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(&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 inode *inode = NULL;
 802
 803repeat:
 804        hlist_for_each_entry(inode, head, i_hash) {
 805                spin_lock(&inode->i_lock);
 806                if (inode->i_sb != sb) {
 807                        spin_unlock(&inode->i_lock);
 808                        continue;
 809                }
 810                if (!test(inode, data)) {
 811                        spin_unlock(&inode->i_lock);
 812                        continue;
 813                }
 814                if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
 815                        __wait_on_freeing_inode(inode);
 816                        goto repeat;
 817                }
 818                __iget(inode);
 819                spin_unlock(&inode->i_lock);
 820                return inode;
 821        }
 822        return NULL;
 823}
 824
 825/*
 826 * find_inode_fast is the fast path version of find_inode, see the comment at
 827 * iget_locked for details.
 828 */
 829static struct inode *find_inode_fast(struct super_block *sb,
 830                                struct hlist_head *head, unsigned long ino)
 831{
 832        struct inode *inode = NULL;
 833
 834repeat:
 835        hlist_for_each_entry(inode, head, i_hash) {
 836                spin_lock(&inode->i_lock);
 837                if (inode->i_ino != ino) {
 838                        spin_unlock(&inode->i_lock);
 839                        continue;
 840                }
 841                if (inode->i_sb != sb) {
 842                        spin_unlock(&inode->i_lock);
 843                        continue;
 844                }
 845                if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
 846                        __wait_on_freeing_inode(inode);
 847                        goto repeat;
 848                }
 849                __iget(inode);
 850                spin_unlock(&inode->i_lock);
 851                return inode;
 852        }
 853        return NULL;
 854}
 855
 856/*
 857 * Each cpu owns a range of LAST_INO_BATCH numbers.
 858 * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
 859 * to renew the exhausted range.
 860 *
 861 * This does not significantly increase overflow rate because every CPU can
 862 * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
 863 * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
 864 * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
 865 * overflow rate by 2x, which does not seem too significant.
 866 *
 867 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
 868 * error if st_ino won't fit in target struct field. Use 32bit counter
 869 * here to attempt to avoid that.
 870 */
 871#define LAST_INO_BATCH 1024
 872static DEFINE_PER_CPU(unsigned int, last_ino);
 873
 874unsigned int get_next_ino(void)
 875{
 876        unsigned int *p = &get_cpu_var(last_ino);
 877        unsigned int res = *p;
 878
 879#ifdef CONFIG_SMP
 880        if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
 881                static atomic_t shared_last_ino;
 882                int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
 883
 884                res = next - LAST_INO_BATCH;
 885        }
 886#endif
 887
 888        *p = ++res;
 889        put_cpu_var(last_ino);
 890        return res;
 891}
 892EXPORT_SYMBOL(get_next_ino);
 893
 894/**
 895 *      new_inode_pseudo        - obtain an inode
 896 *      @sb: superblock
 897 *
 898 *      Allocates a new inode for given superblock.
 899 *      Inode wont be chained in superblock s_inodes list
 900 *      This means :
 901 *      - fs can't be unmount
 902 *      - quotas, fsnotify, writeback can't work
 903 */
 904struct inode *new_inode_pseudo(struct super_block *sb)
 905{
 906        struct inode *inode = alloc_inode(sb);
 907
 908        if (inode) {
 909                spin_lock(&inode->i_lock);
 910                inode->i_state = 0;
 911                spin_unlock(&inode->i_lock);
 912                INIT_LIST_HEAD(&inode->i_sb_list);
 913        }
 914        return inode;
 915}
 916
 917/**
 918 *      new_inode       - obtain an inode
 919 *      @sb: superblock
 920 *
 921 *      Allocates a new inode for given superblock. The default gfp_mask
 922 *      for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
 923 *      If HIGHMEM pages are unsuitable or it is known that pages allocated
 924 *      for the page cache are not reclaimable or migratable,
 925 *      mapping_set_gfp_mask() must be called with suitable flags on the
 926 *      newly created inode's mapping
 927 *
 928 */
 929struct inode *new_inode(struct super_block *sb)
 930{
 931        struct inode *inode;
 932
 933        spin_lock_prefetch(&inode_sb_list_lock);
 934
 935        inode = new_inode_pseudo(sb);
 936        if (inode)
 937                inode_sb_list_add(inode);
 938        return inode;
 939}
 940EXPORT_SYMBOL(new_inode);
 941
 942#ifdef CONFIG_DEBUG_LOCK_ALLOC
 943void lockdep_annotate_inode_mutex_key(struct inode *inode)
 944{
 945        if (S_ISDIR(inode->i_mode)) {
 946                struct file_system_type *type = inode->i_sb->s_type;
 947
 948                /* Set new key only if filesystem hasn't already changed it */
 949                if (lockdep_match_class(&inode->i_mutex, &type->i_mutex_key)) {
 950                        /*
 951                         * ensure nobody is actually holding i_mutex
 952                         */
 953                        mutex_destroy(&inode->i_mutex);
 954                        mutex_init(&inode->i_mutex);
 955                        lockdep_set_class(&inode->i_mutex,
 956                                          &type->i_mutex_dir_key);
 957                }
 958        }
 959}
 960EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
 961#endif
 962
 963/**
 964 * unlock_new_inode - clear the I_NEW state and wake up any waiters
 965 * @inode:      new inode to unlock
 966 *
 967 * Called when the inode is fully initialised to clear the new state of the
 968 * inode and wake up anyone waiting for the inode to finish initialisation.
 969 */
 970void unlock_new_inode(struct inode *inode)
 971{
 972        lockdep_annotate_inode_mutex_key(inode);
 973        spin_lock(&inode->i_lock);
 974        WARN_ON(!(inode->i_state & I_NEW));
 975        inode->i_state &= ~I_NEW;
 976        smp_mb();
 977        wake_up_bit(&inode->i_state, __I_NEW);
 978        spin_unlock(&inode->i_lock);
 979}
 980EXPORT_SYMBOL(unlock_new_inode);
 981
 982/**
 983 * iget5_locked - obtain an inode from a mounted file system
 984 * @sb:         super block of file system
 985 * @hashval:    hash value (usually inode number) to get
 986 * @test:       callback used for comparisons between inodes
 987 * @set:        callback used to initialize a new struct inode
 988 * @data:       opaque data pointer to pass to @test and @set
 989 *
 990 * Search for the inode specified by @hashval and @data in the inode cache,
 991 * and if present it is return it with an increased reference count. This is
 992 * a generalized version of iget_locked() for file systems where the inode
 993 * number is not sufficient for unique identification of an inode.
 994 *
 995 * If the inode is not in cache, allocate a new inode and return it locked,
 996 * hashed, and with the I_NEW flag set. The file system gets to fill it in
 997 * before unlocking it via unlock_new_inode().
 998 *
 999 * Note both @test and @set are called with the inode_hash_lock held, so can't
1000 * sleep.
1001 */
1002struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
1003                int (*test)(struct inode *, void *),
1004                int (*set)(struct inode *, void *), void *data)
1005{
1006        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1007        struct inode *inode;
1008
1009        spin_lock(&inode_hash_lock);
1010        inode = find_inode(sb, head, test, data);
1011        spin_unlock(&inode_hash_lock);
1012
1013        if (inode) {
1014                wait_on_inode(inode);
1015                return inode;
1016        }
1017
1018        inode = alloc_inode(sb);
1019        if (inode) {
1020                struct inode *old;
1021
1022                spin_lock(&inode_hash_lock);
1023                /* We released the lock, so.. */
1024                old = find_inode(sb, head, test, data);
1025                if (!old) {
1026                        if (set(inode, data))
1027                                goto set_failed;
1028
1029                        spin_lock(&inode->i_lock);
1030                        inode->i_state = I_NEW;
1031                        hlist_add_head(&inode->i_hash, head);
1032                        spin_unlock(&inode->i_lock);
1033                        inode_sb_list_add(inode);
1034                        spin_unlock(&inode_hash_lock);
1035
1036                        /* Return the locked inode with I_NEW set, the
1037                         * caller is responsible for filling in the contents
1038                         */
1039                        return inode;
1040                }
1041
1042                /*
1043                 * Uhhuh, somebody else created the same inode under
1044                 * us. Use the old inode instead of the one we just
1045                 * allocated.
1046                 */
1047                spin_unlock(&inode_hash_lock);
1048                destroy_inode(inode);
1049                inode = old;
1050                wait_on_inode(inode);
1051        }
1052        return inode;
1053
1054set_failed:
1055        spin_unlock(&inode_hash_lock);
1056        destroy_inode(inode);
1057        return NULL;
1058}
1059EXPORT_SYMBOL(iget5_locked);
1060
1061/**
1062 * iget_locked - obtain an inode from a mounted file system
1063 * @sb:         super block of file system
1064 * @ino:        inode number to get
1065 *
1066 * Search for the inode specified by @ino in the inode cache and if present
1067 * return it with an increased reference count. This is for file systems
1068 * where the inode number is sufficient for unique identification of an inode.
1069 *
1070 * If the inode is not in cache, allocate a new inode and return it locked,
1071 * hashed, and with the I_NEW flag set.  The file system gets to fill it in
1072 * before unlocking it via unlock_new_inode().
1073 */
1074struct inode *iget_locked(struct super_block *sb, unsigned long ino)
1075{
1076        struct hlist_head *head = inode_hashtable + hash(sb, ino);
1077        struct inode *inode;
1078
1079        spin_lock(&inode_hash_lock);
1080        inode = find_inode_fast(sb, head, ino);
1081        spin_unlock(&inode_hash_lock);
1082        if (inode) {
1083                wait_on_inode(inode);
1084                return inode;
1085        }
1086
1087        inode = alloc_inode(sb);
1088        if (inode) {
1089                struct inode *old;
1090
1091                spin_lock(&inode_hash_lock);
1092                /* We released the lock, so.. */
1093                old = find_inode_fast(sb, head, ino);
1094                if (!old) {
1095                        inode->i_ino = ino;
1096                        spin_lock(&inode->i_lock);
1097                        inode->i_state = I_NEW;
1098                        hlist_add_head(&inode->i_hash, head);
1099                        spin_unlock(&inode->i_lock);
1100                        inode_sb_list_add(inode);
1101                        spin_unlock(&inode_hash_lock);
1102
1103                        /* Return the locked inode with I_NEW set, the
1104                         * caller is responsible for filling in the contents
1105                         */
1106                        return inode;
1107                }
1108
1109                /*
1110                 * Uhhuh, somebody else created the same inode under
1111                 * us. Use the old inode instead of the one we just
1112                 * allocated.
1113                 */
1114                spin_unlock(&inode_hash_lock);
1115                destroy_inode(inode);
1116                inode = old;
1117                wait_on_inode(inode);
1118        }
1119        return inode;
1120}
1121EXPORT_SYMBOL(iget_locked);
1122
1123/*
1124 * search the inode cache for a matching inode number.
1125 * If we find one, then the inode number we are trying to
1126 * allocate is not unique and so we should not use it.
1127 *
1128 * Returns 1 if the inode number is unique, 0 if it is not.
1129 */
1130static int test_inode_iunique(struct super_block *sb, unsigned long ino)
1131{
1132        struct hlist_head *b = inode_hashtable + hash(sb, ino);
1133        struct inode *inode;
1134
1135        spin_lock(&inode_hash_lock);
1136        hlist_for_each_entry(inode, b, i_hash) {
1137                if (inode->i_ino == ino && inode->i_sb == sb) {
1138                        spin_unlock(&inode_hash_lock);
1139                        return 0;
1140                }
1141        }
1142        spin_unlock(&inode_hash_lock);
1143
1144        return 1;
1145}
1146
1147/**
1148 *      iunique - get a unique inode number
1149 *      @sb: superblock
1150 *      @max_reserved: highest reserved inode number
1151 *
1152 *      Obtain an inode number that is unique on the system for a given
1153 *      superblock. This is used by file systems that have no natural
1154 *      permanent inode numbering system. An inode number is returned that
1155 *      is higher than the reserved limit but unique.
1156 *
1157 *      BUGS:
1158 *      With a large number of inodes live on the file system this function
1159 *      currently becomes quite slow.
1160 */
1161ino_t iunique(struct super_block *sb, ino_t max_reserved)
1162{
1163        /*
1164         * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1165         * error if st_ino won't fit in target struct field. Use 32bit counter
1166         * here to attempt to avoid that.
1167         */
1168        static DEFINE_SPINLOCK(iunique_lock);
1169        static unsigned int counter;
1170        ino_t res;
1171
1172        spin_lock(&iunique_lock);
1173        do {
1174                if (counter <= max_reserved)
1175                        counter = max_reserved + 1;
1176                res = counter++;
1177        } while (!test_inode_iunique(sb, res));
1178        spin_unlock(&iunique_lock);
1179
1180        return res;
1181}
1182EXPORT_SYMBOL(iunique);
1183
1184struct inode *igrab(struct inode *inode)
1185{
1186        spin_lock(&inode->i_lock);
1187        if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1188                __iget(inode);
1189                spin_unlock(&inode->i_lock);
1190        } else {
1191                spin_unlock(&inode->i_lock);
1192                /*
1193                 * Handle the case where s_op->clear_inode is not been
1194                 * called yet, and somebody is calling igrab
1195                 * while the inode is getting freed.
1196                 */
1197                inode = NULL;
1198        }
1199        return inode;
1200}
1201EXPORT_SYMBOL(igrab);
1202
1203/**
1204 * ilookup5_nowait - search for an inode in the inode cache
1205 * @sb:         super block of file system to search
1206 * @hashval:    hash value (usually inode number) to search for
1207 * @test:       callback used for comparisons between inodes
1208 * @data:       opaque data pointer to pass to @test
1209 *
1210 * Search for the inode specified by @hashval and @data in the inode cache.
1211 * If the inode is in the cache, the inode is returned with an incremented
1212 * reference count.
1213 *
1214 * Note: I_NEW is not waited upon so you have to be very careful what you do
1215 * with the returned inode.  You probably should be using ilookup5() instead.
1216 *
1217 * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1218 */
1219struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
1220                int (*test)(struct inode *, void *), void *data)
1221{
1222        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1223        struct inode *inode;
1224
1225        spin_lock(&inode_hash_lock);
1226        inode = find_inode(sb, head, test, data);
1227        spin_unlock(&inode_hash_lock);
1228
1229        return inode;
1230}
1231EXPORT_SYMBOL(ilookup5_nowait);
1232
1233/**
1234 * ilookup5 - search for an inode in the inode cache
1235 * @sb:         super block of file system to search
1236 * @hashval:    hash value (usually inode number) to search for
1237 * @test:       callback used for comparisons between inodes
1238 * @data:       opaque data pointer to pass to @test
1239 *
1240 * Search for the inode specified by @hashval and @data in the inode cache,
1241 * and if the inode is in the cache, return the inode with an incremented
1242 * reference count.  Waits on I_NEW before returning the inode.
1243 * returned with an incremented reference count.
1244 *
1245 * This is a generalized version of ilookup() for file systems where the
1246 * inode number is not sufficient for unique identification of an inode.
1247 *
1248 * Note: @test is called with the inode_hash_lock held, so can't sleep.
1249 */
1250struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1251                int (*test)(struct inode *, void *), void *data)
1252{
1253        struct inode *inode = ilookup5_nowait(sb, hashval, test, data);
1254
1255        if (inode)
1256                wait_on_inode(inode);
1257        return inode;
1258}
1259EXPORT_SYMBOL(ilookup5);
1260
1261/**
1262 * ilookup - search for an inode in the inode cache
1263 * @sb:         super block of file system to search
1264 * @ino:        inode number to search for
1265 *
1266 * Search for the inode @ino in the inode cache, and if the inode is in the
1267 * cache, the inode is returned with an incremented reference count.
1268 */
1269struct inode *ilookup(struct super_block *sb, unsigned long ino)
1270{
1271        struct hlist_head *head = inode_hashtable + hash(sb, ino);
1272        struct inode *inode;
1273
1274        spin_lock(&inode_hash_lock);
1275        inode = find_inode_fast(sb, head, ino);
1276        spin_unlock(&inode_hash_lock);
1277
1278        if (inode)
1279                wait_on_inode(inode);
1280        return inode;
1281}
1282EXPORT_SYMBOL(ilookup);
1283
1284int insert_inode_locked(struct inode *inode)
1285{
1286        struct super_block *sb = inode->i_sb;
1287        ino_t ino = inode->i_ino;
1288        struct hlist_head *head = inode_hashtable + hash(sb, ino);
1289
1290        while (1) {
1291                struct inode *old = NULL;
1292                spin_lock(&inode_hash_lock);
1293                hlist_for_each_entry(old, head, i_hash) {
1294                        if (old->i_ino != ino)
1295                                continue;
1296                        if (old->i_sb != sb)
1297                                continue;
1298                        spin_lock(&old->i_lock);
1299                        if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1300                                spin_unlock(&old->i_lock);
1301                                continue;
1302                        }
1303                        break;
1304                }
1305                if (likely(!old)) {
1306                        spin_lock(&inode->i_lock);
1307                        inode->i_state |= I_NEW;
1308                        hlist_add_head(&inode->i_hash, head);
1309                        spin_unlock(&inode->i_lock);
1310                        spin_unlock(&inode_hash_lock);
1311                        return 0;
1312                }
1313                __iget(old);
1314                spin_unlock(&old->i_lock);
1315                spin_unlock(&inode_hash_lock);
1316                wait_on_inode(old);
1317                if (unlikely(!inode_unhashed(old))) {
1318                        iput(old);
1319                        return -EBUSY;
1320                }
1321                iput(old);
1322        }
1323}
1324EXPORT_SYMBOL(insert_inode_locked);
1325
1326int insert_inode_locked4(struct inode *inode, unsigned long hashval,
1327                int (*test)(struct inode *, void *), void *data)
1328{
1329        struct super_block *sb = inode->i_sb;
1330        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1331
1332        while (1) {
1333                struct inode *old = NULL;
1334
1335                spin_lock(&inode_hash_lock);
1336                hlist_for_each_entry(old, head, i_hash) {
1337                        if (old->i_sb != sb)
1338                                continue;
1339                        if (!test(old, data))
1340                                continue;
1341                        spin_lock(&old->i_lock);
1342                        if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1343                                spin_unlock(&old->i_lock);
1344                                continue;
1345                        }
1346                        break;
1347                }
1348                if (likely(!old)) {
1349                        spin_lock(&inode->i_lock);
1350                        inode->i_state |= I_NEW;
1351                        hlist_add_head(&inode->i_hash, head);
1352                        spin_unlock(&inode->i_lock);
1353                        spin_unlock(&inode_hash_lock);
1354                        return 0;
1355                }
1356                __iget(old);
1357                spin_unlock(&old->i_lock);
1358                spin_unlock(&inode_hash_lock);
1359                wait_on_inode(old);
1360                if (unlikely(!inode_unhashed(old))) {
1361                        iput(old);
1362                        return -EBUSY;
1363                }
1364                iput(old);
1365        }
1366}
1367EXPORT_SYMBOL(insert_inode_locked4);
1368
1369
1370int generic_delete_inode(struct inode *inode)
1371{
1372        return 1;
1373}
1374EXPORT_SYMBOL(generic_delete_inode);
1375
1376/*
1377 * Called when we're dropping the last reference
1378 * to an inode.
1379 *
1380 * Call the FS "drop_inode()" function, defaulting to
1381 * the legacy UNIX filesystem behaviour.  If it tells
1382 * us to evict inode, do so.  Otherwise, retain inode
1383 * in cache if fs is alive, sync and evict if fs is
1384 * shutting down.
1385 */
1386static void iput_final(struct inode *inode)
1387{
1388        struct super_block *sb = inode->i_sb;
1389        const struct super_operations *op = inode->i_sb->s_op;
1390        int drop;
1391
1392        WARN_ON(inode->i_state & I_NEW);
1393
1394        if (op->drop_inode)
1395                drop = op->drop_inode(inode);
1396        else
1397                drop = generic_drop_inode(inode);
1398
1399        if (!drop && (sb->s_flags & MS_ACTIVE)) {
1400                inode->i_state |= I_REFERENCED;
1401                inode_add_lru(inode);
1402                spin_unlock(&inode->i_lock);
1403                return;
1404        }
1405
1406        if (!drop) {
1407                inode->i_state |= I_WILL_FREE;
1408                spin_unlock(&inode->i_lock);
1409                write_inode_now(inode, 1);
1410                spin_lock(&inode->i_lock);
1411                WARN_ON(inode->i_state & I_NEW);
1412                inode->i_state &= ~I_WILL_FREE;
1413        }
1414
1415        inode->i_state |= I_FREEING;
1416        if (!list_empty(&inode->i_lru))
1417                inode_lru_list_del(inode);
1418        spin_unlock(&inode->i_lock);
1419
1420        evict(inode);
1421}
1422
1423/**
1424 *      iput    - put an inode
1425 *      @inode: inode to put
1426 *
1427 *      Puts an inode, dropping its usage count. If the inode use count hits
1428 *      zero, the inode is then freed and may also be destroyed.
1429 *
1430 *      Consequently, iput() can sleep.
1431 */
1432void iput(struct inode *inode)
1433{
1434        if (inode) {
1435                BUG_ON(inode->i_state & I_CLEAR);
1436
1437                if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock))
1438                        iput_final(inode);
1439        }
1440}
1441EXPORT_SYMBOL(iput);
1442
1443/**
1444 *      bmap    - find a block number in a file
1445 *      @inode: inode of file
1446 *      @block: block to find
1447 *
1448 *      Returns the block number on the device holding the inode that
1449 *      is the disk block number for the block of the file requested.
1450 *      That is, asked for block 4 of inode 1 the function will return the
1451 *      disk block relative to the disk start that holds that block of the
1452 *      file.
1453 */
1454sector_t bmap(struct inode *inode, sector_t block)
1455{
1456        sector_t res = 0;
1457        if (inode->i_mapping->a_ops->bmap)
1458                res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1459        return res;
1460}
1461EXPORT_SYMBOL(bmap);
1462
1463/*
1464 * With relative atime, only update atime if the previous atime is
1465 * earlier than either the ctime or mtime or if at least a day has
1466 * passed since the last atime update.
1467 */
1468static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
1469                             struct timespec now)
1470{
1471
1472        if (!(mnt->mnt_flags & MNT_RELATIME))
1473                return 1;
1474        /*
1475         * Is mtime younger than atime? If yes, update atime:
1476         */
1477        if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1478                return 1;
1479        /*
1480         * Is ctime younger than atime? If yes, update atime:
1481         */
1482        if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1483                return 1;
1484
1485        /*
1486         * Is the previous atime value older than a day? If yes,
1487         * update atime:
1488         */
1489        if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1490                return 1;
1491        /*
1492         * Good, we can skip the atime update:
1493         */
1494        return 0;
1495}
1496
1497/*
1498 * This does the actual work of updating an inodes time or version.  Must have
1499 * had called mnt_want_write() before calling this.
1500 */
1501static int update_time(struct inode *inode, struct timespec *time, int flags)
1502{
1503        if (inode->i_op->update_time)
1504                return inode->i_op->update_time(inode, time, flags);
1505
1506        if (flags & S_ATIME)
1507                inode->i_atime = *time;
1508        if (flags & S_VERSION)
1509                inode_inc_iversion(inode);
1510        if (flags & S_CTIME)
1511                inode->i_ctime = *time;
1512        if (flags & S_MTIME)
1513                inode->i_mtime = *time;
1514        mark_inode_dirty_sync(inode);
1515        return 0;
1516}
1517
1518/**
1519 *      touch_atime     -       update the access time
1520 *      @path: the &struct path to update
1521 *
1522 *      Update the accessed time on an inode and mark it for writeback.
1523 *      This function automatically handles read only file systems and media,
1524 *      as well as the "noatime" flag and inode specific "noatime" markers.
1525 */
1526void touch_atime(struct path *path)
1527{
1528        struct vfsmount *mnt = path->mnt;
1529        struct inode *inode = path->dentry->d_inode;
1530        struct timespec now;
1531
1532        if (inode->i_flags & S_NOATIME)
1533                return;
1534        if (IS_NOATIME(inode))
1535                return;
1536        if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1537                return;
1538
1539        if (mnt->mnt_flags & MNT_NOATIME)
1540                return;
1541        if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1542                return;
1543
1544        now = current_fs_time(inode->i_sb);
1545
1546        if (!relatime_need_update(mnt, inode, now))
1547                return;
1548
1549        if (timespec_equal(&inode->i_atime, &now))
1550                return;
1551
1552        if (!sb_start_write_trylock(inode->i_sb))
1553                return;
1554
1555        if (__mnt_want_write(mnt))
1556                goto skip_update;
1557        /*
1558         * File systems can error out when updating inodes if they need to
1559         * allocate new space to modify an inode (such is the case for
1560         * Btrfs), but since we touch atime while walking down the path we
1561         * really don't care if we failed to update the atime of the file,
1562         * so just ignore the return value.
1563         * We may also fail on filesystems that have the ability to make parts
1564         * of the fs read only, e.g. subvolumes in Btrfs.
1565         */
1566        update_time(inode, &now, S_ATIME);
1567        __mnt_drop_write(mnt);
1568skip_update:
1569        sb_end_write(inode->i_sb);
1570}
1571EXPORT_SYMBOL(touch_atime);
1572
1573/*
1574 * The logic we want is
1575 *
1576 *      if suid or (sgid and xgrp)
1577 *              remove privs
1578 */
1579int should_remove_suid(struct dentry *dentry)
1580{
1581        umode_t mode = dentry->d_inode->i_mode;
1582        int kill = 0;
1583
1584        /* suid always must be killed */
1585        if (unlikely(mode & S_ISUID))
1586                kill = ATTR_KILL_SUID;
1587
1588        /*
1589         * sgid without any exec bits is just a mandatory locking mark; leave
1590         * it alone.  If some exec bits are set, it's a real sgid; kill it.
1591         */
1592        if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1593                kill |= ATTR_KILL_SGID;
1594
1595        if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
1596                return kill;
1597
1598        return 0;
1599}
1600EXPORT_SYMBOL(should_remove_suid);
1601
1602static int __remove_suid(struct dentry *dentry, int kill)
1603{
1604        struct iattr newattrs;
1605
1606        newattrs.ia_valid = ATTR_FORCE | kill;
1607        return notify_change(dentry, &newattrs);
1608}
1609
1610int file_remove_suid(struct file *file)
1611{
1612        struct dentry *dentry = file->f_path.dentry;
1613        struct inode *inode = dentry->d_inode;
1614        int killsuid;
1615        int killpriv;
1616        int error = 0;
1617
1618        /* Fast path for nothing security related */
1619        if (IS_NOSEC(inode))
1620                return 0;
1621
1622        killsuid = should_remove_suid(dentry);
1623        killpriv = security_inode_need_killpriv(dentry);
1624
1625        if (killpriv < 0)
1626                return killpriv;
1627        if (killpriv)
1628                error = security_inode_killpriv(dentry);
1629        if (!error && killsuid)
1630                error = __remove_suid(dentry, killsuid);
1631        if (!error && (inode->i_sb->s_flags & MS_NOSEC))
1632                inode->i_flags |= S_NOSEC;
1633
1634        return error;
1635}
1636EXPORT_SYMBOL(file_remove_suid);
1637
1638/**
1639 *      file_update_time        -       update mtime and ctime time
1640 *      @file: file accessed
1641 *
1642 *      Update the mtime and ctime members of an inode and mark the inode
1643 *      for writeback.  Note that this function is meant exclusively for
1644 *      usage in the file write path of filesystems, and filesystems may
1645 *      choose to explicitly ignore update via this function with the
1646 *      S_NOCMTIME inode flag, e.g. for network filesystem where these
1647 *      timestamps are handled by the server.  This can return an error for
1648 *      file systems who need to allocate space in order to update an inode.
1649 */
1650
1651int file_update_time(struct file *file)
1652{
1653        struct inode *inode = file_inode(file);
1654        struct timespec now;
1655        int sync_it = 0;
1656        int ret;
1657
1658        /* First try to exhaust all avenues to not sync */
1659        if (IS_NOCMTIME(inode))
1660                return 0;
1661
1662        now = current_fs_time(inode->i_sb);
1663        if (!timespec_equal(&inode->i_mtime, &now))
1664                sync_it = S_MTIME;
1665
1666        if (!timespec_equal(&inode->i_ctime, &now))
1667                sync_it |= S_CTIME;
1668
1669        if (IS_I_VERSION(inode))
1670                sync_it |= S_VERSION;
1671
1672        if (!sync_it)
1673                return 0;
1674
1675        /* Finally allowed to write? Takes lock. */
1676        if (__mnt_want_write_file(file))
1677                return 0;
1678
1679        ret = update_time(inode, &now, sync_it);
1680        __mnt_drop_write_file(file);
1681
1682        return ret;
1683}
1684EXPORT_SYMBOL(file_update_time);
1685
1686int inode_needs_sync(struct inode *inode)
1687{
1688        if (IS_SYNC(inode))
1689                return 1;
1690        if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1691                return 1;
1692        return 0;
1693}
1694EXPORT_SYMBOL(inode_needs_sync);
1695
1696int inode_wait(void *word)
1697{
1698        schedule();
1699        return 0;
1700}
1701EXPORT_SYMBOL(inode_wait);
1702
1703/*
1704 * If we try to find an inode in the inode hash while it is being
1705 * deleted, we have to wait until the filesystem completes its
1706 * deletion before reporting that it isn't found.  This function waits
1707 * until the deletion _might_ have completed.  Callers are responsible
1708 * to recheck inode state.
1709 *
1710 * It doesn't matter if I_NEW is not set initially, a call to
1711 * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
1712 * will DTRT.
1713 */
1714static void __wait_on_freeing_inode(struct inode *inode)
1715{
1716        wait_queue_head_t *wq;
1717        DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
1718        wq = bit_waitqueue(&inode->i_state, __I_NEW);
1719        prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1720        spin_unlock(&inode->i_lock);
1721        spin_unlock(&inode_hash_lock);
1722        schedule();
1723        finish_wait(wq, &wait.wait);
1724        spin_lock(&inode_hash_lock);
1725}
1726
1727static __initdata unsigned long ihash_entries;
1728static int __init set_ihash_entries(char *str)
1729{
1730        if (!str)
1731                return 0;
1732        ihash_entries = simple_strtoul(str, &str, 0);
1733        return 1;
1734}
1735__setup("ihash_entries=", set_ihash_entries);
1736
1737/*
1738 * Initialize the waitqueues and inode hash table.
1739 */
1740void __init inode_init_early(void)
1741{
1742        unsigned int loop;
1743
1744        /* If hashes are distributed across NUMA nodes, defer
1745         * hash allocation until vmalloc space is available.
1746         */
1747        if (hashdist)
1748                return;
1749
1750        inode_hashtable =
1751                alloc_large_system_hash("Inode-cache",
1752                                        sizeof(struct hlist_head),
1753                                        ihash_entries,
1754                                        14,
1755                                        HASH_EARLY,
1756                                        &i_hash_shift,
1757                                        &i_hash_mask,
1758                                        0,
1759                                        0);
1760
1761        for (loop = 0; loop < (1U << i_hash_shift); loop++)
1762                INIT_HLIST_HEAD(&inode_hashtable[loop]);
1763}
1764
1765void __init inode_init(void)
1766{
1767        unsigned int loop;
1768
1769        /* inode slab cache */
1770        inode_cachep = kmem_cache_create("inode_cache",
1771                                         sizeof(struct inode),
1772                                         0,
1773                                         (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1774                                         SLAB_MEM_SPREAD),
1775                                         init_once);
1776
1777        /* Hash may have been set up in inode_init_early */
1778        if (!hashdist)
1779                return;
1780
1781        inode_hashtable =
1782                alloc_large_system_hash("Inode-cache",
1783                                        sizeof(struct hlist_head),
1784                                        ihash_entries,
1785                                        14,
1786                                        0,
1787                                        &i_hash_shift,
1788                                        &i_hash_mask,
1789                                        0,
1790                                        0);
1791
1792        for (loop = 0; loop < (1U << i_hash_shift); loop++)
1793                INIT_HLIST_HEAD(&inode_hashtable[loop]);
1794}
1795
1796void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
1797{
1798        inode->i_mode = mode;
1799        if (S_ISCHR(mode)) {
1800                inode->i_fop = &def_chr_fops;
1801                inode->i_rdev = rdev;
1802        } else if (S_ISBLK(mode)) {
1803                inode->i_fop = &def_blk_fops;
1804                inode->i_rdev = rdev;
1805        } else if (S_ISFIFO(mode))
1806                inode->i_fop = &pipefifo_fops;
1807        else if (S_ISSOCK(mode))
1808                inode->i_fop = &bad_sock_fops;
1809        else
1810                printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
1811                                  " inode %s:%lu\n", mode, inode->i_sb->s_id,
1812                                  inode->i_ino);
1813}
1814EXPORT_SYMBOL(init_special_inode);
1815
1816/**
1817 * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
1818 * @inode: New inode
1819 * @dir: Directory inode
1820 * @mode: mode of the new inode
1821 */
1822void inode_init_owner(struct inode *inode, const struct inode *dir,
1823                        umode_t mode)
1824{
1825        inode->i_uid = current_fsuid();
1826        if (dir && dir->i_mode & S_ISGID) {
1827                inode->i_gid = dir->i_gid;
1828                if (S_ISDIR(mode))
1829                        mode |= S_ISGID;
1830        } else
1831                inode->i_gid = current_fsgid();
1832        inode->i_mode = mode;
1833}
1834EXPORT_SYMBOL(inode_init_owner);
1835
1836/**
1837 * inode_owner_or_capable - check current task permissions to inode
1838 * @inode: inode being checked
1839 *
1840 * Return true if current either has CAP_FOWNER to the inode, or
1841 * owns the file.
1842 */
1843bool inode_owner_or_capable(const struct inode *inode)
1844{
1845        if (uid_eq(current_fsuid(), inode->i_uid))
1846                return true;
1847        if (inode_capable(inode, CAP_FOWNER))
1848                return true;
1849        return false;
1850}
1851EXPORT_SYMBOL(inode_owner_or_capable);
1852
1853/*
1854 * Direct i/o helper functions
1855 */
1856static void __inode_dio_wait(struct inode *inode)
1857{
1858        wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP);
1859        DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP);
1860
1861        do {
1862                prepare_to_wait(wq, &q.wait, TASK_UNINTERRUPTIBLE);
1863                if (atomic_read(&inode->i_dio_count))
1864                        schedule();
1865        } while (atomic_read(&inode->i_dio_count));
1866        finish_wait(wq, &q.wait);
1867}
1868
1869/**
1870 * inode_dio_wait - wait for outstanding DIO requests to finish
1871 * @inode: inode to wait for
1872 *
1873 * Waits for all pending direct I/O requests to finish so that we can
1874 * proceed with a truncate or equivalent operation.
1875 *
1876 * Must be called under a lock that serializes taking new references
1877 * to i_dio_count, usually by inode->i_mutex.
1878 */
1879void inode_dio_wait(struct inode *inode)
1880{
1881        if (atomic_read(&inode->i_dio_count))
1882                __inode_dio_wait(inode);
1883}
1884EXPORT_SYMBOL(inode_dio_wait);
1885
1886/*
1887 * inode_dio_done - signal finish of a direct I/O requests
1888 * @inode: inode the direct I/O happens on
1889 *
1890 * This is called once we've finished processing a direct I/O request,
1891 * and is used to wake up callers waiting for direct I/O to be quiesced.
1892 */
1893void inode_dio_done(struct inode *inode)
1894{
1895        if (atomic_dec_and_test(&inode->i_dio_count))
1896                wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
1897}
1898EXPORT_SYMBOL(inode_dio_done);
1899
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