touch_atime - update the access time
1393 * @mnt: mount the inode is accessed on
1394 * @dentry: dentry accessed
1395 *
1396 * Update the accessed time on an inode and mark it for writeback.
1397 * This function automatically handles read only file systems and media,
1398 * as well as the "noatime" flag and inode specific "noatime" markers.
1399 */
1400void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
1401{
1402    struct inode *inode = dentry->d_inode;
1403    struct timespec now;
1404
1405    if (inode->i_flags & S_NOATIME)
1406        return;
1407    if (IS_NOATIME(inode))
1408        return;
1409    if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1410        return;
1411
1412    if (mnt->mnt_flags & MNT_NOATIME)
1413        return;
1414    if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1415        return;
1416
1417    now = current_fs_time(inode->i_sb);
1418
1419    if (!relatime_need_update(mnt, inode, now))
1420        return;
1421
1422    if (timespec_equal(&inode->i_atime, &now))
1423        return;
1424
1425    if (mnt_want_write(mnt))
1426        return;
1427
1428    inode->i_atime = now;
1429    mark_inode_dirty_sync(inode);
1430    mnt_drop_write(mnt);
1431}
1432EXPORT_SYMBOL(touch_atime);
1433
1434/**
1435 * file_update_time - update mtime and ctime time
1436 * @file: file accessed
1437 *
1438 * Update the mtime and ctime members of an inode and mark the inode
1439 * for writeback. Note that this function is meant exclusively for
1440 * usage in the file write path of filesystems, and filesystems may
1441 * choose to explicitly ignore update via this function with the
1442 * S_NOCMTIME inode flag, e.g. for network filesystem where these
1443 * timestamps are handled by the server.
1444 */
1445
1446void file_update_time(struct file *file)
1447{
1448    struct inode *inode = file->f_path.dentry->d_inode;
1449    struct timespec now;
1450    enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
1451
1452    /* First try to exhaust all avenues to not sync */
1453    if (IS_NOCMTIME(inode))
1454        return;
1455
1456    now = current_fs_time(inode->i_sb);
1457    if (!timespec_equal(&inode->i_mtime, &now))
1458        sync_it = S_MTIME;
1459
1460    if (!timespec_equal(&inode->i_ctime, &now))
1461        sync_it |= S_CTIME;
1462
1463    if (IS_I_VERSION(inode))
1464        sync_it |= S_VERSION;
1465
1466    if (!sync_it)
1467        return;
1468
1469    /* Finally allowed to write? Takes lock. */
1470    if (mnt_want_write_file(file))
1471        return;
1472
1473    /* Only change inode inside the lock region */
1474    if (sync_it & S_VERSION)
1475        inode_inc_iversion(inode);
1476    if (sync_it & S_CTIME)
1477        inode->i_ctime = now;
1478    if (sync_it & S_MTIME)
1479        inode->i_mtime = now;
1480    mark_inode_dirty_sync(inode);
1481    mnt_drop_write(file->f_path.mnt);
1482}
1483EXPORT_SYMBOL(file_update_time);
1484
1485int inode_needs_sync(struct inode *inode)
1486{
1487    if (IS_SYNC(inode))
1488        return 1;
1489    if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1490        return 1;
1491    return 0;
1492}
1493EXPORT_SYMBOL(inode_needs_sync);
1494
1495int inode_wait(void *word)
1496{
1497    schedule();
1498    return 0;
1499}
1500EXPORT_SYMBOL(inode_wait);
1501
1502/*
1503 * If we try to find an inode in the inode hash while it is being
1504 * deleted, we have to wait until the filesystem completes its
1505 * deletion before reporting that it isn't found. This function waits
1506 * until the deletion _might_ have completed. Callers are responsible
1507 * to recheck inode state.
1508 *
1509 * It doesn't matter if I_NEW is not set initially, a call to
1510 * wake_up_inode() after removing from the hash list will DTRT.
1511 *
1512 * This is called with inode_lock held.
1513 */
1514static void __wait_on_freeing_inode(struct inode *inode)
1515{
1516    wait_queue_head_t *wq;
1517    DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
1518    wq = bit_waitqueue(&inode->i_state, __I_NEW);
1519    prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1520    spin_unlock(&inode_lock);
1521    schedule();
1522    finish_wait(wq, &wait.wait);
1523    spin_lock(&inode_lock);
1524}
1525
1526static __initdata unsigned long ihash_entries;
1527static int __init set_ihash_entries(char *str)
1528{
1529    if (!str)
1530        return 0;
1531    ihash_entries = simple_strtoul(str, &str, 0);
1532    return 1;
1533}
1534__setup("ihash_entries=", set_ihash_entries);
1535
1536/*
1537 * Initialize the waitqueues and inode hash table.
1538 */
1539void __init inode_init_early(void)
1540{
1541    int loop;
1542
1543    /* If hashes are distributed across NUMA nodes, defer
1544     * hash allocation until vmalloc space is available.
1545     */
1546    if (hashdist)
1547        return;
1548
1549    inode_hashtable =
1550        alloc_large_system_hash("Inode-cache",
1551                    sizeof(struct hlist_head),
1552                    ihash_entries,
1553                    14,
1554                    HASH_EARLY,
1555                    &i_hash_shift,
1556                    &i_hash_mask,
1557                    0);
1558
1559    for (loop = 0; loop < (1 << i_hash_shift); loop++)
1560        INIT_HLIST_HEAD(&inode_hashtable[loop]);
1561}
1562
1563void __init inode_init(void)
1564{
1565    int loop;
1566
1567    /* inode slab cache */
1568    inode_cachep = kmem_cache_create("inode_cache",
1569                     sizeof(struct inode),
1570                     0,
1571                     (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1572                     SLAB_MEM_SPREAD),
1573                     init_once);
1574    register_shrinker(&icache_shrinker);
1575
1576    /* Hash may have been set up in inode_init_early */
1577    if (!hashdist)
1578        return;
1579
1580    inode_hashtable =
1581        alloc_large_system_hash("Inode-cache",
1582                    sizeof(struct hlist_head),
1583                    ihash_entries,
1584                    14,
1585                    0,
1586                    &i_hash_shift,
1587                    &i_hash_mask,
1588                    0);
1589
1590    for (loop = 0; loop < (1 << i_hash_shift); loop++)
1591        INIT_HLIST_HEAD(&inode_hashtable[loop]);
1592}
1593
1594void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
1595{
1596    inode->i_mode = mode;
1597    if (S_ISCHR(mode)) {
1598        inode->i_fop = &def_chr_fops;
1599        inode->i_rdev = rdev;
1600    } else if (S_ISBLK(mode)) {
1601        inode->i_fop = &def_blk_fops;
1602        inode->i_rdev = rdev;
1603    } else if (S_ISFIFO(mode))
1604        inode->i_fop = &def_fifo_fops;
1605    else if (S_ISSOCK(mode))
1606        inode->i_fop = &bad_sock_fops;
1607    else
1608        printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
1609                  " inode %s:%lu\n", mode, inode->i_sb->s_id,
1610                  inode->i_ino);
1611}
1612EXPORT_SYMBOL(init_special_inode);
1613

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