linux/fs/inode.c
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   1/*
   2 * (C) 1997 Linus Torvalds
   3 * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation)
   4 */
   5#include <linux/export.h>
   6#include <linux/fs.h>
   7#include <linux/mm.h>
   8#include <linux/backing-dev.h>
   9#include <linux/hash.h>
  10#include <linux/swap.h>
  11#include <linux/security.h>
  12#include <linux/cdev.h>
  13#include <linux/bootmem.h>
  14#include <linux/fsnotify.h>
  15#include <linux/mount.h>
  16#include <linux/posix_acl.h>
  17#include <linux/prefetch.h>
  18#include <linux/buffer_head.h> /* for inode_has_buffers */
  19#include <linux/ratelimit.h>
  20#include "internal.h"
  21
  22/*
  23 * Inode locking rules:
  24 *
  25 * inode->i_lock protects:
  26 *   inode->i_state, inode->i_hash, __iget()
  27 * inode->i_sb->s_inode_lru_lock protects:
  28 *   inode->i_sb->s_inode_lru, inode->i_lru
  29 * inode_sb_list_lock protects:
  30 *   sb->s_inodes, inode->i_sb_list
  31 * bdi->wb.list_lock protects:
  32 *   bdi->wb.b_{dirty,io,more_io}, inode->i_wb_list
  33 * inode_hash_lock protects:
  34 *   inode_hashtable, inode->i_hash
  35 *
  36 * Lock ordering:
  37 *
  38 * inode_sb_list_lock
  39 *   inode->i_lock
  40 *     inode->i_sb->s_inode_lru_lock
  41 *
  42 * bdi->wb.list_lock
  43 *   inode->i_lock
  44 *
  45 * inode_hash_lock
  46 *   inode_sb_list_lock
  47 *   inode->i_lock
  48 *
  49 * iunique_lock
  50 *   inode_hash_lock
  51 */
  52
  53static unsigned int i_hash_mask __read_mostly;
  54static unsigned int i_hash_shift __read_mostly;
  55static struct hlist_head *inode_hashtable __read_mostly;
  56static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
  57
  58__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock);
  59
  60/*
  61 * Empty aops. Can be used for the cases where the user does not
  62 * define any of the address_space operations.
  63 */
  64const struct address_space_operations empty_aops = {
  65};
  66EXPORT_SYMBOL(empty_aops);
  67
  68/*
  69 * Statistics gathering..
  70 */
  71struct inodes_stat_t inodes_stat;
  72
  73static DEFINE_PER_CPU(unsigned int, nr_inodes);
  74static DEFINE_PER_CPU(unsigned int, nr_unused);
  75
  76static struct kmem_cache *inode_cachep __read_mostly;
  77
  78static int get_nr_inodes(void)
  79{
  80        int i;
  81        int sum = 0;
  82        for_each_possible_cpu(i)
  83                sum += per_cpu(nr_inodes, i);
  84        return sum < 0 ? 0 : sum;
  85}
  86
  87static inline int get_nr_inodes_unused(void)
  88{
  89        int i;
  90        int sum = 0;
  91        for_each_possible_cpu(i)
  92                sum += per_cpu(nr_unused, i);
  93        return sum < 0 ? 0 : sum;
  94}
  95
  96int get_nr_dirty_inodes(void)
  97{
  98        /* not actually dirty inodes, but a wild approximation */
  99        int nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
 100        return nr_dirty > 0 ? nr_dirty : 0;
 101}
 102
 103/*
 104 * Handle nr_inode sysctl
 105 */
 106#ifdef CONFIG_SYSCTL
 107int proc_nr_inodes(ctl_table *table, int write,
 108                   void __user *buffer, size_t *lenp, loff_t *ppos)
 109{
 110        inodes_stat.nr_inodes = get_nr_inodes();
 111        inodes_stat.nr_unused = get_nr_inodes_unused();
 112        return proc_dointvec(table, write, buffer, lenp, ppos);
 113}
 114#endif
 115
 116/**
 117 * inode_init_always - perform inode structure intialisation
 118 * @sb: superblock inode belongs to
 119 * @inode: inode to initialise
 120 *
 121 * These are initializations that need to be done on every inode
 122 * allocation as the fields are not initialised by slab allocation.
 123 */
 124int inode_init_always(struct super_block *sb, struct inode *inode)
 125{
 126        static const struct inode_operations empty_iops;
 127        static const struct file_operations empty_fops;
 128        struct address_space *const mapping = &inode->i_data;
 129
 130        inode->i_sb = sb;
 131        inode->i_blkbits = sb->s_blocksize_bits;
 132        inode->i_flags = 0;
 133        atomic_set(&inode->i_count, 1);
 134        inode->i_op = &empty_iops;
 135        inode->i_fop = &empty_fops;
 136        inode->__i_nlink = 1;
 137        inode->i_opflags = 0;
 138        i_uid_write(inode, 0);
 139        i_gid_write(inode, 0);
 140        atomic_set(&inode->i_writecount, 0);
 141        inode->i_size = 0;
 142        inode->i_blocks = 0;
 143        inode->i_bytes = 0;
 144        inode->i_generation = 0;
 145#ifdef CONFIG_QUOTA
 146        memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
 147#endif
 148        inode->i_pipe = NULL;
 149        inode->i_bdev = NULL;
 150        inode->i_cdev = NULL;
 151        inode->i_rdev = 0;
 152        inode->dirtied_when = 0;
 153
 154        if (security_inode_alloc(inode))
 155                goto out;
 156        spin_lock_init(&inode->i_lock);
 157        lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
 158
 159        mutex_init(&inode->i_mutex);
 160        lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
 161
 162        atomic_set(&inode->i_dio_count, 0);
 163
 164        mapping->a_ops = &empty_aops;
 165        mapping->host = inode;
 166        mapping->flags = 0;
 167        mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
 168        mapping->private_data = NULL;
 169        mapping->backing_dev_info = &default_backing_dev_info;
 170        mapping->writeback_index = 0;
 171
 172        /*
 173         * If the block_device provides a backing_dev_info for client
 174         * inodes then use that.  Otherwise the inode share the bdev's
 175         * backing_dev_info.
 176         */
 177        if (sb->s_bdev) {
 178                struct backing_dev_info *bdi;
 179
 180                bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
 181                mapping->backing_dev_info = bdi;
 182        }
 183        inode->i_private = NULL;
 184        inode->i_mapping = mapping;
 185        INIT_HLIST_HEAD(&inode->i_dentry);      /* buggered by rcu freeing */
 186#ifdef CONFIG_FS_POSIX_ACL
 187        inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
 188#endif
 189
 190#ifdef CONFIG_FSNOTIFY
 191        inode->i_fsnotify_mask = 0;
 192#endif
 193
 194        this_cpu_inc(nr_inodes);
 195
 196        return 0;
 197out:
 198        return -ENOMEM;
 199}
 200EXPORT_SYMBOL(inode_init_always);
 201
 202static struct inode *alloc_inode(struct super_block *sb)
 203{
 204        struct inode *inode;
 205
 206        if (sb->s_op->alloc_inode)
 207                inode = sb->s_op->alloc_inode(sb);
 208        else
 209                inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
 210
 211        if (!inode)
 212                return NULL;
 213
 214        if (unlikely(inode_init_always(sb, inode))) {
 215                if (inode->i_sb->s_op->destroy_inode)
 216                        inode->i_sb->s_op->destroy_inode(inode);
 217                else
 218                        kmem_cache_free(inode_cachep, inode);
 219                return NULL;
 220        }
 221
 222        return inode;
 223}
 224
 225void free_inode_nonrcu(struct inode *inode)
 226{
 227        kmem_cache_free(inode_cachep, inode);
 228}
 229EXPORT_SYMBOL(free_inode_nonrcu);
 230
 231void __destroy_inode(struct inode *inode)
 232{
 233        BUG_ON(inode_has_buffers(inode));
 234        security_inode_free(inode);
 235        fsnotify_inode_delete(inode);
 236        if (!inode->i_nlink) {
 237                WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);
 238                atomic_long_dec(&inode->i_sb->s_remove_count);
 239        }
 240
 241#ifdef CONFIG_FS_POSIX_ACL
 242        if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
 243                posix_acl_release(inode->i_acl);
 244        if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
 245                posix_acl_release(inode->i_default_acl);
 246#endif
 247        this_cpu_dec(nr_inodes);
 248}
 249EXPORT_SYMBOL(__destroy_inode);
 250
 251static void i_callback(struct rcu_head *head)
 252{
 253        struct inode *inode = container_of(head, struct inode, i_rcu);
 254        kmem_cache_free(inode_cachep, inode);
 255}
 256
 257static void destroy_inode(struct inode *inode)
 258{
 259        BUG_ON(!list_empty(&inode->i_lru));
 260        __destroy_inode(inode);
 261        if (inode->i_sb->s_op->destroy_inode)
 262                inode->i_sb->s_op->destroy_inode(inode);
 263        else
 264                call_rcu(&inode->i_rcu, i_callback);
 265}
 266
 267/**
 268 * drop_nlink - directly drop an inode's link count
 269 * @inode: inode
 270 *
 271 * This is a low-level filesystem helper to replace any
 272 * direct filesystem manipulation of i_nlink.  In cases
 273 * where we are attempting to track writes to the
 274 * filesystem, a decrement to zero means an imminent
 275 * write when the file is truncated and actually unlinked
 276 * on the filesystem.
 277 */
 278void drop_nlink(struct inode *inode)
 279{
 280        WARN_ON(inode->i_nlink == 0);
 281        inode->__i_nlink--;
 282        if (!inode->i_nlink)
 283                atomic_long_inc(&inode->i_sb->s_remove_count);
 284}
 285EXPORT_SYMBOL(drop_nlink);
 286
 287/**
 288 * clear_nlink - directly zero an inode's link count
 289 * @inode: inode
 290 *
 291 * This is a low-level filesystem helper to replace any
 292 * direct filesystem manipulation of i_nlink.  See
 293 * drop_nlink() for why we care about i_nlink hitting zero.
 294 */
 295void clear_nlink(struct inode *inode)
 296{
 297        if (inode->i_nlink) {
 298                inode->__i_nlink = 0;
 299                atomic_long_inc(&inode->i_sb->s_remove_count);
 300        }
 301}
 302EXPORT_SYMBOL(clear_nlink);
 303
 304/**
 305 * set_nlink - directly set an inode's link count
 306 * @inode: inode
 307 * @nlink: new nlink (should be non-zero)
 308 *
 309 * This is a low-level filesystem helper to replace any
 310 * direct filesystem manipulation of i_nlink.
 311 */
 312void set_nlink(struct inode *inode, unsigned int nlink)
 313{
 314        if (!nlink) {
 315                clear_nlink(inode);
 316        } else {
 317                /* Yes, some filesystems do change nlink from zero to one */
 318                if (inode->i_nlink == 0)
 319                        atomic_long_dec(&inode->i_sb->s_remove_count);
 320
 321                inode->__i_nlink = nlink;
 322        }
 323}
 324EXPORT_SYMBOL(set_nlink);
 325
 326/**
 327 * inc_nlink - directly increment an inode's link count
 328 * @inode: inode
 329 *
 330 * This is a low-level filesystem helper to replace any
 331 * direct filesystem manipulation of i_nlink.  Currently,
 332 * it is only here for parity with dec_nlink().
 333 */
 334void inc_nlink(struct inode *inode)
 335{
 336        if (WARN_ON(inode->i_nlink == 0))
 337                atomic_long_dec(&inode->i_sb->s_remove_count);
 338
 339        inode->__i_nlink++;
 340}
 341EXPORT_SYMBOL(inc_nlink);
 342
 343void address_space_init_once(struct address_space *mapping)
 344{
 345        memset(mapping, 0, sizeof(*mapping));
 346        INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
 347        spin_lock_init(&mapping->tree_lock);
 348        mutex_init(&mapping->i_mmap_mutex);
 349        INIT_LIST_HEAD(&mapping->private_list);
 350        spin_lock_init(&mapping->private_lock);
 351        mapping->i_mmap = RB_ROOT;
 352        INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
 353}
 354EXPORT_SYMBOL(address_space_init_once);
 355
 356/*
 357 * These are initializations that only need to be done
 358 * once, because the fields are idempotent across use
 359 * of the inode, so let the slab aware of that.
 360 */
 361void inode_init_once(struct inode *inode)
 362{
 363        memset(inode, 0, sizeof(*inode));
 364        INIT_HLIST_NODE(&inode->i_hash);
 365        INIT_LIST_HEAD(&inode->i_devices);
 366        INIT_LIST_HEAD(&inode->i_wb_list);
 367        INIT_LIST_HEAD(&inode->i_lru);
 368        address_space_init_once(&inode->i_data);
 369        i_size_ordered_init(inode);
 370#ifdef CONFIG_FSNOTIFY
 371        INIT_HLIST_HEAD(&inode->i_fsnotify_marks);
 372#endif
 373}
 374EXPORT_SYMBOL(inode_init_once);
 375
 376static void init_once(void *foo)
 377{
 378        struct inode *inode = (struct inode *) foo;
 379
 380        inode_init_once(inode);
 381}
 382
 383/*
 384 * inode->i_lock must be held
 385 */
 386void __iget(struct inode *inode)
 387{
 388        atomic_inc(&inode->i_count);
 389}
 390
 391/*
 392 * get additional reference to inode; caller must already hold one.
 393 */
 394void ihold(struct inode *inode)
 395{
 396        WARN_ON(atomic_inc_return(&inode->i_count) < 2);
 397}
 398EXPORT_SYMBOL(ihold);
 399
 400static void inode_lru_list_add(struct inode *inode)
 401{
 402        spin_lock(&inode->i_sb->s_inode_lru_lock);
 403        if (list_empty(&inode->i_lru)) {
 404                list_add(&inode->i_lru, &inode->i_sb->s_inode_lru);
 405                inode->i_sb->s_nr_inodes_unused++;
 406                this_cpu_inc(nr_unused);
 407        }
 408        spin_unlock(&inode->i_sb->s_inode_lru_lock);
 409}
 410
 411/*
 412 * Add inode to LRU if needed (inode is unused and clean).
 413 *
 414 * Needs inode->i_lock held.
 415 */
 416void inode_add_lru(struct inode *inode)
 417{
 418        if (!(inode->i_state & (I_DIRTY | I_SYNC | I_FREEING | I_WILL_FREE)) &&
 419            !atomic_read(&inode->i_count) && inode->i_sb->s_flags & MS_ACTIVE)
 420                inode_lru_list_add(inode);
 421}
 422
 423
 424static void inode_lru_list_del(struct inode *inode)
 425{
 426        spin_lock(&inode->i_sb->s_inode_lru_lock);
 427        if (!list_empty(&inode->i_lru)) {
 428                list_del_init(&inode->i_lru);
 429                inode->i_sb->s_nr_inodes_unused--;
 430                this_cpu_dec(nr_unused);
 431        }
 432        spin_unlock(&inode->i_sb->s_inode_lru_lock);
 433}
 434
 435/**
 436 * inode_sb_list_add - add inode to the superblock list of inodes
 437 * @inode: inode to add
 438 */
 439void inode_sb_list_add(struct inode *inode)
 440{
 441        spin_lock(&inode_sb_list_lock);
 442        list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
 443        spin_unlock(&inode_sb_list_lock);
 444}
 445EXPORT_SYMBOL_GPL(inode_sb_list_add);
 446
 447static inline void inode_sb_list_del(struct inode *inode)
 448{
 449        if (!list_empty(&inode->i_sb_list)) {
 450                spin_lock(&inode_sb_list_lock);
 451                list_del_init(&inode->i_sb_list);
 452                spin_unlock(&inode_sb_list_lock);
 453        }
 454}
 455
 456static unsigned long hash(struct super_block *sb, unsigned long hashval)
 457{
 458        unsigned long tmp;
 459
 460        tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
 461                        L1_CACHE_BYTES;
 462        tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
 463        return tmp & i_hash_mask;
 464}
 465
 466/**
 467 *      __insert_inode_hash - hash an inode
 468 *      @inode: unhashed inode
 469 *      @hashval: unsigned long value used to locate this object in the
 470 *              inode_hashtable.
 471 *
 472 *      Add an inode to the inode hash for this superblock.
 473 */
 474void __insert_inode_hash(struct inode *inode, unsigned long hashval)
 475{
 476        struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
 477
 478        spin_lock(&inode_hash_lock);
 479        spin_lock(&inode->i_lock);
 480        hlist_add_head(&inode->i_hash, b);
 481        spin_unlock(&inode->i_lock);
 482        spin_unlock(&inode_hash_lock);
 483}
 484EXPORT_SYMBOL(__insert_inode_hash);
 485
 486/**
 487 *      __remove_inode_hash - remove an inode from the hash
 488 *      @inode: inode to unhash
 489 *
 490 *      Remove an inode from the superblock.
 491 */
 492void __remove_inode_hash(struct inode *inode)
 493{
 494        spin_lock(&inode_hash_lock);
 495        spin_lock(&inode->i_lock);
 496        hlist_del_init(&inode->i_hash);
 497        spin_unlock(&inode->i_lock);
 498        spin_unlock(&inode_hash_lock);
 499}
 500EXPORT_SYMBOL(__remove_inode_hash);
 501
 502void clear_inode(struct inode *inode)
 503{
 504        might_sleep();
 505        /*
 506         * We have to cycle tree_lock here because reclaim can be still in the
 507         * process of removing the last page (in __delete_from_page_cache())
 508         * and we must not free mapping under it.
 509         */
 510        spin_lock_irq(&inode->i_data.tree_lock);
 511        BUG_ON(inode->i_data.nrpages);
 512        spin_unlock_irq(&inode->i_data.tree_lock);
 513        BUG_ON(!list_empty(&inode->i_data.private_list));
 514        BUG_ON(!(inode->i_state & I_FREEING));
 515        BUG_ON(inode->i_state & I_CLEAR);
 516        /* don't need i_lock here, no concurrent mods to i_state */
 517        inode->i_state = I_FREEING | I_CLEAR;
 518}
 519EXPORT_SYMBOL(clear_inode);
 520
 521/*
 522 * Free the inode passed in, removing it from the lists it is still connected
 523 * to. We remove any pages still attached to the inode and wait for any IO that
 524 * is still in progress before finally destroying the inode.
 525 *
 526 * An inode must already be marked I_FREEING so that we avoid the inode being
 527 * moved back onto lists if we race with other code that manipulates the lists
 528 * (e.g. writeback_single_inode). The caller is responsible for setting this.
 529 *
 530 * An inode must already be removed from the LRU list before being evicted from
 531 * the cache. This should occur atomically with setting the I_FREEING state
 532 * flag, so no inodes here should ever be on the LRU when being evicted.
 533 */
 534static void evict(struct inode *inode)
 535{
 536        const struct super_operations *op = inode->i_sb->s_op;
 537
 538        BUG_ON(!(inode->i_state & I_FREEING));
 539        BUG_ON(!list_empty(&inode->i_lru));
 540
 541        if (!list_empty(&inode->i_wb_list))
 542                inode_wb_list_del(inode);
 543
 544        inode_sb_list_del(inode);
 545
 546        /*
 547         * Wait for flusher thread to be done with the inode so that filesystem
 548         * does not start destroying it while writeback is still running. Since
 549         * the inode has I_FREEING set, flusher thread won't start new work on
 550         * the inode.  We just have to wait for running writeback to finish.
 551         */
 552        inode_wait_for_writeback(inode);
 553
 554        if (op->evict_inode) {
 555                op->evict_inode(inode);
 556        } else {
 557                if (inode->i_data.nrpages)
 558                        truncate_inode_pages(&inode->i_data, 0);
 559                clear_inode(inode);
 560        }
 561        if (S_ISBLK(inode->i_mode) && inode->i_bdev)
 562                bd_forget(inode);
 563        if (S_ISCHR(inode->i_mode) && inode->i_cdev)
 564                cd_forget(inode);
 565
 566        remove_inode_hash(inode);
 567
 568        spin_lock(&inode->i_lock);
 569        wake_up_bit(&inode->i_state, __I_NEW);
 570        BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
 571        spin_unlock(&inode->i_lock);
 572
 573        destroy_inode(inode);
 574}
 575
 576/*
 577 * dispose_list - dispose of the contents of a local list
 578 * @head: the head of the list to free
 579 *
 580 * Dispose-list gets a local list with local inodes in it, so it doesn't
 581 * need to worry about list corruption and SMP locks.
 582 */
 583static void dispose_list(struct list_head *head)
 584{
 585        while (!list_empty(head)) {
 586                struct inode *inode;
 587
 588                inode = list_first_entry(head, struct inode, i_lru);
 589                list_del_init(&inode->i_lru);
 590
 591                evict(inode);
 592        }
 593}
 594
 595/**
 596 * evict_inodes - evict all evictable inodes for a superblock
 597 * @sb:         superblock to operate on
 598 *
 599 * Make sure that no inodes with zero refcount are retained.  This is
 600 * called by superblock shutdown after having MS_ACTIVE flag removed,
 601 * so any inode reaching zero refcount during or after that call will
 602 * be immediately evicted.
 603 */
 604void evict_inodes(struct super_block *sb)
 605{
 606        struct inode *inode, *next;
 607        LIST_HEAD(dispose);
 608
 609        spin_lock(&inode_sb_list_lock);
 610        list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
 611                if (atomic_read(&inode->i_count))
 612                        continue;
 613
 614                spin_lock(&inode->i_lock);
 615                if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
 616                        spin_unlock(&inode->i_lock);
 617                        continue;
 618                }
 619
 620                inode->i_state |= I_FREEING;
 621                inode_lru_list_del(inode);
 622                spin_unlock(&inode->i_lock);
 623                list_add(&inode->i_lru, &dispose);
 624        }
 625        spin_unlock(&inode_sb_list_lock);
 626
 627        dispose_list(&dispose);
 628}
 629
 630/**
 631 * invalidate_inodes    - attempt to free all inodes on a superblock
 632 * @sb:         superblock to operate on
 633 * @kill_dirty: flag to guide handling of dirty inodes
 634 *
 635 * Attempts to free all inodes for a given superblock.  If there were any
 636 * busy inodes return a non-zero value, else zero.
 637 * If @kill_dirty is set, discard dirty inodes too, otherwise treat
 638 * them as busy.
 639 */
 640int invalidate_inodes(struct super_block *sb, bool kill_dirty)
 641{
 642        int busy = 0;
 643        struct inode *inode, *next;
 644        LIST_HEAD(dispose);
 645
 646        spin_lock(&inode_sb_list_lock);
 647        list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
 648                spin_lock(&inode->i_lock);
 649                if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
 650                        spin_unlock(&inode->i_lock);
 651                        continue;
 652                }
 653                if (inode->i_state & I_DIRTY && !kill_dirty) {
 654                        spin_unlock(&inode->i_lock);
 655                        busy = 1;
 656                        continue;
 657                }
 658                if (atomic_read(&inode->i_count)) {
 659                        spin_unlock(&inode->i_lock);
 660                        busy = 1;
 661                        continue;
 662                }
 663
 664                inode->i_state |= I_FREEING;
 665                inode_lru_list_del(inode);
 666                spin_unlock(&inode->i_lock);
 667                list_add(&inode->i_lru, &dispose);
 668        }
 669        spin_unlock(&inode_sb_list_lock);
 670
 671        dispose_list(&dispose);
 672
 673        return busy;
 674}
 675
 676static int can_unuse(struct inode *inode)
 677{
 678        if (inode->i_state & ~I_REFERENCED)
 679                return 0;
 680        if (inode_has_buffers(inode))
 681                return 0;
 682        if (atomic_read(&inode->i_count))
 683                return 0;
 684        if (inode->i_data.nrpages)
 685                return 0;
 686        return 1;
 687}
 688
 689/*
 690 * Walk the superblock inode LRU for freeable inodes and attempt to free them.
 691 * This is called from the superblock shrinker function with a number of inodes
 692 * to trim from the LRU. Inodes to be freed are moved to a temporary list and
 693 * then are freed outside inode_lock by dispose_list().
 694 *
 695 * Any inodes which are pinned purely because of attached pagecache have their
 696 * pagecache removed.  If the inode has metadata buffers attached to
 697 * mapping->private_list then try to remove them.
 698 *
 699 * If the inode has the I_REFERENCED flag set, then it means that it has been
 700 * used recently - the flag is set in iput_final(). When we encounter such an
 701 * inode, clear the flag and move it to the back of the LRU so it gets another
 702 * pass through the LRU before it gets reclaimed. This is necessary because of
 703 * the fact we are doing lazy LRU updates to minimise lock contention so the
 704 * LRU does not have strict ordering. Hence we don't want to reclaim inodes
 705 * with this flag set because they are the inodes that are out of order.
 706 */
 707void prune_icache_sb(struct super_block *sb, int nr_to_scan)
 708{
 709        LIST_HEAD(freeable);
 710        int nr_scanned;
 711        unsigned long reap = 0;
 712
 713        spin_lock(&sb->s_inode_lru_lock);
 714        for (nr_scanned = nr_to_scan; nr_scanned >= 0; nr_scanned--) {
 715                struct inode *inode;
 716
 717                if (list_empty(&sb->s_inode_lru))
 718                        break;
 719
 720                inode = list_entry(sb->s_inode_lru.prev, struct inode, i_lru);
 721
 722                /*
 723                 * we are inverting the sb->s_inode_lru_lock/inode->i_lock here,
 724                 * so use a trylock. If we fail to get the lock, just move the
 725                 * inode to the back of the list so we don't spin on it.
 726                 */
 727                if (!spin_trylock(&inode->i_lock)) {
 728                        list_move_tail(&inode->i_lru, &sb->s_inode_lru);
 729                        continue;
 730                }
 731
 732                /*
 733                 * Referenced or dirty inodes are still in use. Give them
 734                 * another pass through the LRU as we canot reclaim them now.
 735                 */
 736                if (atomic_read(&inode->i_count) ||
 737                    (inode->i_state & ~I_REFERENCED)) {
 738                        list_del_init(&inode->i_lru);
 739                        spin_unlock(&inode->i_lock);
 740                        sb->s_nr_inodes_unused--;
 741                        this_cpu_dec(nr_unused);
 742                        continue;
 743                }
 744
 745                /* recently referenced inodes get one more pass */
 746                if (inode->i_state & I_REFERENCED) {
 747                        inode->i_state &= ~I_REFERENCED;
 748                        list_move(&inode->i_lru, &sb->s_inode_lru);
 749                        spin_unlock(&inode->i_lock);
 750                        continue;
 751                }
 752                if (inode_has_buffers(inode) || inode->i_data.nrpages) {
 753                        __iget(inode);
 754                        spin_unlock(&inode->i_lock);
 755                        spin_unlock(&sb->s_inode_lru_lock);
 756                        if (remove_inode_buffers(inode))
 757                                reap += invalidate_mapping_pages(&inode->i_data,
 758                                                                0, -1);
 759                        iput(inode);
 760                        spin_lock(&sb->s_inode_lru_lock);
 761
 762                        if (inode != list_entry(sb->s_inode_lru.next,
 763                                                struct inode, i_lru))
 764                                continue;       /* wrong inode or list_empty */
 765                        /* avoid lock inversions with trylock */
 766                        if (!spin_trylock(&inode->i_lock))
 767                                continue;
 768                        if (!can_unuse(inode)) {
 769                                spin_unlock(&inode->i_lock);
 770                                continue;
 771                        }
 772                }
 773                WARN_ON(inode->i_state & I_NEW);
 774                inode->i_state |= I_FREEING;
 775                spin_unlock(&inode->i_lock);
 776
 777                list_move(&inode->i_lru, &freeable);
 778                sb->s_nr_inodes_unused--;
 779                this_cpu_dec(nr_unused);
 780        }
 781        if (current_is_kswapd())
 782                __count_vm_events(KSWAPD_INODESTEAL, reap);
 783        else
 784                __count_vm_events(PGINODESTEAL, reap);
 785        spin_unlock(&sb->s_inode_lru_lock);
 786        if (current->reclaim_state)
 787                current->reclaim_state->reclaimed_slab += reap;
 788
 789        dispose_list(&freeable);
 790}
 791
 792static void __wait_on_freeing_inode(struct inode *inode);
 793/*
 794 * Called with the inode lock held.
 795 */
 796static struct inode *find_inode(struct super_block *sb,
 797                                struct hlist_head *head,
 798                                int (*test)(struct inode *, void *),
 799                                void *data)
 800{
 801        struct hlist_node *node;
 802        struct inode *inode = NULL;
 803
 804repeat:
 805        hlist_for_each_entry(inode, node, head, i_hash) {
 806                spin_lock(&inode->i_lock);
 807                if (inode->i_sb != sb) {
 808                        spin_unlock(&inode->i_lock);
 809                        continue;
 810                }
 811                if (!test(inode, data)) {
 812                        spin_unlock(&inode->i_lock);
 813                        continue;
 814                }
 815                if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
 816                        __wait_on_freeing_inode(inode);
 817                        goto repeat;
 818                }
 819                __iget(inode);
 820                spin_unlock(&inode->i_lock);
 821                return inode;
 822        }
 823        return NULL;
 824}
 825
 826/*
 827 * find_inode_fast is the fast path version of find_inode, see the comment at
 828 * iget_locked for details.
 829 */
 830static struct inode *find_inode_fast(struct super_block *sb,
 831                                struct hlist_head *head, unsigned long ino)
 832{
 833        struct hlist_node *node;
 834        struct inode *inode = NULL;
 835
 836repeat:
 837        hlist_for_each_entry(inode, node, head, i_hash) {
 838                spin_lock(&inode->i_lock);
 839                if (inode->i_ino != ino) {
 840                        spin_unlock(&inode->i_lock);
 841                        continue;
 842                }
 843                if (inode->i_sb != sb) {
 844                        spin_unlock(&inode->i_lock);
 845                        continue;
 846                }
 847                if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
 848                        __wait_on_freeing_inode(inode);
 849                        goto repeat;
 850                }
 851                __iget(inode);
 852                spin_unlock(&inode->i_lock);
 853                return inode;
 854        }
 855        return NULL;
 856}
 857
 858/*
 859 * Each cpu owns a range of LAST_INO_BATCH numbers.
 860 * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
 861 * to renew the exhausted range.
 862 *
 863 * This does not significantly increase overflow rate because every CPU can
 864 * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
 865 * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
 866 * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
 867 * overflow rate by 2x, which does not seem too significant.
 868 *
 869 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
 870 * error if st_ino won't fit in target struct field. Use 32bit counter
 871 * here to attempt to avoid that.
 872 */
 873#define LAST_INO_BATCH 1024
 874static DEFINE_PER_CPU(unsigned int, last_ino);
 875
 876unsigned int get_next_ino(void)
 877{
 878        unsigned int *p = &get_cpu_var(last_ino);
 879        unsigned int res = *p;
 880
 881#ifdef CONFIG_SMP
 882        if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
 883                static atomic_t shared_last_ino;
 884                int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
 885
 886                res = next - LAST_INO_BATCH;
 887        }
 888#endif
 889
 890        *p = ++res;
 891        put_cpu_var(last_ino);
 892        return res;
 893}
 894EXPORT_SYMBOL(get_next_ino);
 895
 896/**
 897 *      new_inode_pseudo        - obtain an inode
 898 *      @sb: superblock
 899 *
 900 *      Allocates a new inode for given superblock.
 901 *      Inode wont be chained in superblock s_inodes list
 902 *      This means :
 903 *      - fs can't be unmount
 904 *      - quotas, fsnotify, writeback can't work
 905 */
 906struct inode *new_inode_pseudo(struct super_block *sb)
 907{
 908        struct inode *inode = alloc_inode(sb);
 909
 910        if (inode) {
 911                spin_lock(&inode->i_lock);
 912                inode->i_state = 0;
 913                spin_unlock(&inode->i_lock);
 914                INIT_LIST_HEAD(&inode->i_sb_list);
 915        }
 916        return inode;
 917}
 918
 919/**
 920 *      new_inode       - obtain an inode
 921 *      @sb: superblock
 922 *
 923 *      Allocates a new inode for given superblock. The default gfp_mask
 924 *      for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
 925 *      If HIGHMEM pages are unsuitable or it is known that pages allocated
 926 *      for the page cache are not reclaimable or migratable,
 927 *      mapping_set_gfp_mask() must be called with suitable flags on the
 928 *      newly created inode's mapping
 929 *
 930 */
 931struct inode *new_inode(struct super_block *sb)
 932{
 933        struct inode *inode;
 934
 935        spin_lock_prefetch(&inode_sb_list_lock);
 936
 937        inode = new_inode_pseudo(sb);
 938        if (inode)
 939                inode_sb_list_add(inode);
 940        return inode;
 941}
 942EXPORT_SYMBOL(new_inode);
 943
 944#ifdef CONFIG_DEBUG_LOCK_ALLOC
 945void lockdep_annotate_inode_mutex_key(struct inode *inode)
 946{
 947        if (S_ISDIR(inode->i_mode)) {
 948                struct file_system_type *type = inode->i_sb->s_type;
 949
 950                /* Set new key only if filesystem hasn't already changed it */
 951                if (lockdep_match_class(&inode->i_mutex, &type->i_mutex_key)) {
 952                        /*
 953                         * ensure nobody is actually holding i_mutex
 954                         */
 955                        mutex_destroy(&inode->i_mutex);
 956                        mutex_init(&inode->i_mutex);
 957                        lockdep_set_class(&inode->i_mutex,
 958                                          &type->i_mutex_dir_key);
 959                }
 960        }
 961}
 962EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
 963#endif
 964
 965/**
 966 * unlock_new_inode - clear the I_NEW state and wake up any waiters
 967 * @inode:      new inode to unlock
 968 *
 969 * Called when the inode is fully initialised to clear the new state of the
 970 * inode and wake up anyone waiting for the inode to finish initialisation.
 971 */
 972void unlock_new_inode(struct inode *inode)
 973{
 974        lockdep_annotate_inode_mutex_key(inode);
 975        spin_lock(&inode->i_lock);
 976        WARN_ON(!(inode->i_state & I_NEW));
 977        inode->i_state &= ~I_NEW;
 978        smp_mb();
 979        wake_up_bit(&inode->i_state, __I_NEW);
 980        spin_unlock(&inode->i_lock);
 981}
 982EXPORT_SYMBOL(unlock_new_inode);
 983
 984/**
 985 * iget5_locked - obtain an inode from a mounted file system
 986 * @sb:         super block of file system
 987 * @hashval:    hash value (usually inode number) to get
 988 * @test:       callback used for comparisons between inodes
 989 * @set:        callback used to initialize a new struct inode
 990 * @data:       opaque data pointer to pass to @test and @set
 991 *
 992 * Search for the inode specified by @hashval and @data in the inode cache,
 993 * and if present it is return it with an increased reference count. This is
 994 * a generalized version of iget_locked() for file systems where the inode
 995 * number is not sufficient for unique identification of an inode.
 996 *
 997 * If the inode is not in cache, allocate a new inode and return it locked,
 998 * hashed, and with the I_NEW flag set. The file system gets to fill it in
 999 * before unlocking it via unlock_new_inode().
1000 *
1001 * Note both @test and @set are called with the inode_hash_lock held, so can't
1002 * sleep.
1003 */
1004struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1005                int (*test)(struct inode *, void *),
1006                int (*set)(struct inode *, void *), void *data)
1007{
1008        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1009        struct inode *inode;
1010
1011        spin_lock(&inode_hash_lock);
1012        inode = find_inode(sb, head, test, data);
1013        spin_unlock(&inode_hash_lock);
1014
1015        if (inode) {
1016                wait_on_inode(inode);
1017                return inode;
1018        }
1019
1020        inode = alloc_inode(sb);
1021        if (inode) {
1022                struct inode *old;
1023
1024                spin_lock(&inode_hash_lock);
1025                /* We released the lock, so.. */
1026                old = find_inode(sb, head, test, data);
1027                if (!old) {
1028                        if (set(inode, data))
1029                                goto set_failed;
1030
1031                        spin_lock(&inode->i_lock);
1032                        inode->i_state = I_NEW;
1033                        hlist_add_head(&inode->i_hash, head);
1034                        spin_unlock(&inode->i_lock);
1035                        inode_sb_list_add(inode);
1036                        spin_unlock(&inode_hash_lock);
1037
1038                        /* Return the locked inode with I_NEW set, the
1039                         * caller is responsible for filling in the contents
1040                         */
1041                        return inode;
1042                }
1043
1044                /*
1045                 * Uhhuh, somebody else created the same inode under
1046                 * us. Use the old inode instead of the one we just
1047                 * allocated.
1048                 */
1049                spin_unlock(&inode_hash_lock);
1050                destroy_inode(inode);
1051                inode = old;
1052                wait_on_inode(inode);
1053        }
1054        return inode;
1055
1056set_failed:
1057        spin_unlock(&inode_hash_lock);
1058        destroy_inode(inode);
1059        return NULL;
1060}
1061EXPORT_SYMBOL(iget5_locked);
1062
1063/**
1064 * iget_locked - obtain an inode from a mounted file system
1065 * @sb:         super block of file system
1066 * @ino:        inode number to get
1067 *
1068 * Search for the inode specified by @ino in the inode cache and if present
1069 * return it with an increased reference count. This is for file systems
1070 * where the inode number is sufficient for unique identification of an inode.
1071 *
1072 * If the inode is not in cache, allocate a new inode and return it locked,
1073 * hashed, and with the I_NEW flag set.  The file system gets to fill it in
1074 * before unlocking it via unlock_new_inode().
1075 */
1076struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1077{
1078        struct hlist_head *head = inode_hashtable + hash(sb, ino);
1079        struct inode *inode;
1080
1081        spin_lock(&inode_hash_lock);
1082        inode = find_inode_fast(sb, head, ino);
1083        spin_unlock(&inode_hash_lock);
1084        if (inode) {
1085                wait_on_inode(inode);
1086                return inode;
1087        }
1088
1089        inode = alloc_inode(sb);
1090        if (inode) {
1091                struct inode *old;
1092
1093                spin_lock(&inode_hash_lock);
1094                /* We released the lock, so.. */
1095                old = find_inode_fast(sb, head, ino);
1096                if (!old) {
1097                        inode->i_ino = ino;
1098                        spin_lock(&inode->i_lock);
1099                        inode->i_state = I_NEW;
1100                        hlist_add_head(&inode->i_hash, head);
1101                        spin_unlock(&inode->i_lock);
1102                        inode_sb_list_add(inode);
1103                        spin_unlock(&inode_hash_lock);
1104
1105                        /* Return the locked inode with I_NEW set, the
1106                         * caller is responsible for filling in the contents
1107                         */
1108                        return inode;
1109                }
1110
1111                /*
1112                 * Uhhuh, somebody else created the same inode under
1113                 * us. Use the old inode instead of the one we just
1114                 * allocated.
1115                 */
1116                spin_unlock(&inode_hash_lock);
1117                destroy_inode(inode);
1118                inode = old;
1119                wait_on_inode(inode);
1120        }
1121        return inode;
1122}
1123EXPORT_SYMBOL(iget_locked);
1124
1125/*
1126 * search the inode cache for a matching inode number.
1127 * If we find one, then the inode number we are trying to
1128 * allocate is not unique and so we should not use it.
1129 *
1130 * Returns 1 if the inode number is unique, 0 if it is not.
1131 */
1132static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1133{
1134        struct hlist_head *b = inode_hashtable + hash(sb, ino);
1135        struct hlist_node *node;
1136        struct inode *inode;
1137
1138        spin_lock(&inode_hash_lock);
1139        hlist_for_each_entry(inode, node, b, i_hash) {
1140                if (inode->i_ino == ino && inode->i_sb == sb) {
1141                        spin_unlock(&inode_hash_lock);
1142                        return 0;
1143                }
1144        }
1145        spin_unlock(&inode_hash_lock);
1146
1147        return 1;
1148}
1149
1150/**
1151 *      iunique - get a unique inode number
1152 *      @sb: superblock
1153 *      @max_reserved: highest reserved inode number
1154 *
1155 *      Obtain an inode number that is unique on the system for a given
1156 *      superblock. This is used by file systems that have no natural
1157 *      permanent inode numbering system. An inode number is returned that
1158 *      is higher than the reserved limit but unique.
1159 *
1160 *      BUGS:
1161 *      With a large number of inodes live on the file system this function
1162 *      currently becomes quite slow.
1163 */
1164ino_t iunique(struct super_block *sb, ino_t max_reserved)
1165{
1166        /*
1167         * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1168         * error if st_ino won't fit in target struct field. Use 32bit counter
1169         * here to attempt to avoid that.
1170         */
1171        static DEFINE_SPINLOCK(iunique_lock);
1172        static unsigned int counter;
1173        ino_t res;
1174
1175        spin_lock(&iunique_lock);
1176        do {
1177                if (counter <= max_reserved)
1178                        counter = max_reserved + 1;
1179                res = counter++;
1180        } while (!test_inode_iunique(sb, res));
1181        spin_unlock(&iunique_lock);
1182
1183        return res;
1184}
1185EXPORT_SYMBOL(iunique);
1186
1187struct inode *igrab(struct inode *inode)
1188{
1189        spin_lock(&inode->i_lock);
1190        if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1191                __iget(inode);
1192                spin_unlock(&inode->i_lock);
1193        } else {
1194                spin_unlock(&inode->i_lock);
1195                /*
1196                 * Handle the case where s_op->clear_inode is not been
1197                 * called yet, and somebody is calling igrab
1198                 * while the inode is getting freed.
1199                 */
1200                inode = NULL;
1201        }
1202        return inode;
1203}
1204EXPORT_SYMBOL(igrab);
1205
1206/**
1207 * ilookup5_nowait - search for an inode in the inode cache
1208 * @sb:         super block of file system to search
1209 * @hashval:    hash value (usually inode number) to search for
1210 * @test:       callback used for comparisons between inodes
1211 * @data:       opaque data pointer to pass to @test
1212 *
1213 * Search for the inode specified by @hashval and @data in the inode cache.
1214 * If the inode is in the cache, the inode is returned with an incremented
1215 * reference count.
1216 *
1217 * Note: I_NEW is not waited upon so you have to be very careful what you do
1218 * with the returned inode.  You probably should be using ilookup5() instead.
1219 *
1220 * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1221 */
1222struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1223                int (*test)(struct inode *, void *), void *data)
1224{
1225        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1226        struct inode *inode;
1227
1228        spin_lock(&inode_hash_lock);
1229        inode = find_inode(sb, head, test, data);
1230        spin_unlock(&inode_hash_lock);
1231
1232        return inode;
1233}
1234EXPORT_SYMBOL(ilookup5_nowait);
1235
1236/**
1237 * ilookup5 - search for an inode in the inode cache
1238 * @sb:         super block of file system to search
1239 * @hashval:    hash value (usually inode number) to search for
1240 * @test:       callback used for comparisons between inodes
1241 * @data:       opaque data pointer to pass to @test
1242 *
1243 * Search for the inode specified by @hashval and @data in the inode cache,
1244 * and if the inode is in the cache, return the inode with an incremented
1245 * reference count.  Waits on I_NEW before returning the inode.
1246 * returned with an incremented reference count.
1247 *
1248 * This is a generalized version of ilookup() for file systems where the
1249 * inode number is not sufficient for unique identification of an inode.
1250 *
1251 * Note: @test is called with the inode_hash_lock held, so can't sleep.
1252 */
1253struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1254                int (*test)(struct inode *, void *), void *data)
1255{
1256        struct inode *inode = ilookup5_nowait(sb, hashval, test, data);
1257
1258        if (inode)
1259                wait_on_inode(inode);
1260        return inode;
1261}
1262EXPORT_SYMBOL(ilookup5);
1263
1264/**
1265 * ilookup - search for an inode in the inode cache
1266 * @sb:         super block of file system to search
1267 * @ino:        inode number to search for
1268 *
1269 * Search for the inode @ino in the inode cache, and if the inode is in the
1270 * cache, the inode is returned with an incremented reference count.
1271 */
1272struct inode *ilookup(struct super_block *sb, unsigned long ino)
1273{
1274        struct hlist_head *head = inode_hashtable + hash(sb, ino);
1275        struct inode *inode;
1276
1277        spin_lock(&inode_hash_lock);
1278        inode = find_inode_fast(sb, head, ino);
1279        spin_unlock(&inode_hash_lock);
1280
1281        if (inode)
1282                wait_on_inode(inode);
1283        return inode;
1284}
1285EXPORT_SYMBOL(ilookup);
1286
1287int insert_inode_locked(struct inode *inode)
1288{
1289        struct super_block *sb = inode->i_sb;
1290        ino_t ino = inode->i_ino;
1291        struct hlist_head *head = inode_hashtable + hash(sb, ino);
1292
1293        while (1) {
1294                struct hlist_node *node;
1295                struct inode *old = NULL;
1296                spin_lock(&inode_hash_lock);
1297                hlist_for_each_entry(old, node, head, i_hash) {
1298                        if (old->i_ino != ino)
1299                                continue;
1300                        if (old->i_sb != sb)
1301                                continue;
1302                        spin_lock(&old->i_lock);
1303                        if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1304                                spin_unlock(&old->i_lock);
1305                                continue;
1306                        }
1307                        break;
1308                }
1309                if (likely(!node)) {
1310                        spin_lock(&inode->i_lock);
1311                        inode->i_state |= I_NEW;
1312                        hlist_add_head(&inode->i_hash, head);
1313                        spin_unlock(&inode->i_lock);
1314                        spin_unlock(&inode_hash_lock);
1315                        return 0;
1316                }
1317                __iget(old);
1318                spin_unlock(&old->i_lock);
1319                spin_unlock(&inode_hash_lock);
1320                wait_on_inode(old);
1321                if (unlikely(!inode_unhashed(old))) {
1322                        iput(old);
1323                        return -EBUSY;
1324                }
1325                iput(old);
1326        }
1327}
1328EXPORT_SYMBOL(insert_inode_locked);
1329
1330int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1331                int (*test)(struct inode *, void *), void *data)
1332{
1333        struct super_block *sb = inode->i_sb;
1334        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1335
1336        while (1) {
1337                struct hlist_node *node;
1338                struct inode *old = NULL;
1339
1340                spin_lock(&inode_hash_lock);
1341                hlist_for_each_entry(old, node, head, i_hash) {
1342                        if (old->i_sb != sb)
1343                                continue;
1344                        if (!test(old, data))
1345                                continue;
1346                        spin_lock(&old->i_lock);
1347                        if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1348                                spin_unlock(&old->i_lock);
1349                                continue;
1350                        }
1351                        break;
1352                }
1353                if (likely(!node)) {
1354                        spin_lock(&inode->i_lock);
1355                        inode->i_state |= I_NEW;
1356                        hlist_add_head(&inode->i_hash, head);
1357                        spin_unlock(&inode->i_lock);
1358                        spin_unlock(&inode_hash_lock);
1359                        return 0;
1360                }
1361                __iget(old);
1362                spin_unlock(&old->i_lock);
1363                spin_unlock(&inode_hash_lock);
1364                wait_on_inode(old);
1365                if (unlikely(!inode_unhashed(old))) {
1366                        iput(old);
1367                        return -EBUSY;
1368                }
1369                iput(old);
1370        }
1371}
1372EXPORT_SYMBOL(insert_inode_locked4);
1373
1374
1375int generic_delete_inode(struct inode *inode)
1376{
1377        return 1;
1378}
1379EXPORT_SYMBOL(generic_delete_inode);
1380
1381/*
1382 * Called when we're dropping the last reference
1383 * to an inode.
1384 *
1385 * Call the FS "drop_inode()" function, defaulting to
1386 * the legacy UNIX filesystem behaviour.  If it tells
1387 * us to evict inode, do so.  Otherwise, retain inode
1388 * in cache if fs is alive, sync and evict if fs is
1389 * shutting down.
1390 */
1391static void iput_final(struct inode *inode)
1392{
1393        struct super_block *sb = inode->i_sb;
1394        const struct super_operations *op = inode->i_sb->s_op;
1395        int drop;
1396
1397        WARN_ON(inode->i_state & I_NEW);
1398
1399        if (op->drop_inode)
1400                drop = op->drop_inode(inode);
1401        else
1402                drop = generic_drop_inode(inode);
1403
1404        if (!drop && (sb->s_flags & MS_ACTIVE)) {
1405                inode->i_state |= I_REFERENCED;
1406                inode_add_lru(inode);
1407                spin_unlock(&inode->i_lock);
1408                return;
1409        }
1410
1411        if (!drop) {
1412                inode->i_state |= I_WILL_FREE;
1413                spin_unlock(&inode->i_lock);
1414                write_inode_now(inode, 1);
1415                spin_lock(&inode->i_lock);
1416                WARN_ON(inode->i_state & I_NEW);
1417                inode->i_state &= ~I_WILL_FREE;
1418        }
1419
1420        inode->i_state |= I_FREEING;
1421        if (!list_empty(&inode->i_lru))
1422                inode_lru_list_del(inode);
1423        spin_unlock(&inode->i_lock);
1424
1425        evict(inode);
1426}
1427
1428/**
1429 *      iput    - put an inode
1430 *      @inode: inode to put
1431 *
1432 *      Puts an inode, dropping its usage count. If the inode use count hits
1433 *      zero, the inode is then freed and may also be destroyed.
1434 *
1435 *      Consequently, iput() can sleep.
1436 */
1437void iput(struct inode *inode)
1438{
1439        if (inode) {
1440                BUG_ON(inode->i_state & I_CLEAR);
1441
1442                if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock))
1443                        iput_final(inode);
1444        }
1445}
1446EXPORT_SYMBOL(iput);
1447
1448/**
1449 *      bmap    - find a block number in a file
1450 *      @inode: inode of file
1451 *      @block: block to find
1452 *
1453 *      Returns the block number on the device holding the inode that
1454 *      is the disk block number for the block of the file requested.
1455 *      That is, asked for block 4 of inode 1 the function will return the
1456 *      disk block relative to the disk start that holds that block of the
1457 *      file.
1458 */
1459sector_t bmap(struct inode *inode, sector_t block)
1460{
1461        sector_t res = 0;
1462        if (inode->i_mapping->a_ops->bmap)
1463                res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1464        return res;
1465}
1466EXPORT_SYMBOL(bmap);
1467
1468/*
1469 * With relative atime, only update atime if the previous atime is
1470 * earlier than either the ctime or mtime or if at least a day has
1471 * passed since the last atime update.
1472 */
1473static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1474                             struct timespec now)
1475{
1476
1477        if (!(mnt->mnt_flags & MNT_RELATIME))
1478                return 1;
1479        /*
1480         * Is mtime younger than atime? If yes, update atime:
1481         */
1482        if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1483                return 1;
1484        /*
1485         * Is ctime younger than atime? If yes, update atime:
1486         */
1487        if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1488                return 1;
1489
1490        /*
1491         * Is the previous atime value older than a day? If yes,
1492         * update atime:
1493         */
1494        if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1495                return 1;
1496        /*
1497         * Good, we can skip the atime update:
1498         */
1499        return 0;
1500}
1501
1502/*
1503 * This does the actual work of updating an inodes time or version.  Must have
1504 * had called mnt_want_write() before calling this.
1505 */
1506static int update_time(struct inode *inode, struct timespec *time, int flags)
1507{
1508        if (inode->i_op->update_time)
1509                return inode->i_op->update_time(inode, time, flags);
1510
1511        if (flags & S_ATIME)
1512                inode->i_atime = *time;
1513        if (flags & S_VERSION)
1514                inode_inc_iversion(inode);
1515        if (flags & S_CTIME)
1516                inode->i_ctime = *time;
1517        if (flags & S_MTIME)
1518                inode->i_mtime = *time;
1519        mark_inode_dirty_sync(inode);
1520        return 0;
1521}
1522
1523/**
1524 *      touch_atime     -       update the access time
1525 *      @path: the &struct path to update
1526 *
1527 *      Update the accessed time on an inode and mark it for writeback.
1528 *      This function automatically handles read only file systems and media,
1529 *      as well as the "noatime" flag and inode specific "noatime" markers.
1530 */
1531void touch_atime(struct path *path)
1532{
1533        struct vfsmount *mnt = path->mnt;
1534        struct inode *inode = path->dentry->d_inode;
1535        struct timespec now;
1536
1537        if (inode->i_flags & S_NOATIME)
1538                return;
1539        if (IS_NOATIME(inode))
1540                return;
1541        if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1542                return;
1543
1544        if (mnt->mnt_flags & MNT_NOATIME)
1545                return;
1546        if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1547                return;
1548
1549        now = current_fs_time(inode->i_sb);
1550
1551        if (!relatime_need_update(mnt, inode, now))
1552                return;
1553
1554        if (timespec_equal(&inode->i_atime, &now))
1555                return;
1556
1557        if (!sb_start_write_trylock(inode->i_sb))
1558                return;
1559
1560        if (__mnt_want_write(mnt))
1561                goto skip_update;
1562        /*
1563         * File systems can error out when updating inodes if they need to
1564         * allocate new space to modify an inode (such is the case for
1565         * Btrfs), but since we touch atime while walking down the path we
1566         * really don't care if we failed to update the atime of the file,
1567         * so just ignore the return value.
1568         * We may also fail on filesystems that have the ability to make parts
1569         * of the fs read only, e.g. subvolumes in Btrfs.
1570         */
1571        update_time(inode, &now, S_ATIME);
1572        __mnt_drop_write(mnt);
1573skip_update:
1574        sb_end_write(inode->i_sb);
1575}
1576EXPORT_SYMBOL(touch_atime);
1577
1578/*
1579 * The logic we want is
1580 *
1581 *      if suid or (sgid and xgrp)
1582 *              remove privs
1583 */
1584int should_remove_suid(struct dentry *dentry)
1585{
1586        umode_t mode = dentry->d_inode->i_mode;
1587        int kill = 0;
1588
1589        /* suid always must be killed */
1590        if (unlikely(mode & S_ISUID))
1591                kill = ATTR_KILL_SUID;
1592
1593        /*
1594         * sgid without any exec bits is just a mandatory locking mark; leave
1595         * it alone.  If some exec bits are set, it's a real sgid; kill it.
1596         */
1597        if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1598                kill |= ATTR_KILL_SGID;
1599
1600        if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
1601                return kill;
1602
1603        return 0;
1604}
1605EXPORT_SYMBOL(should_remove_suid);
1606
1607static int __remove_suid(struct dentry *dentry, int kill)
1608{
1609        struct iattr newattrs;
1610
1611        newattrs.ia_valid = ATTR_FORCE | kill;
1612        return notify_change(dentry, &newattrs);
1613}
1614
1615int file_remove_suid(struct file *file)
1616{
1617        struct dentry *dentry = file->f_path.dentry;
1618        struct inode *inode = dentry->d_inode;
1619        int killsuid;
1620        int killpriv;
1621        int error = 0;
1622
1623        /* Fast path for nothing security related */
1624        if (IS_NOSEC(inode))
1625                return 0;
1626
1627        killsuid = should_remove_suid(dentry);
1628        killpriv = security_inode_need_killpriv(dentry);
1629
1630        if (killpriv < 0)
1631                return killpriv;
1632        if (killpriv)
1633                error = security_inode_killpriv(dentry);
1634        if (!error && killsuid)
1635                error = __remove_suid(dentry, killsuid);
1636        if (!error && (inode->i_sb->s_flags & MS_NOSEC))
1637                inode->i_flags |= S_NOSEC;
1638
1639        return error;
1640}
1641EXPORT_SYMBOL(file_remove_suid);
1642
1643/**
1644 *      file_update_time        -       update mtime and ctime time
1645 *      @file: file accessed
1646 *
1647 *      Update the mtime and ctime members of an inode and mark the inode
1648 *      for writeback.  Note that this function is meant exclusively for
1649 *      usage in the file write path of filesystems, and filesystems may
1650 *      choose to explicitly ignore update via this function with the
1651 *      S_NOCMTIME inode flag, e.g. for network filesystem where these
1652 *      timestamps are handled by the server.  This can return an error for
1653 *      file systems who need to allocate space in order to update an inode.
1654 */
1655
1656int file_update_time(struct file *file)
1657{
1658        struct inode *inode = file->f_path.dentry->d_inode;
1659        struct timespec now;
1660        int sync_it = 0;
1661        int ret;
1662
1663        /* First try to exhaust all avenues to not sync */
1664        if (IS_NOCMTIME(inode))
1665                return 0;
1666
1667        now = current_fs_time(inode->i_sb);
1668        if (!timespec_equal(&inode->i_mtime, &now))
1669                sync_it = S_MTIME;
1670
1671        if (!timespec_equal(&inode->i_ctime, &now))
1672                sync_it |= S_CTIME;
1673
1674        if (IS_I_VERSION(inode))
1675                sync_it |= S_VERSION;
1676
1677        if (!sync_it)
1678                return 0;
1679
1680        /* Finally allowed to write? Takes lock. */
1681        if (__mnt_want_write_file(file))
1682                return 0;
1683
1684        ret = update_time(inode, &now, sync_it);
1685        __mnt_drop_write_file(file);
1686
1687        return ret;
1688}
1689EXPORT_SYMBOL(file_update_time);
1690
1691int inode_needs_sync(struct inode *inode)
1692{
1693        if (IS_SYNC(inode))
1694                return 1;
1695        if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1696                return 1;
1697        return 0;
1698}
1699EXPORT_SYMBOL(inode_needs_sync);
1700
1701int inode_wait(void *word)
1702{
1703        schedule();
1704        return 0;
1705}
1706EXPORT_SYMBOL(inode_wait);
1707
1708/*
1709 * If we try to find an inode in the inode hash while it is being
1710 * deleted, we have to wait until the filesystem completes its
1711 * deletion before reporting that it isn't found.  This function waits
1712 * until the deletion _might_ have completed.  Callers are responsible
1713 * to recheck inode state.
1714 *
1715 * It doesn't matter if I_NEW is not set initially, a call to
1716 * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
1717 * will DTRT.
1718 */
1719static void __wait_on_freeing_inode(struct inode *inode)
1720{
1721        wait_queue_head_t *wq;
1722        DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
1723        wq = bit_waitqueue(&inode->i_state, __I_NEW);
1724        prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1725        spin_unlock(&inode->i_lock);
1726        spin_unlock(&inode_hash_lock);
1727        schedule();
1728        finish_wait(wq, &wait.wait);
1729        spin_lock(&inode_hash_lock);
1730}
1731
1732static __initdata unsigned long ihash_entries;
1733static int __init set_ihash_entries(char *str)
1734{
1735        if (!str)
1736                return 0;
1737        ihash_entries = simple_strtoul(str, &str, 0);
1738        return 1;
1739}
1740__setup("ihash_entries=", set_ihash_entries);
1741
1742/*
1743 * Initialize the waitqueues and inode hash table.
1744 */
1745void __init inode_init_early(void)
1746{
1747        unsigned int loop;
1748
1749        /* If hashes are distributed across NUMA nodes, defer
1750         * hash allocation until vmalloc space is available.
1751         */
1752        if (hashdist)
1753                return;
1754
1755        inode_hashtable =
1756                alloc_large_system_hash("Inode-cache",
1757                                        sizeof(struct hlist_head),
1758                                        ihash_entries,
1759                                        14,
1760                                        HASH_EARLY,
1761                                        &i_hash_shift,
1762                                        &i_hash_mask,
1763                                        0,
1764                                        0);
1765
1766        for (loop = 0; loop < (1U << i_hash_shift); loop++)
1767                INIT_HLIST_HEAD(&inode_hashtable[loop]);
1768}
1769
1770void __init inode_init(void)
1771{
1772        unsigned int loop;
1773
1774        /* inode slab cache */
1775        inode_cachep = kmem_cache_create("inode_cache",
1776                                         sizeof(struct inode),
1777                                         0,
1778                                         (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1779                                         SLAB_MEM_SPREAD),
1780                                         init_once);
1781
1782        /* Hash may have been set up in inode_init_early */
1783        if (!hashdist)
1784                return;
1785
1786        inode_hashtable =
1787                alloc_large_system_hash("Inode-cache",
1788                                        sizeof(struct hlist_head),
1789                                        ihash_entries,
1790                                        14,
1791                                        0,
1792                                        &i_hash_shift,
1793                                        &i_hash_mask,
1794                                        0,
1795                                        0);
1796
1797        for (loop = 0; loop < (1U << i_hash_shift); loop++)
1798                INIT_HLIST_HEAD(&inode_hashtable[loop]);
1799}
1800
1801void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
1802{
1803        inode->i_mode = mode;
1804        if (S_ISCHR(mode)) {
1805                inode->i_fop = &def_chr_fops;
1806                inode->i_rdev = rdev;
1807        } else if (S_ISBLK(mode)) {
1808                inode->i_fop = &def_blk_fops;
1809                inode->i_rdev = rdev;
1810        } else if (S_ISFIFO(mode))
1811                inode->i_fop = &def_fifo_fops;
1812        else if (S_ISSOCK(mode))
1813                inode->i_fop = &bad_sock_fops;
1814        else
1815                printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
1816                                  " inode %s:%lu\n", mode, inode->i_sb->s_id,
1817                                  inode->i_ino);
1818}
1819EXPORT_SYMBOL(init_special_inode);
1820
1821/**
1822 * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
1823 * @inode: New inode
1824 * @dir: Directory inode
1825 * @mode: mode of the new inode
1826 */
1827void inode_init_owner(struct inode *inode, const struct inode *dir,
1828                        umode_t mode)
1829{
1830        inode->i_uid = current_fsuid();
1831        if (dir && dir->i_mode & S_ISGID) {
1832                inode->i_gid = dir->i_gid;
1833                if (S_ISDIR(mode))
1834                        mode |= S_ISGID;
1835        } else
1836                inode->i_gid = current_fsgid();
1837        inode->i_mode = mode;
1838}
1839EXPORT_SYMBOL(inode_init_owner);
1840
1841/**
1842 * inode_owner_or_capable - check current task permissions to inode
1843 * @inode: inode being checked
1844 *
1845 * Return true if current either has CAP_FOWNER to the inode, or
1846 * owns the file.
1847 */
1848bool inode_owner_or_capable(const struct inode *inode)
1849{
1850        if (uid_eq(current_fsuid(), inode->i_uid))
1851                return true;
1852        if (inode_capable(inode, CAP_FOWNER))
1853                return true;
1854        return false;
1855}
1856EXPORT_SYMBOL(inode_owner_or_capable);
1857
1858/*
1859 * Direct i/o helper functions
1860 */
1861static void __inode_dio_wait(struct inode *inode)
1862{
1863        wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP);
1864        DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP);
1865
1866        do {
1867                prepare_to_wait(wq, &q.wait, TASK_UNINTERRUPTIBLE);
1868                if (atomic_read(&inode->i_dio_count))
1869                        schedule();
1870        } while (atomic_read(&inode->i_dio_count));
1871        finish_wait(wq, &q.wait);
1872}
1873
1874/**
1875 * inode_dio_wait - wait for outstanding DIO requests to finish
1876 * @inode: inode to wait for
1877 *
1878 * Waits for all pending direct I/O requests to finish so that we can
1879 * proceed with a truncate or equivalent operation.
1880 *
1881 * Must be called under a lock that serializes taking new references
1882 * to i_dio_count, usually by inode->i_mutex.
1883 */
1884void inode_dio_wait(struct inode *inode)
1885{
1886        if (atomic_read(&inode->i_dio_count))
1887                __inode_dio_wait(inode);
1888}
1889EXPORT_SYMBOL(inode_dio_wait);
1890
1891/*
1892 * inode_dio_done - signal finish of a direct I/O requests
1893 * @inode: inode the direct I/O happens on
1894 *
1895 * This is called once we've finished processing a direct I/O request,
1896 * and is used to wake up callers waiting for direct I/O to be quiesced.
1897 */
1898void inode_dio_done(struct inode *inode)
1899{
1900        if (atomic_dec_and_test(&inode->i_dio_count))
1901                wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
1902}
1903EXPORT_SYMBOL(inode_dio_done);
1904
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