Root/fs/inode.c

1/*
2 * (C) 1997 Linus Torvalds
3 * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation)
4 */
5#include <linux/fs.h>
6#include <linux/mm.h>
7#include <linux/dcache.h>
8#include <linux/init.h>
9#include <linux/slab.h>
10#include <linux/writeback.h>
11#include <linux/module.h>
12#include <linux/backing-dev.h>
13#include <linux/wait.h>
14#include <linux/rwsem.h>
15#include <linux/hash.h>
16#include <linux/swap.h>
17#include <linux/security.h>
18#include <linux/pagemap.h>
19#include <linux/cdev.h>
20#include <linux/bootmem.h>
21#include <linux/fsnotify.h>
22#include <linux/mount.h>
23#include <linux/async.h>
24#include <linux/posix_acl.h>
25#include <linux/prefetch.h>
26#include <linux/ima.h>
27#include <linux/cred.h>
28#include <linux/buffer_head.h> /* for inode_has_buffers */
29#include "internal.h"
30
31/*
32 * Inode locking rules:
33 *
34 * inode->i_lock protects:
35 * inode->i_state, inode->i_hash, __iget()
36 * inode_lru_lock protects:
37 * inode_lru, inode->i_lru
38 * inode_sb_list_lock protects:
39 * sb->s_inodes, inode->i_sb_list
40 * inode_wb_list_lock protects:
41 * bdi->wb.b_{dirty,io,more_io}, inode->i_wb_list
42 * inode_hash_lock protects:
43 * inode_hashtable, inode->i_hash
44 *
45 * Lock ordering:
46 *
47 * inode_sb_list_lock
48 * inode->i_lock
49 * inode_lru_lock
50 *
51 * inode_wb_list_lock
52 * inode->i_lock
53 *
54 * inode_hash_lock
55 * inode_sb_list_lock
56 * inode->i_lock
57 *
58 * iunique_lock
59 * inode_hash_lock
60 */
61
62static unsigned int i_hash_mask __read_mostly;
63static unsigned int i_hash_shift __read_mostly;
64static struct hlist_head *inode_hashtable __read_mostly;
65static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
66
67static LIST_HEAD(inode_lru);
68static DEFINE_SPINLOCK(inode_lru_lock);
69
70__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock);
71__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_wb_list_lock);
72
73/*
74 * iprune_sem provides exclusion between the icache shrinking and the
75 * umount path.
76 *
77 * We don't actually need it to protect anything in the umount path,
78 * but only need to cycle through it to make sure any inode that
79 * prune_icache took off the LRU list has been fully torn down by the
80 * time we are past evict_inodes.
81 */
82static DECLARE_RWSEM(iprune_sem);
83
84/*
85 * Empty aops. Can be used for the cases where the user does not
86 * define any of the address_space operations.
87 */
88const struct address_space_operations empty_aops = {
89};
90EXPORT_SYMBOL(empty_aops);
91
92/*
93 * Statistics gathering..
94 */
95struct inodes_stat_t inodes_stat;
96
97static DEFINE_PER_CPU(unsigned int, nr_inodes);
98
99static struct kmem_cache *inode_cachep __read_mostly;
100
101static int get_nr_inodes(void)
102{
103    int i;
104    int sum = 0;
105    for_each_possible_cpu(i)
106        sum += per_cpu(nr_inodes, i);
107    return sum < 0 ? 0 : sum;
108}
109
110static inline int get_nr_inodes_unused(void)
111{
112    return inodes_stat.nr_unused;
113}
114
115int get_nr_dirty_inodes(void)
116{
117    /* not actually dirty inodes, but a wild approximation */
118    int nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
119    return nr_dirty > 0 ? nr_dirty : 0;
120}
121
122/*
123 * Handle nr_inode sysctl
124 */
125#ifdef CONFIG_SYSCTL
126int proc_nr_inodes(ctl_table *table, int write,
127           void __user *buffer, size_t *lenp, loff_t *ppos)
128{
129    inodes_stat.nr_inodes = get_nr_inodes();
130    return proc_dointvec(table, write, buffer, lenp, ppos);
131}
132#endif
133
134/**
135 * inode_init_always - perform inode structure intialisation
136 * @sb: superblock inode belongs to
137 * @inode: inode to initialise
138 *
139 * These are initializations that need to be done on every inode
140 * allocation as the fields are not initialised by slab allocation.
141 */
142int inode_init_always(struct super_block *sb, struct inode *inode)
143{
144    static const struct inode_operations empty_iops;
145    static const struct file_operations empty_fops;
146    struct address_space *const mapping = &inode->i_data;
147
148    inode->i_sb = sb;
149    inode->i_blkbits = sb->s_blocksize_bits;
150    inode->i_flags = 0;
151    atomic_set(&inode->i_count, 1);
152    inode->i_op = &empty_iops;
153    inode->i_fop = &empty_fops;
154    inode->i_nlink = 1;
155    inode->i_uid = 0;
156    inode->i_gid = 0;
157    atomic_set(&inode->i_writecount, 0);
158    inode->i_size = 0;
159    inode->i_blocks = 0;
160    inode->i_bytes = 0;
161    inode->i_generation = 0;
162#ifdef CONFIG_QUOTA
163    memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
164#endif
165    inode->i_pipe = NULL;
166    inode->i_bdev = NULL;
167    inode->i_cdev = NULL;
168    inode->i_rdev = 0;
169    inode->dirtied_when = 0;
170
171    if (security_inode_alloc(inode))
172        goto out;
173    spin_lock_init(&inode->i_lock);
174    lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
175
176    mutex_init(&inode->i_mutex);
177    lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
178
179    init_rwsem(&inode->i_alloc_sem);
180    lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
181
182    mapping->a_ops = &empty_aops;
183    mapping->host = inode;
184    mapping->flags = 0;
185    mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
186    mapping->assoc_mapping = NULL;
187    mapping->backing_dev_info = &default_backing_dev_info;
188    mapping->writeback_index = 0;
189
190    /*
191     * If the block_device provides a backing_dev_info for client
192     * inodes then use that. Otherwise the inode share the bdev's
193     * backing_dev_info.
194     */
195    if (sb->s_bdev) {
196        struct backing_dev_info *bdi;
197
198        bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
199        mapping->backing_dev_info = bdi;
200    }
201    inode->i_private = NULL;
202    inode->i_mapping = mapping;
203#ifdef CONFIG_FS_POSIX_ACL
204    inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
205#endif
206
207#ifdef CONFIG_FSNOTIFY
208    inode->i_fsnotify_mask = 0;
209#endif
210
211    this_cpu_inc(nr_inodes);
212
213    return 0;
214out:
215    return -ENOMEM;
216}
217EXPORT_SYMBOL(inode_init_always);
218
219static struct inode *alloc_inode(struct super_block *sb)
220{
221    struct inode *inode;
222
223    if (sb->s_op->alloc_inode)
224        inode = sb->s_op->alloc_inode(sb);
225    else
226        inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
227
228    if (!inode)
229        return NULL;
230
231    if (unlikely(inode_init_always(sb, inode))) {
232        if (inode->i_sb->s_op->destroy_inode)
233            inode->i_sb->s_op->destroy_inode(inode);
234        else
235            kmem_cache_free(inode_cachep, inode);
236        return NULL;
237    }
238
239    return inode;
240}
241
242void free_inode_nonrcu(struct inode *inode)
243{
244    kmem_cache_free(inode_cachep, inode);
245}
246EXPORT_SYMBOL(free_inode_nonrcu);
247
248void __destroy_inode(struct inode *inode)
249{
250    BUG_ON(inode_has_buffers(inode));
251    security_inode_free(inode);
252    fsnotify_inode_delete(inode);
253#ifdef CONFIG_FS_POSIX_ACL
254    if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
255        posix_acl_release(inode->i_acl);
256    if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
257        posix_acl_release(inode->i_default_acl);
258#endif
259    this_cpu_dec(nr_inodes);
260}
261EXPORT_SYMBOL(__destroy_inode);
262
263static void i_callback(struct rcu_head *head)
264{
265    struct inode *inode = container_of(head, struct inode, i_rcu);
266    INIT_LIST_HEAD(&inode->i_dentry);
267    kmem_cache_free(inode_cachep, inode);
268}
269
270static void destroy_inode(struct inode *inode)
271{
272    BUG_ON(!list_empty(&inode->i_lru));
273    __destroy_inode(inode);
274    if (inode->i_sb->s_op->destroy_inode)
275        inode->i_sb->s_op->destroy_inode(inode);
276    else
277        call_rcu(&inode->i_rcu, i_callback);
278}
279
280void address_space_init_once(struct address_space *mapping)
281{
282    memset(mapping, 0, sizeof(*mapping));
283    INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
284    spin_lock_init(&mapping->tree_lock);
285    mutex_init(&mapping->i_mmap_mutex);
286    INIT_LIST_HEAD(&mapping->private_list);
287    spin_lock_init(&mapping->private_lock);
288    INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
289    INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
290}
291EXPORT_SYMBOL(address_space_init_once);
292
293/*
294 * These are initializations that only need to be done
295 * once, because the fields are idempotent across use
296 * of the inode, so let the slab aware of that.
297 */
298void inode_init_once(struct inode *inode)
299{
300    memset(inode, 0, sizeof(*inode));
301    INIT_HLIST_NODE(&inode->i_hash);
302    INIT_LIST_HEAD(&inode->i_dentry);
303    INIT_LIST_HEAD(&inode->i_devices);
304    INIT_LIST_HEAD(&inode->i_wb_list);
305    INIT_LIST_HEAD(&inode->i_lru);
306    address_space_init_once(&inode->i_data);
307    i_size_ordered_init(inode);
308#ifdef CONFIG_FSNOTIFY
309    INIT_HLIST_HEAD(&inode->i_fsnotify_marks);
310#endif
311}
312EXPORT_SYMBOL(inode_init_once);
313
314static void init_once(void *foo)
315{
316    struct inode *inode = (struct inode *) foo;
317
318    inode_init_once(inode);
319}
320
321/*
322 * inode->i_lock must be held
323 */
324void __iget(struct inode *inode)
325{
326    atomic_inc(&inode->i_count);
327}
328
329/*
330 * get additional reference to inode; caller must already hold one.
331 */
332void ihold(struct inode *inode)
333{
334    WARN_ON(atomic_inc_return(&inode->i_count) < 2);
335}
336EXPORT_SYMBOL(ihold);
337
338static void inode_lru_list_add(struct inode *inode)
339{
340    spin_lock(&inode_lru_lock);
341    if (list_empty(&inode->i_lru)) {
342        list_add(&inode->i_lru, &inode_lru);
343        inodes_stat.nr_unused++;
344    }
345    spin_unlock(&inode_lru_lock);
346}
347
348static void inode_lru_list_del(struct inode *inode)
349{
350    spin_lock(&inode_lru_lock);
351    if (!list_empty(&inode->i_lru)) {
352        list_del_init(&inode->i_lru);
353        inodes_stat.nr_unused--;
354    }
355    spin_unlock(&inode_lru_lock);
356}
357
358/**
359 * inode_sb_list_add - add inode to the superblock list of inodes
360 * @inode: inode to add
361 */
362void inode_sb_list_add(struct inode *inode)
363{
364    spin_lock(&inode_sb_list_lock);
365    list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
366    spin_unlock(&inode_sb_list_lock);
367}
368EXPORT_SYMBOL_GPL(inode_sb_list_add);
369
370static inline void inode_sb_list_del(struct inode *inode)
371{
372    spin_lock(&inode_sb_list_lock);
373    list_del_init(&inode->i_sb_list);
374    spin_unlock(&inode_sb_list_lock);
375}
376
377static unsigned long hash(struct super_block *sb, unsigned long hashval)
378{
379    unsigned long tmp;
380
381    tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
382            L1_CACHE_BYTES;
383    tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
384    return tmp & i_hash_mask;
385}
386
387/**
388 * __insert_inode_hash - hash an inode
389 * @inode: unhashed inode
390 * @hashval: unsigned long value used to locate this object in the
391 * inode_hashtable.
392 *
393 * Add an inode to the inode hash for this superblock.
394 */
395void __insert_inode_hash(struct inode *inode, unsigned long hashval)
396{
397    struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
398
399    spin_lock(&inode_hash_lock);
400    spin_lock(&inode->i_lock);
401    hlist_add_head(&inode->i_hash, b);
402    spin_unlock(&inode->i_lock);
403    spin_unlock(&inode_hash_lock);
404}
405EXPORT_SYMBOL(__insert_inode_hash);
406
407/**
408 * remove_inode_hash - remove an inode from the hash
409 * @inode: inode to unhash
410 *
411 * Remove an inode from the superblock.
412 */
413void remove_inode_hash(struct inode *inode)
414{
415    spin_lock(&inode_hash_lock);
416    spin_lock(&inode->i_lock);
417    hlist_del_init(&inode->i_hash);
418    spin_unlock(&inode->i_lock);
419    spin_unlock(&inode_hash_lock);
420}
421EXPORT_SYMBOL(remove_inode_hash);
422
423void end_writeback(struct inode *inode)
424{
425    might_sleep();
426    /*
427     * We have to cycle tree_lock here because reclaim can be still in the
428     * process of removing the last page (in __delete_from_page_cache())
429     * and we must not free mapping under it.
430     */
431    spin_lock_irq(&inode->i_data.tree_lock);
432    BUG_ON(inode->i_data.nrpages);
433    spin_unlock_irq(&inode->i_data.tree_lock);
434    BUG_ON(!list_empty(&inode->i_data.private_list));
435    BUG_ON(!(inode->i_state & I_FREEING));
436    BUG_ON(inode->i_state & I_CLEAR);
437    inode_sync_wait(inode);
438    /* don't need i_lock here, no concurrent mods to i_state */
439    inode->i_state = I_FREEING | I_CLEAR;
440}
441EXPORT_SYMBOL(end_writeback);
442
443/*
444 * Free the inode passed in, removing it from the lists it is still connected
445 * to. We remove any pages still attached to the inode and wait for any IO that
446 * is still in progress before finally destroying the inode.
447 *
448 * An inode must already be marked I_FREEING so that we avoid the inode being
449 * moved back onto lists if we race with other code that manipulates the lists
450 * (e.g. writeback_single_inode). The caller is responsible for setting this.
451 *
452 * An inode must already be removed from the LRU list before being evicted from
453 * the cache. This should occur atomically with setting the I_FREEING state
454 * flag, so no inodes here should ever be on the LRU when being evicted.
455 */
456static void evict(struct inode *inode)
457{
458    const struct super_operations *op = inode->i_sb->s_op;
459
460    BUG_ON(!(inode->i_state & I_FREEING));
461    BUG_ON(!list_empty(&inode->i_lru));
462
463    inode_wb_list_del(inode);
464    inode_sb_list_del(inode);
465
466    if (op->evict_inode) {
467        op->evict_inode(inode);
468    } else {
469        if (inode->i_data.nrpages)
470            truncate_inode_pages(&inode->i_data, 0);
471        end_writeback(inode);
472    }
473    if (S_ISBLK(inode->i_mode) && inode->i_bdev)
474        bd_forget(inode);
475    if (S_ISCHR(inode->i_mode) && inode->i_cdev)
476        cd_forget(inode);
477
478    remove_inode_hash(inode);
479
480    spin_lock(&inode->i_lock);
481    wake_up_bit(&inode->i_state, __I_NEW);
482    BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
483    spin_unlock(&inode->i_lock);
484
485    destroy_inode(inode);
486}
487
488/*
489 * dispose_list - dispose of the contents of a local list
490 * @head: the head of the list to free
491 *
492 * Dispose-list gets a local list with local inodes in it, so it doesn't
493 * need to worry about list corruption and SMP locks.
494 */
495static void dispose_list(struct list_head *head)
496{
497    while (!list_empty(head)) {
498        struct inode *inode;
499
500        inode = list_first_entry(head, struct inode, i_lru);
501        list_del_init(&inode->i_lru);
502
503        evict(inode);
504    }
505}
506
507/**
508 * evict_inodes - evict all evictable inodes for a superblock
509 * @sb: superblock to operate on
510 *
511 * Make sure that no inodes with zero refcount are retained. This is
512 * called by superblock shutdown after having MS_ACTIVE flag removed,
513 * so any inode reaching zero refcount during or after that call will
514 * be immediately evicted.
515 */
516void evict_inodes(struct super_block *sb)
517{
518    struct inode *inode, *next;
519    LIST_HEAD(dispose);
520
521    spin_lock(&inode_sb_list_lock);
522    list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
523        if (atomic_read(&inode->i_count))
524            continue;
525
526        spin_lock(&inode->i_lock);
527        if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
528            spin_unlock(&inode->i_lock);
529            continue;
530        }
531
532        inode->i_state |= I_FREEING;
533        inode_lru_list_del(inode);
534        spin_unlock(&inode->i_lock);
535        list_add(&inode->i_lru, &dispose);
536    }
537    spin_unlock(&inode_sb_list_lock);
538
539    dispose_list(&dispose);
540
541    /*
542     * Cycle through iprune_sem to make sure any inode that prune_icache
543     * moved off the list before we took the lock has been fully torn
544     * down.
545     */
546    down_write(&iprune_sem);
547    up_write(&iprune_sem);
548}
549
550/**
551 * invalidate_inodes - attempt to free all inodes on a superblock
552 * @sb: superblock to operate on
553 * @kill_dirty: flag to guide handling of dirty inodes
554 *
555 * Attempts to free all inodes for a given superblock. If there were any
556 * busy inodes return a non-zero value, else zero.
557 * If @kill_dirty is set, discard dirty inodes too, otherwise treat
558 * them as busy.
559 */
560int invalidate_inodes(struct super_block *sb, bool kill_dirty)
561{
562    int busy = 0;
563    struct inode *inode, *next;
564    LIST_HEAD(dispose);
565
566    spin_lock(&inode_sb_list_lock);
567    list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
568        spin_lock(&inode->i_lock);
569        if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
570            spin_unlock(&inode->i_lock);
571            continue;
572        }
573        if (inode->i_state & I_DIRTY && !kill_dirty) {
574            spin_unlock(&inode->i_lock);
575            busy = 1;
576            continue;
577        }
578        if (atomic_read(&inode->i_count)) {
579            spin_unlock(&inode->i_lock);
580            busy = 1;
581            continue;
582        }
583
584        inode->i_state |= I_FREEING;
585        inode_lru_list_del(inode);
586        spin_unlock(&inode->i_lock);
587        list_add(&inode->i_lru, &dispose);
588    }
589    spin_unlock(&inode_sb_list_lock);
590
591    dispose_list(&dispose);
592
593    return busy;
594}
595
596static int can_unuse(struct inode *inode)
597{
598    if (inode->i_state & ~I_REFERENCED)
599        return 0;
600    if (inode_has_buffers(inode))
601        return 0;
602    if (atomic_read(&inode->i_count))
603        return 0;
604    if (inode->i_data.nrpages)
605        return 0;
606    return 1;
607}
608
609/*
610 * Scan `goal' inodes on the unused list for freeable ones. They are moved to a
611 * temporary list and then are freed outside inode_lru_lock by dispose_list().
612 *
613 * Any inodes which are pinned purely because of attached pagecache have their
614 * pagecache removed. If the inode has metadata buffers attached to
615 * mapping->private_list then try to remove them.
616 *
617 * If the inode has the I_REFERENCED flag set, then it means that it has been
618 * used recently - the flag is set in iput_final(). When we encounter such an
619 * inode, clear the flag and move it to the back of the LRU so it gets another
620 * pass through the LRU before it gets reclaimed. This is necessary because of
621 * the fact we are doing lazy LRU updates to minimise lock contention so the
622 * LRU does not have strict ordering. Hence we don't want to reclaim inodes
623 * with this flag set because they are the inodes that are out of order.
624 */
625static void prune_icache(int nr_to_scan)
626{
627    LIST_HEAD(freeable);
628    int nr_scanned;
629    unsigned long reap = 0;
630
631    down_read(&iprune_sem);
632    spin_lock(&inode_lru_lock);
633    for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
634        struct inode *inode;
635
636        if (list_empty(&inode_lru))
637            break;
638
639        inode = list_entry(inode_lru.prev, struct inode, i_lru);
640
641        /*
642         * we are inverting the inode_lru_lock/inode->i_lock here,
643         * so use a trylock. If we fail to get the lock, just move the
644         * inode to the back of the list so we don't spin on it.
645         */
646        if (!spin_trylock(&inode->i_lock)) {
647            list_move(&inode->i_lru, &inode_lru);
648            continue;
649        }
650
651        /*
652         * Referenced or dirty inodes are still in use. Give them
653         * another pass through the LRU as we canot reclaim them now.
654         */
655        if (atomic_read(&inode->i_count) ||
656            (inode->i_state & ~I_REFERENCED)) {
657            list_del_init(&inode->i_lru);
658            spin_unlock(&inode->i_lock);
659            inodes_stat.nr_unused--;
660            continue;
661        }
662
663        /* recently referenced inodes get one more pass */
664        if (inode->i_state & I_REFERENCED) {
665            inode->i_state &= ~I_REFERENCED;
666            list_move(&inode->i_lru, &inode_lru);
667            spin_unlock(&inode->i_lock);
668            continue;
669        }
670        if (inode_has_buffers(inode) || inode->i_data.nrpages) {
671            __iget(inode);
672            spin_unlock(&inode->i_lock);
673            spin_unlock(&inode_lru_lock);
674            if (remove_inode_buffers(inode))
675                reap += invalidate_mapping_pages(&inode->i_data,
676                                0, -1);
677            iput(inode);
678            spin_lock(&inode_lru_lock);
679
680            if (inode != list_entry(inode_lru.next,
681                        struct inode, i_lru))
682                continue; /* wrong inode or list_empty */
683            /* avoid lock inversions with trylock */
684            if (!spin_trylock(&inode->i_lock))
685                continue;
686            if (!can_unuse(inode)) {
687                spin_unlock(&inode->i_lock);
688                continue;
689            }
690        }
691        WARN_ON(inode->i_state & I_NEW);
692        inode->i_state |= I_FREEING;
693        spin_unlock(&inode->i_lock);
694
695        list_move(&inode->i_lru, &freeable);
696        inodes_stat.nr_unused--;
697    }
698    if (current_is_kswapd())
699        __count_vm_events(KSWAPD_INODESTEAL, reap);
700    else
701        __count_vm_events(PGINODESTEAL, reap);
702    spin_unlock(&inode_lru_lock);
703
704    dispose_list(&freeable);
705    up_read(&iprune_sem);
706}
707
708/*
709 * shrink_icache_memory() will attempt to reclaim some unused inodes. Here,
710 * "unused" means that no dentries are referring to the inodes: the files are
711 * not open and the dcache references to those inodes have already been
712 * reclaimed.
713 *
714 * This function is passed the number of inodes to scan, and it returns the
715 * total number of remaining possibly-reclaimable inodes.
716 */
717static int shrink_icache_memory(struct shrinker *shrink,
718                struct shrink_control *sc)
719{
720    int nr = sc->nr_to_scan;
721    gfp_t gfp_mask = sc->gfp_mask;
722
723    if (nr) {
724        /*
725         * Nasty deadlock avoidance. We may hold various FS locks,
726         * and we don't want to recurse into the FS that called us
727         * in clear_inode() and friends..
728         */
729        if (!(gfp_mask & __GFP_FS))
730            return -1;
731        prune_icache(nr);
732    }
733    return (get_nr_inodes_unused() / 100) * sysctl_vfs_cache_pressure;
734}
735
736static struct shrinker icache_shrinker = {
737    .shrink = shrink_icache_memory,
738    .seeks = DEFAULT_SEEKS,
739};
740
741static void __wait_on_freeing_inode(struct inode *inode);
742/*
743 * Called with the inode lock held.
744 */
745static struct inode *find_inode(struct super_block *sb,
746                struct hlist_head *head,
747                int (*test)(struct inode *, void *),
748                void *data)
749{
750    struct hlist_node *node;
751    struct inode *inode = NULL;
752
753repeat:
754    hlist_for_each_entry(inode, node, head, i_hash) {
755        spin_lock(&inode->i_lock);
756        if (inode->i_sb != sb) {
757            spin_unlock(&inode->i_lock);
758            continue;
759        }
760        if (!test(inode, data)) {
761            spin_unlock(&inode->i_lock);
762            continue;
763        }
764        if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
765            __wait_on_freeing_inode(inode);
766            goto repeat;
767        }
768        __iget(inode);
769        spin_unlock(&inode->i_lock);
770        return inode;
771    }
772    return NULL;
773}
774
775/*
776 * find_inode_fast is the fast path version of find_inode, see the comment at
777 * iget_locked for details.
778 */
779static struct inode *find_inode_fast(struct super_block *sb,
780                struct hlist_head *head, unsigned long ino)
781{
782    struct hlist_node *node;
783    struct inode *inode = NULL;
784
785repeat:
786    hlist_for_each_entry(inode, node, head, i_hash) {
787        spin_lock(&inode->i_lock);
788        if (inode->i_ino != ino) {
789            spin_unlock(&inode->i_lock);
790            continue;
791        }
792        if (inode->i_sb != sb) {
793            spin_unlock(&inode->i_lock);
794            continue;
795        }
796        if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
797            __wait_on_freeing_inode(inode);
798            goto repeat;
799        }
800        __iget(inode);
801        spin_unlock(&inode->i_lock);
802        return inode;
803    }
804    return NULL;
805}
806
807/*
808 * Each cpu owns a range of LAST_INO_BATCH numbers.
809 * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
810 * to renew the exhausted range.
811 *
812 * This does not significantly increase overflow rate because every CPU can
813 * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
814 * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
815 * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
816 * overflow rate by 2x, which does not seem too significant.
817 *
818 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
819 * error if st_ino won't fit in target struct field. Use 32bit counter
820 * here to attempt to avoid that.
821 */
822#define LAST_INO_BATCH 1024
823static DEFINE_PER_CPU(unsigned int, last_ino);
824
825unsigned int get_next_ino(void)
826{
827    unsigned int *p = &get_cpu_var(last_ino);
828    unsigned int res = *p;
829
830#ifdef CONFIG_SMP
831    if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
832        static atomic_t shared_last_ino;
833        int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
834
835        res = next - LAST_INO_BATCH;
836    }
837#endif
838
839    *p = ++res;
840    put_cpu_var(last_ino);
841    return res;
842}
843EXPORT_SYMBOL(get_next_ino);
844
845/**
846 * new_inode - obtain an inode
847 * @sb: superblock
848 *
849 * Allocates a new inode for given superblock. The default gfp_mask
850 * for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
851 * If HIGHMEM pages are unsuitable or it is known that pages allocated
852 * for the page cache are not reclaimable or migratable,
853 * mapping_set_gfp_mask() must be called with suitable flags on the
854 * newly created inode's mapping
855 *
856 */
857struct inode *new_inode(struct super_block *sb)
858{
859    struct inode *inode;
860
861    spin_lock_prefetch(&inode_sb_list_lock);
862
863    inode = alloc_inode(sb);
864    if (inode) {
865        spin_lock(&inode->i_lock);
866        inode->i_state = 0;
867        spin_unlock(&inode->i_lock);
868        inode_sb_list_add(inode);
869    }
870    return inode;
871}
872EXPORT_SYMBOL(new_inode);
873
874/**
875 * unlock_new_inode - clear the I_NEW state and wake up any waiters
876 * @inode: new inode to unlock
877 *
878 * Called when the inode is fully initialised to clear the new state of the
879 * inode and wake up anyone waiting for the inode to finish initialisation.
880 */
881void unlock_new_inode(struct inode *inode)
882{
883#ifdef CONFIG_DEBUG_LOCK_ALLOC
884    if (S_ISDIR(inode->i_mode)) {
885        struct file_system_type *type = inode->i_sb->s_type;
886
887        /* Set new key only if filesystem hasn't already changed it */
888        if (!lockdep_match_class(&inode->i_mutex,
889            &type->i_mutex_key)) {
890            /*
891             * ensure nobody is actually holding i_mutex
892             */
893            mutex_destroy(&inode->i_mutex);
894            mutex_init(&inode->i_mutex);
895            lockdep_set_class(&inode->i_mutex,
896                      &type->i_mutex_dir_key);
897        }
898    }
899#endif
900    spin_lock(&inode->i_lock);
901    WARN_ON(!(inode->i_state & I_NEW));
902    inode->i_state &= ~I_NEW;
903    wake_up_bit(&inode->i_state, __I_NEW);
904    spin_unlock(&inode->i_lock);
905}
906EXPORT_SYMBOL(unlock_new_inode);
907
908/**
909 * iget5_locked - obtain an inode from a mounted file system
910 * @sb: super block of file system
911 * @hashval: hash value (usually inode number) to get
912 * @test: callback used for comparisons between inodes
913 * @set: callback used to initialize a new struct inode
914 * @data: opaque data pointer to pass to @test and @set
915 *
916 * Search for the inode specified by @hashval and @data in the inode cache,
917 * and if present it is return it with an increased reference count. This is
918 * a generalized version of iget_locked() for file systems where the inode
919 * number is not sufficient for unique identification of an inode.
920 *
921 * If the inode is not in cache, allocate a new inode and return it locked,
922 * hashed, and with the I_NEW flag set. The file system gets to fill it in
923 * before unlocking it via unlock_new_inode().
924 *
925 * Note both @test and @set are called with the inode_hash_lock held, so can't
926 * sleep.
927 */
928struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
929        int (*test)(struct inode *, void *),
930        int (*set)(struct inode *, void *), void *data)
931{
932    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
933    struct inode *inode;
934
935    spin_lock(&inode_hash_lock);
936    inode = find_inode(sb, head, test, data);
937    spin_unlock(&inode_hash_lock);
938
939    if (inode) {
940        wait_on_inode(inode);
941        return inode;
942    }
943
944    inode = alloc_inode(sb);
945    if (inode) {
946        struct inode *old;
947
948        spin_lock(&inode_hash_lock);
949        /* We released the lock, so.. */
950        old = find_inode(sb, head, test, data);
951        if (!old) {
952            if (set(inode, data))
953                goto set_failed;
954
955            spin_lock(&inode->i_lock);
956            inode->i_state = I_NEW;
957            hlist_add_head(&inode->i_hash, head);
958            spin_unlock(&inode->i_lock);
959            inode_sb_list_add(inode);
960            spin_unlock(&inode_hash_lock);
961
962            /* Return the locked inode with I_NEW set, the
963             * caller is responsible for filling in the contents
964             */
965            return inode;
966        }
967
968        /*
969         * Uhhuh, somebody else created the same inode under
970         * us. Use the old inode instead of the one we just
971         * allocated.
972         */
973        spin_unlock(&inode_hash_lock);
974        destroy_inode(inode);
975        inode = old;
976        wait_on_inode(inode);
977    }
978    return inode;
979
980set_failed:
981    spin_unlock(&inode_hash_lock);
982    destroy_inode(inode);
983    return NULL;
984}
985EXPORT_SYMBOL(iget5_locked);
986
987/**
988 * iget_locked - obtain an inode from a mounted file system
989 * @sb: super block of file system
990 * @ino: inode number to get
991 *
992 * Search for the inode specified by @ino in the inode cache and if present
993 * return it with an increased reference count. This is for file systems
994 * where the inode number is sufficient for unique identification of an inode.
995 *
996 * If the inode is not in cache, allocate a new inode and return it locked,
997 * hashed, and with the I_NEW flag set. The file system gets to fill it in
998 * before unlocking it via unlock_new_inode().
999 */
1000struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1001{
1002    struct hlist_head *head = inode_hashtable + hash(sb, ino);
1003    struct inode *inode;
1004
1005    spin_lock(&inode_hash_lock);
1006    inode = find_inode_fast(sb, head, ino);
1007    spin_unlock(&inode_hash_lock);
1008    if (inode) {
1009        wait_on_inode(inode);
1010        return inode;
1011    }
1012
1013    inode = alloc_inode(sb);
1014    if (inode) {
1015        struct inode *old;
1016
1017        spin_lock(&inode_hash_lock);
1018        /* We released the lock, so.. */
1019        old = find_inode_fast(sb, head, ino);
1020        if (!old) {
1021            inode->i_ino = ino;
1022            spin_lock(&inode->i_lock);
1023            inode->i_state = I_NEW;
1024            hlist_add_head(&inode->i_hash, head);
1025            spin_unlock(&inode->i_lock);
1026            inode_sb_list_add(inode);
1027            spin_unlock(&inode_hash_lock);
1028
1029            /* Return the locked inode with I_NEW set, the
1030             * caller is responsible for filling in the contents
1031             */
1032            return inode;
1033        }
1034
1035        /*
1036         * Uhhuh, somebody else created the same inode under
1037         * us. Use the old inode instead of the one we just
1038         * allocated.
1039         */
1040        spin_unlock(&inode_hash_lock);
1041        destroy_inode(inode);
1042        inode = old;
1043        wait_on_inode(inode);
1044    }
1045    return inode;
1046}
1047EXPORT_SYMBOL(iget_locked);
1048
1049/*
1050 * search the inode cache for a matching inode number.
1051 * If we find one, then the inode number we are trying to
1052 * allocate is not unique and so we should not use it.
1053 *
1054 * Returns 1 if the inode number is unique, 0 if it is not.
1055 */
1056static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1057{
1058    struct hlist_head *b = inode_hashtable + hash(sb, ino);
1059    struct hlist_node *node;
1060    struct inode *inode;
1061
1062    spin_lock(&inode_hash_lock);
1063    hlist_for_each_entry(inode, node, b, i_hash) {
1064        if (inode->i_ino == ino && inode->i_sb == sb) {
1065            spin_unlock(&inode_hash_lock);
1066            return 0;
1067        }
1068    }
1069    spin_unlock(&inode_hash_lock);
1070
1071    return 1;
1072}
1073
1074/**
1075 * iunique - get a unique inode number
1076 * @sb: superblock
1077 * @max_reserved: highest reserved inode number
1078 *
1079 * Obtain an inode number that is unique on the system for a given
1080 * superblock. This is used by file systems that have no natural
1081 * permanent inode numbering system. An inode number is returned that
1082 * is higher than the reserved limit but unique.
1083 *
1084 * BUGS:
1085 * With a large number of inodes live on the file system this function
1086 * currently becomes quite slow.
1087 */
1088ino_t iunique(struct super_block *sb, ino_t max_reserved)
1089{
1090    /*
1091     * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1092     * error if st_ino won't fit in target struct field. Use 32bit counter
1093     * here to attempt to avoid that.
1094     */
1095    static DEFINE_SPINLOCK(iunique_lock);
1096    static unsigned int counter;
1097    ino_t res;
1098
1099    spin_lock(&iunique_lock);
1100    do {
1101        if (counter <= max_reserved)
1102            counter = max_reserved + 1;
1103        res = counter++;
1104    } while (!test_inode_iunique(sb, res));
1105    spin_unlock(&iunique_lock);
1106
1107    return res;
1108}
1109EXPORT_SYMBOL(iunique);
1110
1111struct inode *igrab(struct inode *inode)
1112{
1113    spin_lock(&inode->i_lock);
1114    if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1115        __iget(inode);
1116        spin_unlock(&inode->i_lock);
1117    } else {
1118        spin_unlock(&inode->i_lock);
1119        /*
1120         * Handle the case where s_op->clear_inode is not been
1121         * called yet, and somebody is calling igrab
1122         * while the inode is getting freed.
1123         */
1124        inode = NULL;
1125    }
1126    return inode;
1127}
1128EXPORT_SYMBOL(igrab);
1129
1130/**
1131 * ilookup5_nowait - search for an inode in the inode cache
1132 * @sb: super block of file system to search
1133 * @hashval: hash value (usually inode number) to search for
1134 * @test: callback used for comparisons between inodes
1135 * @data: opaque data pointer to pass to @test
1136 *
1137 * Search for the inode specified by @hashval and @data in the inode cache.
1138 * If the inode is in the cache, the inode is returned with an incremented
1139 * reference count.
1140 *
1141 * Note: I_NEW is not waited upon so you have to be very careful what you do
1142 * with the returned inode. You probably should be using ilookup5() instead.
1143 *
1144 * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1145 */
1146struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1147        int (*test)(struct inode *, void *), void *data)
1148{
1149    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1150    struct inode *inode;
1151
1152    spin_lock(&inode_hash_lock);
1153    inode = find_inode(sb, head, test, data);
1154    spin_unlock(&inode_hash_lock);
1155
1156    return inode;
1157}
1158EXPORT_SYMBOL(ilookup5_nowait);
1159
1160/**
1161 * ilookup5 - search for an inode in the inode cache
1162 * @sb: super block of file system to search
1163 * @hashval: hash value (usually inode number) to search for
1164 * @test: callback used for comparisons between inodes
1165 * @data: opaque data pointer to pass to @test
1166 *
1167 * Search for the inode specified by @hashval and @data in the inode cache,
1168 * and if the inode is in the cache, return the inode with an incremented
1169 * reference count. Waits on I_NEW before returning the inode.
1170 * returned with an incremented reference count.
1171 *
1172 * This is a generalized version of ilookup() for file systems where the
1173 * inode number is not sufficient for unique identification of an inode.
1174 *
1175 * Note: @test is called with the inode_hash_lock held, so can't sleep.
1176 */
1177struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1178        int (*test)(struct inode *, void *), void *data)
1179{
1180    struct inode *inode = ilookup5_nowait(sb, hashval, test, data);
1181
1182    if (inode)
1183        wait_on_inode(inode);
1184    return inode;
1185}
1186EXPORT_SYMBOL(ilookup5);
1187
1188/**
1189 * ilookup - search for an inode in the inode cache
1190 * @sb: super block of file system to search
1191 * @ino: inode number to search for
1192 *
1193 * Search for the inode @ino in the inode cache, and if the inode is in the
1194 * cache, the inode is returned with an incremented reference count.
1195 */
1196struct inode *ilookup(struct super_block *sb, unsigned long ino)
1197{
1198    struct hlist_head *head = inode_hashtable + hash(sb, ino);
1199    struct inode *inode;
1200
1201    spin_lock(&inode_hash_lock);
1202    inode = find_inode_fast(sb, head, ino);
1203    spin_unlock(&inode_hash_lock);
1204
1205    if (inode)
1206        wait_on_inode(inode);
1207    return inode;
1208}
1209EXPORT_SYMBOL(ilookup);
1210
1211int insert_inode_locked(struct inode *inode)
1212{
1213    struct super_block *sb = inode->i_sb;
1214    ino_t ino = inode->i_ino;
1215    struct hlist_head *head = inode_hashtable + hash(sb, ino);
1216
1217    while (1) {
1218        struct hlist_node *node;
1219        struct inode *old = NULL;
1220        spin_lock(&inode_hash_lock);
1221        hlist_for_each_entry(old, node, head, i_hash) {
1222            if (old->i_ino != ino)
1223                continue;
1224            if (old->i_sb != sb)
1225                continue;
1226            spin_lock(&old->i_lock);
1227            if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1228                spin_unlock(&old->i_lock);
1229                continue;
1230            }
1231            break;
1232        }
1233        if (likely(!node)) {
1234            spin_lock(&inode->i_lock);
1235            inode->i_state |= I_NEW;
1236            hlist_add_head(&inode->i_hash, head);
1237            spin_unlock(&inode->i_lock);
1238            spin_unlock(&inode_hash_lock);
1239            return 0;
1240        }
1241        __iget(old);
1242        spin_unlock(&old->i_lock);
1243        spin_unlock(&inode_hash_lock);
1244        wait_on_inode(old);
1245        if (unlikely(!inode_unhashed(old))) {
1246            iput(old);
1247            return -EBUSY;
1248        }
1249        iput(old);
1250    }
1251}
1252EXPORT_SYMBOL(insert_inode_locked);
1253
1254int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1255        int (*test)(struct inode *, void *), void *data)
1256{
1257    struct super_block *sb = inode->i_sb;
1258    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1259
1260    while (1) {
1261        struct hlist_node *node;
1262        struct inode *old = NULL;
1263
1264        spin_lock(&inode_hash_lock);
1265        hlist_for_each_entry(old, node, head, i_hash) {
1266            if (old->i_sb != sb)
1267                continue;
1268            if (!test(old, data))
1269                continue;
1270            spin_lock(&old->i_lock);
1271            if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1272                spin_unlock(&old->i_lock);
1273                continue;
1274            }
1275            break;
1276        }
1277        if (likely(!node)) {
1278            spin_lock(&inode->i_lock);
1279            inode->i_state |= I_NEW;
1280            hlist_add_head(&inode->i_hash, head);
1281            spin_unlock(&inode->i_lock);
1282            spin_unlock(&inode_hash_lock);
1283            return 0;
1284        }
1285        __iget(old);
1286        spin_unlock(&old->i_lock);
1287        spin_unlock(&inode_hash_lock);
1288        wait_on_inode(old);
1289        if (unlikely(!inode_unhashed(old))) {
1290            iput(old);
1291            return -EBUSY;
1292        }
1293        iput(old);
1294    }
1295}
1296EXPORT_SYMBOL(insert_inode_locked4);
1297
1298
1299int generic_delete_inode(struct inode *inode)
1300{
1301    return 1;
1302}
1303EXPORT_SYMBOL(generic_delete_inode);
1304
1305/*
1306 * Normal UNIX filesystem behaviour: delete the
1307 * inode when the usage count drops to zero, and
1308 * i_nlink is zero.
1309 */
1310int generic_drop_inode(struct inode *inode)
1311{
1312    return !inode->i_nlink || inode_unhashed(inode);
1313}
1314EXPORT_SYMBOL_GPL(generic_drop_inode);
1315
1316/*
1317 * Called when we're dropping the last reference
1318 * to an inode.
1319 *
1320 * Call the FS "drop_inode()" function, defaulting to
1321 * the legacy UNIX filesystem behaviour. If it tells
1322 * us to evict inode, do so. Otherwise, retain inode
1323 * in cache if fs is alive, sync and evict if fs is
1324 * shutting down.
1325 */
1326static void iput_final(struct inode *inode)
1327{
1328    struct super_block *sb = inode->i_sb;
1329    const struct super_operations *op = inode->i_sb->s_op;
1330    int drop;
1331
1332    WARN_ON(inode->i_state & I_NEW);
1333
1334    if (op && op->drop_inode)
1335        drop = op->drop_inode(inode);
1336    else
1337        drop = generic_drop_inode(inode);
1338
1339    if (!drop && (sb->s_flags & MS_ACTIVE)) {
1340        inode->i_state |= I_REFERENCED;
1341        if (!(inode->i_state & (I_DIRTY|I_SYNC)))
1342            inode_lru_list_add(inode);
1343        spin_unlock(&inode->i_lock);
1344        return;
1345    }
1346
1347    if (!drop) {
1348        inode->i_state |= I_WILL_FREE;
1349        spin_unlock(&inode->i_lock);
1350        write_inode_now(inode, 1);
1351        spin_lock(&inode->i_lock);
1352        WARN_ON(inode->i_state & I_NEW);
1353        inode->i_state &= ~I_WILL_FREE;
1354    }
1355
1356    inode->i_state |= I_FREEING;
1357    inode_lru_list_del(inode);
1358    spin_unlock(&inode->i_lock);
1359
1360    evict(inode);
1361}
1362
1363/**
1364 * iput - put an inode
1365 * @inode: inode to put
1366 *
1367 * Puts an inode, dropping its usage count. If the inode use count hits
1368 * zero, the inode is then freed and may also be destroyed.
1369 *
1370 * Consequently, iput() can sleep.
1371 */
1372void iput(struct inode *inode)
1373{
1374    if (inode) {
1375        BUG_ON(inode->i_state & I_CLEAR);
1376
1377        if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock))
1378            iput_final(inode);
1379    }
1380}
1381EXPORT_SYMBOL(iput);
1382
1383/**
1384 * bmap - find a block number in a file
1385 * @inode: inode of file
1386 * @block: block to find
1387 *
1388 * Returns the block number on the device holding the inode that
1389 * is the disk block number for the block of the file requested.
1390 * That is, asked for block 4 of inode 1 the function will return the
1391 * disk block relative to the disk start that holds that block of the
1392 * file.
1393 */
1394sector_t bmap(struct inode *inode, sector_t block)
1395{
1396    sector_t res = 0;
1397    if (inode->i_mapping->a_ops->bmap)
1398        res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1399    return res;
1400}
1401EXPORT_SYMBOL(bmap);
1402
1403/*
1404 * With relative atime, only update atime if the previous atime is
1405 * earlier than either the ctime or mtime or if at least a day has
1406 * passed since the last atime update.
1407 */
1408static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1409                 struct timespec now)
1410{
1411
1412    if (!(mnt->mnt_flags & MNT_RELATIME))
1413        return 1;
1414    /*
1415     * Is mtime younger than atime? If yes, update atime:
1416     */
1417    if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1418        return 1;
1419    /*
1420     * Is ctime younger than atime? If yes, update atime:
1421     */
1422    if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1423        return 1;
1424
1425    /*
1426     * Is the previous atime value older than a day? If yes,
1427     * update atime:
1428     */
1429    if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1430        return 1;
1431    /*
1432     * Good, we can skip the atime update:
1433     */
1434    return 0;
1435}
1436
1437/**
1438 * touch_atime - update the access time
1439 * @mnt: mount the inode is accessed on
1440 * @dentry: dentry accessed
1441 *
1442 * Update the accessed time on an inode and mark it for writeback.
1443 * This function automatically handles read only file systems and media,
1444 * as well as the "noatime" flag and inode specific "noatime" markers.
1445 */
1446void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
1447{
1448    struct inode *inode = dentry->d_inode;
1449    struct timespec now;
1450
1451    if (inode->i_flags & S_NOATIME)
1452        return;
1453    if (IS_NOATIME(inode))
1454        return;
1455    if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1456        return;
1457
1458    if (mnt->mnt_flags & MNT_NOATIME)
1459        return;
1460    if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1461        return;
1462
1463    now = current_fs_time(inode->i_sb);
1464
1465    if (!relatime_need_update(mnt, inode, now))
1466        return;
1467
1468    if (timespec_equal(&inode->i_atime, &now))
1469        return;
1470
1471    if (mnt_want_write(mnt))
1472        return;
1473
1474    inode->i_atime = now;
1475    mark_inode_dirty_sync(inode);
1476    mnt_drop_write(mnt);
1477}
1478EXPORT_SYMBOL(touch_atime);
1479
1480/**
1481 * file_update_time - update mtime and ctime time
1482 * @file: file accessed
1483 *
1484 * Update the mtime and ctime members of an inode and mark the inode
1485 * for writeback. Note that this function is meant exclusively for
1486 * usage in the file write path of filesystems, and filesystems may
1487 * choose to explicitly ignore update via this function with the
1488 * S_NOCMTIME inode flag, e.g. for network filesystem where these
1489 * timestamps are handled by the server.
1490 */
1491
1492void file_update_time(struct file *file)
1493{
1494    struct inode *inode = file->f_path.dentry->d_inode;
1495    struct timespec now;
1496    enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
1497
1498    /* First try to exhaust all avenues to not sync */
1499    if (IS_NOCMTIME(inode))
1500        return;
1501
1502    now = current_fs_time(inode->i_sb);
1503    if (!timespec_equal(&inode->i_mtime, &now))
1504        sync_it = S_MTIME;
1505
1506    if (!timespec_equal(&inode->i_ctime, &now))
1507        sync_it |= S_CTIME;
1508
1509    if (IS_I_VERSION(inode))
1510        sync_it |= S_VERSION;
1511
1512    if (!sync_it)
1513        return;
1514
1515    /* Finally allowed to write? Takes lock. */
1516    if (mnt_want_write_file(file))
1517        return;
1518
1519    /* Only change inode inside the lock region */
1520    if (sync_it & S_VERSION)
1521        inode_inc_iversion(inode);
1522    if (sync_it & S_CTIME)
1523        inode->i_ctime = now;
1524    if (sync_it & S_MTIME)
1525        inode->i_mtime = now;
1526    mark_inode_dirty_sync(inode);
1527    mnt_drop_write(file->f_path.mnt);
1528}
1529EXPORT_SYMBOL(file_update_time);
1530
1531int inode_needs_sync(struct inode *inode)
1532{
1533    if (IS_SYNC(inode))
1534        return 1;
1535    if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1536        return 1;
1537    return 0;
1538}
1539EXPORT_SYMBOL(inode_needs_sync);
1540
1541int inode_wait(void *word)
1542{
1543    schedule();
1544    return 0;
1545}
1546EXPORT_SYMBOL(inode_wait);
1547
1548/*
1549 * If we try to find an inode in the inode hash while it is being
1550 * deleted, we have to wait until the filesystem completes its
1551 * deletion before reporting that it isn't found. This function waits
1552 * until the deletion _might_ have completed. Callers are responsible
1553 * to recheck inode state.
1554 *
1555 * It doesn't matter if I_NEW is not set initially, a call to
1556 * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
1557 * will DTRT.
1558 */
1559static void __wait_on_freeing_inode(struct inode *inode)
1560{
1561    wait_queue_head_t *wq;
1562    DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
1563    wq = bit_waitqueue(&inode->i_state, __I_NEW);
1564    prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1565    spin_unlock(&inode->i_lock);
1566    spin_unlock(&inode_hash_lock);
1567    schedule();
1568    finish_wait(wq, &wait.wait);
1569    spin_lock(&inode_hash_lock);
1570}
1571
1572static __initdata unsigned long ihash_entries;
1573static int __init set_ihash_entries(char *str)
1574{
1575    if (!str)
1576        return 0;
1577    ihash_entries = simple_strtoul(str, &str, 0);
1578    return 1;
1579}
1580__setup("ihash_entries=", set_ihash_entries);
1581
1582/*
1583 * Initialize the waitqueues and inode hash table.
1584 */
1585void __init inode_init_early(void)
1586{
1587    int loop;
1588
1589    /* If hashes are distributed across NUMA nodes, defer
1590     * hash allocation until vmalloc space is available.
1591     */
1592    if (hashdist)
1593        return;
1594
1595    inode_hashtable =
1596        alloc_large_system_hash("Inode-cache",
1597                    sizeof(struct hlist_head),
1598                    ihash_entries,
1599                    14,
1600                    HASH_EARLY,
1601                    &i_hash_shift,
1602                    &i_hash_mask,
1603                    0);
1604
1605    for (loop = 0; loop < (1 << i_hash_shift); loop++)
1606        INIT_HLIST_HEAD(&inode_hashtable[loop]);
1607}
1608
1609void __init inode_init(void)
1610{
1611    int loop;
1612
1613    /* inode slab cache */
1614    inode_cachep = kmem_cache_create("inode_cache",
1615                     sizeof(struct inode),
1616                     0,
1617                     (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1618                     SLAB_MEM_SPREAD),
1619                     init_once);
1620    register_shrinker(&icache_shrinker);
1621
1622    /* Hash may have been set up in inode_init_early */
1623    if (!hashdist)
1624        return;
1625
1626    inode_hashtable =
1627        alloc_large_system_hash("Inode-cache",
1628                    sizeof(struct hlist_head),
1629                    ihash_entries,
1630                    14,
1631                    0,
1632                    &i_hash_shift,
1633                    &i_hash_mask,
1634                    0);
1635
1636    for (loop = 0; loop < (1 << i_hash_shift); loop++)
1637        INIT_HLIST_HEAD(&inode_hashtable[loop]);
1638}
1639
1640void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
1641{
1642    inode->i_mode = mode;
1643    if (S_ISCHR(mode)) {
1644        inode->i_fop = &def_chr_fops;
1645        inode->i_rdev = rdev;
1646    } else if (S_ISBLK(mode)) {
1647        inode->i_fop = &def_blk_fops;
1648        inode->i_rdev = rdev;
1649    } else if (S_ISFIFO(mode))
1650        inode->i_fop = &def_fifo_fops;
1651    else if (S_ISSOCK(mode))
1652        inode->i_fop = &bad_sock_fops;
1653    else
1654        printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
1655                  " inode %s:%lu\n", mode, inode->i_sb->s_id,
1656                  inode->i_ino);
1657}
1658EXPORT_SYMBOL(init_special_inode);
1659
1660/**
1661 * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
1662 * @inode: New inode
1663 * @dir: Directory inode
1664 * @mode: mode of the new inode
1665 */
1666void inode_init_owner(struct inode *inode, const struct inode *dir,
1667            mode_t mode)
1668{
1669    inode->i_uid = current_fsuid();
1670    if (dir && dir->i_mode & S_ISGID) {
1671        inode->i_gid = dir->i_gid;
1672        if (S_ISDIR(mode))
1673            mode |= S_ISGID;
1674    } else
1675        inode->i_gid = current_fsgid();
1676    inode->i_mode = mode;
1677}
1678EXPORT_SYMBOL(inode_init_owner);
1679
1680/**
1681 * inode_owner_or_capable - check current task permissions to inode
1682 * @inode: inode being checked
1683 *
1684 * Return true if current either has CAP_FOWNER to the inode, or
1685 * owns the file.
1686 */
1687bool inode_owner_or_capable(const struct inode *inode)
1688{
1689    struct user_namespace *ns = inode_userns(inode);
1690
1691    if (current_user_ns() == ns && current_fsuid() == inode->i_uid)
1692        return true;
1693    if (ns_capable(ns, CAP_FOWNER))
1694        return true;
1695    return false;
1696}
1697EXPORT_SYMBOL(inode_owner_or_capable);
1698

Archive Download this file



interactive