Root/fs/inode.c

Source at commit 9845c1745d3d531a5b9544f5322c62bfb4d4e9bc created 1 year 2 months ago.
By Xiangfu, rtc: jz4740 fix hwclock give time out
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->i_sb->s_inode_lru_lock protects:
37 * inode->i_sb->s_inode_lru, inode->i_lru
38 * inode_sb_list_lock protects:
39 * sb->s_inodes, inode->i_sb_list
40 * bdi->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->i_sb->s_inode_lru_lock
50 *
51 * bdi->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
67__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock);
68
69/*
70 * Empty aops. Can be used for the cases where the user does not
71 * define any of the address_space operations.
72 */
73const struct address_space_operations empty_aops = {
74};
75EXPORT_SYMBOL(empty_aops);
76
77/*
78 * Statistics gathering..
79 */
80struct inodes_stat_t inodes_stat;
81
82static DEFINE_PER_CPU(unsigned int, nr_inodes);
83static DEFINE_PER_CPU(unsigned int, nr_unused);
84
85static struct kmem_cache *inode_cachep __read_mostly;
86
87static int get_nr_inodes(void)
88{
89    int i;
90    int sum = 0;
91    for_each_possible_cpu(i)
92        sum += per_cpu(nr_inodes, i);
93    return sum < 0 ? 0 : sum;
94}
95
96static inline int get_nr_inodes_unused(void)
97{
98    int i;
99    int sum = 0;
100    for_each_possible_cpu(i)
101        sum += per_cpu(nr_unused, i);
102    return sum < 0 ? 0 : sum;
103}
104
105int get_nr_dirty_inodes(void)
106{
107    /* not actually dirty inodes, but a wild approximation */
108    int nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
109    return nr_dirty > 0 ? nr_dirty : 0;
110}
111
112/*
113 * Handle nr_inode sysctl
114 */
115#ifdef CONFIG_SYSCTL
116int proc_nr_inodes(ctl_table *table, int write,
117           void __user *buffer, size_t *lenp, loff_t *ppos)
118{
119    inodes_stat.nr_inodes = get_nr_inodes();
120    inodes_stat.nr_unused = get_nr_inodes_unused();
121    return proc_dointvec(table, write, buffer, lenp, ppos);
122}
123#endif
124
125/**
126 * inode_init_always - perform inode structure intialisation
127 * @sb: superblock inode belongs to
128 * @inode: inode to initialise
129 *
130 * These are initializations that need to be done on every inode
131 * allocation as the fields are not initialised by slab allocation.
132 */
133int inode_init_always(struct super_block *sb, struct inode *inode)
134{
135    static const struct inode_operations empty_iops;
136    static const struct file_operations empty_fops;
137    struct address_space *const mapping = &inode->i_data;
138
139    inode->i_sb = sb;
140    inode->i_blkbits = sb->s_blocksize_bits;
141    inode->i_flags = 0;
142    atomic_set(&inode->i_count, 1);
143    inode->i_op = &empty_iops;
144    inode->i_fop = &empty_fops;
145    inode->__i_nlink = 1;
146    inode->i_opflags = 0;
147    inode->i_uid = 0;
148    inode->i_gid = 0;
149    atomic_set(&inode->i_writecount, 0);
150    inode->i_size = 0;
151    inode->i_blocks = 0;
152    inode->i_bytes = 0;
153    inode->i_generation = 0;
154#ifdef CONFIG_QUOTA
155    memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
156#endif
157    inode->i_pipe = NULL;
158    inode->i_bdev = NULL;
159    inode->i_cdev = NULL;
160    inode->i_rdev = 0;
161    inode->dirtied_when = 0;
162
163    if (security_inode_alloc(inode))
164        goto out;
165    spin_lock_init(&inode->i_lock);
166    lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
167
168    mutex_init(&inode->i_mutex);
169    lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
170
171    atomic_set(&inode->i_dio_count, 0);
172
173    mapping->a_ops = &empty_aops;
174    mapping->host = inode;
175    mapping->flags = 0;
176    mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
177    mapping->assoc_mapping = NULL;
178    mapping->backing_dev_info = &default_backing_dev_info;
179    mapping->writeback_index = 0;
180
181    /*
182     * If the block_device provides a backing_dev_info for client
183     * inodes then use that. Otherwise the inode share the bdev's
184     * backing_dev_info.
185     */
186    if (sb->s_bdev) {
187        struct backing_dev_info *bdi;
188
189        bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
190        mapping->backing_dev_info = bdi;
191    }
192    inode->i_private = NULL;
193    inode->i_mapping = mapping;
194#ifdef CONFIG_FS_POSIX_ACL
195    inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
196#endif
197
198#ifdef CONFIG_FSNOTIFY
199    inode->i_fsnotify_mask = 0;
200#endif
201
202    this_cpu_inc(nr_inodes);
203
204    return 0;
205out:
206    return -ENOMEM;
207}
208EXPORT_SYMBOL(inode_init_always);
209
210static struct inode *alloc_inode(struct super_block *sb)
211{
212    struct inode *inode;
213
214    if (sb->s_op->alloc_inode)
215        inode = sb->s_op->alloc_inode(sb);
216    else
217        inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
218
219    if (!inode)
220        return NULL;
221
222    if (unlikely(inode_init_always(sb, inode))) {
223        if (inode->i_sb->s_op->destroy_inode)
224            inode->i_sb->s_op->destroy_inode(inode);
225        else
226            kmem_cache_free(inode_cachep, inode);
227        return NULL;
228    }
229
230    return inode;
231}
232
233void free_inode_nonrcu(struct inode *inode)
234{
235    kmem_cache_free(inode_cachep, inode);
236}
237EXPORT_SYMBOL(free_inode_nonrcu);
238
239void __destroy_inode(struct inode *inode)
240{
241    BUG_ON(inode_has_buffers(inode));
242    security_inode_free(inode);
243    fsnotify_inode_delete(inode);
244#ifdef CONFIG_FS_POSIX_ACL
245    if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
246        posix_acl_release(inode->i_acl);
247    if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
248        posix_acl_release(inode->i_default_acl);
249#endif
250    this_cpu_dec(nr_inodes);
251}
252EXPORT_SYMBOL(__destroy_inode);
253
254static void i_callback(struct rcu_head *head)
255{
256    struct inode *inode = container_of(head, struct inode, i_rcu);
257    INIT_LIST_HEAD(&inode->i_dentry);
258    kmem_cache_free(inode_cachep, inode);
259}
260
261static void destroy_inode(struct inode *inode)
262{
263    BUG_ON(!list_empty(&inode->i_lru));
264    __destroy_inode(inode);
265    if (inode->i_sb->s_op->destroy_inode)
266        inode->i_sb->s_op->destroy_inode(inode);
267    else
268        call_rcu(&inode->i_rcu, i_callback);
269}
270
271void address_space_init_once(struct address_space *mapping)
272{
273    memset(mapping, 0, sizeof(*mapping));
274    INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
275    spin_lock_init(&mapping->tree_lock);
276    mutex_init(&mapping->i_mmap_mutex);
277    INIT_LIST_HEAD(&mapping->private_list);
278    spin_lock_init(&mapping->private_lock);
279    INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
280    INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
281}
282EXPORT_SYMBOL(address_space_init_once);
283
284/*
285 * These are initializations that only need to be done
286 * once, because the fields are idempotent across use
287 * of the inode, so let the slab aware of that.
288 */
289void inode_init_once(struct inode *inode)
290{
291    memset(inode, 0, sizeof(*inode));
292    INIT_HLIST_NODE(&inode->i_hash);
293    INIT_LIST_HEAD(&inode->i_dentry);
294    INIT_LIST_HEAD(&inode->i_devices);
295    INIT_LIST_HEAD(&inode->i_wb_list);
296    INIT_LIST_HEAD(&inode->i_lru);
297    address_space_init_once(&inode->i_data);
298    i_size_ordered_init(inode);
299#ifdef CONFIG_FSNOTIFY
300    INIT_HLIST_HEAD(&inode->i_fsnotify_marks);
301#endif
302}
303EXPORT_SYMBOL(inode_init_once);
304
305static void init_once(void *foo)
306{
307    struct inode *inode = (struct inode *) foo;
308
309    inode_init_once(inode);
310}
311
312/*
313 * inode->i_lock must be held
314 */
315void __iget(struct inode *inode)
316{
317    atomic_inc(&inode->i_count);
318}
319
320/*
321 * get additional reference to inode; caller must already hold one.
322 */
323void ihold(struct inode *inode)
324{
325    WARN_ON(atomic_inc_return(&inode->i_count) < 2);
326}
327EXPORT_SYMBOL(ihold);
328
329static void inode_lru_list_add(struct inode *inode)
330{
331    spin_lock(&inode->i_sb->s_inode_lru_lock);
332    if (list_empty(&inode->i_lru)) {
333        list_add(&inode->i_lru, &inode->i_sb->s_inode_lru);
334        inode->i_sb->s_nr_inodes_unused++;
335        this_cpu_inc(nr_unused);
336    }
337    spin_unlock(&inode->i_sb->s_inode_lru_lock);
338}
339
340static void inode_lru_list_del(struct inode *inode)
341{
342    spin_lock(&inode->i_sb->s_inode_lru_lock);
343    if (!list_empty(&inode->i_lru)) {
344        list_del_init(&inode->i_lru);
345        inode->i_sb->s_nr_inodes_unused--;
346        this_cpu_dec(nr_unused);
347    }
348    spin_unlock(&inode->i_sb->s_inode_lru_lock);
349}
350
351/**
352 * inode_sb_list_add - add inode to the superblock list of inodes
353 * @inode: inode to add
354 */
355void inode_sb_list_add(struct inode *inode)
356{
357    spin_lock(&inode_sb_list_lock);
358    list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
359    spin_unlock(&inode_sb_list_lock);
360}
361EXPORT_SYMBOL_GPL(inode_sb_list_add);
362
363static inline void inode_sb_list_del(struct inode *inode)
364{
365    if (!list_empty(&inode->i_sb_list)) {
366        spin_lock(&inode_sb_list_lock);
367        list_del_init(&inode->i_sb_list);
368        spin_unlock(&inode_sb_list_lock);
369    }
370}
371
372static unsigned long hash(struct super_block *sb, unsigned long hashval)
373{
374    unsigned long tmp;
375
376    tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
377            L1_CACHE_BYTES;
378    tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
379    return tmp & i_hash_mask;
380}
381
382/**
383 * __insert_inode_hash - hash an inode
384 * @inode: unhashed inode
385 * @hashval: unsigned long value used to locate this object in the
386 * inode_hashtable.
387 *
388 * Add an inode to the inode hash for this superblock.
389 */
390void __insert_inode_hash(struct inode *inode, unsigned long hashval)
391{
392    struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
393
394    spin_lock(&inode_hash_lock);
395    spin_lock(&inode->i_lock);
396    hlist_add_head(&inode->i_hash, b);
397    spin_unlock(&inode->i_lock);
398    spin_unlock(&inode_hash_lock);
399}
400EXPORT_SYMBOL(__insert_inode_hash);
401
402/**
403 * __remove_inode_hash - remove an inode from the hash
404 * @inode: inode to unhash
405 *
406 * Remove an inode from the superblock.
407 */
408void __remove_inode_hash(struct inode *inode)
409{
410    spin_lock(&inode_hash_lock);
411    spin_lock(&inode->i_lock);
412    hlist_del_init(&inode->i_hash);
413    spin_unlock(&inode->i_lock);
414    spin_unlock(&inode_hash_lock);
415}
416EXPORT_SYMBOL(__remove_inode_hash);
417
418void end_writeback(struct inode *inode)
419{
420    might_sleep();
421    /*
422     * We have to cycle tree_lock here because reclaim can be still in the
423     * process of removing the last page (in __delete_from_page_cache())
424     * and we must not free mapping under it.
425     */
426    spin_lock_irq(&inode->i_data.tree_lock);
427    BUG_ON(inode->i_data.nrpages);
428    spin_unlock_irq(&inode->i_data.tree_lock);
429    BUG_ON(!list_empty(&inode->i_data.private_list));
430    BUG_ON(!(inode->i_state & I_FREEING));
431    BUG_ON(inode->i_state & I_CLEAR);
432    inode_sync_wait(inode);
433    /* don't need i_lock here, no concurrent mods to i_state */
434    inode->i_state = I_FREEING | I_CLEAR;
435}
436EXPORT_SYMBOL(end_writeback);
437
438/*
439 * Free the inode passed in, removing it from the lists it is still connected
440 * to. We remove any pages still attached to the inode and wait for any IO that
441 * is still in progress before finally destroying the inode.
442 *
443 * An inode must already be marked I_FREEING so that we avoid the inode being
444 * moved back onto lists if we race with other code that manipulates the lists
445 * (e.g. writeback_single_inode). The caller is responsible for setting this.
446 *
447 * An inode must already be removed from the LRU list before being evicted from
448 * the cache. This should occur atomically with setting the I_FREEING state
449 * flag, so no inodes here should ever be on the LRU when being evicted.
450 */
451static void evict(struct inode *inode)
452{
453    const struct super_operations *op = inode->i_sb->s_op;
454
455    BUG_ON(!(inode->i_state & I_FREEING));
456    BUG_ON(!list_empty(&inode->i_lru));
457
458    if (!list_empty(&inode->i_wb_list))
459        inode_wb_list_del(inode);
460
461    inode_sb_list_del(inode);
462
463    if (op->evict_inode) {
464        op->evict_inode(inode);
465    } else {
466        if (inode->i_data.nrpages)
467            truncate_inode_pages(&inode->i_data, 0);
468        end_writeback(inode);
469    }
470    if (S_ISBLK(inode->i_mode) && inode->i_bdev)
471        bd_forget(inode);
472    if (S_ISCHR(inode->i_mode) && inode->i_cdev)
473        cd_forget(inode);
474
475    remove_inode_hash(inode);
476
477    spin_lock(&inode->i_lock);
478    wake_up_bit(&inode->i_state, __I_NEW);
479    BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
480    spin_unlock(&inode->i_lock);
481
482    destroy_inode(inode);
483}
484
485/*
486 * dispose_list - dispose of the contents of a local list
487 * @head: the head of the list to free
488 *
489 * Dispose-list gets a local list with local inodes in it, so it doesn't
490 * need to worry about list corruption and SMP locks.
491 */
492static void dispose_list(struct list_head *head)
493{
494    while (!list_empty(head)) {
495        struct inode *inode;
496
497        inode = list_first_entry(head, struct inode, i_lru);
498        list_del_init(&inode->i_lru);
499
500        evict(inode);
501    }
502}
503
504/**
505 * evict_inodes - evict all evictable inodes for a superblock
506 * @sb: superblock to operate on
507 *
508 * Make sure that no inodes with zero refcount are retained. This is
509 * called by superblock shutdown after having MS_ACTIVE flag removed,
510 * so any inode reaching zero refcount during or after that call will
511 * be immediately evicted.
512 */
513void evict_inodes(struct super_block *sb)
514{
515    struct inode *inode, *next;
516    LIST_HEAD(dispose);
517
518    spin_lock(&inode_sb_list_lock);
519    list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
520        if (atomic_read(&inode->i_count))
521            continue;
522
523        spin_lock(&inode->i_lock);
524        if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
525            spin_unlock(&inode->i_lock);
526            continue;
527        }
528
529        inode->i_state |= I_FREEING;
530        inode_lru_list_del(inode);
531        spin_unlock(&inode->i_lock);
532        list_add(&inode->i_lru, &dispose);
533    }
534    spin_unlock(&inode_sb_list_lock);
535
536    dispose_list(&dispose);
537}
538
539/**
540 * invalidate_inodes - attempt to free all inodes on a superblock
541 * @sb: superblock to operate on
542 * @kill_dirty: flag to guide handling of dirty inodes
543 *
544 * Attempts to free all inodes for a given superblock. If there were any
545 * busy inodes return a non-zero value, else zero.
546 * If @kill_dirty is set, discard dirty inodes too, otherwise treat
547 * them as busy.
548 */
549int invalidate_inodes(struct super_block *sb, bool kill_dirty)
550{
551    int busy = 0;
552    struct inode *inode, *next;
553    LIST_HEAD(dispose);
554
555    spin_lock(&inode_sb_list_lock);
556    list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
557        spin_lock(&inode->i_lock);
558        if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
559            spin_unlock(&inode->i_lock);
560            continue;
561        }
562        if (inode->i_state & I_DIRTY && !kill_dirty) {
563            spin_unlock(&inode->i_lock);
564            busy = 1;
565            continue;
566        }
567        if (atomic_read(&inode->i_count)) {
568            spin_unlock(&inode->i_lock);
569            busy = 1;
570            continue;
571        }
572
573        inode->i_state |= I_FREEING;
574        inode_lru_list_del(inode);
575        spin_unlock(&inode->i_lock);
576        list_add(&inode->i_lru, &dispose);
577    }
578    spin_unlock(&inode_sb_list_lock);
579
580    dispose_list(&dispose);
581
582    return busy;
583}
584
585static int can_unuse(struct inode *inode)
586{
587    if (inode->i_state & ~I_REFERENCED)
588        return 0;
589    if (inode_has_buffers(inode))
590        return 0;
591    if (atomic_read(&inode->i_count))
592        return 0;
593    if (inode->i_data.nrpages)
594        return 0;
595    return 1;
596}
597
598/*
599 * Walk the superblock inode LRU for freeable inodes and attempt to free them.
600 * This is called from the superblock shrinker function with a number of inodes
601 * to trim from the LRU. Inodes to be freed are moved to a temporary list and
602 * then are freed outside inode_lock by dispose_list().
603 *
604 * Any inodes which are pinned purely because of attached pagecache have their
605 * pagecache removed. If the inode has metadata buffers attached to
606 * mapping->private_list then try to remove them.
607 *
608 * If the inode has the I_REFERENCED flag set, then it means that it has been
609 * used recently - the flag is set in iput_final(). When we encounter such an
610 * inode, clear the flag and move it to the back of the LRU so it gets another
611 * pass through the LRU before it gets reclaimed. This is necessary because of
612 * the fact we are doing lazy LRU updates to minimise lock contention so the
613 * LRU does not have strict ordering. Hence we don't want to reclaim inodes
614 * with this flag set because they are the inodes that are out of order.
615 */
616void prune_icache_sb(struct super_block *sb, int nr_to_scan)
617{
618    LIST_HEAD(freeable);
619    int nr_scanned;
620    unsigned long reap = 0;
621
622    spin_lock(&sb->s_inode_lru_lock);
623    for (nr_scanned = nr_to_scan; nr_scanned >= 0; nr_scanned--) {
624        struct inode *inode;
625
626        if (list_empty(&sb->s_inode_lru))
627            break;
628
629        inode = list_entry(sb->s_inode_lru.prev, struct inode, i_lru);
630
631        /*
632         * we are inverting the sb->s_inode_lru_lock/inode->i_lock here,
633         * so use a trylock. If we fail to get the lock, just move the
634         * inode to the back of the list so we don't spin on it.
635         */
636        if (!spin_trylock(&inode->i_lock)) {
637            list_move_tail(&inode->i_lru, &sb->s_inode_lru);
638            continue;
639        }
640
641        /*
642         * Referenced or dirty inodes are still in use. Give them
643         * another pass through the LRU as we canot reclaim them now.
644         */
645        if (atomic_read(&inode->i_count) ||
646            (inode->i_state & ~I_REFERENCED)) {
647            list_del_init(&inode->i_lru);
648            spin_unlock(&inode->i_lock);
649            sb->s_nr_inodes_unused--;
650            this_cpu_dec(nr_unused);
651            continue;
652        }
653
654        /* recently referenced inodes get one more pass */
655        if (inode->i_state & I_REFERENCED) {
656            inode->i_state &= ~I_REFERENCED;
657            list_move(&inode->i_lru, &sb->s_inode_lru);
658            spin_unlock(&inode->i_lock);
659            continue;
660        }
661        if (inode_has_buffers(inode) || inode->i_data.nrpages) {
662            __iget(inode);
663            spin_unlock(&inode->i_lock);
664            spin_unlock(&sb->s_inode_lru_lock);
665            if (remove_inode_buffers(inode))
666                reap += invalidate_mapping_pages(&inode->i_data,
667                                0, -1);
668            iput(inode);
669            spin_lock(&sb->s_inode_lru_lock);
670
671            if (inode != list_entry(sb->s_inode_lru.next,
672                        struct inode, i_lru))
673                continue; /* wrong inode or list_empty */
674            /* avoid lock inversions with trylock */
675            if (!spin_trylock(&inode->i_lock))
676                continue;
677            if (!can_unuse(inode)) {
678                spin_unlock(&inode->i_lock);
679                continue;
680            }
681        }
682        WARN_ON(inode->i_state & I_NEW);
683        inode->i_state |= I_FREEING;
684        spin_unlock(&inode->i_lock);
685
686        list_move(&inode->i_lru, &freeable);
687        sb->s_nr_inodes_unused--;
688        this_cpu_dec(nr_unused);
689    }
690    if (current_is_kswapd())
691        __count_vm_events(KSWAPD_INODESTEAL, reap);
692    else
693        __count_vm_events(PGINODESTEAL, reap);
694    spin_unlock(&sb->s_inode_lru_lock);
695
696    dispose_list(&freeable);
697}
698
699static void __wait_on_freeing_inode(struct inode *inode);
700/*
701 * Called with the inode lock held.
702 */
703static struct inode *find_inode(struct super_block *sb,
704                struct hlist_head *head,
705                int (*test)(struct inode *, void *),
706                void *data)
707{
708    struct hlist_node *node;
709    struct inode *inode = NULL;
710
711repeat:
712    hlist_for_each_entry(inode, node, head, i_hash) {
713        spin_lock(&inode->i_lock);
714        if (inode->i_sb != sb) {
715            spin_unlock(&inode->i_lock);
716            continue;
717        }
718        if (!test(inode, data)) {
719            spin_unlock(&inode->i_lock);
720            continue;
721        }
722        if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
723            __wait_on_freeing_inode(inode);
724            goto repeat;
725        }
726        __iget(inode);
727        spin_unlock(&inode->i_lock);
728        return inode;
729    }
730    return NULL;
731}
732
733/*
734 * find_inode_fast is the fast path version of find_inode, see the comment at
735 * iget_locked for details.
736 */
737static struct inode *find_inode_fast(struct super_block *sb,
738                struct hlist_head *head, unsigned long ino)
739{
740    struct hlist_node *node;
741    struct inode *inode = NULL;
742
743repeat:
744    hlist_for_each_entry(inode, node, head, i_hash) {
745        spin_lock(&inode->i_lock);
746        if (inode->i_ino != ino) {
747            spin_unlock(&inode->i_lock);
748            continue;
749        }
750        if (inode->i_sb != sb) {
751            spin_unlock(&inode->i_lock);
752            continue;
753        }
754        if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
755            __wait_on_freeing_inode(inode);
756            goto repeat;
757        }
758        __iget(inode);
759        spin_unlock(&inode->i_lock);
760        return inode;
761    }
762    return NULL;
763}
764
765/*
766 * Each cpu owns a range of LAST_INO_BATCH numbers.
767 * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
768 * to renew the exhausted range.
769 *
770 * This does not significantly increase overflow rate because every CPU can
771 * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
772 * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
773 * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
774 * overflow rate by 2x, which does not seem too significant.
775 *
776 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
777 * error if st_ino won't fit in target struct field. Use 32bit counter
778 * here to attempt to avoid that.
779 */
780#define LAST_INO_BATCH 1024
781static DEFINE_PER_CPU(unsigned int, last_ino);
782
783unsigned int get_next_ino(void)
784{
785    unsigned int *p = &get_cpu_var(last_ino);
786    unsigned int res = *p;
787
788#ifdef CONFIG_SMP
789    if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
790        static atomic_t shared_last_ino;
791        int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
792
793        res = next - LAST_INO_BATCH;
794    }
795#endif
796
797    *p = ++res;
798    put_cpu_var(last_ino);
799    return res;
800}
801EXPORT_SYMBOL(get_next_ino);
802
803/**
804 * new_inode_pseudo - obtain an inode
805 * @sb: superblock
806 *
807 * Allocates a new inode for given superblock.
808 * Inode wont be chained in superblock s_inodes list
809 * This means :
810 * - fs can't be unmount
811 * - quotas, fsnotify, writeback can't work
812 */
813struct inode *new_inode_pseudo(struct super_block *sb)
814{
815    struct inode *inode = alloc_inode(sb);
816
817    if (inode) {
818        spin_lock(&inode->i_lock);
819        inode->i_state = 0;
820        spin_unlock(&inode->i_lock);
821        INIT_LIST_HEAD(&inode->i_sb_list);
822    }
823    return inode;
824}
825
826/**
827 * new_inode - obtain an inode
828 * @sb: superblock
829 *
830 * Allocates a new inode for given superblock. The default gfp_mask
831 * for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
832 * If HIGHMEM pages are unsuitable or it is known that pages allocated
833 * for the page cache are not reclaimable or migratable,
834 * mapping_set_gfp_mask() must be called with suitable flags on the
835 * newly created inode's mapping
836 *
837 */
838struct inode *new_inode(struct super_block *sb)
839{
840    struct inode *inode;
841
842    spin_lock_prefetch(&inode_sb_list_lock);
843
844    inode = new_inode_pseudo(sb);
845    if (inode)
846        inode_sb_list_add(inode);
847    return inode;
848}
849EXPORT_SYMBOL(new_inode);
850
851#ifdef CONFIG_DEBUG_LOCK_ALLOC
852void lockdep_annotate_inode_mutex_key(struct inode *inode)
853{
854    if (S_ISDIR(inode->i_mode)) {
855        struct file_system_type *type = inode->i_sb->s_type;
856
857        /* Set new key only if filesystem hasn't already changed it */
858        if (!lockdep_match_class(&inode->i_mutex,
859            &type->i_mutex_key)) {
860            /*
861             * ensure nobody is actually holding i_mutex
862             */
863            mutex_destroy(&inode->i_mutex);
864            mutex_init(&inode->i_mutex);
865            lockdep_set_class(&inode->i_mutex,
866                      &type->i_mutex_dir_key);
867        }
868    }
869}
870EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
871#endif
872
873/**
874 * unlock_new_inode - clear the I_NEW state and wake up any waiters
875 * @inode: new inode to unlock
876 *
877 * Called when the inode is fully initialised to clear the new state of the
878 * inode and wake up anyone waiting for the inode to finish initialisation.
879 */
880void unlock_new_inode(struct inode *inode)
881{
882    lockdep_annotate_inode_mutex_key(inode);
883    spin_lock(&inode->i_lock);
884    WARN_ON(!(inode->i_state & I_NEW));
885    inode->i_state &= ~I_NEW;
886    wake_up_bit(&inode->i_state, __I_NEW);
887    spin_unlock(&inode->i_lock);
888}
889EXPORT_SYMBOL(unlock_new_inode);
890
891/**
892 * iget5_locked - obtain an inode from a mounted file system
893 * @sb: super block of file system
894 * @hashval: hash value (usually inode number) to get
895 * @test: callback used for comparisons between inodes
896 * @set: callback used to initialize a new struct inode
897 * @data: opaque data pointer to pass to @test and @set
898 *
899 * Search for the inode specified by @hashval and @data in the inode cache,
900 * and if present it is return it with an increased reference count. This is
901 * a generalized version of iget_locked() for file systems where the inode
902 * number is not sufficient for unique identification of an inode.
903 *
904 * If the inode is not in cache, allocate a new inode and return it locked,
905 * hashed, and with the I_NEW flag set. The file system gets to fill it in
906 * before unlocking it via unlock_new_inode().
907 *
908 * Note both @test and @set are called with the inode_hash_lock held, so can't
909 * sleep.
910 */
911struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
912        int (*test)(struct inode *, void *),
913        int (*set)(struct inode *, void *), void *data)
914{
915    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
916    struct inode *inode;
917
918    spin_lock(&inode_hash_lock);
919    inode = find_inode(sb, head, test, data);
920    spin_unlock(&inode_hash_lock);
921
922    if (inode) {
923        wait_on_inode(inode);
924        return inode;
925    }
926
927    inode = alloc_inode(sb);
928    if (inode) {
929        struct inode *old;
930
931        spin_lock(&inode_hash_lock);
932        /* We released the lock, so.. */
933        old = find_inode(sb, head, test, data);
934        if (!old) {
935            if (set(inode, data))
936                goto set_failed;
937
938            spin_lock(&inode->i_lock);
939            inode->i_state = I_NEW;
940            hlist_add_head(&inode->i_hash, head);
941            spin_unlock(&inode->i_lock);
942            inode_sb_list_add(inode);
943            spin_unlock(&inode_hash_lock);
944
945            /* Return the locked inode with I_NEW set, the
946             * caller is responsible for filling in the contents
947             */
948            return inode;
949        }
950
951        /*
952         * Uhhuh, somebody else created the same inode under
953         * us. Use the old inode instead of the one we just
954         * allocated.
955         */
956        spin_unlock(&inode_hash_lock);
957        destroy_inode(inode);
958        inode = old;
959        wait_on_inode(inode);
960    }
961    return inode;
962
963set_failed:
964    spin_unlock(&inode_hash_lock);
965    destroy_inode(inode);
966    return NULL;
967}
968EXPORT_SYMBOL(iget5_locked);
969
970/**
971 * iget_locked - obtain an inode from a mounted file system
972 * @sb: super block of file system
973 * @ino: inode number to get
974 *
975 * Search for the inode specified by @ino in the inode cache and if present
976 * return it with an increased reference count. This is for file systems
977 * where the inode number is sufficient for unique identification of an inode.
978 *
979 * If the inode is not in cache, allocate a new inode and return it locked,
980 * hashed, and with the I_NEW flag set. The file system gets to fill it in
981 * before unlocking it via unlock_new_inode().
982 */
983struct inode *iget_locked(struct super_block *sb, unsigned long ino)
984{
985    struct hlist_head *head = inode_hashtable + hash(sb, ino);
986    struct inode *inode;
987
988    spin_lock(&inode_hash_lock);
989    inode = find_inode_fast(sb, head, ino);
990    spin_unlock(&inode_hash_lock);
991    if (inode) {
992        wait_on_inode(inode);
993        return inode;
994    }
995
996    inode = alloc_inode(sb);
997    if (inode) {
998        struct inode *old;
999
1000        spin_lock(&inode_hash_lock);
1001        /* We released the lock, so.. */
1002        old = find_inode_fast(sb, head, ino);
1003        if (!old) {
1004            inode->i_ino = ino;
1005            spin_lock(&inode->i_lock);
1006            inode->i_state = I_NEW;
1007            hlist_add_head(&inode->i_hash, head);
1008            spin_unlock(&inode->i_lock);
1009            inode_sb_list_add(inode);
1010            spin_unlock(&inode_hash_lock);
1011
1012            /* Return the locked inode with I_NEW set, the
1013             * caller is responsible for filling in the contents
1014             */
1015            return inode;
1016        }
1017
1018        /*
1019         * Uhhuh, somebody else created the same inode under
1020         * us. Use the old inode instead of the one we just
1021         * allocated.
1022         */
1023        spin_unlock(&inode_hash_lock);
1024        destroy_inode(inode);
1025        inode = old;
1026        wait_on_inode(inode);
1027    }
1028    return inode;
1029}
1030EXPORT_SYMBOL(iget_locked);
1031
1032/*
1033 * search the inode cache for a matching inode number.
1034 * If we find one, then the inode number we are trying to
1035 * allocate is not unique and so we should not use it.
1036 *
1037 * Returns 1 if the inode number is unique, 0 if it is not.
1038 */
1039static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1040{
1041    struct hlist_head *b = inode_hashtable + hash(sb, ino);
1042    struct hlist_node *node;
1043    struct inode *inode;
1044
1045    spin_lock(&inode_hash_lock);
1046    hlist_for_each_entry(inode, node, b, i_hash) {
1047        if (inode->i_ino == ino && inode->i_sb == sb) {
1048            spin_unlock(&inode_hash_lock);
1049            return 0;
1050        }
1051    }
1052    spin_unlock(&inode_hash_lock);
1053
1054    return 1;
1055}
1056
1057/**
1058 * iunique - get a unique inode number
1059 * @sb: superblock
1060 * @max_reserved: highest reserved inode number
1061 *
1062 * Obtain an inode number that is unique on the system for a given
1063 * superblock. This is used by file systems that have no natural
1064 * permanent inode numbering system. An inode number is returned that
1065 * is higher than the reserved limit but unique.
1066 *
1067 * BUGS:
1068 * With a large number of inodes live on the file system this function
1069 * currently becomes quite slow.
1070 */
1071ino_t iunique(struct super_block *sb, ino_t max_reserved)
1072{
1073    /*
1074     * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1075     * error if st_ino won't fit in target struct field. Use 32bit counter
1076     * here to attempt to avoid that.
1077     */
1078    static DEFINE_SPINLOCK(iunique_lock);
1079    static unsigned int counter;
1080    ino_t res;
1081
1082    spin_lock(&iunique_lock);
1083    do {
1084        if (counter <= max_reserved)
1085            counter = max_reserved + 1;
1086        res = counter++;
1087    } while (!test_inode_iunique(sb, res));
1088    spin_unlock(&iunique_lock);
1089
1090    return res;
1091}
1092EXPORT_SYMBOL(iunique);
1093
1094struct inode *igrab(struct inode *inode)
1095{
1096    spin_lock(&inode->i_lock);
1097    if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1098        __iget(inode);
1099        spin_unlock(&inode->i_lock);
1100    } else {
1101        spin_unlock(&inode->i_lock);
1102        /*
1103         * Handle the case where s_op->clear_inode is not been
1104         * called yet, and somebody is calling igrab
1105         * while the inode is getting freed.
1106         */
1107        inode = NULL;
1108    }
1109    return inode;
1110}
1111EXPORT_SYMBOL(igrab);
1112
1113/**
1114 * ilookup5_nowait - search for an inode in the inode cache
1115 * @sb: super block of file system to search
1116 * @hashval: hash value (usually inode number) to search for
1117 * @test: callback used for comparisons between inodes
1118 * @data: opaque data pointer to pass to @test
1119 *
1120 * Search for the inode specified by @hashval and @data in the inode cache.
1121 * If the inode is in the cache, the inode is returned with an incremented
1122 * reference count.
1123 *
1124 * Note: I_NEW is not waited upon so you have to be very careful what you do
1125 * with the returned inode. You probably should be using ilookup5() instead.
1126 *
1127 * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1128 */
1129struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1130        int (*test)(struct inode *, void *), void *data)
1131{
1132    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1133    struct inode *inode;
1134
1135    spin_lock(&inode_hash_lock);
1136    inode = find_inode(sb, head, test, data);
1137    spin_unlock(&inode_hash_lock);
1138
1139    return inode;
1140}
1141EXPORT_SYMBOL(ilookup5_nowait);
1142
1143/**
1144 * ilookup5 - search for an inode in the inode cache
1145 * @sb: super block of file system to search
1146 * @hashval: hash value (usually inode number) to search for
1147 * @test: callback used for comparisons between inodes
1148 * @data: opaque data pointer to pass to @test
1149 *
1150 * Search for the inode specified by @hashval and @data in the inode cache,
1151 * and if the inode is in the cache, return the inode with an incremented
1152 * reference count. Waits on I_NEW before returning the inode.
1153 * returned with an incremented reference count.
1154 *
1155 * This is a generalized version of ilookup() for file systems where the
1156 * inode number is not sufficient for unique identification of an inode.
1157 *
1158 * Note: @test is called with the inode_hash_lock held, so can't sleep.
1159 */
1160struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1161        int (*test)(struct inode *, void *), void *data)
1162{
1163    struct inode *inode = ilookup5_nowait(sb, hashval, test, data);
1164
1165    if (inode)
1166        wait_on_inode(inode);
1167    return inode;
1168}
1169EXPORT_SYMBOL(ilookup5);
1170
1171/**
1172 * ilookup - search for an inode in the inode cache
1173 * @sb: super block of file system to search
1174 * @ino: inode number to search for
1175 *
1176 * Search for the inode @ino in the inode cache, and if the inode is in the
1177 * cache, the inode is returned with an incremented reference count.
1178 */
1179struct inode *ilookup(struct super_block *sb, unsigned long ino)
1180{
1181    struct hlist_head *head = inode_hashtable + hash(sb, ino);
1182    struct inode *inode;
1183
1184    spin_lock(&inode_hash_lock);
1185    inode = find_inode_fast(sb, head, ino);
1186    spin_unlock(&inode_hash_lock);
1187
1188    if (inode)
1189        wait_on_inode(inode);
1190    return inode;
1191}
1192EXPORT_SYMBOL(ilookup);
1193
1194int insert_inode_locked(struct inode *inode)
1195{
1196    struct super_block *sb = inode->i_sb;
1197    ino_t ino = inode->i_ino;
1198    struct hlist_head *head = inode_hashtable + hash(sb, ino);
1199
1200    while (1) {
1201        struct hlist_node *node;
1202        struct inode *old = NULL;
1203        spin_lock(&inode_hash_lock);
1204        hlist_for_each_entry(old, node, head, i_hash) {
1205            if (old->i_ino != ino)
1206                continue;
1207            if (old->i_sb != sb)
1208                continue;
1209            spin_lock(&old->i_lock);
1210            if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1211                spin_unlock(&old->i_lock);
1212                continue;
1213            }
1214            break;
1215        }
1216        if (likely(!node)) {
1217            spin_lock(&inode->i_lock);
1218            inode->i_state |= I_NEW;
1219            hlist_add_head(&inode->i_hash, head);
1220            spin_unlock(&inode->i_lock);
1221            spin_unlock(&inode_hash_lock);
1222            return 0;
1223        }
1224        __iget(old);
1225        spin_unlock(&old->i_lock);
1226        spin_unlock(&inode_hash_lock);
1227        wait_on_inode(old);
1228        if (unlikely(!inode_unhashed(old))) {
1229            iput(old);
1230            return -EBUSY;
1231        }
1232        iput(old);
1233    }
1234}
1235EXPORT_SYMBOL(insert_inode_locked);
1236
1237int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1238        int (*test)(struct inode *, void *), void *data)
1239{
1240    struct super_block *sb = inode->i_sb;
1241    struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1242
1243    while (1) {
1244        struct hlist_node *node;
1245        struct inode *old = NULL;
1246
1247        spin_lock(&inode_hash_lock);
1248        hlist_for_each_entry(old, node, head, i_hash) {
1249            if (old->i_sb != sb)
1250                continue;
1251            if (!test(old, data))
1252                continue;
1253            spin_lock(&old->i_lock);
1254            if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1255                spin_unlock(&old->i_lock);
1256                continue;
1257            }
1258            break;
1259        }
1260        if (likely(!node)) {
1261            spin_lock(&inode->i_lock);
1262            inode->i_state |= I_NEW;
1263            hlist_add_head(&inode->i_hash, head);
1264            spin_unlock(&inode->i_lock);
1265            spin_unlock(&inode_hash_lock);
1266            return 0;
1267        }
1268        __iget(old);
1269        spin_unlock(&old->i_lock);
1270        spin_unlock(&inode_hash_lock);
1271        wait_on_inode(old);
1272        if (unlikely(!inode_unhashed(old))) {
1273            iput(old);
1274            return -EBUSY;
1275        }
1276        iput(old);
1277    }
1278}
1279EXPORT_SYMBOL(insert_inode_locked4);
1280
1281
1282int generic_delete_inode(struct inode *inode)
1283{
1284    return 1;
1285}
1286EXPORT_SYMBOL(generic_delete_inode);
1287
1288/*
1289 * Normal UNIX filesystem behaviour: delete the
1290 * inode when the usage count drops to zero, and
1291 * i_nlink is zero.
1292 */
1293int generic_drop_inode(struct inode *inode)
1294{
1295    return !inode->i_nlink || inode_unhashed(inode);
1296}
1297EXPORT_SYMBOL_GPL(generic_drop_inode);
1298
1299/*
1300 * Called when we're dropping the last reference
1301 * to an inode.
1302 *
1303 * Call the FS "drop_inode()" function, defaulting to
1304 * the legacy UNIX filesystem behaviour. If it tells
1305 * us to evict inode, do so. Otherwise, retain inode
1306 * in cache if fs is alive, sync and evict if fs is
1307 * shutting down.
1308 */
1309static void iput_final(struct inode *inode)
1310{
1311    struct super_block *sb = inode->i_sb;
1312    const struct super_operations *op = inode->i_sb->s_op;
1313    int drop;
1314
1315    WARN_ON(inode->i_state & I_NEW);
1316
1317    if (op->drop_inode)
1318        drop = op->drop_inode(inode);
1319    else
1320        drop = generic_drop_inode(inode);
1321
1322    if (!drop && (sb->s_flags & MS_ACTIVE)) {
1323        inode->i_state |= I_REFERENCED;
1324        if (!(inode->i_state & (I_DIRTY|I_SYNC)))
1325            inode_lru_list_add(inode);
1326        spin_unlock(&inode->i_lock);
1327        return;
1328    }
1329
1330    if (!drop) {
1331        inode->i_state |= I_WILL_FREE;
1332        spin_unlock(&inode->i_lock);
1333        write_inode_now(inode, 1);
1334        spin_lock(&inode->i_lock);
1335        WARN_ON(inode->i_state & I_NEW);
1336        inode->i_state &= ~I_WILL_FREE;
1337    }
1338
1339    inode->i_state |= I_FREEING;
1340    if (!list_empty(&inode->i_lru))
1341        inode_lru_list_del(inode);
1342    spin_unlock(&inode->i_lock);
1343
1344    evict(inode);
1345}
1346
1347/**
1348 * iput - put an inode
1349 * @inode: inode to put
1350 *
1351 * Puts an inode, dropping its usage count. If the inode use count hits
1352 * zero, the inode is then freed and may also be destroyed.
1353 *
1354 * Consequently, iput() can sleep.
1355 */
1356void iput(struct inode *inode)
1357{
1358    if (inode) {
1359        BUG_ON(inode->i_state & I_CLEAR);
1360
1361        if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock))
1362            iput_final(inode);
1363    }
1364}
1365EXPORT_SYMBOL(iput);
1366
1367/**
1368 * bmap - find a block number in a file
1369 * @inode: inode of file
1370 * @block: block to find
1371 *
1372 * Returns the block number on the device holding the inode that
1373 * is the disk block number for the block of the file requested.
1374 * That is, asked for block 4 of inode 1 the function will return the
1375 * disk block relative to the disk start that holds that block of the
1376 * file.
1377 */
1378sector_t bmap(struct inode *inode, sector_t block)
1379{
1380    sector_t res = 0;
1381    if (inode->i_mapping->a_ops->bmap)
1382        res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1383    return res;
1384}
1385EXPORT_SYMBOL(bmap);
1386
1387/*
1388 * With relative atime, only update atime if the previous atime is
1389 * earlier than either the ctime or mtime or if at least a day has
1390 * passed since the last atime update.
1391 */
1392static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1393                 struct timespec now)
1394{
1395
1396    if (!(mnt->mnt_flags & MNT_RELATIME))
1397        return 1;
1398    /*
1399     * Is mtime younger than atime? If yes, update atime:
1400     */
1401    if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1402        return 1;
1403    /*
1404     * Is ctime younger than atime? If yes, update atime:
1405     */
1406    if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1407        return 1;
1408
1409    /*
1410     * Is the previous atime value older than a day? If yes,
1411     * update atime:
1412     */
1413    if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1414        return 1;
1415    /*
1416     * Good, we can skip the atime update:
1417     */
1418    return 0;
1419}
1420
1421/**
1422 * touch_atime - update the access time
1423 * @mnt: mount the inode is accessed on
1424 * @dentry: dentry accessed
1425 *
1426 * Update the accessed time on an inode and mark it for writeback.
1427 * This function automatically handles read only file systems and media,
1428 * as well as the "noatime" flag and inode specific "noatime" markers.
1429 */
1430void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
1431{
1432    struct inode *inode = dentry->d_inode;
1433    struct timespec now;
1434
1435    if (inode->i_flags & S_NOATIME)
1436        return;
1437    if (IS_NOATIME(inode))
1438        return;
1439    if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1440        return;
1441
1442    if (mnt->mnt_flags & MNT_NOATIME)
1443        return;
1444    if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1445        return;
1446
1447    now = current_fs_time(inode->i_sb);
1448
1449    if (!relatime_need_update(mnt, inode, now))
1450        return;
1451
1452    if (timespec_equal(&inode->i_atime, &now))
1453        return;
1454
1455    if (mnt_want_write(mnt))
1456        return;
1457
1458    inode->i_atime = now;
1459    mark_inode_dirty_sync(inode);
1460    mnt_drop_write(mnt);
1461}
1462EXPORT_SYMBOL(touch_atime);
1463
1464/**
1465 * file_update_time - update mtime and ctime time
1466 * @file: file accessed
1467 *
1468 * Update the mtime and ctime members of an inode and mark the inode
1469 * for writeback. Note that this function is meant exclusively for
1470 * usage in the file write path of filesystems, and filesystems may
1471 * choose to explicitly ignore update via this function with the
1472 * S_NOCMTIME inode flag, e.g. for network filesystem where these
1473 * timestamps are handled by the server.
1474 */
1475
1476void file_update_time(struct file *file)
1477{
1478    struct inode *inode = file->f_path.dentry->d_inode;
1479    struct timespec now;
1480    enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
1481
1482    /* First try to exhaust all avenues to not sync */
1483    if (IS_NOCMTIME(inode))
1484        return;
1485
1486    now = current_fs_time(inode->i_sb);
1487    if (!timespec_equal(&inode->i_mtime, &now))
1488        sync_it = S_MTIME;
1489
1490    if (!timespec_equal(&inode->i_ctime, &now))
1491        sync_it |= S_CTIME;
1492
1493    if (IS_I_VERSION(inode))
1494        sync_it |= S_VERSION;
1495
1496    if (!sync_it)
1497        return;
1498
1499    /* Finally allowed to write? Takes lock. */
1500    if (mnt_want_write_file(file))
1501        return;
1502
1503    /* Only change inode inside the lock region */
1504    if (sync_it & S_VERSION)
1505        inode_inc_iversion(inode);
1506    if (sync_it & S_CTIME)
1507        inode->i_ctime = now;
1508    if (sync_it & S_MTIME)
1509        inode->i_mtime = now;
1510    mark_inode_dirty_sync(inode);
1511    mnt_drop_write(file->f_path.mnt);
1512}
1513EXPORT_SYMBOL(file_update_time);
1514
1515int inode_needs_sync(struct inode *inode)
1516{
1517    if (IS_SYNC(inode))
1518        return 1;
1519    if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1520        return 1;
1521    return 0;
1522}
1523EXPORT_SYMBOL(inode_needs_sync);
1524
1525int inode_wait(void *word)
1526{
1527    schedule();
1528    return 0;
1529}
1530EXPORT_SYMBOL(inode_wait);
1531
1532/*
1533 * If we try to find an inode in the inode hash while it is being
1534 * deleted, we have to wait until the filesystem completes its
1535 * deletion before reporting that it isn't found. This function waits
1536 * until the deletion _might_ have completed. Callers are responsible
1537 * to recheck inode state.
1538 *
1539 * It doesn't matter if I_NEW is not set initially, a call to
1540 * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
1541 * will DTRT.
1542 */
1543static void __wait_on_freeing_inode(struct inode *inode)
1544{
1545    wait_queue_head_t *wq;
1546    DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
1547    wq = bit_waitqueue(&inode->i_state, __I_NEW);
1548    prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1549    spin_unlock(&inode->i_lock);
1550    spin_unlock(&inode_hash_lock);
1551    schedule();
1552    finish_wait(wq, &wait.wait);
1553    spin_lock(&inode_hash_lock);
1554}
1555
1556static __initdata unsigned long ihash_entries;
1557static int __init set_ihash_entries(char *str)
1558{
1559    if (!str)
1560        return 0;
1561    ihash_entries = simple_strtoul(str, &str, 0);
1562    return 1;
1563}
1564__setup("ihash_entries=", set_ihash_entries);
1565
1566/*
1567 * Initialize the waitqueues and inode hash table.
1568 */
1569void __init inode_init_early(void)
1570{
1571    int loop;
1572
1573    /* If hashes are distributed across NUMA nodes, defer
1574     * hash allocation until vmalloc space is available.
1575     */
1576    if (hashdist)
1577        return;
1578
1579    inode_hashtable =
1580        alloc_large_system_hash("Inode-cache",
1581                    sizeof(struct hlist_head),
1582                    ihash_entries,
1583                    14,
1584                    HASH_EARLY,
1585                    &i_hash_shift,
1586                    &i_hash_mask,
1587                    0);
1588
1589    for (loop = 0; loop < (1 << i_hash_shift); loop++)
1590        INIT_HLIST_HEAD(&inode_hashtable[loop]);
1591}
1592
1593void __init inode_init(void)
1594{
1595    int loop;
1596
1597    /* inode slab cache */
1598    inode_cachep = kmem_cache_create("inode_cache",
1599                     sizeof(struct inode),
1600                     0,
1601                     (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1602                     SLAB_MEM_SPREAD),
1603                     init_once);
1604
1605    /* Hash may have been set up in inode_init_early */
1606    if (!hashdist)
1607        return;
1608
1609    inode_hashtable =
1610        alloc_large_system_hash("Inode-cache",
1611                    sizeof(struct hlist_head),
1612                    ihash_entries,
1613                    14,
1614                    0,
1615                    &i_hash_shift,
1616                    &i_hash_mask,
1617                    0);
1618
1619    for (loop = 0; loop < (1 << i_hash_shift); loop++)
1620        INIT_HLIST_HEAD(&inode_hashtable[loop]);
1621}
1622
1623void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
1624{
1625    inode->i_mode = mode;
1626    if (S_ISCHR(mode)) {
1627        inode->i_fop = &def_chr_fops;
1628        inode->i_rdev = rdev;
1629    } else if (S_ISBLK(mode)) {
1630        inode->i_fop = &def_blk_fops;
1631        inode->i_rdev = rdev;
1632    } else if (S_ISFIFO(mode))
1633        inode->i_fop = &def_fifo_fops;
1634    else if (S_ISSOCK(mode))
1635        inode->i_fop = &bad_sock_fops;
1636    else
1637        printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
1638                  " inode %s:%lu\n", mode, inode->i_sb->s_id,
1639                  inode->i_ino);
1640}
1641EXPORT_SYMBOL(init_special_inode);
1642
1643/**
1644 * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
1645 * @inode: New inode
1646 * @dir: Directory inode
1647 * @mode: mode of the new inode
1648 */
1649void inode_init_owner(struct inode *inode, const struct inode *dir,
1650            mode_t mode)
1651{
1652    inode->i_uid = current_fsuid();
1653    if (dir && dir->i_mode & S_ISGID) {
1654        inode->i_gid = dir->i_gid;
1655        if (S_ISDIR(mode))
1656            mode |= S_ISGID;
1657    } else
1658        inode->i_gid = current_fsgid();
1659    inode->i_mode = mode;
1660}
1661EXPORT_SYMBOL(inode_init_owner);
1662
1663/**
1664 * inode_owner_or_capable - check current task permissions to inode
1665 * @inode: inode being checked
1666 *
1667 * Return true if current either has CAP_FOWNER to the inode, or
1668 * owns the file.
1669 */
1670bool inode_owner_or_capable(const struct inode *inode)
1671{
1672    struct user_namespace *ns = inode_userns(inode);
1673
1674    if (current_user_ns() == ns && current_fsuid() == inode->i_uid)
1675        return true;
1676    if (ns_capable(ns, CAP_FOWNER))
1677        return true;
1678    return false;
1679}
1680EXPORT_SYMBOL(inode_owner_or_capable);
1681

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